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close this bookTeacher's Guide on Basic Environmental Health (WHO, 1999, 327 p.)
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WHO/SDE/PHE/99.5
English only
Distr: Limited

Prepared by Merri Weinger

Protection of the Human Environment
World Health Organization
Geneva
1999

This Teacher’s Guide is designed to accompany the text, Basic environmental health, by Annalee Yassi, Tord KjellstrTheo de Kok and Tee Guidotti. The Teacher’s Guide was developed to assist teachers in developing interactive, problem-oriented curricula on environmental health themes covered in the text.

Both the text and the Teacher’s Guide were prepared with the support of the United Nations Environment Programme (UNEP), the CRE (Association of European Universities), and the United Nations Educational, Scientific and Cultural Organisation (UNESCO). They form part of a series of materials produced by the former Office of Global and Integrated Environmental Health, World Health Organization, to facilitate and strengthen teaching on health and environment issues worldwide.

Acknowledgements

The former Office of Global and Integrated Environmental Health extends special thanks to Dr Annalee Yassi, from the University of Manitoba, Canada and Dr Evert Nieboer, from McMaster University in Hamilton, Ontario, Canada for their assistance in reviewing and preparing this guide. We would also like to thank the many contributors of problem-solving exercises who have been acknowledged in the text.

Merri Weinger
Education Specialist

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Prepared by Merri Weinger

Purpose of the Teacher’s Guide

This Teacher’s Guide forms part of current efforts by its sponsors (WHO, UNEP, CRE-COPERNICUS, UNESCO) to strengthen environmental health capacity and promote actions that eliminate, prevent or minimize hazards. The quality of our environment and the health effects resulting from environmental factors are of increasing concern in both developed and developing countries. The extent of these health effects is often unknown and the technology to prevent and control environmental hazards needs further development. A variety of well-trained professional groups is needed to identify and effectively address current and future problems related to environment and health.

The Basic Environmental Health text and this Teacher’s Guide are designed to facilitate and promote environmental health teaching in both university settings and in-service training courses for government agency staff, industry professionals and managers, and interested people in non-governmental organizations (NGOs) or community groups. Specific target groups in universities include students in medicine, nursing, other health professions, engineering, environmental science and management, and others needing a basic introduction to environmental health (including students in geography, urban planning, social work and environmental law). In fact, environmental health education is desirable for most professions.

How the guide is structured

The guide is designed to be used in conjunction with the Basic Environmental Health text. It includes an orientation to the recommended teaching approach and the rationale for its use, a description of selected teaching methods, guidelines for organizing a course or workshop, and sample learning activities for many of the topics presented in the text. These learning activities are based on the methods described in the guide. The description of the methods should assist teachers in adapting the exercises to meet the needs of their students.

How to use the guide

The guide can be used to develop programmes on environmental health in a variety of teaching situations and educational settings. For example, teachers can:

- develop a full semester course;
- incorporate curricula on environmental health into existing courses;
- design a short course or workshop based on sections of the book;
- produce a lunch-time or weekend seminar series.

Teaching exercises should be used to adjust the complexity of the course to the needs of individual students or the whole class. In interdisciplinary classes, for example, the teacher may require more in-depth research from students in areas of their own expertise. This allows for each student to achieve a maximum learning experience while contributing to the group. It also simulates real situations in which professionals in different disciplines are expected to understand each other while depending on each other to solve complex problems in the field.

To make teaching exercises more relevant, teachers are encouraged to adapt them to reflect national or local experience or to use local stories, investigations and issues to develop new case studies.

Participatory education

There are various ways of imparting knowledge, developing skills and attitudes, and using the educational environment to promote the social actions necessary for solving environmental health problems. This section describes a participatory approach to education and training which has been successfully applied in environmental health.

Participatory education is an approach to learning that:

- is interactive;
- is based on real-life experiences;
- incorporates dialogue between and among teachers and students;
- critically analyses the organizational and systemic causes of problems.

The goals of participatory education are not only to increase knowledge and skills but also to provide the basis for problem-solving activities after the teaching sessions have ended. Its principles follow the basic tenets of adult education theory on how to promote participation and active learning.

· Adults retain information best when they are actively involved in problem-solving exercises and hands-on learning. They remember 20% of what they hear, 40% of what they hear and see and 80% of what they hear, see and do. Education is, therefore, less effective when people passively receive information, as in a lecture or through a didactic slide presentation. Doing refers to activities such as abstracting information, making a critical appraisal or applying knowledge.

· Education is most effective when it recognizes the context in which it takes place. This should include an analysis of obstacles to applying what has been learned. For example, many of the environmental health fields rely on the collection and analysis of data on environmental impact. Yet in many countries these data are limited and difficult to obtain. A good training programme would acknowledge such data gaps, explore the reasons for their existence, identify strategies for ameliorating the problem and propose mechanisms for working with this constraint in the meantime.

The use of participatory methods should include activities that help students develop critical thinking, practice problem-solving and decision-making, and gain the confidence to take effective actions in the field. Of course, educators who have adopted this approach also recognize that participation in classroom settings alone does not necessarily result in increased student activity or improved environmental health status after training. Participatory education is best seen as one of the key components of a comprehensive prevention strategy that combines effective training with legislation, improved infrastructure and planning, and enlightened policies and procedures.

Objections to using participatory methods in the academic environment include the claim that it requires too much time, that teachers are more comfortable presenting information than developing an interactive activity, and that the students themselves may appear reluctant. Yet participatory exercises can be integrated into sessions as short as one hour and, with practice, become easy to use. Since adults learn in different ways, the use of differing learning approaches is likely to be more effective than using a single approach that may work for some but not for others. Teaching is most successful if the students have the opportunity to engage in multiple-learning modalities: to listen, look at visual aids, ask questions, simulate situations, take part in role-play, read, write, practice with equipment and discuss critical issues.

In addition to incorporating a variety of teaching methods, the instructor should try to set up a physical environment that is conducive to active participation. This means arranging participants in a circle or finding some other way to allow maximum interaction. It means using movable chairs so that the larger group can break into small groups as needed. In large lecture halls, this may be difficult; however, students can still be asked to get into pairs or subgroups of 3-5 students.

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This section provides guidelines for developing the following basic elements of a course curriculum:

1. Goals and objectives.
2. Required background.
3. Subject matter/methods.
4. Selected teaching methods.
5. Audiovisual materials.
6. Reading list, resources.
7. Timetabling.
8. Evaluation.
9. Follow-up.

1. Goals and objectives

Setting goals and objectives is an important first step in conducting any teaching session. Learning goals are the outcomes one hopes to achieve. A learning goal for a course in basic environmental health might be to increase awareness about the health effects of environmental and occupational factors. After setting goals, the next step is to break broad goal statements down into specific objectives or concrete accomplishments to be attained. Each of the chapters in the text is preceded by a list of learning objectives. For example, following a session on “Air pollution”, “participants will be able to describe the major sources of air pollution”.

While most educational programmes outline three major types of learning objective (knowledge, skills and attitudes) this programme, with its emphasis on the practical application of environmental health knowledge, also includes the development of social action skills. The four types of educational objectives are described below.

Knowledge: The information or knowledge that participants will acquire during the educational programme.

Skills: The skills or competencies that participants will develop (e.g. skills related to course content as well as “life skills”, such as information retrieval, problem-solving and communication skills).

Attitudes: The attitudes or beliefs that participants will explore. These may affect participants’ ability to put what is learned into practice.

Social action: Collective (rather than individual) actions directed towards social change. This might entail formulating public policy, implementing monitoring and surveillance programmes, organizing professional associations and promoting community education.

Examples of the four types of objectives are given below:

At the end of the workshop (e.g. on environmental health for public health professionals), participants will be able to:

Knowledge: List the adverse health effects of chemical, physical and biological risk factors.

Skills: Demonstrate the use of EPI INFO, a computer programme for epidemiological data analysis.

Attitudes: Appreciate the need to utilize scientific data on environmental health to make public health decisions.

Social action: Establish a network of environmental health professionals.

These educational objectives, expressed in terms of student competencies, will become an effective tool for managing, monitoring and evaluating the course.

2. Required background

The background knowledge required for a student to benefit from the course or workshop should be stated in a list of prerequisites. If particular background in basic sciences, epidemiology or environmental health is required, this should be stated explicitly. These prerequisites may be waived if the individual concerned is particularly eager to participate in the course and shows adequate aptitude. Additionally, some background reading may be required prior to acceptance onto the course. A pretest may be used to establish the student’s baseline level of knowledge.

3. Subject matter/teaching methods

The curriculum should provide details on what is to be taught and how it will be taught. It is important to select the appropriate methods for the chosen objectives and content areas. The teaching methods chart (see Annex 3) provides a summary of different methods and the objectives that each might fulfil. For example, lectures or information videos primarily fulfil knowledge objectives. Worksheet questionnaires or brainstorming exercises can fulfil knowledge or attitude objectives. Other more comprehensive methods, such as problem-based exercises and role-plays may be aimed at social action objectives, but they may also contain new information and present opportunities to explore attitudes. Behavioural objectives are best achieved by hands-on practice.

Sample exercises are provided for a course on “Basic environmental health” or on single topics from the text and others can be developed by using the following section on teaching methods. A curriculum which incorporates a variety of different teaching methods will be most effective and engaging for students.

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This section describes several teaching methods and provides suggestions for implementing them.

4.1 Small group exercises

The purpose of the small group is to maximize participation and allow people to use their own experiences and available resources to answer questions or solve the problems presented. Small groups can also be used to generate interest in a new topic, to discover new information and to reinforce information learned in a training session. An additional benefit is that small groups provide practice in working as part of a team. Given that environmental health problems generally require input from professionals from a variety of disciplines, the ability to communicate and work effectively in a group is essential. Several applications of small group exercises are discussed below.

4.1.1 Problem-based exercises

In problem-based exercises, students are presented with a realistic situation or case study which incorporates the problem but does not provide solutions. The method requires students to consider a problem as they would have to do in real life, to use both facts and judgement to analyse its causes, and to propose strategies to resolve it. Enough information should be provided to outline the basic problems or issues to be dealt with, but not every detail about a situation needs to be specified. People should be encouraged to improvise the details, calling on their own experience to make them realistic. Depth of coverage depends on the students’ background.

The problem or case can be offered as an example of the relevance of prior learning or as an exercise for applying information that has already been learned. For example, WHO has prepared a series of sample problems for the Global Environmental Epidemiology Network (GEENET) that can be used to teach epidemiology to environmental health professionals (Document WHO/EHG/98.1). One of these sample problems concerns an outbreak of acute illness in West Africa that is found to be due to contamination of flour with parathion, an insecticide. Students are given information about the epidemic, in the order in which incidents occurred, and are asked at each stage to interpret the data and suggest what steps should be taken next to identify the cause of the illness. Problems can often be solved by more than one approach and may result in more than one correct solution or outcome.

In some academic institutions, problem-based learning (PBL) is not simply a teaching method but the foundation for all curriculum development. In contrast to more conventional education in which subject matter is transmitted by the teacher in the form of specific disciplines (e.g. toxicology, epidemiology, biostatistics), students in a PBL curriculum learn information and develop skills by investigating and resolving problems, in small groups or individually. In contrast to the epidemiology exercise described above, problems are presented in a less structured and more open-ended way that requires students to draw from a variety of disciplines to resolve them. In the course of problem-solving, students decide themselves what information is needed, and how and where to obtain it. The teacher serves more as a facilitator or moderator. Education becomes problem-based rather than discipline-based.

In an example from Australia, students in an environmental health course were presented with a scenario of a hypothetical town, Multirad, where citizens are concerned about their potential exposure to radon. The students’ task over a 10-day period was to determine what risk to health existed due to radiation in the town and to decide on a course of action. Students had access to two tutors (an epidemiologist and a radiation physicist), a personal computer with bibliographic databases, and information on indoor radon. The radiation laboratory in the State Department of Health was another resource.

Whether problem-based exercises are the primary entry point for learning or simply incorporated into a varied curriculum, they are an effective approach for teaching subject matter and also encourage the development of valuable life skills such as critical thinking, problem-solving and decision-making.

4.1.2 Conducting small group exercises

A problem-based or other small group exercise must be not only well designed but also well administered. To ensure active participation, groups should consist of between 4-6 people. Varying group composition during the course will encourage wider sharing of experience. Specific tasks or questions should be defined to guide the small group’s work and an agreed time allotted to perform the task. Sample questions might include:

- What are the problems in the situation?
- What are the underlying causes of these problems?
- Is additional information required to fully assess the situation? If so, please describe.
- Where or to whom would you go for (more) information?
- How do you propose to resolve the problem? Who should be involved?
- What would you recommend to prevent such problems from occurring in the future?

Participants should be instructed to select a chairperson to facilitate the discussion and a recorder who will take notes and report back to the plenary session. The teacher’s role is to move among the groups to check on their progress, intervening only when necessary.

The report-back session, which should be the final stage of a small group exercise, is a time to explore what participants learned during the exercise. Rather than simply summarize what each group covered, which may be somewhat tedious, the report-back session can be used to pursue a deeper analysis and to challenge students to defend their strategy or conclusions.

4.2 Role-play

In a role-play, the situation or problem is acted out rather than just described and analysed. Role-plays are especially effective for exploring attitudes and developing interpersonal communication skills. They are also an effective means of discovering relevant information which is unlikely to emerge in more formal circumstances. Role-plays may be conducted with the entire group, followed by discussion in large or small groups. Role descriptions, either verbal or written, are given to the students playing the various roles. Players should be instructed to express their point of view, although the role-play should end without resolution. The role-play simply poses a problem. Interpretations and conclusions will emerge from the ensuing discussion. For example, WHO has incorporated a role-play into the training programme it developed for environmental control professionals in the Global Environmental Technology Network (GETNET). The role-play encourages discussion of the importance of community involvement in pollution control and prevention by staging a meeting between health agency representatives and community residents who are concerned about the health risk from an environmental exposure. Those who play the agency representatives practice their risk communication skills, while those who play residents demonstrate their understanding of community concerns. Following the role-play, the instructor leads a discussion in which students identify the problem, its causes and the different opinions expressed, culminating in potential strategies for improving communication with the community about environmental health.

4.3 Discussion starters (triggers)1

1 Adapted from: Wallerstein N and Weinger M. Health and safety education for worker empowerment. American Journal of Industrial Medicine, 22(5):619-625, 1992

This method serves to pose problems for discussion and analysis leading to action about the issues. Discussion starters are a concrete physical representation of the problem in any form: a written dialogue, a role-play, a case study, a slide, a short video. In any format, discussion starters should have the following characteristics. They should:

- represent a situation which is familiar and easily recognized by the group;

- pose one single problem so that discussion can explore the theme in depth;

- provide no solutions or answers, so that action strategies can emerge from discussion in the group;

- tackle a problem that is not overwhelming, allowing people to come up with small actions for change.

SHOWeD

See:

What do you see here?
What are the issues?

Happening:

What seems to be happening here?
What is each person saying?
How do they feel?

Our:

Does this situation seem familiar?
Is it the same as our situation or different from it?

Why:

What are the causes of this problem?

Do:

What can we do about the problem?

The discussion after presentation of the trigger follows a five-step questioning process which enables the participant to identify a problem, its root causes and an action plan. To lead the discussion, the instructor uses the acronym SHOWeD (see box).

Action steps emerge directly from the dialogue among participants.

4.4 Lectures

Lectures are used to convey a basic body of information. To be most effective, lectures should be brief and should be combined with participatory exercises that enable the students to work with and apply the information that has been presented. Some educators believe that 20 minutes is the longest period during which people can assimilate information presented in a lecture format.

A few pointers to keep in mind are itemized below:

Begin with a summary of what the lecture will cover and why it has practical relevance for the specific audience, and conclude with a similar summary.

Make the lecture relevant by using examples that are familiar to the participants e.g. current events, or situations relevant to the local context.

Make the lecture interesting by using good visual aids.

Increase active participation by inviting questions from the students and by posing questions which require the students to apply the information that is presented to their own situations.

Conclude with a brief summary of key issues.

The main guideline for lecturing is to keep the presentation short to allow time for skill-building and analytic exercises. Three tools for enhancing participation during a lecture are worksheet questionnaires, brainstorming and buzz groups.

- The worksheet questionnaire can introduce a lecture in a participatory format or serve as a catalyst for group discussion. For a lecture, the instructor would write a series of questions on the lecture’s main points. Participants would be instructed to complete the questionnaire at the beginning of the session by themselves, in pairs or small groups. If they are completely unfamiliar with the topic, they should be encouraged to guess the answers. The instructor then reviews the questionnaire, soliciting a show of hands as each potential response is read. Participants with different responses are encouraged to justify their response, which will often lead to a lively discussion. The instructor then presents the correct information and elaborates further as necessary. Participants are generally interested in learning the correct answer and will listen more attentively than if they were hearing a lecture without the worksheet.

- Brainstorming is an exercise in which students in the large group are asked to come up with as many ideas as possible on a given issue. For example, the instructor could brainstorm potential measures to prevent a specific environmental health problem. The brainstorming should be limited to 3-5 minutes. The instructor writes each idea on the flip chart or overhead transparency as it is called out. No comments are allowed on any suggestion during brainstorming. After the ideas have been listed, the instructor works with the group to evaluate and prioritize the list.

- The instructor may break the group into pairs (buzz groups) for a short period to come up with ideas on a particular issue. After these brief conversations, it is easier to return to the plenary and start a discussion on some of the ideas generated in the groups. For example, in a seminar on “Women, health and environment”, the instructor could start the session with a question such as, “Can you think of any occupational or environmental hazards which have specific implications for women?” or a statement like “Take five minutes to share your own experiences of exposure to environmental hazards”. After a brief buzz group on the question, the instructor solicits some of the ideas that were generated, lists them on a flip chart and uses them to help frame the ensuing discussion.

4.5 Discussion

A discussion, which can be either incorporated into a lecture or conducted as a separate learning activity, gives participants the opportunity to present and consider the various sides of an issue. Once a discussion has been initiated using the techniques outlined above, it must be maintained. The following tips will help you to do so.

Ask questions that encourage participants to draw on their experience to make or illustrate points. Call on people if necessary to keep things going.

If students direct questions to you, redirect them to the group. Ask if others have ideas that could address the situation.

Try to involve everyone in the discussion. If one person dominates, try shifting the discussion to another student by saying something like, “Thank you for the information. Maybe someone else would like to add something.” If necessary, stop the discussion and tell the group that you will call on only those who have not yet spoken.

If the discussion loses focus, try to summarize the points that have been made on the flip chart or break into buzz groups to summarize where the discussion stands.

4.6 Planning deck

The planning deck is an activity which involves participants in identifying and ordering the components of a task or procedure to be learned. Environmental health procedures might be steps in conducting a risk assessment or designing an epidemiological study. Participants are divided into small groups and given the task of identifying the steps in a given procedure and reaching consensus on the order of the steps. The first small group to complete the task reports and explains the procedure to the larger group. Groups with different responses can justify their positions, followed by discussion of the desired order and confirmation of the content of the procedure.

4.7 Prioritizing/planning

An effective tool for prioritizing problems is a type of brainstorming using pieces of paper instead of verbal feedback. For example, participants can be asked to rank environmental health problems in their country. In this activity, the instructor ask a question, such as, “What is the most significant environmental health problem in your country?”

Each participant writes one problem in large print on a standard sized piece of paper, using a marker. The instructor than asks for a volunteer to share his/her problem and pass the piece of paper to the front of the room where it is posted up for all to see. Following this, the instructor calls for problems with a similar theme, posting each piece of paper under the previous one to create a vertical column. A new column is created for each new theme. All sheets are posted in the column, even if they repeat the problem. Proceeding in this manner, a visual representation of the most pressing problems is created, with the longest list usually reflecting the problem of greatest concern. Following the identification phase, the instructor can initiate a discussion of each problem, barriers to resolving it and positive action steps that can be taken.

For construction of a quick plan of action, the same process can be used by asking a question such as, “What is one step environmental health professionals can take to increase the visibility of environmental health on the national agenda?” The steps generated by the group can then be evaluated and prioritized.

4.8 Student presentations

Students can be requested to prepare, either individually or in small groups, a presentation for the class. The report might include a description of an environmentally-linked health issue, a summary of studies already implemented concerning this problem, recommendations for additional studies and/or proposed interventions.

After each student’s brief presentation on the case and proposal for follow-up, time should be allotted for questions and discussion.

4.9 Learning activities outside the classroom

4.9.1 Independent study

A variety of independent projects can assist the student in developing investigation and research skills, as well as an inquisitive approach to learning and field work. For example, as part of a module on air pollution, students may be asked to identify the sources of air pollution in their city, current strategies in use to address the problem and responsible agencies. Students can also become involved in intensive study of a particular theme or problem over a period of weeks or months. Student tasks may include research, bibliographic searches, and consultation or interviews with specialists. As individuals or part of a group, students take responsibility for investigating a particular aspect of the theme and presenting it to the rest of the group in a series of classroom sessions.

4.9.2 Field visits

Structured field visits can provide students with an opportunity to apply skills and concepts learned in the classroom in a community setting. In order to focus the students’ attention on local environmental/occupational problems, field visits to local factories, polluted areas or other sites of interest could be organized. The class should be divided into subgroups of 5-6 persons. Each subgroup should be given observation questions or tasks to accomplish. A checklist may be a useful tool to guide and systematize student investigation. Sample questions or tasks might be some of the following:

At the sites observed, what are the common exposures that may cause health effects?

Identify potential methods for exposure measurement (in this case, technical students could practice using sampling equipment).

Consider potential measures for health effects.

Consider problems in designing a research or programmatic intervention.

Discuss prevention and control strategies.

At the end of the field visit, the whole group should be brought together to discuss subgroup observations, findings, recommendations and conclusions.

Field visits also offer an excellent opportunity to develop skills and practice in report writing. Following the visit, students can be asked to prepare a detailed report which addresses the questions posed above, utilizing a format provided by the instructor.

4.9.3 Community-based projects

Community-based projects can be a useful way of involving students in the practice of environmental health. Projects are particularly appropriate for advanced students who have the maturity and experience necessary for conducting independent work (under supervision). Another advantage of projects is that students must work cooperatively as a team. However, projects are also demanding in terms of staff time and require active collaboration from people and agencies outside the teaching institution. Ideally, projects should be based on a real problem, as identified by a client in the community. Hospitals, community clinics and Ministries of Health are common sites for student projects. Projects should not be ambitious as the time available is often limited and the skills of the students are still developing.

4.10 Distance learning

Distance learning has proved particularly useful for continuing education in situations where students are not able to attend classes for reasons such as distance, lack of time or lack of finances. In distance learning, knowledge is gained through individual study of learning materials that have been prepared specially for this purpose. Materials may include written texts, problem-solving exercises, self-administered examinations, audio tapes, video recordings and computer software. Performance is measured by periodic examination and meetings with representatives of the sponsoring institution. Individual study may be combined with group meetings of students, phone conferences and discussion groups using the Internet. A credential, degree or diploma is awarded upon successful completion of targeted objectives.

The advantages of distance learning include cost-effectiveness and increased student control over the pace, place, time and process of learning.

4.11 Computer-assisted learning

While computers are almost always part of distance learning, computer-assisted learning has also been integrated into the classroom setting in environmental health teaching. For example, there are computer programmes, such as EPI-INFO, a software for epidemiological analysis, which can be learned and utilized in the context of problem-solving exercises in the classroom and become an ongoing resource for the student. WHO has prepared a teaching module for GEENET based on EPI-INFO applications.

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Audiovisual aids, such as blackboard, flipchart, overhead transparencies, slides, videotapes and films are effective for communicating new knowledge and increasing student interest and understanding. Here are some tips for using three common audiovisual aids: transparencies, slides and flip charts.

5.1 The overhead projector (OHP) and transparencies

In preparing transparencies, do not overload them. Use the “seven by seven” rule; no more than seven lines of type, no more than seven words per line.

Include a title on each transparency.

Design transparencies so that they can be clearly seen by persons sitting in the back row.

Before starting a presentation, be sure the OHP (or slide projector) has been properly placed in front of the classroom and accurately focused on the projection screen.

Organize transparencies in advance and test them before starting to avoid being embarrassed by texts that are too small or inverted.

Avoid blocking the screen. Talk to the audience, not to the visual aids. Keep shoulder orientation to the audience at all times.

Using a pointer, point at the screen, not at the overhead projector when referring to items on the transparency. Standing at the projector will often block someone’s view of the screen. Hold the pointer in the hand closest to the screen.

Avoid reading the words on the transparency verbatim. Instead, use the transparency as a point of focus or summary of key points for the audience.

Turn off the OHP (or slide projector) when it is not being used to prolong the life of the bulb and to avoid distraction.

Be prepared with extra bulbs and an extension cord for both the overhead and slide projectors.

Have an alternative to the OHP (or slides) in case of equipment or power failure. Flip charts are less expensive and may be more accessible.

If possible, distribute photocopies of transparencies to students. This will enable them to focus on the discussion rather than on copying the text.

Transparencies can also be used as an alternative to the flip chart to record student input during brainstorming and discussion.

5.2 Slides

Be sure to preview slides. For packaged slide shows and videos, draft discussion questions and give participants specific viewing tasks to help maintain their attention.

Use slides as discussion starters to generate problem analysis or to provide information. Rather than lecture, ask group members to comment on what they see or to identify good or bad points in the picture.

Do not plan to show slides continually for more than 20 minutes.

5.3 Flip charts (or blackboards)

Stand to one side of the easel when writing so the audience can read what is being written.

Face the audience, rather than the easel, when speaking. Avoid writing and speaking at the same time.

Utilize the flip chart to record ideas that are generated by the group. Sheets can be posted on the wall and used as an ongoing reference. Flip charts can also be prepared in advance to accompany a presentation.

Having a visual outline of key topics or points on the flip chart helps students to listen effectively.

6. Reading list, resources

The Basic Environmental Health text can be supplemented with readily available and internationally authoritative resources (such as WHO publications) which can be listed in the curriculum documentation.

7. Timetabling

The course timetable should be included in the curriculum. There are several potential formats for teaching environmental health. For example, the book can be used to form the basis of a full semester course (e.g. 14 weeks) or its equivalent which is offered in one three-hour block per week. Other options include incorporating a topic or module within an existing course or a series of lunch-time seminars. Alternatively, a workshop based on sections of the book can be offered for a few days, or for one or two weeks, based on the target audience and objectives.

A continuing education course could also be extended over time, with sessions held once or twice a week. In such cases, a problem-solving approach to learning is helpful since the students have time between sessions to put their new knowledge and skills to the test in real work situations.

8. Evaluation

Evaluation is a continuous process which should occur throughout the course (formative evaluation) and at its conclusion (summative evaluation) to both examine the student’s progress as well as the learning process. Formative evaluation promotes student learning by optimizing the learning experience, while summative evaluation facilitates decisions about learner performance and progress in a course and the assignment of academic grades.

Evaluation is very important for several reasons. It allows the instructor to:

- receive feedback, identify problems and make appropriate mid-course adjustments;
- monitor student performance and assess whether learning objectives are met;
- improve her/his performance in future educational sessions.

Evaluation allows the student to:

- evaluate the course content as well as the instructor’s presentation skills, techniques used, facilities and course organization;

- assess and improve her/his own performance.

Formative evaluation can be accomplished using informal feedback from students at the end of each session, with more in-depth assessments half-way through the course and at its completion. Mid-course evaluation can also include assignments, tests (which incorporate a problem-solving approach) and observation of skills in the classroom (presentations, demonstrations, role-plays, etc.). Since the purpose of formative evaluation is to improve the learning experience, feedback should address the following issues: learning objectives (are they being met?); course content (level of interest, relevance and difficulty); effectiveness of teaching methods and aids; student participation; level of enthusiasm and motivation generated. It is important to emphasize that formative evaluation does not necessarily correlate with an individual’s knowledge about the course material and academic performance.

Summative evaluation often includes similar tools. Final judgements about student progress should be made on the basis of multiple assessments obtained on different occasions using a variety of methods. Students should be informed in advance of the evaluation methods which will be used and should be active participants in the process. Frequently used methods to evaluate student performance include written examinations with multiple choice questions and essay questions, projects or special assignments and oral examinations. Resources for developing evaluation approaches are available in several handbooks (see references).

Evaluation of the course and the teachers by the students is as important as examination of the students. Anonymous questionnaires are often employed for end-of-course assessments. Time should be allowed for this during the class. Students should be asked for both positive and negative feedback and for constructive suggestions as to how the course might be improved. Teachers should remember that it is impossible to meet the needs of all students; students’ comments may even be contradictory.

9. Follow-up

Monitoring the long-term impact of educational programmes is often the most difficult evaluation to undertake well. In addition to cognitive and behavioural objectives, “education for action” also measures to what extent students were able to put their learning into practice. To encourage ongoing application of learning, students can be encouraged to develop an “action plan” before the end of the course or workshop in which they outline concrete steps which they plan to carry out in the 6-12 months following the course. Follow-up activities might include: networking with local health professionals and policy-makers; involvement in ongoing activities by local groups and organizations in areas related to environment and development; participation in legislative initiatives; and pursuit of further health, social and environmental studies. Methods that have been used successfully to evaluate long-term educational impact include questionnaires or interviews six months or one year after the course has taken place, observation of skills/practice, facilitated group discussions, and examination of records (e.g. college acceptance rates, performance on standardized tests).

1. Facilities

For both courses and workshops, it is preferable to have a classroom large enough to seat all participants, preferably with a seating plan that allows face-to-face discussion. If possible, seat small groups of participants around tables facing the front of the room (horseshoe formation). There should preferably be two or three smaller rooms for group work.

2. Equipment and materials

The following equipment and materials are useful when organizing a course.

Table-top name cards at seats and participant name-tags help in facilitating introductions during workshops. A list of participants’ names, addresses and affiliations should also be distributed at the start of the programme.

To prepare material during the course or workshop for distribution to participants, a typewriter (or word-processor) and copying machine are required.

An overhead projector and/or flip chart (or blackboard) are essential to demonstrate key concepts and results of group work. With the help of a flip chart, earlier points can be referred to again if necessary since they are not erased, and important sheets can be detached and put up on the wall for easy reference. Thirty coloured markers are required for certain group activities (see action planning) as well as masking tape to post large sheets of paper on the wall.

A 35mm slide projector, slide tray and extension cord are needed.

To demonstrate computer software and give participants a chance to practice, it is useful to have at least one IBM-compatible microcomputer as well as equipment to show the computer screens to the whole group. A CD-ROM reader for the microcomputer is also helpful for demonstration of modern environmental hazard information systems.

Preparation for teaching the course or workshop

The following steps should be taken when preparing to teach the workshop:

Know your audience. As far as possible, determine who will be attending the course by collecting information such as job descriptions, educational background and experience, current level of understanding or skill in the topic to be studied, training needs and interests, problems and special concerns. This information will be useful in tailoring the course to the particular group’s needs as well as assessing whether there are potential obstacles to achieving the learning objectives. For example, the group may face certain problems that will affect how much they can apply what will be taught. Potential obstacles may be lack of materials or resources (computers, access to data, calculators) or institutional constraints (lack of support from supervisors, training issues are not a priority).

Strategies for assessing audience needs include:

- administer a pre-course questionnaire, survey or test (see sample, Annex 1);

- conduct pre-course interviews with selected participants;

- organize a focused group discussion among selected participants;

- observe workers on the job (for continuing education of professionals);

- administer a pre-course assignment, both to learn about participants’ skills and to obtain case material for the course;

- review written documents, such as academic records, test scores, recommendations, etc.

Adapt the course or training programme. Based on what you know about the participants, make any necessary changes in the programme to meet their particular needs. Identify local examples of environmental problems and potential interventions. If feasible, prepare slides or videos of these examples. Problem-solving exercises can be revised to reflect current events and real issues that participants will face.

Select the trainers (for workshops). Two instructors makes it easier to teach, more interesting for the participants, and allows for better supervision of small groups.

Make facility arrangements. Make arrangements for food and refreshments when appropriate.

Prepare resource materials and equipment. Prepare course handouts, collect resource books to be used in the classroom, as well as any sample equipment and audiovisual materials.

Send information to participants in advance. Ensure that students receive the Basic Environmental Health text or other materials that must be read in advance of a workshop. It is also useful to request written case studies from participants which illustrate success stories in environmental health management and/or unresolved challenges.

Arrange for a field visit. Identify a site where participants can observe environmental and occupational health hazards as well as effective prevention and control measures.

(introduction...)

This section of the Teacher’s Guide includes a series of learning activities which correspond to all the chapter topics. They vary in length and complexity and will therefore be useful for different audiences. The examples which follow demonstrate the general teaching approach described in Part One.

1.1. Environmental health hazards in your country

Time: 3-5 day assignment

Objectives:

If used before the teaching module, students will be able to:

1. Demonstrate their understanding of the relationship between environmental factors and health.

2. Provide examples of the interrelationship between socioeconomic and political factors, environment and health.

OR

At the end of the exercise, students will be able to:

1. List examples of environmental and occupational health hazards in specific country settings.

2. Identify environmental health hazards in everyday life.

Procedures:

1. Provide the assignment on page 24 to students at the beginning, during or at the end of teaching sessions giving the overview of Basic Environmental Health.

2. Ask for 2-3 volunteers representing different jurisdictions.

3. Each volunteer schedules a meeting outside the classroom to brief those who will play the role of the government authority.

4. In the class, those who play the role of the government representatives make a 5-10 minute presentation on the environmental health hazards in the country to the other members of the class who play the participants at an international meeting. You may choose to designate specific roles for members of the audience, such as a representative from a certain political party, someone from the business community, an investigative journalist, a representative from a national environmental group, and so on. Following the presentation, the presenter responds to questions for 15 minutes.

5. Summarize the key environmental health hazards mentioned and conclude.

Alternatives

1. Review in plenary. Use buzz groups or brainstorming to generate lists of environmental health hazards, potential health effects, and socioeconomic and political factors. Follow up with discussion.

2. Divide participants into small groups to discuss:

- common environmental health hazards, with examples from everyday life and related socioeconomic and political factors;

- where and how to find information on the subject, and where data is missing.

3. Use the “prioritizing/planning” technique (see Chapter 12.2) to identify the priority environmental health hazards in the country (or countries) represented. Proceed to discuss the social, economic and political causes of these hazards.

4. Use the “Environmental Health Hazards Overview” Exercise (see Chapter 2.1).

Materials:

Copies of the assignment, flip chart, coloured markers, masking tape. (For small group work, provide discussion questions for the group on flip chart or worksheet.)

Assignment: Environmental health hazards in your country

You have been asked to prepare a brief internal memorandum for a government representative of your country who will soon attend an international meeting regarding environmental health hazards. She wants to know the scope and dimensions of the major environmental health hazards in your jurisdiction, the patterns of illness and the extent to which hazards and illness are linked. Try to find the information you need; if the data are incomplete, explain why. At a minimum, list the factors in everyday life that you think may be causing significant disease or injury. Regardless of the quality of the data available, you must prepare a 1-2 page background paper to help prepare the trip. She wants an honest opinion about the socioeconomic and political factors involved.

1.2. Problem solving exercise: The impact of schistosomiasis haematobium on women in Cameroon1

1 Anthology on women, health and environment, 1994 (Document WHO/EHG/94.11), pp.9 - 11

Time: 2-3 hours

Objectives:

At the end of the exercise, students will be able to:

1. Identify how environmental factors such as waterborne infectious diseases affect women.

2. Use gender as a critical category to analyse and propose potential solutions to a public health problem.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4 - 6 persons). Instruct participants to identify a chairperson and a recorder.

2. Distribute the problem-solving exercise and review the participants’ tasks as well as the questions for discussion. Note that the information provided may, in some cases, be insufficient to draw adequate conclusions. Gaps in data should be noted in responses to questions 4 and 5. Once the exercise has been properly understood, allow participants to work in small groups for one hour (or more, if necessary).

3. Reconvene the groups and invite a response from the first group to the first question. Ask whether other groups have different responses. Summarize, and if necessary expand on, the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. The answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

4. Summarize the results, emphasizing key messages, and conclude the exercise.

Materials:

Problem-solving exercise (Annex 4), flip chart, coloured markers.

Exercise

In a village in Cameroon, 76% of the population is affected by schistosomiasis, with slightly more women infected than men. The disease is contracted by the passage of the parasite Schistosoma haematobium through the skin in water. The effects of the disease can include iron deficiency and anaemia if the infection reaches a level sufficient to cause loss of blood in the urine. The infection results in loss of appetite, fatigue and weakness, along with impaired ability to carry out domestic, agricultural and parental duties.

Other potential effects include genital lesions, as well as reproductive disorders which are particularly devastating for women in the community. Marriage opportunities for those affected may be diminished since potential suitors must be informed of the infection. Many believe that the infection is a venereal disease. Married women who are infected are forbidden sexual contact until they are cured and may even be evicted from the household.

Women’s infection rates are linked to their domestic and agricultural responsibilities which include collecting water, bathing children, laundering, cleaning utensils, preparing and washing foodstuffs, and farming, all of which involve regular and prolonged exposure to infected water. Inadequate sanitation and waste disposal facilities, lack of basic amenities and lack of awareness concerning sources of infection and transmission are other causal factors.

Few villagers can afford the medication needed to treat the infection. Women in particular are disinclined to seek treatment, not only because of financial limitations but also because of the social stigma associated with the disease. Its persistent recurrence fosters the belief that schistosomiasis responds neither to traditional nor western medicine. For these reasons, it is likely that urinogenital schistosomiasis infections in women are significantly underreported.

Your task is to analyse this public health problem and identify potential solutions.

1. What are the environmental issues or problems facing women in this case?

They are exposed to contaminated water, and local environmental conditions are unhygienic. Accepted behaviour, attitudes and customs perpetuate the risks.

2. What are the health effects of these problems?

Infection with the Schistosoma haematobium parasite produces symptoms and effects such as iron deficiency anaemia, loss of blood in urine, fatigue and impaired ability to carry out responsibilities.

3. What are the underlying causes of these problems?

a. Is this problem related to women’s status in society?

Yes. Assuming that women’s infection is due to exposure to contaminated water through the performance of their domestic duties, it is their status which determines the duties which expose them to risk.

b. Is the problem due to women’s exposure to a certain hazard through performing obligatory tasks?

Yes, for the same reasons as stated above.

c. Do biological or physiological factors play a role in this problem?

Yes. If sterility or reproductive difficulties result, women are socially disadvantaged and physiologically impaired.

d. Do women suffer more from the health problem once it occurs, such as through lack of awareness of its impact on them, social stigmatization or lack of access to treatment?

Yes. Women with this disease may be severely stigmatized, whereas no stigma is attached to infected men. The stigma affects women’s ability or willingness to be treated. It also affects their ability to marry or remain married, and hence threatens their economic safety and security. Factors such as these lead to underreporting and to the conventional wisdom that young men constitute the group most exposed to risk of this disease.

4. What other information do you need to fully assess the situation?

What kind of health information is already available?

Is it gender-sensitive?

For what reasons have other groups (adolescent males) mostly been targeted for study?

Why is it thought that these groups are most at risk?

Given their traditional roles, has sufficient attention been given in the past to women’s potential exposure?

5. How would you go about investigating this problem in detail?

a. What cultural/gender issues need to be considered in planning further investigations/studies?

In the society under investigation, what work or other activities done by women are likely to expose them to the same or greater risks than other population groups?

What is the regularity and duration of women’s exposure, during all their roles and responsibilities, compared with that of other groups at risk?

Does exposure to this risk affect women’s ability to perform their roles in other spheres?

What kind of measures could be taken to ascertain whether women are unwilling or unable to report this disease?

b. Whom would you involve in your investigation team?

Medical/public health personnel (to carry out health studies and determine treatment).

Sociologists or anthropologists (to clarify the sociocultural issues for all parties involved).

Community health workers (to liaise between the above two groups and the community).

Community leaders, male and female (to liaise with the above three groups and the community).

Environmental health specialists or engineers (to identify technical solutions).

6. What can be done about the problem?

a. What prevention measures or campaigns would you recommend?

Ascertain which individuals and groups are actually and potentially at risk, and why.

Carry out long-term community education work aimed at encouraging better reporting for treatment and better compliance with the treatment prescribed.

Ensure that effective and affordable medication is available.

Introduce appropriate environmental control technology.

b. Why and how would you involve women in your prevention efforts?

Women doctors who appreciate the cultural impact on infected women should be available for consultation and should be involved in any epidemiological or clinical studies undertaken.

Female community health workers should be available to advise and liaise with women in the community.

c. Why and how would you involve men in your prevention efforts?

Male doctors and community health workers should work with community leaders and heads of household to stress the importance of equal access to treatment for all family members, and to counter the belief that the infection is a venereal disease.

Men of the community should be involved in efforts to deal with water source contamination, to ensure that proposed changes are approved and to reduce the notion that water-related issues are “women’s work”.

1.3. Student presentations

Time: Preparation outside of class

Classroom presentation (optional 15-60 minutes), followed by questions and discussion (15-30 minutes)

Objectives:

At the end of the exercise, students will be able to:

1. Develop a deeper understanding of specific environmental health topics.

2. Utilize interactive teaching approaches in their own presentations or teaching.

Procedures:

1. At the beginning of the course or workshop, advise students to prepare a presentation on an environmental health theme of their choice, drawn from the Basic Environmental Health text, their own research or related materials. In preparing their presentations, students must utilize one or more of the interactive approaches described in the Teacher’s Guide and demonstrated during the course. The lecture method may be chosen, but only in conjunction with other methods, such as buzz groups, brainstorming, use of audiovisual aids, case studies, etc.

2. Develop a schedule of student presentations to coincide with relevant course materials.

Materials:

Copy section on selected teaching methods from Teacher’s Guide for use by students (optional).

2.1. Overview of environmental health hazards

Time: 45 minutes

Objectives:

At the end of the exercise, students will be able to:

1. List the environmental/occupational factors that may cause health effects.
2. Provide examples of hazards in their countries.

Procedures:

(Note to instructor: The hazards chart may be generated in conjunction with Chapter 2 and used again later in the course, e.g. with Chapters 8 or 10.)

1. Ask the group to define the difference between environmental and occupational hazards. Emphasize the overlap between the two areas.

2. Put up a chart on the blackboard or wall using large pieces of paper. The column headings should be different types of hazards, but leave the columns blank. The headings should include: Biological, Physical, Chemical, Mechanical and Psychosocial hazards.

3. Ask students to brainstorm examples of environmental and occupational hazards in their country and the category to which the hazards belong. Fill in the chart on the basis of the students’ comments.

4. See example of what a completed chart could look like (on next page). Fill in additional items that have not been mentioned by the group. Note that certain hazards may fall into more than one category.

5. Discuss the utility of the this framework for hazard classification. In some cases, hazards may be more appropriately categorized by route of exposure, or setting of exposure, rather than type of agent.

Materials:

Large pieces of (flip chart) paper, coloured markers, masking tape.

EXAMPLES OF ENVIRONMENTAL HEALTH HAZARDS BY TYPE OF AGENT

PHYSICAL

CHEMICAL

BIOLOGICAL

PSYCHOSOCIAL

MECHANICAL

Noise

Solvents

Animals (rodents, wild stock, wild animals, pets as allergens)

Lack of recognition for one’s work

Repetitive movement

Lighting

Acids/caustics

Bacteria

Low pay

Poorly designed equipment

Radiation

Metals (lead, cadmium, mercury)

Viruses

Production pressures

Heavy (improper) lifting

Vibration

Dusts (asbestos, silica, wood)

Spores/fungi

Boring, repetitive tasks


Temperature

Pesticides

Insects

Stress


Electricity

Air pollutants/particulates




2.2. Question “can”*

* The “question can” is a box or envelope used to store questions written on small pieces of paper. These will be selected at random by participants as part of the exercise.

Time: 1 hour

Objectives:

(Note to instructor: This exercise may be used to initiate a new topic and assess students’ background understanding of the topic, to review a topic already covered, or to evaluate students’ learning and facilitate their self-evaluation.)

At the end of the exercise, students will be able to:

1. Explain key concepts and content areas in environmental health.
2. Evaluate their own learning (when topics are being reviewed).

Procedures:

1. List key terms or concepts in a particular topic area or prepare questions which review the key concepts and content area or develop short hypothetical scenarios which require participants to solve a problem by applying new knowledge or concepts. Write each term, question or scenario on a separate piece of paper and deposit it in your “question can”. (A cardboard box may serve as a question can. A large envelope may also be used.)

2. Divide participants into small groups and invite each group to pick a question from the can. All groups have a few minutes to come up with a response to their questions or a discussion of the term picked.

3. Ask the first group to read their question and to answer it. Following their response, other groups can add or correct. The instructor summarizes the correct answer and proceeds to the next group.

4. When all groups have responded, begin another round. There can usually be two or three rounds picking questions and answering them.

Alternative

Conduct the exercise in plenary. Invite one student to pick an item from the can and to define the term or answer the question posed. Other students are then asked to join in, as above. Following a brief discussion and agreement on the correct answer, (or adequate descussion of the term) proceed to the next student.

Materials:

Terms or questions on slips of paper, can (box or envelope).
Sample terms and concepts for Chapter 2 (next page) and Chapter 11.1.

Question “can”
Sample terms and concepts
Chapter 2*

* Definitions can be found in the text

Hazard

UV-A

Vector

Hypothermia

Minimal infectious dose

Potential years of life lost (PYLL)

Toxicity

Repetitive strain injuries

Aliphatic hydrocarbons

Electromagnetic field

Aromatic hydrocarbons

Becquerel

Risk

Barometric pressure

Zoonoses

Heat stroke

Agar plates

Osteoporosis

Halogenated hydrocarbons

Ergonomics

Unsaturated hydrocarbons

Active versus passive prevention strategies

Endocrine disruptors

Stress

Organic solvents

Haddon’s matrix

Metabolized

LD50

Metastases

dB(A)

Ames test

Alpha radiation

White finger disease

Ionization radiation

Stochastic effect

Non-Ionizing radiation

Biotransformation

Sievert

Lipophilic


2.3. What’s in this stuff?

Time: 30-45 minutes

Objectives:

At the end of the exercise students will be able to:

1. List the key chemical and physical properties that determine a substance’s toxicity.
2. Define the information one should have about a chemical before using it.

Procedures:

1. Introduce the following role-play and seek two volunteers to play the manager and the salesman:

“You are a manager of a factory that extensively uses solvents in your processes. A representative from a company that has supplied you with chemicals in the past has called to tell you that his company is making a new product that would be great for your company’s needs. What questions do you ask him?”

2. Allow 5-10 minutes for the role-play and then invite additions or corrections from the class.

3. If not mentioned, indicate that the manager should want to know not only about the effectiveness of this product and how it will enhance productivity, but also about its potential health effects on the workers who will be using it and its environmental impact.

The information that should be sought includes:

- What is in it?

- How much is too much? (What dose or quantity of the product is recommended for safe use?)

- What are its potential health effects in the short and long term?

- What kind of protective equipment is required? Are there any other precautions?

- Is it flammable, explosive, reactive, etc? Are there any special recommendations with regard to storage?

- What should be done in case of emergency (respiratory or dermal exposure, spills)?

- How can the product be safely disposed of?

- Is there another product which is less toxic that can be used instead?

For a complete list of chemical and physical properties, refer to a sample “Material Safety Data Sheet”.

4. Summarize and conclude the exercise.

Alternative

Label a container with the name “Brand X”. Tell the class that they are a group of workers who will be working with this product from now on. What would they like to know about it? List their answers on a flip chart.

Materials:

Flip chart, coloured markers, tape.

2.4. Problem-solving exercise: Environmental estrogens

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Time: Two 1-2 hour sessions, allowing time for home study

(Note to instructor: This exercise is designed to be used at the end of Chapter 2 and again at the end of Chapter 3. It is often desirable to distribute Part I of the exercise (Chapter 2) and encourage students to meet outside the classroom, then come to class prepared to discuss the case. This should be repeated again with respect to Chapter 3.)

Objectives:

At the end of the exercise, students will be able to:

1. Understand the basic principles of reproductive and developmental toxicology of DDT and polychlorinated biphenyls (PCBs), persistent organic pollutants (POPs) as a group of toxic chemicals, estrogen mimicry, molecular biology of cancer, classification of carcinogens, epidemiological study designs, rules of causation, selection bias and confounders, and the weight-of-evidence approach.

2. Recognize the need for a critical assessment of available evidence and for using a weight-of-evidence approach in classifying environmental pollutants.

3. Distinguish between research hypotheses and factual knowledge.

4. Appreciate the built-in uncertainties in epidemiological studies.

5. Promote an understanding by the public of the uncertainties and limitations inherent in risk assessment methodologies. Encourage a willingness by the public to participate as subjects in environmental health studies.

Procedures:

(Note to instructor: This exercise requires substantial study by participants, both in the classroom and at home. Divide the workload of retrieving and reviewing references among the class members. A debriefing session is recommended to provide a context for addressing the various questions posed below. Review of Chapters 2 and 3 is, of course, a prerequisite. Additional references to those provided might also be consulted, especially the general references to PCB literature given in the “Emergency Response to a PCB fire” problem scenario.)

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 people). Instruct participants to identify a chairperson and a recorder.

2. Distribute the exercise and review the participants’ tasks.

3. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to the next question. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

4. Summarize the results, emphasizing key messages. The decision to proceed to Part II should be made jointly by the students and instructor.

Materials:

Problem-solving exercise (Annex 5), flip chart, coloured markers, reference documents for classroom review.

Case scenario, background

Steroid hormones are essential for the growth, differentiation and function of many tissues in both animals and humans. The International Agency for Research on Cancer (IARC) (1987) designates steroidal estrogens as used in estrogen replacement therapy as carcinogenic to humans. The risk of endometrial and breast cancers is increased. Environmental estrogens (xenoestrogens) bind to estrogen receptors and have estrogenic activity in model systems. As illustrated in Box 2.1, this group of chemicals includes nonsteroidal estrogens, polycyclic aromatic hydrocarbons, DDT, and a number of PCBs (congeners that have two adjacent nonsubstituted carbon atoms on at least one of the biphenyl rings, including a para position). In addition to being suspected of acting as promoters in the development of estrogen-mediated cancers in humans (Davies et al., 1993), such xenoestrogens are believed to disrupt the immune, nervous and endocrine systems (McLachlan, 1993; EHP, 1995). Considerable and convincing evidence exists that reproductive and developmental processes are impaired in wildlife (such as birds, fish, reptiles and mammals (Colborn and Clement, 1992; Colborn et al., 1993). Comparable causal links in humans are less convincing and still speculative, such as the role of xenoestrogens in an apparent decline in semen quality over the past 50 years (Sharpe and Skakkebaek, 1993; Carlsen et al., 1995; Sate, 1995). The evidence for the involvement of environmental estrogen mimics in the etiology of breast cancer is explored in the present case scenario.

Case scenario, Part I

In a recent prospective cohort study investigating the role of endogenous hormones and environmental factors in cancer development, 58 women with a diagnosis of breast cancer 1-6 months after they entered the cohort (14 290 participants from New York City, 80% Caucasian) were compared to 171 controls selected from the same cohort and matched for menopause status and age. Sera, taken at the time of enrolment between 1985 and 1991 when attending a mammography screening clinic, were analysed for a metabolite of DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane], namely DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], and total PCBs (polychlorinated biphenyls). Limits of detection were 1 µg/L for DDE and 2 µg/L for total PCBs based on three times the standard deviation of the results from the lowest quality-control serum pool standard over the course of the analyses (n=18). DDE was 35% higher in patients than in control subjects (p=0.031),while PCBs were 15% higher (p=0.058). After adjustment for first-degree family history of breast cancer, lifetime lactation and age at first full-term pregnancy, conditional logistic regression analysis showed a four-fold increase in relative risk of breast cancer for an elevation of serum DDE concentrations from 2.0 ng/mL (10th percentile) to 19.1 ng/mL (90th percentile) (p=0.0037 for trend). Other potential confounders considered, but with no effect, were: body mass index, age at menarche, history of benign breast tissue, history of tobacco smoking and/or alcohol drinking, and race. The corresponding association for PCB levels was not significant (p=0.16). It was concluded that environmental chemical contamination with organochlorine residues may be an important etiological factor in breast cancer.

Chapter 2 Questions

1. In simple terms, describe how estrogens regulate the growth, differentiation or function of cells.

The estrogen molecule must first diffuse across the cell membrane, and subsequently seek out a special protein, called its receptor, to which it binds (see Box 2.1). The estrogen-receptor complex then diffuses into the cell nucleus where it seeks out a binding site on DNA corresponding to a specific gene. This action is crucial to beginning a process called transcription, which is the synthesis of the messenger (mRNA). The information on the mRNA is sufficient to synthesize a specific protein or enzyme. This step is followed by an altered functional response such as those mentioned in the question. Xenoestrogens can mimic the role described for endogenous estrogens, resulting in up or down regulation.

2. DDE and PCBs are persistent organic pollutants (POPs). What is meant by this?

POPs are considered persistent because they tend to be resistant to biological, chemical or photolytic breakdown (see Box 2.2). Consequently they remain in the environment for many years. For example, as much as 50% of DDT and related compounds can remain in the soil for 10-15 years after application. For PCBs, the environmental persistence increases with the degree of chlorination, although half-times (t½) range from 10 days to 1.5 years for photo-degradation. In organisms, DDT is relatively persistent but its hydrolysis product DDE is much more so. In humans, DDT has a t½ value of 1.7 years while that of DDE is 6-8 years. PCBs have t½ values of 125-350 days, depending on the degree of chlorination.

3. How is DDT converted to DDE?

DDT is converted by biotransformation to DDE, which requires a specific enzyme (a dehydrochlorinase). HCl, hydrochloric acid, is removed from the >CHCCl3 group that joins the two benzene (phenyl) rings to give the >C=Cl2 moiety.

4. What is the likely source or exposure route of the organochlorines?

In the absence of special sources such as occupational exposures, the diet is the main source of PCBs and DDT. Primary sources are animal fats, eggs and fish. Ingestion is therefore the primary route of intake.

5. Comment on the use of serum PCB and DDE levels as measurements of exposure.

Because of the relatively long half-times in blood, serum PCBs and DDE should reflect the steady state levels in tissue lipids, unless a recent exposure has occurred. Because the organochlorines are associated with serum lipids, it would be more precise to express their concentrations in terms of the total lipid content of the serum samples, since the latter varies from person to person. A single measurement does not constitute a reliable assessment of body burden, and several samples might have been collected over an extended period of time. See also answers to Chapter 3, Question 5.

6. From the toxicokinetic perspective, does it make sense that duration of lactation is an important determinant in the study? Explain.

PCBs and DDE are secreted into breast milk. There is some evidence that maternal serum concentrations decline with longer duration of lactation.

Chapter 3 Questions

1. The study considered in the scenario is a case-control study nested within a prospective cohort study. What are the salient features of these two types of epidemiologic study?

See Section 3.2. Chapter 3 of the WHO Basic Epidemiology text is also very helpful.

2. What are confounders?

Confounding occurs when two risk factors or exposures have not been properly separated and the effect is assigned only to the variable considered. The confounder must be associated with both the disease and the exposure being studied. Confounders have been considered quite adequately in the study of the case scenario.

3. Has selection bias been avoided?

Since the women in the original cohort were enrolled while attending a mammography screening clinic, a true representation of females in the general population may not have been attained and selection bias may have occurred.

4. What are the known risk factors for breast cancer?

Known risk factors for breast cancer include genetic factors (first-degree relatives), endocrine factors (early age of menarche, late onset of menopause, nulliparity and low parity, late age at first pregnancy, exogenously administered estrogen hormones) and environmental factors (dietary fat or caloric intake; moderate alcohol intake).

5. Apply the rules of causation outlined in Table 3.3 to the study at hand.

The rules of causation are summarized in Table 3.3.

Temporal relation: Since the cancer cases were diagnosed 1-6 months after entry into the cohort, the organochlorine level measured corresponds to a situation where almost all the patients had breast cancer at the time of sampling. Since the latency period for breast cancer is 5-20 years, the serum PCBs or DDE assessments do not reflect the exposure during the critical early phases of the development of the disease.

Consistency: Three other case-control studies suggest weak links between environmental organochlorine exposures and breast cancer risk, but a fourth comprehensive study was negative (Wolff and Toniolo, 1995). Nor do much higher occupational exposures suggest this association (IARC, 1987; Safe, 1995).

Strength: The relative risks are low, so if the effect is real it is weak.

Study design: A case-control study is appropriate for identifying a causal link to a specific exposure.

Dose-response relationship: There is a response gradient for DDT (DDE), but not for PCBs.

Plausibility/coherence: Evidence from animal data for the carcinogenicity of both DDT and PCBs is “sufficient” (IARC, 1987).

Mechanism of action: The estrogen mimicry hypothesis is believed to explain the role of these organochlorine compounds as promoters of cancer. Estrogenicity tests indicate that some PCBs and DDT are weakly estrogenic, but surprisingly DDE is not (Safe, 1995).

Reversibility: No data is available.

6. Comment on the authors’ overall conclusion. Is it valid?

Considering that none of the tests shows strong causal links, the evidence may be said to be at most equivocal.

Case scenario, Part II

Two of the investigators of the study described in Part I, participated in a second study conducted in California (Krieger et al., 1994; also see Wolff and Toniolo, 1995). Again the hypothesis tested was that exposure to organochlorines is a risk factor for breast cancer. Study subjects belonged to a cohort of 57 040 women (46 629 white, 8123 black and 2288 Asian) who took a multiphasic health examination between 1964 and 1971, independent of concern about risk of breast cancer. Follow-up was conducted through December 31, 1990 to identify those with histopathologically confirmed primary breast cancer six or more months after their multiphasic examination. From among the women who developed breast cancer (1805 white, 230 black and 62 Asian), a random sample of 50 women in each racial/ethnic group was selected, as were equal numbers of controls matched according to race/ethnicity, date of joining the medical care programme, year of multiphasic examination and age at that time, and length of follow-up. Matched analyses found no difference in DDE or total PCBs, although organochlorine levels were significantly higher (p<0.05) among black and Asian women compared to white women. The mean differences (95% confidence intervals) for DDE were 11.0 (4.3, 17.6) ug/L in the black women and 12.6 (4.3, 17.6) ug/L in the Asian women and, respectively, 0.8 (0.2, 1.4) ug/L and 1.4 (0.8, 1.9) ug/L for PCBs. The detection limits were as stated in Part I. These ethnic differences persisted even after adjusting for available confounders: age at and year of medical examination, body mass index, educational level, poverty level, place of birth (United States or elsewhere), pregnancy history (ever or never). Multivariate analysis showed the absence of a significant association (p<0.05) between exposure to organochlorines and breast cancer, regardless of length of follow-up, year of diagnosis and menopausal status. The conclusion was that the data do not support the hypothesis that exposure to DDE and PCBs increases risk of breast cancer.

Chapter 2 Questions

1. What do we know about the molecular basis of cancer?

Like other cancers, breast cancer appears to require a number of events at the level of genes corresponding to the conversion of proto-oncogenes to oncogenes, or inactivation of pairs of homologous (the copy inherited from the mother and that received from the father) suppressor genes. An oncogene is a gene capable of inducing one or more aspects of the neoplastic phenotype, with the proto-oncogene the normal (healthy) cell homologue. Proto-oncogenes act as central regulators of cell growth (proliferation) and differentiation (progressive diversification in cellular structure and function during the development of an organism). Suppressor genes are genes whose loss of function leads to one or more aspects of the neoplastic phenotype; in normal cells, they effectively act as repressors of biochemical function and cell growth, but this “braking” ability is lost when both copies of the gene are inactivated and thus results in uncontrolled growth. The genetic events mentioned account for the various phases of cancer development: initiation, promotion (cell proliferation), progression (different histological changes) and metastases (spreading). Although such gene damage can occur spontaneously, certain environmental chemicals can inflict it and these are said to be genotoxic. Estrogens are believed to act as cancer promoters by enhancing cell division, thereby increasing the probability that a genetic lesion will occur (Cooper, 1995).

2. Do you have any analytical concerns about the PCB and DDE measurements reported in Parts I and II?

As already indicated in the answer to Question 5 above (Case scenario, Part I), it would have been better to express the PCB and DDE concentrations relative to the total serum lipid content. Further, the collection and analysis of a single sample at a point when the disease has already occurred is a poor way of establishing causality. Thirdly, the detection limit for total PCBs is comparable to the actual concentrations found. This fact is not very reassuring.

3. Does the estrogen hypothesis make biological sense to you (e.g. in terms of nutrition or physiology)?

Safe (1995) shows that environmental organochlorine estrogens contribute an infinitesimal amount to the dietary intake of estrogenic substances, when expressed in estrogen equivalents and compared to intakes of flavonoids in foods or that received in birth control and postmenopausal therapy regimens. Unique disruption of endocrine pathways must therefore occur for xenoestrogens to be effective.

Chapter 3 Questions

1. Is there room for an environmental risk factor to explain breast cancer?

Since the genetic events that lead to breast cancer are often determined by gene-damaging (genotoxic) agents or cancer promoters (epigenetic toxicants), environmental exposure provides a plausible pathway.

2. Does the “xenoestrogen hypothesis” of breast cancer make epidemiological sense? Return to your previous deliberations concerning the rules of causation. You might also consider that epidemiological studies of individuals occupationally exposed to much higher concentrations of PCBs or DDT/DDE do not show a higher incidence of breast cancer (IARC, 1987; Safe, 1995).

Although the Part II study has improved power because of the larger number of cases considered, the ratings for the other tests diagnostic of causation are not upgraded. It is doubtful whether a real risk could have been detected. Therefore the conclusion that the data do not support a causal link is again equivocal.

3. IARC (1987) designates DDT as Group 2B and PCBs as Group 2A carcinogens. Do the results of the two studies discussed suggest that these classifications ought to be upgraded? Justify your answer?

Clearly, the epidemiological (human) evidence will remain limited for PCBs and inadequate for DDT, and no upgrading to Group 1 (designated as carcinogenic in humans) for PCBs or to Group 2A (sufficient animal evidence and limited human evidence) for DDT is in order.

Selected references

Callahan R, Campbell G. Mutations in human breast cancer: an overview J. Natl. Cancer Inst. 1989; 81:1780-1786.

Carlsen E, Giwercman A, Keiding N, Skakkebaek NE. Declining semen quality and increasing incidence of testicular cancer: is there a common cause? Environ. Health Perspect.1995; 103 (Suppl. 7):137-139.

Colborn T, Clement C. (eds.) Chemically induced alterations in sexual and functional development: the wildlife-human connection. New Jersey, Princeton Scientific Publishing Co., 1992.

Colborn T, von Saal FS, Soto AM. Developmental effects of endocrine-disrupting chemicals in wildlife and humans. Environ. Health Perspect. 1993; 101:378-384.

Cooper GM. Oncogenes, 2nd ed. Boston, Jones and Bartlett, 1995.

Davies DL, Bradlow HL, Wolff M, Woodruff T, Hoel DG, Anton-Culver H. Medical hypothesis: xenoestrogens as preventable cause of breast cancer. Environ. Health Perspect.1993; 101:372-377.

Estrogens in the environment. Special issue, Environ. Health Perspect. 1995; (Suppl. 7): 1-178.

Goldstein JL, Brown MS. Genetic aspects of disease. In: Harrison’s principles of internal medicine, 13th ed. (KJ Isselbacher, JB Martin, E Braunwald, AS Fauci, JD Wilson DL Kasper, eds). New York, McGraw-Hill, 1994, pp 339-349.

Hendersen IG. Breast cancer. In: Harrison’s principles of internal medicine, 13th ed. (KJ Isselbacher, JB Martin E. Braunwald, AS Fauci, JD Wilson, DL Kasper, eds). New York, McGraw-Hill, 1994, pp 1840-1850.

Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7. Overall evaluation of carcinogenicity: an updating of IARC monographs Vols 1 to 42. Lyon, International Agency for Research on Cancer, 1987.

Krieger N, Wolff MS, Hiatt RA, Rivera M, Vogelman J, Orentreich N. Breast cancer and serum organochlorines: a prospective study among white, black and Asian women. J. Natl. Cancer Inst. 1994; 86:589-599.

McLachlan JA. Functional toxicology: a new approach to detect biologically active xenobiotics. Env. Health Perspect. 1993; 101:386-387.

Safe SH. Environmental and dietary estrogens and human health: is there a problem? Environ. Health Perspect. 1995; 103:346-361.

Sharpe RM, Skakkeback NE. Are estrogens involved in the falling sperm counts and disorders of the male reproductive system. Lancet 1993; 341:1392-1395.

Wolff MS, Toniolo PG. Environmental organochlorine exposure as a potential etiologic factor in breast cancer. Environ. Health Perspect. 1995; 103 (Suppl. 7):141-145.

Wolff MS, Toniolo PG, Lee EW, Rivera M, Dubin N. Blood levels of organochlorine residues and risk of breast cancer. J. Natl. Cancer Inst. 1993; 85:648-652.

Learner, peer and problem evaluation

Formative evaluation

At the end of each session, but especially after the last one, allow participants to express their thoughts and feelings about their own participation and progress, as well as about the contributions and roles of the instructor/facilitator and fellow learners. Solicit comments about the approaches used (i.e. debate, role-playing, other). A written or oral evaluation concerning achievement of the stated objectives is also a good idea. Can the problem as presented be improved? How?

Summative evaluation

An assessment of the factual knowledge associated with Chapter 2 questions might best be achieved by short answer questions (SAQs) or multiple choice questions (MCQs). Both approaches have acceptable reliability (are the results reproducible on different occasions or by different assessors?) and validity (does it measure: the intended characteristic or learner attribute in the present context, factual knowledge, application of knowledge and reasoning ability?). An effective approach to SAQs is to have a brief description of a real event or observation in which concepts and terms are used in context. Specific answers can then be solicited (e.g. what are estrogen receptors and how do they work?). MCQs also start with a brief description, which is usually followed by a list of alternative answers from which the correct answer(s) should be selected. Evaluation related to Chapter 3 questions might involve the critical evaluation of a recently published epidemiological study, or application of the rules of causation to it. Alternatively, the weight of evidence for a suspected association of an outcome (e.g. human carcinogenicity) to exposure to a specific contaminant might be reviewed.

(introduction...)

Prepared by Merri Weinger

Time: Preparation: 1-1½ hours

Field visit: variable

Objective:

At the end of the exercise, students will be able to:

Describe the rationale and procedures for conducting onsite evaluation of potentially hazardous environmental and workplace settings.

Procedures:

1. Ask students what they think is the purpose of a field visit. Responses should include: to observe and quantify potential sources of contamination, to collect and analyse data (through biological and atmospheric monitoring, interviews, etc.) and to recommend environmental controls and preventive measures.

2. Describe the site that the group will be visiting. Brainstorm a list of potential hazards that one might expect to find.

3. Instruct students that they will be conducting the field investigation as a team of environmental consultants. Define the objective of the visit, which usually includes the identification of potential hazards on the site and the recommendation of necessary control measures (See sample field visits, Chapter 3.1.1.). Divide into small groups to prepare for the visit. Each group should respond to the following questions:

- What do you want to observe during the visit?
- What questions would you like to ask?
- Who do you want to be sure to talk to during the visit? (e.g. in a factory, students may want to interview supervisors, workers, representatives from the medical service, etc.)

4. Invite brief reports from each group. Students should avoid repeating items that have already been mentioned by other groups. The notes from this discussion will serve as a checklist for the team during the visit.

5. Conduct field visit.

6. Debrief visit in the classroom. Invite oral reports from the small groups on potential hazards observed and intervention strategies proposed. Summarize and conclude the exercise.

Alternatives

Field visits can also be an opportunity to practice developing written reports on observations and conclusions. In this case, each team would be required to submit a report according to a format provided by the instructor.

Materials:

Written task for field visit, flip chart, coloured markers, tape.

A. Water purification and recirculation plant

(Visby, Sweden)

(Note to instructor: For general guidelines on conducting a participatory field visit, see Chapter 3.1.)

Objectives of the visit

You are an environmental health specialist whose task is to:

1. Determine whether there are any health risks derived from using the water processed by the Roma water purification and recirculation plant.

2. Determine whether there are any health risks to workers in the plant.

3. If necessary, recommend remedial action.

Potential areas for investigation

(The following list was compiled by the instructor to complement the list generated by students when preparing for the visit in the classroom.)

Plant organisation

1. What is the number of staff in the plant in:

- administration?
- operation?
- maintenance?

2. What is the organizational structure of the plant?

Process

1. What is the volume of water being treated?

2. What is the population served?

3. What is the per capita consumption in the community?

4. What is the method or process used to treat the water?

5. Considering that there is a recirculation process, what percentage of the water is being recirculated and what amount of water is being lost?

6. What difficulties are faced in the treatment process due to the recirculation (e.g. frequent clogging of filters, the need to use more chemicals, etc.)

Water quality

1. What is the quality of the raw water?

2. Which laboratory tests are conducted? Are they conducted at the treatment plant or elsewhere?

3. What are the results of laboratory tests on the treated water? If there has been any contamination, what was the cause? What measures were taken to address the problem?

4. What is the quality control system in the plant? Is it located at different points in the treatment process?

5. How vulnerable is the distribution system?

6. Is there any quality control by local health authorities? If so, what does it consist of?

Worker health and safety

1. What are the key risks to workers in the plant (e.g. falls into sedimentation tanks, electrical hazards)?

2. What is the accident/injury/illness rate among workers over the past 10 years?

3. What facilities or strategies are used to prevent accidents or injuries?

B. Informal food traders

(Cape Town, South Africa)

(Note to instructor: For general guidelines on conducting a participatory field visit, see Chapter 3.1. There are informal food traders or vendors in most countries. They represent a tremendous challenge to enforcers of food hygiene since they are generally unlicensed and often transient.)

Objectives of the visit

You are an environmental health specialist whose task is to inspect the food installations in an informal settlement in Cape Town.

1. What are the potential health hazards on the site?

2. What specific recommendations would you make to prevent an outbreak of foodborne disease?

3. What are potential obstacles to implementing these recommendations?

4. How would you propose to overcome these obstacles?

C. Sewage treatment plant

(Budapest, Hungary)

(Note to instructor: For general guidelines on conducting a participatory field visit, see Chapter 3.1.)

Objectives of the visit

You are an environmental health specialist whose task is to:

1. Determine the aim of the treatment process with special regard to the Danube branch where the effluent is discharged.

2. Determine which special health aspects need to be considered where (and when) the discharged effluent enters the area used for recreational activity.

3. Determine whether there are any health risks to workers in the plant, to those employed in nearby facilities or to passers-by (e.g. cyclists).

4. During the visit, what would you need to ask or observe to accomplish this task?

Field visit checklist

(The following list was compiled by the instructor to complement the list generated by students when preparing for the visit in the classroom.)

Process

1. What is the sewerage system? What problems are caused by it?

2. What is the capacity of the plant? What is the actual average loading?

3. What is the influence of the industrial wastewater on the sewage quality and treatment process?

4. What are the main steps in the treatment technology?

5. What is the technology of the sludge treatment?

6. What is the fate of the treated sludge?

7. When and why is it necessary to chlorinate the effluent?

Water quality

1. What is the quality of the raw sewage?

2. Which laboratory tests are conducted? Are they conducted at the treatment plant or elsewhere?

3. What are the results of laboratory tests on the treated water?

4. How is the chlorination controlled?

5. Is there any odour problem during the process? Is there any measure to control or diminish it?

6. Is there quality control by local health authorities? If so, what does it consist of?

Worker health and safety

1. What are the key risks to workers in the plant? (e.g. falls into sedimentation tanks, electrical hazards, enteric or other infections, etc.)

2. Is there any other hazard for workers?

3. What strategies are used to prevent accidents or injuries?

D. Solid waste facility: Bale and rail

(Cape Town, South Africa)

Objectives of the visit

Bale and Rail is a project which includes the “baling” or compacting and packing of solid waste to be “railed” or sent by train to a conventional waste disposal site.

You are an environmental health specialist who has been asked to evaluate the bale and rail system from a public health perspective. Among other factors, you are concerned about the potential for underground contamination, leaching, health risks to workers and unpleasant odours.

As you conduct the field visit, please consider the following questions:

1. Do you observe any potential health risks for the environment, the employees in the plant or the surrounding community in:

- the bailing process?
- the railing process?
- the disposal site?

2. What interventions would you recommend to prevent potential health risks?

3. In your opinion, from a public health perspective, how does the bale and rail system compare to the conventional solid waste disposal system using long-haul truck transport? Which approach may pose greater health risk to the environment, the workforce and the community, and why?

3.2. The relationship between dose and health outcome: Dose-response versus dose-effect

Prepared by Annalee Yassi*

* Dr Annalee Yassi, Occupational and Environmental Health Unit, University of Manitoba, Winnipeg, Canada

Time: ½ - 1 hour

Objective:

At the end of the exercise, students will be able to:

1. Distinguish between dose-response and dose-effect relationships.

2. Interpret dose-response and dose-effect relationships from data displayed graphically.

Procedures:

1. This exercise is designed to elicit student observations and conclusions about the dose-response and dose-effect curves found in Annex 6. If there is limited response to the request for observations, ask specific questions (e.g. in Figure 5, ask whether there is a relationship between speed and the frequency of injury for seat belt usage and non-usage; then ask them how speed affects this relationship).

2. Place Figure 1, a dose-response curve, on the overhead screen, without the title showing. Ask the students to describe the curve. The students should state that this is a dose-response relationship showing the proportion of individuals in an exposed group that demonstrate a defined effect at a given dose.

3. Place Figure 2, a dose-effect curve, on the overhead screen without the title showing. Ask the students to describe this figure. The students should state that this is a simplified, schematic representation of a dose-effect relationship between the percentage of carboxyhaemoglobin in the blood and the severity of health effects (in this case, a slight headache at about 17% carboxyhaemoglobin, headache and dizziness at approximately 33%, nausea and blackouts at about 48%, unconsciousness at approximately 60% and death at approximately 75% carboxyhaemoglobin).

4. Place Figure 3, a dose-response curve, on the overhead screen without the title showing, but with the legend visible. Ask the students to describe what they see. The students should state that this is a series of dose-response curves for various health effects of lead in children. They should note that decreased aminolevunic acid dehydrase (ALA-D) activity begins at extremely low concentrations of lead in the blood, reaching approximately 90% dysfunction at a concentration of approximately 300mg pb/l. They should be able to continue this commentary for the other effects listed in the legend, noting that severe effects, such as palsy, colic pain and encephalopathy do not begin until a concentration of lead in blood of approximately 1150mg pb/l occurs.

They may observe that the shapes of the dose-response curves are different, and may discuss the implications of these differences. It may also become apparent that the concentration of lead in blood at which a certain percentage of dysfunction in the central nervous system occurs spans a very large range of concentrations. In contrast, the steepness of the curve for ALA-D activity suggests that the percentage of dysfunction increases rapidly at very low concentrations. Ask the students which would be the most sensitive indicator of lead exposure based on this information. The students should answer that ALA-D activity would be the most sensitive to early effects of lead exposure.

5. Place Figure 4, on dose-response relationships, on the overhead screen without the title showing and ask the students to describe what they see.

The students can be expected to note that this is a series of dose-response relationships between occupational sound levels and percentage of workers with impaired hearing, with each curve representing a different age group. The students should note that for any given level of sound exposure, the percentage impairment is greatest in the oldest age group, indicating that both age and noise create impaired hearing. Additionally, they may observe that for any given sound level at work the general population is likely to have a much lower percentage impairment than factory workers exposed to non-industrial noise. A discussion may take place as to why this is so.

6. Place Figure 5, on dose-response relationships, on the overhead screen. Once again, cover the title and ask the students to describe what they see.

The students should mention that the graph shows two dose-response relationships between speed and risk of injury, with one being when seat belts are used and the other when seat belts are not used. One can conclude that for any given speed level, more injuries occur when seat belts are not used than when they are used. The students should also note that as speed increases so does the frequency of injury.

7. Finally, place Figure 6 on the screen. Cover the title and ask the students what they see.

The students should note that this is a dose-response relationship between noise level and annoyance as discovered in two studies, one American and one German. The students may note that as the integrated sound level increases, the percentage of the population that is highly annoyed increases. They would also note that the percentage annoyance at any given sound level is higher in the American study than in the German study. A discussion may ensue as to why this is so.

Materials:

Figures 1 to 6 on transparencies (Annex 6); overhead projector.

4.1. Problem-solving exercise: Emergency response to a PCB fire

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Time: One 2-3-hour classroom sessions (allow time for independent study, if desired)

Objectives:

At the end of the exercise, students will be able to:

1. Review the principles of risk management in the context of emergency preparedness, emergency response and the safe use and disposal of hazardous products.

2. Recognize the need for reliable toxicological data, empirical (analytical) data and interdisciplinary teamwork in emergency response and its follow-up.

3. Organize and implement adequate community preparedness and preventive measures for chemical spills or fires in industrial accidents that pose a health risk to the public.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. The problem scenario is divided into three sequential parts:

- Part I consists of a vignette;
- Part II provides factual information to help students to understand the problem better;
- Part III provides the outcome. The decision to proceed to the next stage should be made jointly by students and instructor. You can schedule plenary sessions to review student responses to the material at any stage in the process and before distributing new information.

3. Distribute the exercise and review the participants’ tasks.

4. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages. The decision to proceed to Part II should be made jointly by students and instructor.

Materials:

Problem-solving exercise in three parts (Annex 7), flip chart, coloured markers.

Case scenario, Part I

Your group has been appointed to coordinate the emergency and follow-up responses to a fire that is burning out of control at a PCB warehouse in a community north-east of the city of Montreal, Canada. The cloud of smoke and soot can be seen a long distance away and is moving in a north-westerly direction. In its path are three towns (total population of approximately 4000), interspersed with farmland (livestock, dairy and crop farms). Fire-fighters are at the scene.

Question 1. What are the PCBs and what hazards do they pose to human health? What information retrieval sources are you going to consult? Remember, immediate answers are required.

Consultation of a material safety data sheet (MSDS) provided by the Fire Marshall’s office indicates that polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that are toxic to the environment and humans; they bioaccumulate in the food chain, occurring in fish and wildlife and are secreted into milk.

Most of what one needs to know about PCBs and related compounds is provided in Part II of the problem scenario. In many countries, PCBs and dioxins have become renowned environmental toxicants, and thus they are among the most feared chemicals. Because there is a gap between their perceived adverse effects and what is documented with certainty, critical reading of the literature is required. For example, using epidemiological guidelines for establishing causal relationships, Swain (1991) arrived at the following conclusions for intrauterine exposure through the consumption of contaminated fish:

(i) consumption of contaminated fish correlates with serum PCB levels;

(ii) evidence for intrauterine exposure to PCBs is consistent between studies;

(iii) evidence for alterations in maternal health status is weak;

(iv) while the Yusho and Yu-Cheng acute exposure incidents demonstrated decreases in size at birth and gestational age, the evidence for the low-dose chronic exposure studies is weak;

(v) effects on behavioural functions and responses in neonates and subtle behavioural and cognitive deficits in infants (6-12 months) appear established with a reasonable degree of certainty;

(vi) effects on cognitive function in early childhood (at 4 years of age) must be regarded as uncorroborated since the evidence originates from a single study.

Recently, Kimbrough (1995) has concluded for PCBs that the “available evidence for cancer and for reproductive effects is inconclusive”. MSDSs constitute quick sources of toxicological and first aid information, but additional knowledge is required to initiate an emergency response. Emergency response personnel such as the Fire Marshall or Medical Officer of Health will have manuals or perhaps on-line information on chemical-specific risk and emergency response. Because of the scale of the problem, medical and toxicoligical experts from government agencies or universities may need to be sought and brought in as quickly as possible.

Question 2. What immediate actions should be taken and who should be involved?

An interdisciplinary and intersectoral emergency team needs to be assembled and a command post set up to work with the fire department, community health officials and local authorities to:

(i) determine the extent of the affected area;

(ii) determine weather conditions (wind direction and velocity; whether rain is anticipated);

(iii) assess the need for evacuation;

(iv)determine the amount of the PCBs consumed in the fire;

(v) determine the extent of exposure to PCBs, PCDDs and PCDFs by collecting samples for immediate analysis (air, water, surface dust inside and outside homes, vegetables, grass, livestock, cows’ milk, etc.);

(vi) implement an analytical quality assurance programme;

(vii) establish medical check-ups and other services;

(viii) carry out health risk assessment;

(ix) issue health advisories;

(x) establish risk communication;

(xi) ensure follow-up (decontamination and restoration; medical);

(xii) decide on the need for an official inquiry.

Case scenario, Part II

Ministry of Environment records show that 500 drums (~100,000 litres) of a dielectric fluid called “askarel”, containing up to 70% PCBs, were stored in the warehouse.

PCBs have the formula C12H10-nCln with n=1 to 10; they constitute a family of 209 compounds called congeners that are characterized by different halogenation and phenyl-ring substitution patterns. PCBs mixed with mineral oil are used as insulating fluids, coolants and lubricants in high temperature electrical equipment. Pyrosynthetic products of PCBs include polychlorinated dibenzofurans (PCDFs) and dibenzodioxins (PCDDs). The Canadian Environmental Contaminants Act limits the use of PCBs, although their continued presence in equipment built before 1 July 1980 is permitted. These regulations also limit the concentration of PCBs in equipment offered for sale or in material released into the environment to 50 parts per million by weight. Further, the release from any one piece of equipment is limited to 1gm per day. Approved methods for the destruction of PCBs are slowly becoming available.

Acute exposure to PCBs (as well as PCDFs and PCDDs) results in a clinical syndrome of “PCB poisoning” characterized by skin abnormalities (chloracne) and oculodermatological symptoms, mucosal surface irritation, abnormal liver function, elevated serum triglycerides and peripheral neuropathy. Non-specific symptoms include excessive fatigue, anorexia and weight loss. Long-term concerns, based on the Yusho (Japan) and Yu-Cheng (Taiwan) epidemics caused by accidental ingestion of rice oil contaminated with PCBs and minor amounts of PCDFs, are reproductive and non-permanent developmental effects in infants, and cancer. These concerns are accentuated by the aftermath of the release of PCDDs in a 1976 explosion in a chemical plant near Seveso, Italy. The International Agency of Research on Cancer (IARC) lists PCBs as Group 2A carcinogens (limited human and sufficient animal evidence); TCDD (2,3,7,8-tetrachlorodibenzo-para-dioxin) is assigned to Group 2B (inadequate human evidence but sufficient animal evidence). PCBs, PCDFs and PCDDs are believed to act as environmental estrogens or antiestrogens (see Exercise 2.4). They are considered to act as endocrine-disrupting contaminants in wildlife species and humans. The quantitative analysis of air, water and biological samples for these compounds requires considerable expertise and sophistication.

Question 3. Should the inhabitants of the three towns be evacuated? Who should make that decision?

Debate whether the toxicological concern and the potential magnitude of the PCB fire are sufficient reasons to evacuate persons living in the immediate pollution zone. The senior health official (e.g. the local Medical Officer of Health) and the Fire Marshall might be in the best position to make this decision. This discussion should take place before Part III of the scenario is handed out.

Question 4. What measures should be implemented for environmental monitoring, biological monitoring and health effects monitoring? Who ought to be involved in such programmes? What group of individuals is likely to be at highest risk?

This has already been partially answered in the answer to Question 2. See also Part III of the problem scenario.

Case scenario, Part III

Residents of the nearby towns were evacuated immediately by the authorities and emergency accommodation was arranged. Specific instructions for evacuees and people living in neighbouring districts were made available through the Ministries of Agriculture (concerning consumption of local vegetables, milk, meat, etc.), Health, and Environment and via 24-hour telephone hotlines. It was strongly recommended that breast-feeding be stopped. Fire-fighters and others who were heavily exposed were given immediate medical attention, monitoring and psychological support (debriefing, counselling if required). A detailed questionnaire issued to 5000 persons was used to assess the probability of exposure. An ad hoc panel was convened, including local, national and international experts. Three task-groups were formed. Task-group I initiated and supervised the collection and analysis of environmental samples (air, dust on interior and exterior surfaces, soil, water, vegetation), as well as biological samples (e.g. serum levels of PCBs in most heavily exposed groups and in maternal milk). The environmental data was employed by task-group II in risk assessment calculations and in determining when to allow people to return home. Task-group III determined what short-term and long-term medical and psychosocial actions were needed for the exposed population and emergency respondents.

About 8% of the PCBs stored in the warehouse were actually burned. Harmonization and quality control of the analytical laboratories identified some aberrant methodologies which were corrected. In most of the environmental samples, PCBs were below the threshold of detection. Because some dust droplets were found that were contaminated with PCBs, dioxins and furans, all the homes and cars in the affected area were washed (special instructions were given). Although local vegetables were only minutely contaminated, an embargo was placed on this year’s crop of produce. No traces of contaminants were found in blood, milk and faeces of animals tested. Milk from the area was allowed to go for pasteurization two weeks after the exposure. Government compensation for losses was made available. The determination of PCDDs, PCDFs and planar PCB congeners (the most toxic group) in breast milk during the first three days showed no elevation. Women were reassured and breast-feeding was resumed. Breast milk analyses during the subsequent weeks and months confirmed the initial conclusion of negligible exposure. Although 5000 people in all were medically examined and tested, only some of the fire-fighters, police and emergency respondents who participated in containment and clean-up had higher-than-average liver enzyme levels in their sera. These latter individuals also showed some symptoms of the PCB poisoning syndrome, had evidence of mild elevation of serum PCBs, and will be subjected to long-term follow-up. These findings indicated improper protection when on emergency duty. Psychosocial impact assessments will also be pursued for at least six months. Quantitative risk calculations confirmed that, other than the “heavily exposed” groups, the general public were not at risk and would not be resettled provided the required precautionary measures were followed. The evacuation decision was judged to be justified.

Question 5. In your assessment, were the actual emergency responses and follow-up adequate?

Have a debate on how the manner in which this emergency was handled relates to the type of response that could be launched in your own community. Is there emergency preparedness and a response team? If this is not known, the students might want to find out the details.

Question 6. What risk communication issues can you identify?

Many citizens and fire-fighters will be quite worried. An approach to risk communication is needed that is sensitive to how people feel about PCBs and dioxins. Dioxins are usually referred to incorrectly as one of the most toxic substances known; this is true for guinea pigs but not for humans. An issue such as the continued benefit of breast-feeding when there is some risk of contamination requires careful thought and communication sensitivity.

Question 7. What follow-up measures do you recommend?

Medical follow-up of the most exposed individuals, namely the frontline response team (i.e. fire-fighters, police, clean-up crews) seems warranted. Periodic biological monitoring would assess the loss of the persistent pollutants from the blood compartment. An official enquiry about safeguards and regulations associated with storage of dangerous chemicals appears necessary. High temperature incineration appears to be a suitable disposal alternative for PCBs.

Selected references

Axelson O. Seveso: disentangling the dioxin enigma. Epidemiology 1993; 4:389-392.

Dewailly E, Tremblay-Rousseau H, Carrier G, Groulx X, Gringras S, Boggess K, Stanley J, Weber JP. PCDDs, PCDFs and PCBs in human milk of women exposed to a PCB fire and of women from the general population of the Province of Quebec, Canada. Chemosphere 1991; 23:1831-1835.

Hay A. What caused the Seveso explosion? Nature 1978; 273:582-583.

Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7. Overall evaluation of carcinogenicity: an updating of IARC monographs, Vols 1 to 42. Lyon, International Agency for Research on Cancer, 1987.

International Programme on Chemical Safety. Environmental health criteria No.88. Polychlorinated dibenzo-para-dioxins and dibenzofurans. Geneva, World Health Organization, 1989.

International Programme on Chemical Safety. Environmental health criteria No.140. Polychlorinated biphenyls and terphenyls (2nd edition). Geneva, World Health Organization, 1993.

James RC, Busch H, Tamburro CH, Roberts SM, Schell JD, Harbison RD. Polychlorinated biphenyl exposure and human disease. J. Occup. Med. 1993; 35:136-148.

Kimbrough RD. Polychlorinated biphenyls (PCBs) and human health: an update. CRC Crit. Rev. Toxicol. 1995; 25:133-163.

Swain WR. Effects of organochlorine chemicals on the reproductive outcome of humans who consumed contaminated Great Lakes fish: an epidemiologic consideration. J. Toxicol. Environ. Health. 1991; 33:587-639.

U.S. Public Health Service. Toxicological profile for 2,3,7,8-Tetrachlorodi-benzo-p-dioxin. Atlanta, GA, Agency for Toxic Substances and Disease Registry, 1989 (Document ATSDR/TP-88/23).

U.S. Public Health Service. Toxicological profile for selected PCBs (Aroclor-1260, -1254, -1248, -1242, -1232, -1221, and -1016), Atlanta, GA, Agency for Toxic Substances and Disease Registry, 1989 (Document ATSDR/TP-88/21).

Learner, peer and problem evaluation

Formative evaluation

At the end of each session, but especially after the last one, allow participants to express their thoughts and feelings about their own participation and progress, as well as about the contributions and roles of the instructor/facilitator and fellow learners. Solicit comments about the approaches used (i.e. debate, role-playing, other). A written or oral evaluation concerning achievement of the stated objectives is also a good idea. Can the problem as presented be improved? How?

Summative evaluation

A test with questions that require short essay answers (e.g. 4-5 lines) and which explore the learners’ knowledge, understanding and ability to apply the new knowledge inherent in the study objectives might be tried. Alternatively, have the students prepare an investigative/critical assessment of a major environmental health risk in their own community and the local state of preparedness for dealing with an emergency situation and follow-up.

4.2. Problem-solving exercise: Mercury poisoning in the Amazon

Adapted from A. Yassi, D. Mergler and E. Nieboer*

* Dr Annalee Yassi, Occupational and Environmental Health Unit, University of Manitoba, Winnipeg, Canada

Dr Donna Mergler, Universitu Quc ontr (UQAM), Canada

Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada


Time: One 30 minute session, and one 2-3 hour block

Objectives:

At the end of the exercise, students will be able to:

1. Review the principles of risk management: assessment, perception, communication, reduction and prevention.

2. Encourage community participation in research projects and develop effective risk communication strategies.

3. Acknowledge the need for scientific data and cultural sensitivity in the formulation of occupational and public health decisions.

4. List the measures for mercury-containment and prevention of exposure.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 people). Instruct participants to identify a chairperson and a recorder. The students should define issues and distribute tasks before the 2-3 hour classroom session.

2. Distribute the exercise and review the participants’ tasks. It may be preferable to assign a certain number of questions to the group and then reconvene to ensure that all are proceeding well.

3. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

4. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 8), flip chart, coloured markers.

Case scenario

Gold mining in Brazil has been associated with a wide variety of concerns, especially contamination of the environment with mercury (Pfeiffer et al., 1993). Most of Brazil’s gold is produced by non-organized prospectors called garimpeiros. After gravimetric preconcentration, amalgamation is carried out by passing a water slurry of the ground ore over mercury-coated copper plates to which the gold particles adhere. Periodically, the gold-mercury amalgam is scraped off. The gold itself is recovered by heating, which is carried out by distillation in the local towns, in huts beside the river, or by driving off the mercury to the air by direct heating at river banks without any containment or personal protection. There are approximately 1 million garimpieros in the Brazilian Amazon, generating the release annually of about 130 tons of mercury to the environment; of this, it is estimated that 65-83% is released to the atmosphere and the remainder to soils or rivers (Pfeiffer et al., 1993).

Metallic mercury in the environment is transformed after oxidation into methylmercury by the activity of bacteria present in soil, sediments and suspended particulates in water. Organic mercury is highly assimilable into the trophic chains where it can be biomagnified a million-fold between initial transformation and the ultimate predatory species. (You will learn more about biomagnification in Chapter 7.) Fish with mercury concentrations exceeding the 0.5 mg/gm have been caught downstream from the gold mining area (Malm et al., 1990).

On the Tapajos river system where extensive gold mining efforts have focused (see Box 11.5 in the textbook), a physician working in the area became concerned. He was assessing the effect of mercury vapour on gold miners and his positive findings led him to wonder whether the communities living downstream of the gold mining activities might be at risk from methylmercury exposure. Both psychological and neurological symptoms are associated with chronic exposure to mercury vapour (IPCS, 1991). Acute inhalation results in interstitial pneumonitis. Mercury concentrations in whole blood reflect current and recent exposures to inorganic mercury (usually experienced as mercury vapour). The time required for the lowering of inorganic mercury in the blood compartment by a factor of 2 (t½) is 3 days, with a minor decay component characterized by t½ = 30 days. Methylmercury poisoning results in a neurological disorder called Minamata disease, which first occurred in the 1950s following mercury contamination of Minamata Bay, Japan (IPCS, 1990; see boxes 4.9 and 7.5 in the textbook). The exposure levels in that situation, however, were thought to be considerably higher. Total mercury level in hair and whole blood constitute good exposure indices to methylmercury. On average, the hair-to-blood concentration ratio observed is 250 (IPCS, 1990; Akagi et al., 1995). In both matrices, it is present primarily as the alkyl compound. National health agencies use 10-20 mg/g total mercury in hair (equivalent to 40-80 mg/L in whole blood) as the maternal concentration range for which some risk exists of neurological/developmental effects in neonates, with 6 mg/g in hair and 20 mg/L in whole blood as having no adverse effect or safe levels. For methylmercury, t½ values for its removal are 45-70 days for the whole-body, blood or hair compartments.

Queston 1. What do you know about mercury poisoning (refer to Chapters 2 and 9 if necessary).

It was brought to the physician’s attention that there was an agreement concerning environmental sciences between the Universidade Federal do Para and the Universitu Quebec ontr (UQAM). The Brazilian group was particularly interested in building up its expertise in this area and in establishing a laboratory capable of measuring mercury on a regional university campus.

IPCS (1990) and IPCS (1991) provide excellent summaries of the toxicology of methylmercury and inorganic mercury, respectively. The latter includes mercury vapour and mercurous and mercuric (Hg2+) salts. Briefly, mercury salts are corrosive and damage most tissues they come into contact with. When ingested and absorbed systemically, complex nephritis (i.e. kidney inflammation) results and the neurological effects resemble those of mercury vapour. Acute inhalation of mercury vapour results in severe pulmonary damage as well as kidney injury. Chronic effects produce weight loss, fatigue, anorexia and gastrointestinal complaints. As inorganic mercury poisoning progresses, three main effects are gingivitis, tremors and increased excitability (erethism). By contrast, Minimata disease due to exposure to methylmercury constitutes a progressive nervous system syndrome that involves: numbness and tingling of lips, tongue and distal extremities; loss of motor coordination with gait ataxia, tremor, loss of fine movement, muscular rigidity and even seizures; constriction of the visual fields, hearing loss, speech disturbances, coma, followed by death.

Question 2. What types of environmental and health assessment studies might be carried out? (Review Chapter 3 if necessary.)

The researchers decided to examine the origin, transportation and pathways of mercury poisoning and to look at indicators of health deterioration consistent with methylmercury exposure among riverbank populations.

Mercury levels in the air, soil, river and drinking water, sediments and aquatic organisms (especially fish) had to be assessed. Exposure of garimpeiros to mercury vapour could be assessed by whole-blood mercury levels and that of villagers to methylmercury by whole-blood and hair mercury. Speciation-specific analytical protocols are available to distinguish between total mercury and methylmercury contents in both these matrices. This distinction can be helpful in identifying the mercury source (i.e. whether exposure is to mercury vapour in the air or to methylmercury in fish). In the absence of overt clinical symptoms of mercury exposure, early indications of nervous system deterioriation using quantitative neurobehavioural and neurophysiological measurements constitute a sensitive health outcome.

Question 3. Should developed countries be involved in this sort of problem assessment?

A debate is suggested for this issue.

Question 4. What professionals (disciplines) should be involved? Who else should participate?

In March 1994, the research team principals (the physician, a neurotoxicologist, an environmental biologist, a cytogeneticist, a biogeochemist and an analytical chemist) met with the leaders and community health agents of two villages on the Tapajos River. The researchers proposed a public meeting to explain the objectives of the planned study to the villagers and emphasized that a limited number of the village’s 450 inhabitants would be selected for the human health component.

It is clear that an interdisciplinary team is required.

Question 5. What questions might the villagers have?

The villagers had the same questions that other exposed groups have. More specifically, they wanted to know who would inform them of the results and what solutions there might be. Of the 40 people asked to participate, 39 responded positively. None was working as a garimpeiro. A battery of tests designed to examine early changes in nervous system functions, consistent with our knowledge of methylmercury poisoning, were administered under standard conditions to provide quantitative measurements of nervous system dysfunction which could be examined with respect to hair mercury levels. Samples were taken from the soil, sediment, water, foliage and fish in order to identify the source of exposure.

Question 6. Should the details of the results be shared with villagers? How might this be achieved?

A year later, the researchers presented their preliminary results to the community health coordinators and village leaders. It was intended to ask advice from the local officials on how to present the results in the social and cultural contexts of the villagers (Wheatly, 1996). In a public meeting, the leaders were informed that, in spite of the small number of subjects studied, there were significant reductions in visual and motor functions that appeared to be related to the quantity of mercury in hair, which varied from 6 mg/g to 38 mg/g among the study group (geometric mean of 14 mg/g). More technically speaking, statistically significant correlations were observed between hair mercury levels and loss of colour discrimination capacity (p = 0.05) and manual dexterity (p < 0.01, females only) (Lebel et al., 1996). Convincing evidence was also obtained from colleagues at the Universidade Federal do Rio de Janeiro about the contamination by mercury of river water, soil, sediments and fish (Mal et al., 1990; Nriagu et al., 1992; Pfeiffer et al., 1993).

A role-play would help to define the villagers’ questions and risk communication issues. The cultural and social context needs to be addressed. The article by Wheatley (1996) might be helpful.

Question 7. Based on the information provided, estimate the dose (risk) ratio.

Although rather simplistic, the mercury hair levels might be compared with the no-effect, “safe” level (NOAEL): Dose (Risk) Ratio 2.3 ranging 1.0 to 6.3

Question 8. Should a follow-up study be planned? Should the villagers be part of this decision?

Given the positive results of the preliminary study the research team returned in March 1995 to plan a full-scale study of a larger cohort. They learned that in the intervening year other researchers from Japan, the United States and Europe had been there and had taken hair and blood samples and performed neurobehavioural testing on the children. The response to the UQAM Brazilian investigators was: “Why should we participate in yet another study?” “What will we gain from it?” “Foreign scientists come, take bits and pieces of us and never return!”

A follow-up study of a larger number of subjects is warranted in order to establish NOAELs with greater certainty. Neonates might also be more closely examined for developmental impairments. Since this goal involves the participation of the villagers, they need to be consulted. A role-play approach might again be helpful. (The full-scale study has recently been completed and has confirmed that visual and motor functions were indeed affected by methylmercury in a dose-related fashion.)

Question 9. What should the UQAM/Brazilian team say now?

The investigators explained that it is probably a good thing that several studies are being done in this area since if many studies show that there is a problem then actions can be initiated more rapidly. They informed the villagers that all the studies of their research group were carried out in close collaboration with the exposed populations and that this one would not be different.

Although one answer is provided, other arguments to justify the research might be considered. Have a debate!

Question 10. What might be some short-term solutions and what might they tell the community now?

The investigators discussed with the community feasible and realistic options for reducing mercury levels. They visited the homes of all participants and gave them the information on their hair mercury levels, answering questions and discussing solutions. On the last morning the teachers invited the investigators to address students to explain the study. “Where is the mercury?” asked the investigators. “In the fish!” the students answered. “And what can we do?” “Eat more fish that don’t eat other fish.”

Because of biomagnification, piscivorous fish may be expected to exhibit the highest methylmercury concentrations. This has been confirmed (Nriagu et al., 1992). The size of edible fish is another parameter that is considered in fish consumption advisories; not surprisingly, the mercury content increases with size or age. For example, in Cameron Lake in southern Ontario, Canada, walleye fish species up to 35 cm in length have no long-term restrictions on consumption since the mercury levels are <0.5 mg/g; for those of length 35-55 cm, intake should be limited to 0.2 kg/wk because mercury levels are between 0.5-1.0 mg/g; the limit is 0.1 kg/wk for lengths 55-65 cm, with average mercury concentrations of 1.0-1.5 mg/g; and no consumption is allowed at all for larger fish (mercury exceeds 1.5 mg/g).

Question 11. What occupational and environmental preventive measures might be implemented? Use the perspectives “at the source”, “along the path” and “at the person” in your deliberations. Environmental, biological and health effects monitoring, as well as alternative gold extraction procedures, should be considered.

(i) Containment at the source. Both the exposure of garimpeiros to mercury vapour and its release to the ambient air could be curtailed by improved containment during the amalgam heating stage. Obviously, the discontinuation of the direct heating procedure to drive off the mercury should be encouraged. Extraction procedures without amalgam formation are also possible, although they will bring their own environmental contamination concerns (e.g. extraction with cyanide; Cohn and Stern, 1994). Deforestation is also suspected of contributing significantly to the mobilization of mercury both from anthropogenic sources and present naturally in soils (see Box 11.5 of the textbook). This complicates containment strategies.

(ii) Containment along the path. Every effort needs to be made to prevent the contamination of soils, sediments and water with mercury. Mercury-rich tailings need to be processed further (e.g. extraction of mercury with cyanide) or disposed of in a manner that ensures containment and stability (e.g. through revegetation).

(iii) Containment at the target/person. Personal protection for the garimpeiros, such as a suitable respirator, may be needed even if the mercury distillation from the amalgam is contained. Portable air monitoring devices for mercury vapour are available to monitor exposure levels. It is unlikely that personal protection and environmental monitoring are realistic for the garimpeiros. Fish consumption advisories would help considerably in reducing methylmercury intake for the villagers, although this may not be realistic or socially acceptable.

Clearly, continuous environmental and biological monitoring are required to ensure the implementation of effective protective and preventive actions. Clinicians should be on guard for clinical evidence of exposure, especially in newborns.

Question 12. How is it useful to link occupational and environmental health here? (You may wish to review the section in Chapter 1 that addressed this.)

This case study demonstrates that industrial activity often contaminates both the work environment and the general environment. In such cases, occupational health and environmental health are inherently connected and so are the solutions. This heightens the need for hazard control and management. Although in the case considered the forms of mercury the workers and villagers were exposed to were somewhat different, there was enough overlap in health outcomes (e.g. nervous system dysfunction) for both types of exposures to be carefully documented in epidemiological studies.

Question 13. Is this problem a local one? Could it happen in developed countries? Is there a reason for global concern about mercury contamination?

A little literature research indicates that mercury contamination is a global problem. Volcanic activity, oceans and weathering of the earth’s crust (which is enhanced by acidification and flooding) are natural sources of mercury. The world wide oceanic output of elemental mercury is estimated at about 30-40% of the annual atmospheric Hg-emissions; microbial activity is primarily responsible by converting mercury ions (Hg2+ or Hg2+) to mercury vapour. Long-range transport has been established. These components of the mercury cycle explain the contamination of fish in lakes far-removed from industrial activity such as in northern parts of Canada where fish-eating native communities have been affected.

Learner, peer and problem evaluation

Formative evaluation

At the end of each session, but especially after the last one, allow participants to express their thoughts and feelings about their own participation and progress, as well as about the contributions and roles of the instructor/facilitator and fellow learners. Solicit comments about the approaches used (i.e. debate, role-playing, other). A written or oral evaluation concerning achievement of the stated objectives is also a good idea. Can the problem as presented be improved? How?

Summative evaluation

Devise a test, preferably incorporating a new problem scenario, to examine the learners’ knowledge, understanding and application of the new knowledge inherent in the study objectives.

Selected references

Akagi H, Malm O, Branches FJP, Kinjo Y, Kashima Y, Guimarases JRD, Oliveira RB, Haraguchi K, Pfeiffer WC, Takizawa Y, Kato H. Human exposure to mercury due to gold mining in the Tapajos River Basin, Amazon, Brazil: speciation of mercury in human hair, blood and urine. Water Air Soil Pollut. 1995; 80: 85-94.

Cohn JG, Stern EW. Gold and gold compounds. In: Kirk-Othmer encyclopedia of chemical technology, 4th ed., Vol. 12 (JI Kroschwitz, M Howe-Grant, eds.). New York, Wiley, 1994, pp. 738-767.

International Programme on Chemical Safety. Environmental Health Criteria No. 101. Methylmercury. Geneva, World Health Organization, 1990.

International Programme on Chemical Safety. Environmental Health Criteria No. 118. Inorganic mercury. Geneva, World Health Organization, 1991.

Lebel J, Mergler D, Lucotte M, Amorim M, Dolbec J, Miranda D, ArantG, Rheault I, Pichet P. Evidence of early nervous system dysfunction in Amazonian populations exposed to low-levels of methylmercury. Neurotoxicol. 1996; 17: 157-168.

Malm O, Pfeiffer WC, Souza CMM, Reuther R. Mercury pollution due to gold mining in the Madeira River Basin, Brazil. Ambio 1990; 19: 11-15.

Nriagu JO, Pfeiffer WC, Malm O, de Souza CMM, Mierle G. Mercury pollution in Brazil. Nature 1992; 356: 389.

Pfeiffer WC, Lacerda LD, Salomons W, Malm O. Environmental fate of mercury from gold mining in the Brazilian Amazon. Environ. Rev. 1993; 1: 26-37.

Wheatley MA. The importance of social and cultural effects of mercury on aboriginal peoples. Neurotoxicol. 1996; 17: 251-256.

(introduction...)

Prepared by Merri Weinger

Time: 2 hours

Objectives:

At the end of the exercise, students will be able to:

1. Define the purpose of community involvement in environmental health issues.

2. List three barriers to effective community involvement.

3. List three strategies for improving communication with the community about environmental health.

Procedures:

Community involvement questionnaire (20 minutes)

1. Ask students to complete a brief questionnaire which addresses attitudes to community involvement and obstacles to effective communication (Annex 8).

2. When students have completed the questionnaire, facilitate a group discussion about their responses. Ask for a show of hands as you read each statement and each response. Encourage volunteers with different responses to justify their response. As the instructor, try to avoid making a definitive statement about the “correct” attitude. Instead, encourage participants to consider all points of view.

3. Conclude with a discussion of the barriers to and benefits of community involvement. Write out a list of each on large pieces of paper.

Suggestions for involving the community in environmental/occupational health issues (20 minutes)

1. Define risk communication (i.e. the range of interactions with the community about environmental hazards and potential health risks.) Interactions may include: presentations or workshops, community meetings, advisory committees, telephone conversations, use of mass media, and written or audiovisual materials.

2. Review tips for involving the community and communicating more effectively about environmental and occupational health risks:

· Pay as much attention to the non-technical factors that influence how the community perceives risk as to scientific variables. (But don’t underestimate the community’s ability to understand the science.)

The risks that elicit public concern may not be the same as the ones that scientists have identified as most dangerous to health. For example, voluntary risks are accepted more readily than those that are imposed (e.g. an individual decision to smoke versus exposure to air pollution). Natural risks (e.g. earthquakes) seem more acceptable than artificial risks (e.g. from industrial sources). A chemical with a strong odour is perceived to be more hazardous than an odourless chemical.

· As far as possible, involve the community in the decision-making process on the environmental issues that affect them.

Involve everyone who has an interest in the issue.

· Listen to the community’s specific concerns.

Try to identify with your audience; put yourself in their place.

· Provide adequate background when explaining risk numbers.

- If you are explaining numbers derived from a risk assessment, explain the risk assessment process before you present the numbers.

- Make sure to show the routes of exposure using clear and simple graphics. Frequently, the issue is not whether a dangerous substance exists in relatively high quantities, but whether the routes of exposure put people at risk.

- Speak clearly and use simple, non-technical language.

- Always try to include a discussion of actions that are in progress to address an environmental health problem. Be sure to let people know what you can and cannot do.

3. Ask participants to add any suggestions that have not been mentioned.

Role-play and discussion of risk communication scenario (1 hour and 20 minutes)

1. Distribute risk communication scenario to the group. See sample risk communication scenario (section 4.3.2. at the end of this exercise).

2. Explain the exercise. Two students will play the role of agency representatives who will make a brief presentation to a community meeting about the health risks and plan of action of the agency. The other participants will play people attending the meeting. Brainstorm a list of potential attendees (government leaders, local residents, legislators, environmental group, press, chamber of commerce, etc.) and ask the group to anticipate the questions and concerns of each group.

3. Identify two volunteers who will develop and deliver a five-minute presentation to the community group to be followed by 5-10 minutes of questions from the audience. Volunteers leave and prepare their presentation (15 minutes).

4. During this time, the other participants select roles from among the list of potential attendees and formulate questions or comments for agency representatives (e.g. local resident: “What about our children? Do you have any plans for how they will be protected?”)

5. Identify two observers who will not assume roles, but will observe and evaluate the speakers on the basis of a list of criteria such as:

· Was the presentation clear and comprehensive?

· Did the speakers adequately address the audience concerns (especially the non-technical factors described above)?

· Was the “body language” appropriate (e.g. eye contact, posture, gestures)?

· Were you satisfied with the explanation of risk and the proposed plan of action?

6. When the volunteer speakers return, review the criteria which will be used for evaluating the meeting. Instruct the speakers to convene and run the meeting. Inform the team when the time for both the presentation and the question and answer period is over.

7. Following the “meeting”, discuss the strengths of the presentation and areas for improvement. Invite speakers to comment on their experience first, then observers, then open the discussion to the whole group.

8. Conclude by asking participants to state something they learned from the risk communication session that they might be able to apply if faced with a similar situation in the future.

Alternative

An alternative to conducting a community meeting (role-play) in the classroom is to analyse the scenario in small groups using a worksheet (Annex 11). The groups are then invited to share their responses in plenary.

Materials:

Student’s questionnaire (Annex 9), risk communication scenario, evaluation criteria on flip chart, coloured markers, tape.

4.3.1. Worksheet questionnaire: Introduction to risk communication

Question 1. Communicating with the public about health risks is more likely to unduly alarm people than keeping quiet.

Agree______

Disagree______

Why?

Communicating with the public about health risks may provide people with an opportunity to express their concerns, but not giving people this opportunity is likely to increase rather than decrease alarm. It is better to initiate communication with the public earlier (at the beginning of a health investigation) rather than later. In this way, a positive relationship between the agency (e.g. the Ministry of Health) and the public has a better chance to develop.

Question 2. We should not go to the public until we have solutions to occupational or environmental health problems.

Agree______

Disagree______

Why?

Problems can seem easier to deal with when coupled with solutions. But failing to involve people in decisions that affect their lives may result in tremendous opposition. People should be given background on the uncertainty of the science so that they do not assume that something is wrong if the agency does not know all the answers. The agency should explain what is being done to find answers.

Because people feel more comfortable about risks over which they have control, it is important to find ways to involve them in problem-solving on an environmental health issue. Encouraging community monitoring of the problem, as well as providing a contact person to call for information or to report problems, can help people exert more control over risks and thus feel more comfortable with them.

Question 3. The best way to determine which hazards or risk situations require scientific attention is to listen to those affected by the occupational or environmental problems (e.g. workers or community members).

Agree______

Disagree______

Why?

The affected community can be an important source of information when approaching an environmental pollution problem. Workers and community members have often been the first to identify a potential hazard in their environment and propose potential strategies for resolving the problem.

Question 4. Environmental health issues are too difficult for the public to understand.

Agree______

Disagree______

Why?

Environmental health issues can be very complex but, as demonstrated by citizen’s groups in many parts of the world, lay people can learn a great deal about technical topics that are of importance to them. For example, citizens have successfully organized themselves to call into question the construction of new, potentially polluting industries or hazardous waste sites in their neighborhoods.

Question 5. If we could explain risks clearly enough, people would accept them.

Agree______

Disagree______

Why?

Explaining risks clearly is important, but data are not the only factors which influence people’s perception of risk. For example, while scientists may discuss a low level of risk which is “acceptable”, the community may feel that no level of risk is acceptable. People may also be outraged that they must be subjected to a certain risk (e.g. industrial pollution) which is beyond their control. It is important to pay attention to these other factors when communicating with people about environmental health risks.

Question 6. I see risk communication as an important part of the environmental health specialist’s job.

Agree______

Disagree______

Why?

Although the environmental health specialist may be hired for another function, risk communication should be an important part of the job of anyone involved in both occupational and environmental health and public service. In the course of their work, environmental health professionals should be able to communicate effectively about potential health risks with a variety of groups and individuals (e.g. workers, community residents, representatives of government and industry, policy-makers and health professionals).

(Adapted from Hance, Chess and Sandman, Improving dialogue with communities: a short guide for government risk communication. Environmental Communication Research Program, Rutgers University, New Brunswick, NJ, 1988.)

4.3.2. Community involvement scenario

(Note: This scenario is based on a recent waste management assessment conducted by the World Health Organization Regional Office for Europe in two Romanian cities, Timosoara and Brasov. For the purposes of this exercise, data from both cities as well as other sites has been incorporated. The exercise has been adapted and used successfully in Jordan, South Africa and Thailand, indicating the relevance and timeliness of landfill siting issues around the world.)

Timosoara is a medium-sized city in the western part of Romania. It is an important border crossing to the former Yugoslavia. The municipality of Timisoara plans to construct a centralized solid waste landfill for use by city residents and suburban settlements. Currently, solid waste is being disposed of in an open landfill together with street and commercial waste, industrial waste (hazardous and non-hazardous) and hospital waste.

Plans for the new site emerged from a study which found that the current site poses a series of environmental health risks. It is inadequately located near urban dwellings; is not equipped with the necessary facilities such as bottom liners, drainage system, fencing and monitoring walls; is overloaded; and allows for the co-disposal of domestic waste with industrial hazardous waste and for the disposal of new materials and chemicals that are not biodegradable, are persistent in the environment or whose behaviour in the environment is unknown.

The proposed new landfill is close to the highways and would serve approximately 50% of the population. Since the siting of this new landfill is extremely controversial, the municipality of Timisoara has called a meeting with representatives of the community to address the concerns about the proposed new facility. At the meeting, you will represent the municipality. Your job is to inform the community about the utility of the proposed new landfill, explain potential health risks and anticipate and address any other concerns.

What follows is a list of the arguments supporting and opposing the construction of the facility which may be raised at the meeting.

Arguments supporting the solid waste landfill (agency perspective)

1. The site is accessible to major urban centres and suburban settlements for their solid disposal needs, yet distant from residential areas. (The closest population centre is 2 km from the site.)

2. The site is a pre-excavated pit which was formerly a clay extraction area for a brick factory. The pit is ideal for a disposal site since this land is otherwise unusable. The former excavation also provides an abundance of soil for lining the landfill and covering the layers of waste. The soil contains more than 70% silt and clay in the proper combination to prevent leakage into groundwater.

3. The site has a supportive climate with an evaporation rate which almost doubles the rainfall in the area.

4. Smells from the site will be minimized by covering the garbage with soil daily, by constructing a fence around the site to prevent wind and by planting trees in the area.

5. The site will be closely regulated, including periodic sampling of groundwater. Any leachate will be handled using the latest mechanical and scientific interventions. In addition, the site will be staffed for 16 hours a day to prevent improper dumping.

6. Alternative sites are not feasible due to the high costs of land purchase or the high cost of transport to remote areas.

7. If this centralized facility is not constructed, each community will construct its own facility (in as many as 17 sites), multiplying the potential for environmental pollution close to population centres.

Arguments opposing construction of the solid waste landfill (community perspective)

1. The site is too close to population centres - just 2 km away.

2. The land for the proposed site is the subject of litigation between Sag commune and Timosoara city. Members of Sag commune feel that the land should be returned to them.

3. The site will smell bad - just like the old landfill.

4. The site will pollute the groundwater.

5. Nearby landowners are concerned that they will never be able to sell property in the vicinity of the landfill. Their property will be worth nothing.

6. The scavengers who live around the old landfill oppose the construction of a regulated site. They earn their livelihood by collecting and selling discarded aluminum and metals from the old site. With a regulated site where open entry is prohibited, how will they live?

5.1. Problem-solving exercise: Epidemic asthma

1 From: Problem-based training exercises for environmental epidemiology. Geneva, World Health Organization, 1998 (revised version, Document WHO/EHG/98.1)

Prepared by: Ruth A. Etzel*

* Dr Ruth A. Etzel, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA

Time: 3 hours

Objectives:

At the end of the exercise, students will be able to:

1. Develop a case definition.
2. Interpret descriptive data.
3. Construct histograms.
4. Plot the distribution of cases.
5. Construct 2x2 tables.
6. Calculate risk ratios (odds ratios).
7. Identify intervention strategies for prevention of epidemic asthma.

Procedures:

1. This is an unfolding exercise designed to mirror the real-life conditions of an environmental health practitioner in the field. Students are asked to analyse the information as it becomes available and to draw conclusions. Students should be instructed to work page by page and not to look ahead. Sessions for reporting back may take place after a series of questions or at the conclusion of the entire exercise.

2. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 people). Instruct participants to identify a chairperson and a recorder.

3. Distribute the exercise and review the participants’ tasks.

4. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this format until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 12), flip chart, coloured markers.

Case scenario, Part I

Barcelona is a city of 1.7 million situated on the Mediterranean Sea.

During the last week of January 1986, several physicians contacted public health authorities to report an increase in the number of persons who had come to the emergency rooms of the four large urban hospitals seeking medical care for acute severe asthma. Specifically, on Tuesday 21 January 1986 a total of over 130 people had sought care at these hospitals for difficulty in breathing. Most of these people were thought to be suffering asthma attacks. The attacks struck very suddenly and caused such severe problems that 10% of the patients required ventilatory support and 2% died.

Question 1. What is asthma?

Asthma is a noncontagious disease of the lungs in which reversible obstruction of the airways occurs. It is characterized by coughing, wheezing and difficulty in breathing, often preceded by inhalation of dusts or other allergens. The lungs are typically normal between attacks.

Question 2. Is this an epidemic of asthma? What further information do you need?

The presence of an epidemic cannot be determined without knowing the background rate of an illness and whether alterations in the surveillance system have occurred recently. Review the definition of an epidemic: “The occurrence in a community or region of cases of an illness, specific health-related behaviour, or other health-related events clearly in excess of normal expectancy”.

In field investigations, assume that epidemics noticed by clinicians are real epidemics until proven otherwise.

Question 3. Review of the hospital records reveals that the four hospitals treated 288 persons with asthma during January 1986. Now can you determine if this is an epidemic?

Not yet. You will need to get more information about the number of emergency room visits for asthmatic symptoms during the past few months.

Question 4. Develop a preliminary case definition.

A case definition is not rigid; it can be refined as more information is obtained. A case definition should specify person, place and time. The narrower the criteria, the fewer the cases that will be identified; the looser the criteria, the more likely it is that some of those considered to be cases may turn out to have other diseases.

The following case definition was developed:

“A case of asthma is a person over 14 years of age who came to one of the four hospitals emergency rooms with wheezing, coughing or difficulty breathing who was diagnosed by a physician as having asthma, asthmatic bronchitis, spastic bronchitis, bronchial hyperactivity, asthmatic status or bronchospasm.”

Table 1. Number of persons over 14 years of age who presented with acute asthma to the city’s four hospital emergency rooms in the previous year (1985).

Month

Number

Month

Number

Month

Number

January

199

May

165

September

181

February

146

June

128

October

166

March

180

July

138

November

182

April

155

August

124

December

147

Question 5. Do you now have sufficient information to determine if there is an epidemic of asthma?

The number of cases (288) seen in January 1986 is clearly in excess of normal expectancy. This indicates that there was an epidemic of asthma in January 1986.

Table 2. Number of persons over 14 years of age who presented with acute asthma to the city’s four hospital emergency rooms in January 1986.

Day

Number

Day

Number

Day

Number

Day

Number

Day

Number

1

5

8

9

14

6

20

11

26

8

2

8

9

7

15

7

21

96

27

8

3

8

10

9

16

6

22

9

28

7

4

5

11

9

17

7

23

4

29

3

5

5

12

5

18

4

24

0

30

8

6

4

13

8

19

9

25

8

31

2

7

4









Question 6. Using the attached graph paper, draw a bar chart of the data tabulated above in Table 2. What additional information does the bar chart provide?

The shape of the bar chart suggests an outbreak with a common source. The epidemic appears to be at its peak on January 21 (Figure 1).


Figure 1. Number of persons seeninemergency rooms during January with acute asthma, Barcelona, 1986

Question 7. What other information would be useful to characterize the epidemic?

Person

- age, sex

Time

- time of day

Place

- where asthma attack occurred; hospital emergency room.

Question 8. On the attached city map, using dots, show the geographic distribution of the place of onset of illness (Table 3) for the 96 persons who came to the emergency rooms with acute asthma on 21 January. What does this distribution suggest?

This distribution (Figure 2) suggests that persons became ill with asthma predominantly in Region 1 and Region 2 of the city, assuming that the populations of the regions are roughly equal.


Figure 2 - City Map

WHO98125

Question 9. Using the attached graph paper, draw a bar chart of the cases by hour of occurrence (Table 3). What hypotheses are suggested?

This distribution suggests that onset of the illness peaked between 11:00 and noon. Most persons reported onset between 10:00 and 16:00 (Figure 3). The fact that attacks tended to occur around midday suggests that the causative factor could derive from daytime activities (e.g. wharf loading).

Table 3. Data regarding age, sex, time and place of onset of illness, for each of the persons who came to the emergency room with acute asthma on 21 January 1986.

Age

Sex

Time of onset

Place of onset(Region)

41

F

10:55

4

28

M

12:50

2

27

M

13:40

2

40

F

12:00

3

30

F

13:25

2

19

F

02:20

3

17

F

11:05

2

40

M

17:15

1

28

M

13:50

2

49

M

17:10

1

47

F

14:30

1

29

M

11:10

2

28

F

14:30

2

38

M

11:35

1

49

F

18:20

3

59

M

22:10

6

39

M

11:25

1

40

M

11:05

1

59

M

21:20

3

41

M

11:08

10

10

M

23:15

7

27

F

12:05

2

27

M

12:40

2

20

F

09:25

8

27

M

11:40

2

18

F

12:30

2

30

M

12:15

2

48

M

16.50

2

30

F

12:25

2

29

F

13:20

2

37

M

12:17

1

38

M

12:35

1

39

M

12:25

1

40

M

12:05

1

37

F

11:30

1

41

M

12:08

10

40

M

19:15

6

37

M

10:17

1

38

M

10:35

1

38

F

10:45

1

39

F

10:25

1

39

M

10:25

1

40

M

10:05

1

15

F

23:25

6

18

M

00:50

3

70

M

15:15

2

18

F

00:30

7

50

M

11:15

2

40

M

10:00

3

41

M

10:08

10

28

F

13:30

2

48

F

16:30

1

29

M

13:10

2

30

M

13:15

2

27

F

14:05

2

57

M

14:40

2

28

M

14:50

2

30

F

11:25

2

29

F

14:20

2

29

M

14:10

2

50

M

14:15

2

30

F

14:25

2

41

M

12:55

4

40

F

15:25

2

57

F

15:05

2

47

M

15:40

2

58

M

15:50

2

41

F

11:50

4

48

F

15:30

2

69

M

15:10

2

40

F

15:25

2

27

F

13:05

2

47

M

16:50

2

89

M

12:10

2

49

F

15:20

2

29

F

12:20

2

19

F

17:20

1

67

F

12:30

1

40

F

17:25

1

29

F

11:20

2

78

F

11:30

2

68

M

12:45

1

19

F

12:25

1

38

M

18:50

1

48

F

18:30

10

37

M

11:17

1

49

M

19:10

3

38

F

11:45

1

40

F

19:25

7

59

M

11:25

1

60

M

11:00

3

19

M

05:10

3

20

M

06:15

8

47

M

15:30

1

67

M

16:40

2

28

M

11:50

2


Figure 3. Hourly distribution of admissions

Case scenario, Part II

In your discussions with emergency room personnel, you learn that this is not the first time that the hospitals have been overwhelmed with patients suffering from acute asthma attacks. You are told that “asthma epidemic days” have occurred on 12 other occasions during the past two years.

Noting the clustering of asthma emergency room visits in space and time, you request data on air pollution in the city during the past two years. For Tuesday 21 January, air pollution levels were below normal for the city. The 24-hour average level of sulphur dioxide was 54 mg/m2 and that of black smoke was 98 mg/m3. The highest hourly mean for nitrogen dioxide was 10 ppb. Twenty-four hour pollen and spore counts were also below average for that time of year. Meteorological data showed high atmospheric pressure and stagnancy of the air with very low wind speed.

Question 10. What conclusions can you draw from this information?

Since the number of cases of asthma on 21 January was so extraordinary and the air pollution levels were certainly no higher than normal (indeed, below normal), it is reasonable to conclude that these air pollutants were not the cause of the asthma epidemic.

Since many persons reported that they were affected in the centre of the city, near the waterfront, you decide to find out more information about the activities there. You learn that the following eight products were loaded or unloaded from barges and boats in the harbour during the past two years:

coal

cotton

gasoline

soybeans

fuel oil

coffee

corn

butane.

Question 11. How would you use this information to further explore this problem?

You might consider looking at whether any of these products were being loaded or unloaded on 21 January 1986.

You ask for the dates on which each of these products were loaded or unloaded from barges or boats. This information is shown in Table 4.

Table 4


Days product is handled
(Loaded or unloaded)

Days product is NOT handled
(Loaded or unloaded)


Asthma epidemic days

Asthma epidemic days

Product

NO

YES

NO

YES

Coal

196

4

521

9

Fuel oil

150

3

567

10

Gasoline

180

2

537

11

Cotton

399

7

318

6

Coffee

300

5

417

8

Corn

135

1

582

12

Soybeans

249

13

468

0

Butane

140

1

577

12

Question 12. Using the information in Table 4, complete the tables on the following pages and calculate the risk ratios. Optional: calculate the confidence interval (C.I.) for each table, using the formulas presented in class discussion. Also, the computer software EPIINFO may be demonstrated to calculate confidence intervals.

See attached sheets for calculations (Figure 4).

Question 13. How do you interpret the risk ratios and confidence intervals you have calculated?

There is a strong association between epidemic asthma days and the loading or unloading of soybeans from barges or boats. Note that the confidence intervals for all the other products overlap 1, which indicates that they showed no statistically significant association with epidemic asthma days.

Question 14. Now substitute a 1.0 for the 0 in cell B (soybeans) and re-calculate.

The second calculation indicates what the magnitude of the relative risk would have been if there had been at least one asthma day when no soybeans were unloaded. Actually, asthma days occurred only on the days soybeans were unloaded, resulting in a 0 in the B cell of the 2x2 table. This illustrates that when one cell of a 2x2 table contains a zero, it is not possible to define (i.e. to quantify) the risk ratio, although in this case it was unquantifiably high.

Question 15. How would you proceed from here?

It would be useful to make a visit to the waterfront to observe the loading and unloading of soybeans from barges and boats. Does this activity occur near Region 1 and Region 2 of the city? Does it occur at the middle of the day? How could the cases have been exposed to the loading or unloading activities?


Figure 4. Risk ratios and confidence intervals based on Table 4.

Risk Ratio and 95% C.I. calculations were made using the EPI INFO software package, Version 5. USD, Inc., Stone Mountain Georgia, USA, 1990.

95% C.I. are exact confidence intervals.

Case scenario, Part III

Question 16. Develop a strategy for prevention of asthma epidemics in the city.

Once you have determined the route of exposure of the persons with asthma to the loading or unloading of soybeans, you can take appropriate measures to reduce that exposure. Since the soybean exposure emanates from a single source, an engineering solution should be feasible. You should ask the companies responsible for loading and unloading to reduce the amount of soybean dust which is released into the air during the process. A bag filter at the top of the silo may be a very effective way of accomplishing this.

Question 17. How would you assess the costs of this prevention strategy compared to the costs of the emergency visits for asthma attacks?

You could find out the costs of the new bag filters and compare that to the costs of emergency room treatment, including days lost from work, hospitalization and drugs.

Based on: Anto JM et al. Community outbreaks of asthma associated with inhalation of soybean dust. New England journal of medicine, 1989, 320(17): 1097-1102.

For further study of methodology for epidemiologic studies of asthma, the following review article is recommended: Anto JM, Sunyer J. Epidemiologic studies of asthma epidemics in Barcelona. Chest, November 1990 (supplement): 185s-189s.

5.2. Problem-solving exercise: AECI/MACASSAR sulfur fire

Prepared by Stuart A. Batterman*

* Dr. Stuart Batterman, Department of Environmental and Industrial Health, School of Public Health, Ann Arbor, Michigan, USA

Time: Three 3-hour sessions

Objectives:

At the end of the exercise, students will be able to:

1. List the steps in planning and coordinating responses to emergencies.

2. Demonstrate the use of air quality standards, environmental monitoring and modelling techniques (optional) in coordinating emergency response strategies.

3. Recognize the social and legal dimensions of public health decision-making.

Procedures:

(Note to instructor: Parts 1 and 2 of this exercise would be appropriate for university students in a variety of environmental health specialty areas. Part 3, which involves dispersion modelling techniques, would be most appropriate for engineering students. The exercise can still be effectively used if Part 3 is deleted.)

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 people). Instruct participants to identify a chairperson and a recorder.

2. Distribute the exercise and review the participants’ tasks.

3. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

4. Summarize the results, emphasizing key messages. The decision to proceed to Part II should be made jointly by the students and instructor.

Materials:

Problem-solving exercise (Annex 13), flip chart, coloured markers. Reference documents for classroom review.

Case scenario, Part I

After several days of brush fires in the vicinity, a huge stockpile of sulfur caught fire late on a Saturday afternoon. The stockpile site belonged to AECI, the largest manufacturer of chemicals and explosives in South Africa.

Due to strong and persistent winds, the fire cannot be extinguished and a total of about 7000 tons of sulfur has already burned. While the fire site is several kilometres away from large population areas, the township of Macassar (population 40,000) is 2.5 km downwind, and many suburbs of Cape Town (population 1.5 million) are 10-30 km distant. From about 21:00 on Saturday to 01:00 on Sunday morning, the most intense period of burning, the prevailing winds blow to the west-north-west.

Symptoms among residents in the vicinity of Macassar increase in prevalence and intensity up to midnight and beyond. Residents, mostly black, working class and poor, report a number of irritative effects (e.g. burning and irritation of eyes, nose and throat, coughing, shortness of breath, chest pain, stomach cramps and vomiting). Figure 1 shows the general area


Figure 1. Map showing portions of Western Cape Province.

The smaller inset map shows a 6 km × 6 km region near the fire. “F” = fire site; “M” = sites of existing continuous SO2 monitoring instruments; heavy dots = farms visited after the fire to investigate vegetative damage; shaded areas are mountains and/or nature preserves.

Question 1. What happens when sulfur burns? What are appropriate protective levels for the resulting toxic gases? Can occupational and ambient air standards be used?

When burned in air, most sulfur will be oxidized to sulfur dioxide (SO2). Guidance and standards for SO2 have existed for many years, and exposures to low levels of SO2 are common and generally well understood. SO2 is emitted during combustion of fossil fuels that contain sulfur (e.g. by coal and oil power plants, steel mills, refineries, smelters). Low levels of SO2 can constrict air passages in the lungs and cause asthma attacks. At higher levels, SO2 affects breathing, aggravates existing respiratory and cardiovascular diseases, especially for asthmatics, individuals with bronchitis or emphysema, children and the elderly. Still higher concentrations can result in skin and eye irritation, and even death.

Table 1 shows several potentially applicable standards or benchmarks for SO2 exposures. The USA has three health and welfare based standards that are part of the National Ambient Air Quality Standards: an annual arithmetic mean of 0.03 ppm (80 ug/m3); a 24-hour level of 0.14 ppm (365 ug/m3); and a 3-hour level of 0.50 ppm (1 300 ug/m3). The first two standards are primary (health-related) standards, while the 3-hour NAAQS is a secondary (welfare-related) standard. The annual mean standard is not to be exceeded, while the short-term standards are not to be exceeded more than once per year. Recently, an “intervention level” standard has been proposed to deal with high short-term SO2 levels. Using five-minute averages, the programme establishes a “concern level” of 0.6 ppm and an “endangerment” level of 2 ppm (2 January 1997, US Federal Register). These very short-term levels are established as protective of asthmatics engaged in mild physical activity. Table 1 shows WHO guidance levels. These are lower than US standards and guidelines.

It is important to realize that the SO2 dose and resulting health impacts of an exposure depend on both concentration and exposure time. While considerable variability exists, the ambient standards indicate that levels where health effects may occur in sensitive populations are about 0.1 ppm for 24-hour averages, and 0.1-1 ppm for 1-hour averages. One-hour concentrations of 10 ppm are highly irritative; concentrations of 100 ppm (the level immediately dangerous to life and health, or IDLH) may cause a rapid death.

Note that occupational levels are higher than environmental levels and are designed for healthy and possibly adapted workers, not for the general public.

Table 1. Summary of SO2 standards and guidelines.

Type

Standard or guideline

Average

Concentration

Ambient

WHO guideline

24 hour

0,06 ppm

WHO guideline

1 hour

0,16 ppm

WHO guideline

10 min.

0,24 ppm

Ambient

US NAAQS

Annual

0,03 ppm

US NAAQS

24 hour

0,14 ppm

US NAAQS

3 hour peak

0,50 ppm

US EPA intervention level “concern”

5 min

0,60 ppm

US EPA intervention level “endangerment”

5 min

2 ppm

Emergency

IDLH

30 min

100 ppm

Occupational

NIOSH/OSHA STEL

15 min

5 ppm

ACGIH/TLV-TWA

8 hour

2 ppm

Question 2. What immediate steps should be taken to protect public health? What would you recommend?

Some possible responses might include:

- step up fire-fighting efforts (although in the case scenario the maximum effort was already being expended);

- implement means to communicate with residents (few had telephones, and at late hour, messages on radio or television would be ineffective; the township eventually resorted to knocking on every other door);

- suggest that people stay indoors and close windows (however, many people live in shanty towns and probably cannot seal their homes; also, this strategy will not work if the plume stays overhead for an extended time as gases will eventually enter the house);

- plan an evacuation route and coordinate with medical, emergency, public safety and other personnel;

- notify medical personnel and begin establishing emergency clinics nearby, but in a safe area;

- notify emergency responders and begin assembling safety, respiratory and personal protection equipment; notify police;

- evacuate susceptible residents (e.g. children, asthmatics, pregnant women, etc.);

- evacuate all residents (few residents own cars, so buses would be required; about 800 bus trips would be required for all 40 000 residents, so 50-100 buses would be needed to accomplish the evacuation within several hours;

- halt traffic on major roads crossing the plumes.

Question 3. What information is needed to assess the situation and confirm your decision?

Necessary information includes:

- the direction of the wind and the plume from the fire;

- the number of people downwind of the fire;

- the exposures or concentration expected in populated areas, based on monitoring or predictions (well-established means exist for monitoring SO2, ranging from relatively sophisticated real-time instruments to simple colorimetric “Draeger” tubes);

- evaluation of the likelihood and significance of exposures and health effects (SO2 is one of the best understood air pollutants and standards are commonly available; even so, there is little experience with short but extremely high exposure levels).

Case scenario, Part II

On early Saturday evening, residents of Macassar were told to stay indoors and to close doors and windows. Due to high winds (8-12 m/s), fire-fighting efforts were ineffective and the fire intensity increased. Macassar was directly downwind. Because the wind direction did not vary from about 20.00 to 01.00 in the morning, concentrations in even well sealed homes increased and exposures were prolonged. Residents began to experience increasingly intense discomfort, eye and skin irritation, breathing difficulty, gastrointestinal cramps and respiratory distress. Shortly after midnight, an evacuation of the town was attempted in a chaotic operation. Between 3000 and 5000 residents were moved to a shopping mall in Firgrove about 5 km distant. Most left after midnight. Despite this effort, approximately nine deaths occurred, including two men (both asthmatics) driving in opposite directions along a highway. In addition, between 1000 and 2000 people visited emergency respiratory clinics that were set up soon afterwards near the affected community, and approximately 15 people were later diagnosed with chronic asthma-like respiratory disease. The chemical company sponsored several emergency actions, including setting up local clinics where some health services (e.g. spirometry) were provided in the days and weeks after the fire.

Question 4. What information, if any, should be obtained from evacuees?

- Basic information (e.g. name and residence) is essential.

- Information that might show the dose (e.g. time leaving the area, time spent in the area, any actions taken, type of house, etc.) is important.

- Symptom data (e.g. check for burning eyes, burning throat, cough, wheeze, shortness of breath, vomiting, anxiety, fainting, fear) is also important.

- Note that the distress of evacuees, the late hour of the night, poor planning, limited resources and general ensuing chaos is likely to hamper data collection efforts, and most information may best be collected in community in the next few days.

- Follow-up checks might investigate the persistence (one day, one week, one month, etc.) of nose, throat, chest or stomach problems.

Question 5. What concerns might you have for the health of the evacuees?

The mental health concerns might be considerable. These may include problems stemming from fear of what may happen to their homes and possessions left behind, fear for their own health and the health of family members and friends, and the effects resulting from social, emotional and possibly economic disruption of their lives due to evacuation. Issues such as the conditions of their temporary accommodation should be explored, including sanitation and privacy. Particular attention should be paid to the children. The physical health concerns are more obvious, but should also be discussed.

Question 6. How might company sponsorship of the clinics affect their credibility and utilization?

- Diagnosis and damages may be based on clinic records, and the company has interests in limiting claims against it.

- Oversight by government health officers is necessary to provide independent assessment of impact.

- For a variety of reasons (including poverty, little education, lack of political power), Macassar is medically underserved and the health status of residents appears substandard. Thus, health records of pre-existing conditions are minimal.

- A complex issue is case-finding. Essentially, residents were self-referred to the clinic. Thus, most persons visiting the clinic experienced health problems during or after the fire. While many visits were made to the clinic, there was no baseline or reference level of health status in the community. As a consequence, only the most severe cases of respiratory dysfunction were attributed to the fire. Also, because spirometry lung function tests could not be performed reliably with children, no childhood diagnoses of fire-related impact were made.

Case scenario, Part III

In the days and months following the fire, a moderate amount of sampling and analysis was performed to investigate impacts related to the fire. Many residents suffering symptoms made repeat visits to local clinics. Symptom information was collected for about 1000 individuals, and spirometry was done on several hundred. Additional analysis was focused on ecological impact (e.g. impact on vineyards some 10-25 km distant).

Approximately one year later, the duration and extent of exposures on the nearby population were estimated using dispersion modelling. Using the best available data, air concentrations were predicted for each hour of the fire. Figure 2 depicts a Gaussian plume model imposed on a photo of the fire taken on Sunday morning (winds had considerably decreased and much of the fire was out by this time). The plume has Gaussian profiles, depicting the spread of pollutants in the crosswind and vertical dimensions.

Some of the dispersion model results are displayed in Figure 3 using “isopleths” or lines of equal concentrations (like contour maps). The maximum one hour concentration ranged from about 10 to 200 ppm, and much of the area was exposed to 100 ppm for one hour. Thus, levels appear to have approached or exceeded the IDLH value. Firgrove (where Macassar evacuees were accommodated) was in a relatively low concentration area. Note that the maximum hourly concentrations are not necessarily coincident in time, i.e. one cannot tell from the map what hour the exposure occurred. The second highest hourly concentrations ranged from 10 to 40 ppm, and the 24-hour averages were from 1 to 15 ppm. These estimates indicate that concentrations in the Macassar community exceeded by 20-1000 times levels designed to be protective of health.


Figure 2. Depiction of the plume resulting from the fire.

The plume width and plume height follow Gaussian curves which are adjusted in practice (but not in the figure) to match characteristics of the fire’s plume. Such models allow concentrations to be estimated at many locations.


Figure 3. Isopleths showing the maximum 1 hour SO2 concentrations in ppm in the Macassar area.

The modelled area is 6 x 6 km, with the sulfur fire located in the south-east corner and designated “F”. The complex pattern results from wind shifts over the fire; most of the time, winds blew to the west-north-west.

Question 7. What is air quality dispersion modelling? What information is required?

- Air quality dispersion models are mathematical tools used to predict air concentrations and other impacts resulting from pollution sources. Such models have a long history and broad use. They are suitable for predicting ambient air quality concentrations, surface depositions and other results from various types of emission sources over a range of distance scales (50 m to 100 km or more) and many time scales (short-term to annual average). Many models can be run on a personal computer or laptop, and many are based on a Gaussian plume formulation, as shown in Figure 2.

- The basic inputs to dispersion models include source information (e.g. emission rate, temperature), surface meteorology (e.g. wind direction, wind speed), upper air data and site information.

Question 8. How can a modelling analysis be used?

- In this case, the model is run after the event to estimate concentration of the substance in the air and the numbers of people affected.

- The modelling can help identify individuals who were highly exposed for further follow-up.

- Modeling results can be used to help design a case-control study, where health outcomes of exposed individuals are compared to those of unexposed individuals. Model predictions would be used to determine concentrations. Clearly, monitoring would be preferable, given the uncertainties in modelling (see below), but this is the best that can be accomplished for the AECI fire. Note the difference between case-finding using the suggested case-control approach, and that accomplished at Macassar where self-referred visits to the clinic were used.

- There are several very user-friendly models like “ALOHA” or “CAMEO” which can be used in an emergency and are designed for first-responders. This would have been very helpful at Macassar to show zones which should be evacuated. Fire-fighters and others may be trained to use these models.

Question 9. What are some of the uncertainties in dispersion modelling and the exposure assessment? What data would be useful?

Many exposure assessments have been performed, and many knowledge gaps and questions can be anticipated, as follows.

- The identification and quantification of the emission rates in a fire are poorly quantified. Still, errors are unlikely to exceed 50%.

- The meteorology may be complex and include large wind shifts. The use of valid onsite short-term meteorological data to support air quality impact analyses is necessary. It is best to have local data. Most of the data used came from Cape Town airport, about 20 km distant. Substantial wind shifts in mountainous and coastal areas are expected.

- There were limited demographic, activity and health data on the affected community (e.g. population density, housing characteristics like air exchange rate, and activity patterns like time outdoors). Staying indoors and keeping windows closed during the fire probably decreased exposures by 25-75% due to limited air exchange rates.

- There was very little monitoring during the fire. Two SO2 monitoring stations existed at Bothasig and Table View, 33 and 38 km north-west of the fire site and near oil refineries (see Figure 1). These instruments went “off-scale” for several minutes when the SO2 plume reached them; Bothasig at 2.5 ppm and Table View at 1.4 ppm. These concentrations were reasonably matched by the model predictions, helping to confirm model assumptions. Onsite monitoring might have been possible.

- There are data gaps in our knowledge about adverse health effects from specific hazardous substances. Sometimes, indirect exposure pathways may present significant risks from chemical emissions, although inhalation is likely to be the primary concern for the fire’s episodic SO2 release. More significant here, however, is the lack of knowledge regarding brief, but very high exposures to SO2.

Selected references

Documentation of the threshold limit value, 4th ed. Cincinnati, OH, American Conference of Governmental Industrial Hygienists, 1980, pp. 377-378.

Batterman S. An Evaluation of SO2 concentrations resulting from the AECI Fire. Report to the Legal Resources Centre, Cape Town, South Africa, 26 Jan. 1997.

Industrial Source Complex Dispersion Model, version 93109. US Environmental Protection Agency Research Triangle Park, NC, 1993.

Nappo C J et al. l982. The workshop on the representativeness of meteorological observations, June l98l. Bull. Amer. Meteor. Soc. 1982, 63(7):761-764.

Newhouse MT, Dolovich M, Obminski G, Wolff RK. Effect of TLV levels of S02 and H2504 on bronchial clearance in exercising man. Arch. Environ. Health 1978, 33:24-32.

On-Site meteorological program guidance for regulatory modeling applications. US Environmental Protection Agency, Research Triangle Park, NC, June 1987, revised 1996.

White N. A survey of the health effects on helderbug community of smoke exposure from a sulfur fire. Cape Town, University of Cape Town, 1996.

6.1. Problem-solving exercise: Water for Tonoumassť, a village in Togo

Prepared by Evert Nieboer and Annalee Yassi*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Dr Annalee Yassi, Occupational and Environmental Health Unit, University of Manitoba, Winnipeg, Canada

Adapted with permission from Water for TonoumassCarleton (Ontario, Canada); Local Committee of CUSO

Time: Two 1-hour sessions

Objectives:

At the end of the exercise, students will be able to:

1. Define health, according to the WHO definition; describe the basic needs for human survival, the relationship between environmental factors and health, the significance of clean water as a determinant of health, the obstacles to resolving environmental problems, the nature and extent of waterborne diseases, and the major sources of water contamination.

2. Endorse or develop a holistic view of health and environmental health; appreciate gender tolerance and religious, cultural and social sensitivities; distinguish between community and individual rights, views and initiatives.

3. Appreciate the need to empower the community to recognize, define and resolve significant environmental health problems through teamwork, community spirit and individual responsibility and effort; promote public education about the link between safe water and good health.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. The case scenario has two parts. Both parts are followed by questions related to the material covered in Chapter 1 and Chapter 6 of the text. Distribute Part I and review the participants’ tasks.

3. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

4. Summarize the results, emphasizing key messages. The decision to proceed to Part II should be made jointly by the students and the instructor.

Materials:

Problem-solving exercise (Annex 14), flip chart, coloured markers.

Case scenario, Part I

Togo is a long and narrow country in Africa that stretches 580 km north from the Gulf of Guinea. It is flanked by Ghana on the west and Benin on the east. It has an average rainfall of 100 cm/year which is considerably less than that received in other tropical areas. The United Nations classifies Togo as a “least developed country”. Tonoumasss a village of about 100 inhabitants located 50 km or so north of the coastal capital of LomThe surrounding area is a mixture of forested land (teak, mahogany, bamboo) and agricultural land (small farms growing coffee, cacao and cotton). Regionally, about 18% of the people have access to safe drinking-water. Fetching water is considered “women’s work”. Women spend 1-4 hours daily in the wet season (March to July) and as much as 8 hours in the dry period (December to March) in walking the 15 km to the nearest river. While there, they wash the family’s clothes and carry about 15 litres of water back to the village. Housework, child care, farming and handicraft production/sale needs to be taken care of after arriving home about midday. The water they collect is rarely safe. Drinking it can lead to a parasitical disease caused by the guinea worm, as well as typhoid, hepatitis, schistosomiasis, dysentery and other intestinal infections. As a result, up to 40% of the children die before the age of five. Those that survive miss a lot of school because of chronic illness. The ability of adults to work is also affected by parasitic disease and repeated infections. Not surprisingly, back ailments are prevalent among women.

Chapter 1 Questions

1. Meeting human survival needs is consistent with the UN Universal Declaration of Human Rights (1948). What obstacles exist in rural Togo to achieving this priority?

The answer to this question lends itself to a group discussion. The obstacles to a human right “to a standard of living adequate for the health and well-being of themselves and their family, including food, clothing, housing, health care and the necessary social services” are many. They include: poverty; poor health; apparent lack of resources; lack of local infrastructure and services; lack of clean water; lack of education (link between safe water and good health not understood); cultural/social practices (duties of women versus men, low expectations of female decision-makers).

2. From the perspective of the WHO definition of health, what is the health status of the Tonoumassillagers?

Judging by the mortality rate among children, the prevalence of chronic infectious diseases, the lack of social services, the mental anguish of losing loved ones, and the demanding tasks of fetching water and obtaining other essential items for survival, the health status of the Tonoumassommunity is poor. A group discussion is suggested.

3. Discuss the interaction between human activity in Tonoumassnd the biological environment.

Clearly the presence of bacterial, viral and parasitic pathogens in the drinking-water reduces health and has a negative impact on all human activity including the ability to work (adults) or to attend school (children).

4. Poverty is considered the greatest risk factor of poor health and a major obstacle to resolving environmental health problems. Discuss this in the context of Tonoumass/B>

Togo is a “least developed country” with a very low per capita income. Public services are absent and thus there is neither a central water supply nor adequate sanitation. Without treatment, the water that is available constitutes a serious health risk. This results in high prevalence of communicable diseases, high infant mortality rates, chronic poor health and short life expectancy. Outside help is needed to escape from this inevitable cycle of ill-health and poverty. Have a group discussion to bring out these points.

5. Do you consider the women of Tonoumasss a “vulnerable group” in terms of susceptibility to poor health? Explain.

The women carry a superhuman burden as the primary providers, and this is accentuated by the physical demands of fetching water. About 15-20 kg need to be carried over long distances each day. Lack of proper rest, absence of recovery time and physical back injuries make the women more vulnerable to poor health.

Chapter 6 Questions

1. Review the causes of the diseases mentioned.

2. What categories of communicable disease linked to water appear to be involved in the case scenario?

Disease

Pathogen

Type of water-related disease

Dracunculiasis

Dracunculus medinensis (guinea worm)

Water-based (ingested)

Typhoid fever

Salmonella bacteria

Waterborne and water-washed (ingested)

Schistosomiasis

Schistosoma flukes (trematode)

Water-based (penetrates skin)

Dysentery

Shigella bacteria; the amoeba Entamoeba histolytica

Waterborne and water-washed (ingested)

Hepatitis A, E

RNA virus

Waterborne and water-washed (ingested)

3. The small wet season in the period September to December is disappearing in the maritime region of Togo. Within the context of water scarcity, what might be the cause? Is this development consistent with global trends?

Aridity is the only cause of permanent water scarcity that is due to a dry climate. Global warming might well explain the trend. The extensive agricultural land use could lead to water shortages through water-stress or desertification.

4. Would water treatment have helped the Tonoumassater problem? What might have been done?

The simple use of a chemical disinfectant such as a chlorinating agent would have made the water safer.

5. What options other than water treatment might be considered?

Other options available to reduce the chance of infection include: elimination of unsanitary storage or use of water; protection of food during preparation and storage; improved personal hygiene; and the use of sanitary latrines or toilets. Of course, drilling a local well might be a more effective option.

Case scenario, Part II

During the 1980s, the Government of Togo with the help of Canadian Universities Services Overseas (CUSO) initiated a rural water supply project. The village of Tonoumassecame aware of this through a female extension officer and, because there was dissatisfaction with the lack of water, appointed a committee. One of the requirements of the project was that at least half of the committee members should be women. The men grumbled and predicted failure, but grudgingly went along with the idea. Although pump installation was free, the villagers had to agree to clean the installation site, provide materials and labour for the concrete apron, send two people to learn how to maintain the pump, and to pay for all future repairs. A formal agreement was signed in a public ceremony in the presence of high-ranking government officials.

Tonoumassillagers chose to set up a collective farm plot and required each family to contribute a day’s work per week. Sales of produce from this venture were 10 times more than was needed to cover the pump maintenance costs. Consequently, the village had a fund that could be used for other community improvements. Effectively this constituted the first local taxes Tonoumassver raised.

In eight general meetings for villagers and project managers (mostly female), rural extension workers and trained villagers took time to explain the connection between clean water and sanitary conditions and good health (including use of covered water containers, curtailment of the soiling of houses and yards, and a general programme to keep the village clean). A reduction in illness became apparent soon after the pump was installed and the concomitant improvements were made.

An interesting aside concerns respect for religion and culture. After consulting the spirits of the dead, village elders agreed with the modern-day technicians about the location of the water source and the placement of the pump

Chapter 1 Questions

1. Was the requirement of female membership of the project committee a reasonable one?

2. Discuss the required contribution to the collective farm plot in terms of individual versus community initiatives/rights.

A debate might be an effective way of exploring possible perspectives.

3. Empowerment is an important motivational principle. What was its role in the pump project and how was it achieved?

It appears that the community bought into the project through training and education: villagers were enabled to understand the connection between safe water and sanitary conditions and good health. Their direct involvement in setting up a committee and in the decision process brought ownership and thus empowerment. The decision to set up a collective farm plot and their required input of labour extended their ownership. The revenues generated empowered the community to consider other improvements. The community effort was also facilitated by the endorsement of the religious leaders. A role-play simulating a public meeting about water-based, waterborne and water-washed diseases might be considered.

4. To what extent did the principle that community decision-making needs to integrate ecological, cultural, health, technical and economic dimensions apply to Tonoumass/B>

Ecological dimensions: limited water resources; climate; biological environment (pathogens); water table and reservoir; soiling of houses and yards.

Cultural dimensions: roles of women and men; religious practices.

Health dimensions: recognition of the link between disease and biologically contaminated water and unsanitary conditions.

Technical dimensions: selection of site yielding water; selection and installation of the pump; pump maintenance.

Economic dimensions: limited outside help was needed to start the project; a dependable source of revenue was generated through the collective farm plot, permitting pump maintenance and other community projects; low level of water consumption permitted a simple solution.

5. The ability to respond to community environmental health problems is said to depend on economic prosperity. Was that the only determinant in the pump project?

By United Nations standards, Togo’s economic state is weak (a “least developed country”). Economic prosperity was virtually absent. Clearly, teamwork, individual effort, empowerment and motivation are also essential ingredients for solving environmental health problems. The Tonoumassroject illustrates that prosperity must be viewed as a relative parameter. The experience gained also increases the chance of future problem-solving.

6. How did the pump project make life better in Tonoumass/B>

- Fewer people get sick and fewer children will die.

- More children can attend school more regularly.

- By eliminating the strenuous duties of fetching water, women can grow more food, feed their families better, and sell the surplus to buy other goods.

- Women’s input is essential in future projects.

- The villagers have learned to work together and now have the experience to solve other problems and to build a stronger community.

Chapter 6 Questions

1. What criteria were used in selecting the site for the pump?

Criteria for site selection presumably included: location of the water table; proximity to agricultural land (because of possible drainage and discharge in relation to use of fertilizers, pesticides, manure, etc.); protection of site from other human activities (e.g. industrial activity releasing chemicals to the air, water or soil; garbage disposal); protection from surface drainage and flooding; distance from latrines and toilets.

2. Why is adequate sanitation crucial to a safe local water supply?

Contamination of drinking-water sources by human waste is the most common source of communicable disease. Any improvement in sanitation services should therefore yield immediate health improvements.

3. Suggest some routine monitoring to test for indicator organisms in the well water.

The most widely used microbiological indicator is the coliform group of organisms, which has an operational definition. In practice, the coliforms are almost always of intestinal origin, with Escherichia coli being the most common. They have life spans that are comparable to those of the pathogenic bacteria Salmonella and Shigella, and behave similarly during water purification. The maximum acceptable concentration for total coliforms is no organisms detectable per 100 ml. Practical rules for determining compliance take into consideration variation in enumeration because of non-uniform distribution patterns.

4. Outline strategies, other than improving sanitation services, for safeguarding the water supply.

See answer to Question 1 above.

Learner, peer and problem evaluation

Formative evaluation

At the end of each session, but especially after the last one, allow participants to express their thoughts and feelings about their own participation and progress, as well as about the contributions and roles of the instructor/facilitator and fellow learners. Solicit comments about the approaches used (i.e., debate, role-playing, other). A written or oral evaluation concerning achievement of the stated objectives is also a good idea. Can the problem as presented be improved? How?

Summative Evaluation

Devise a test, preferably incorporating a new problem scenario, to examine the learners’ knowledge, understanding and application of the new knowledge inherent in the study objectives.

Selected references

Canadian Universities Services Overseas. Water for TonoumassThe story of a village in Togo. Ottawa, Carleton Local Committee of CUSO, 1988.

Isselbacher KJ, Martin JB, Braunwald E, Fauci AS, Wilson JD, Kasper DL. Harrrison’s principles of internal medicine, 13th ed. New York, McGraw-Hill, 1994, pp 485-938.

Tin UU, Lun Wai U, Ba Tun U, Mya Win U, Thein Dan U, Than Sein U. “We want water, not gold.” World Health Forum 1988; 9:519-525.

Our planet, our health, Geneva, World Health Organization, 1992, pp 106-144.

The International Drinking Water Supply and Sanitation Decade. Review of regional and global data (as at 31 December 1983). Geneva, World Health Organization, 1994 (Offset Publication, No. 92).

6.2. Role-play: Waterborne outbreak in a Romanian town

Prepared by Anca Dumitrescu and Theo de Kok*

* Dr Anca Dumitrescu, Institute of Hygiene, Public Health Services and Management, Romania

Dr Theo de Kok, Faculty of Natural Sciences, Open University, Heerlen, Netherlands

Time: 2 hours

Objectives:

At the end of the exercise, students will be able to:

1. Understand the importance of the source of water used for the production of drinking-water.

2. Indicate the multiple causes of a waterborne outbreak of disease and their relative importance.

3. Appreciate the importance of clear legislation with well-defined responsibilities.

4. Appreciate the challenge of achieving consensus on environmental health actions.

Procedures:

Introduction to the case study and role-play (15 minutes)

1. Introduce the case study of the waterborne outbreak and the role-play exercise using the attached transparencies and written description. Explain that the overall objective of the role-play is to demonstrate and experience the process of decision-making and action planning in order to meet environmental health objectives, which in this case involves safeguarding the distribution of high-quality drinking-water.

2. Divide the class into three groups: the water company, the local authorities (mayor) and the Department of Sanitary Inspection. (Note: If the class is large you may form two groups in each category. Prior to the role-play, allow some extra time for those chosen as representatives of each group to consolidate their position.)

3. Instruct all groups to prepare themselves for a meeting in the city hall where one selected representative will be asked to present the group’s position in a role-play and come to agreement with representatives from the other groups on how to prevent this type of situation from occurring in the future.

Preparation for the role-play (30 minutes)

4. The tasks for each group are:

- to clarify its position;
- to anticipate and prepare to respond to the positions of the other groups;
- to prepare a proposal on how to proceed and collaborate in the future in order to meet the needs of one’s own interest group, the other groups and the community. (See transparency of guidelines for group work).

5. Visit groups to ensure that they are progressing well in defining their positions.

Meeting at city hall (30 minutes)

6. Invite a representative from each group to play their role in the meeting and negotiate about the solution of the problem. Begin the role-play. (Optional: You may decide to let the rest of the class act as members of the local population who attend the hearing at city hall. If so, allow time for comments and questions from the public.)

Discussion of the role-play (15 minutes)

7. Following the role-play, engage the class in a discussion of:

- the definition of the key arguments raised and their scientific validity;

- the underlying causes of the problem (i.e. system of communication among the groups, clear definition of responsibilities, sound attitudes of the key role-players, comprehensive legislation);

- what can be done to avoid other outbreaks in the future (i.e. financial solutions, legislative improvements, improved interpersonal and communication skills, encouraging teamwork when addressing this kind of problem).

8. Summarize and conclude the exercise.

Materials:

Case description, transparencies, guidelines for small group work, overhead projector, flip chart, coloured markers.

Case description

Waterborne outbreak in a Romanian town

This case study is based on a real outbreak that occurred in a small Romanian town in 1993. The town of “T” is in central Romania and has 9500 inhabitants. “T” is supplied with drinking-water from two sources: groundwater from deep wells of good quality and surface water from the river “S”, which needs treatment. Water from both sources is mixed and chlorinated before distribution.

In 1993, the Department of Sanitary Inspection repeatedly found that the water quality did not meet the standards, that regulations were violated and that the waterworks were poorly managed. The director of the plant had been informed about the health risk related to the distribution of non-disinfected water and penalties were applied several times (see transparency).

The most relevant legislation regarding the drinking-water supply includes:

- the decree on the protection of sources of water used for the production of drinking-water;

- the standard, “Quality of drinking-water”, based on the WHO guidelines;

- the national law, “Health of the Population”, which states that the Department of Sanitary Inspection is responsible for issuing permits for waterworks and for supervision of producers (the producer is responsible for: the quality of the drinking-water; monitoring of the quality of drinking-water that is distributed; notification of any alteration or malfunctions in the system; maintenance of an appropriate reserve of chloride);

- the law, “Local Authority”, which states that the waterworks are supervised by the mayor of the town (see transparency).

The outbreak

A waterborne outbreak started in town “T” on 19 November 1993. There were 101 cases of acute diarrhoea; 8 cases needed treatment in hospital. There were no deaths and the severity of disease was either mild or moderate. From the faeces, Shigella flexneri was isolated.

Prior to the outbreak, on 16 November, the water company stopped the chlorination of the surface water because of a shortage of chlorine. This event was not reported to the Department of Sanitary Inspection or to the local authorities. The first cases of disease were reported by the general practitioners three days after the non-disinfected water began to be distributed.

During the epidemiological inquiry, staff members of the waterworks were not willing to collaborate with the Department of Sanitary Inspection. The director of the waterworks reaffirmed that the town was supplied with groundwater of good quality, which did not need disinfection. The Department of Sanitary Inspection demonstrated that this was false. Based on the analysis of the hardness of the water, it was concluded that mixed water had been distributed instead of just groundwater. Laboratory analysis showed that, although the raw water complied with the standards, the water in the distribution system did not. The latter contained no chlorine and the total number of coliform exceeded the standard.

After the outbreak occurred, the pipe for surface water was sealed and the town was supplied with only groundwater. Other measures that were taken included disinfection of water pipes and storage tanks and the reintroduction of chlorination. The director of the waterworks and the mayor of the town had to pay fines. The public prosecutor was informed and the director was taken to court.

Role-Play
Waterborne outbreak in a Romanian town

Objective

To develop a unified action plan which meets environmental health objectives.

Case Situation

Population:

Romanian town “T”: 9500 inhabitants

Sources of water:

- groundwater from deep wells
- surface water from river “S”

Events during 1993:

- repeated violation of sanitary standards
- repeated violation of regulations
- poor management

- repeated penalties

Romanian drinking water legislation

- Decree on protection of sources

- Standard “Quality of drinking-water” free chlorine, total chlorine, chemical quality, microbiological safety

- Law “Health of the Population”

Department of Sanitary Inspection:

- issues permits
- supervises the producer

Water company:

- monitors water quality
- reports on changes in water quality

- maintains a reserve of chlorine

Outbreak 19-26 November 1993

Cases:

101 cases of acute diarrhoea
8 cases admitted to hospital
no fatal cases

Water supply prior to the outbreak:

surface water + groundwater

Laboratory analysis:

- raw water O.K.
- water in distribution system contains no chlorine, total + faecal coliform above standard

- faeces of cases: Shigella flexneri

Guidelines for small group preparation for meeting in city hall

3 groups:

1. Water company (director)
2. Local authority (mayor)
3. Department of Sanitary Inspection

Task:

1. Briefly summarize the main issues in the situation (i.e. legal, technical, financial) and your conclusions on what caused the problem. Based on this summary, clarify the position of your group.

2. Anticipate and prepare to respond to the positions of the other groups.

3. Prepare a proposal on how to proceed and collaborate in the future in order to meet the needs of your group, the other groups and the community.

4. Select someone to represent your group at the meeting.

6.3. Problem-solving exercise: Water availability and trachoma1

1 Based in part on a report by West S et al. Water availability and trachoma. Bulletin of the World Health Organization, 1989, 67(1): 71-75. Published in WHO/EHG/98.1

Prepared by Nancy V. Hicks*

* Dr. Nancy Hicks, former consultant, WHO

Time: 3 hours

Objectives:

At the end of the exercise, students will be able to:

1. Utilize knowledge of local customs and lifestyles to design interview instruments.

2. Construct a tabular presentation and calculate percentages using raw data.

3. Identify methods for data collection and interpret tabular data.

4. Draw conclusions from study findings.

5. List intervention strategies for preventing trachoma

Procedures:

1. This is an unfolding exercise in four parts, designed to mirror the real-life conditions of an environmental health practitioner in the field. Students are asked to analyse the information as it becomes available and to draw conclusions. If all parts of the exercise are distributed at the same time, students should be instructed to work page by page and not to look ahead. Otherwise each part can be distributed separately. The decision to proceed to the next part can be made jointly by the students and instructor. Report-back sessions can take place after each part or at the conclusion of the entire exercise.

2. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

3. Distribute the exercise and review the participants’ tasks.

4. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 15), flip chart, coloured markers.

Case scenario, Part I

A major cause of blindness in developing countries is trachoma resulting from repeated infections. Lack of water and increasing distance from the home to the water source has been reported to be associated with the disease, which can be hyperendemic in dusty, dry regions. However, the association is not entirely borne out by the results of all studies.

You are the epidemiologist for a region of 20 villages where the incidence of trachoma is very high. Before promoting increased water supplies as an effective method for preventing trachoma, you decide to investigate the impact of distance to water supply on the prevalence of trachoma and on water use habits among families in your region. You are concerned that factors other than water availability may influence water use for hygiene purposes.

You decide to conduct a risk factor survey for trachoma among a random sample of 20 villages. Interviews (using a pre-tested structured questionnaire) will be conducted by trained local women.

Question 1. Devising items for an epidemiological questionnaire is not always straightforward. For example, you are interested in knowing the time needed to walk one way to a water source. However, in pretesting your questionnaire, you discover that this is difficult to communicate in the interview. How would you creatively deal with this problem in terms of the characteristics of the population that you might be working with?

Knowing the culture of the people to be studied is very important. If the investigator is not wholly familiar with the lifestyle of the population he/she is studying, local residents should be identified to assist in phrasing questions so that they are meaningful and fit within the reference framework of the target population. Anthropologists are frequently skilled in this area. Pretesting the questionnaire for comprehension and revising it as appropriate should be done before it is administered to the study sample.

In this study, the investigators took a unique but practical approach. In order to provide a locally appropriate reference, a series of common household tasks were timed and these were used as examples by the interviewers. For example, “less than 30 minutes” was the time necessary to build a fire and boil water.

Case scenario, Part II

A preliminary summary of your study data indicate that 389 households are located less than 30 minutes from the nearest water supply, 844 are within ½-2 hours, and 705 are more than 2 hours away. In the first group of 389 households, 148 households have no children with trachoma, 97 households have at least one child with trachoma, and in 144 households all children are affected. In the second group of 844 households, 228 have no children with trachoma, 202 households have at least one child with trachoma, and in 414 households all children are affected. In the third group of 705 households, 204 households have no children with trachoma, 148 households have at least one child with trachoma, and in 353 households all children are affected.

Question 2. Presenting study findings in a clear and concise way is very important. Construct a tabular presentation of your data. In addition to absolute numbers of children in each category, include a column with the corresponding percentages.

Percentage of households with children aged 1-7 years with trachoma, according to the time (distance) to the nearest water source.

Trachoma status of household (%)*

Time to water source
(number of households)

No children affected

Some children Affected

All children affected

<30 minutes (389)

148 (38)

97 (25)

144 (37)

0.5-2 hours (844)

228 (27)

202 (24)

414 (49)

>2 hours (705)

204 (29)

148 (21)

353 (50)

*c2=2514, P<0.001

Question 3. Now, give an interpretation of your data.

The distance to the water source is associated with the prevalence of trachoma. The proportion of households in which all children had trachoma increased with the time to the source from 37% among those living within 30 minutes, to 49% for those who lived within 0.5-2 hours, to 50% among those living more than 2 hours away.

Concomitantly, the proportion of households in which no children had trachoma decreased as the distance to the water source increased. The proportion of households in which some but not all the children were infected with trachoma also declined as the distance to the source increased.

There appeared to be little difference in the risk of trachoma once the households were more than 30 minutes from the water source.

Case scenario, Part III

Table 1 below presents the results of logistic regression (a statistical procedure that calculates the association of a particular risk factor with the outcome while controlling for the influence of other variables). (You are now a statistics expert!)

Table 1. Results of logistic regression analysis of the association between trachoma in the household by time (distance) to water source, quantity of household water, and other factors

Variable

Odds ratio

95% confidence interval

Time to water source:




0.5-2 hours

1.45

1.08-1.95


>2 hours

1.37

.01-1.87

Quantity of water




Medium

1.01

0.76-1.35


High

0.84

0.61-1.15

No. of children




2

2.49

1.93-3.23


³3

5.16

3.63-7.37

Herding cows

1.85

1.35-2.56

House with a metal roof (vs. flat or thatched)

0.63

0.47-0.86

Traditional religion (vs. Christian or Muslim)

1.71

1.28-2.30

Sleeping next to a cooking fire

1.48

1.14-19.20

Presence of unclean faces:




some children

1.30

0.82-2.08


all children

1.70

1.22-2.35

Question 4. How do you interpret the study results in Table 1?

The risk of trachoma in the household as a fraction of distance to water, irrespective of the amount of water consumed and other confounding factors, was assessed using a logistic regression analysis. Although the students may not have studied logistic regression yet, they know what an odds ratio is.

The results suggest that, although the distance to the water source was associated with an increased risk of trachoma, the risk did not vary with the amount of water brought into the house (odds ratio of 1.01 and 0.84 for medium and large quantities, respectively). Again, the risk was similar for all households that were more than 30 minutes from the water source.

Case scenario, Part IV

Table 2. Distribution of children with clean faces, according to the time (distance) to the water source and the quantity of household water



Percentage of households with children

N

All clean

Some clean

All not clean

Time to water source:*


<30 minutes

386

15

16

70


0.5-2 hours

831

11

14

75


>2 hours

691

10

9

81

Quantity of water


High

577

10

16

74


Medium

815

12

12

76


Low

516

12

10

78

* c2 = 21.85; P = 0.01

Question 5. Give an interpretation of the data in Table 2.

The distance travelled to water was itself probably not the determining factor in altering the risk of trachoma, but rather how the water was used within the household. You might, therefore, investigate the relationships between the water variables and the observation of children with clean faces, on the assumption that if either the water source was closer or a greater amount of water was brought into the household, personal hygiene might improve, leading to a decreased risk of trachoma.

The distance to the water source was significantly associated with the presence of children with clean faces in the households. However, the decrease in cleanliness with increasing distance was not large: in 70% of households within 30 minutes of a water source all children had dirty faces, compared with 81% of households that were more than 2 hours away. The relationships between the presence of children with clean faces and the quantity of water brought into the house was even less marked. Essentially, the proportion of households in which all the children had clean faces was the same, regardless of the amount of water that was brought into the house daily.

Data on whether the study children had clean faces were gathered by a subjective appraisal by the interviewers.

Question 6. Comment on the way these data were gathered.

The subjectivity and timing are worrying and could be sources of systematic bias. What one interviewer calls “dirty”, another interviewer might judge to be “clean”. This leads to misclassification due to interviewer bias. There is no indication of a consistent criterion for what constitutes a “clean” face. Hopefully, if this happened, it would happen equally between both groups and would be non-differential misclassification, with the result of driving the odds ratio towards the null value (decreasing the association if there truly is an association).

Timing is also worrying here. If the interviewer happened to visit the house shortly after the children’s faces were washed (whether morning or afternoon), he/she would be likely to record the face as “clean”. If, however, the home visit was conducted after the children had been playing for a long while, the interviewer would probably record “dirty”. The fact that this was a one-time appraisal, and that there was no consistent criterion to guide the interviewers makes this information less credible.

In addition, children’s faces were less likely to be clean if they were male, aged over 4 years, and if there was another child in the house whose face was also unclean. This clustering of children with unclean faces in households suggests further that hygiene behaviour is governed by family attitudes.

When mothers were asked why their children’s faces were not washed more frequently, almost half indicated lack of water as the reason. This response did not, however, vary markedly with the observed cleanliness of the children. This suggests that, although mothers whose children had clean faces may have perceived that lack of water was a constraint to face-washing, in daily practice they did manage to keep their children clean.

Question 7. What are your overall conclusions from this study?

These findings suggest that while access to water may be associated with trachoma, increased risk of the disease is probably not a simple direct function of water availability. And while time is an important factor (mothers who must travel further to obtain water have less time to keep their children clean), the difference in the number of children with clean faces in households located 2 hours or less from water sources compared to households located more than 2 hours from water sources was not large.

Question 8. How will these study findings influence your opinion concerning increased and closer water supplies as an effective public health intervention for preventing trachoma and blindness?

Simply providing each village with a functioning water supply may not reduce the prevalence of trachoma in children since the prevalence was not different in villages with and without a constructed water supply. These findings suggest that an important determinant of water use for hygienic purposes is the value placed on the water that is collected. For example, mothers who must travel long distances for water may be less likely to use it for face-washing, regardless of the actual amount of water in the home. Thus, the mother’s perception that there is insufficient water for face-washing must be interpreted within the context of the utilization priorities she places on the water available in the home, and not as an absolute pronouncement on the unavailability of water. Even if it were theoretically possible to have a water source within 30 minutes of each home, there is no assurance that water usage patterns would be altered. In fact, results from other studies indicate that, even when a water source is brought closer to home, the amount of water brought into the house does not change dramatically. Classification of mothers’ values regarding water usage and their priorities for its allocation should be sought through collaborative efforts between epidemiologists and anthropologists.

7.1. Typical cases of foodborne diseases

Prepared by Gerald Moy*

* Dr Gerald Moy, Scientist, World Health Organization

Cases 1 and 2 are adapted from Food Safety: It’s All in Your Hands.

Ministry of National Health and Welfare, Canada, 1993

Time: 15 minutes to 1 hour

Objective:

At the end of the exercise, students will be able to:

List the primary causes of foodborne diseases and preventive measures.

Procedures:

1. Divide class into small groups to discuss the three short cases (15 minutes). The exercise can be used for a quick review with a more experienced group and to introduce the topic in less experienced groups.

2. Review each case, inviting reports from the groups.

3. Summarize and conclude.

Materials:

Problem-based exercises (Annex 16), flip chart, markers, tape.

Background information for instructors

Every year, people around the world are reported ill from foodborne illnesses, more commonly known as food poisoning. Many cases remain unreported so the extent of the problem is difficult to estimate. However, in many developed countries upwards of 10% of the population are thought to be affected each year. The most common cause of reported cases are foods which have been improperly handled in food service establishments, or in the home. Often the largest outbreaks are a result of food which has been mishandled in food-processing establishments.

All of the following cases actually took place and could easily occur again if food is not handled safely.

Case No. 1: The long-remembered wedding feast in Peru

It was to be the happiest day of Magda’s life. Relatives and friends from both sides of the family would be coming over for a lavish wedding feast. Her mother had worked late into the night preparing her best dishes for the guests. She finally went to bed at 04:00 in the morning after making sure that the food was attractively arranged on the tables. The next day was hot (over 30° C) but everyone enjoyed the good food. However, later that night, many people who attended the wedding started to experience severe stomach pains, nausea, vomiting and, in some cases, diarrhoea. While Magda felt fine, her new husband became so sick he had to go to the hospital.

Question 1. What might have caused the illness? What could have been done to prevent it?

To determine the answers to these questions, local health authorities interviewed everyone who attended the wedding, including people who did not suffer from the illness. It was determined that the people who had eaten the potato salad were the ones who also became ill. Samples of the potato salad were sent to the laboratory and it was found to contain high numbers of the bacterium Staphylococcus aureus, a common cause of acute foodborne disease.

This outbreak could have been avoided if the potato salad had been kept cool (less than 10° C). At cooler temperatures, the dangerous organism would not have multiplied rapidly to produce toxins as it did at the warmer temperature. Alternatively, the potato salad could have been made shortly before it was to be served. The important point, however, is that food which is otherwise properly prepared can become a source of illness, and perhaps even death, if it is left in the “danger zone” (temperatures between 10° and 60° C) for too long (4 or 5 hours).

Case No. 2: Deadly dessert in Canada

One September evening, patients at a hospital in Scarborough, Ontario, were served tapioca pudding for dessert. Later the next day, patients began showing the symptoms of food poisoning (cramps, chills, vomiting, diarrhoea). In all, 103 patients became ill and two of these, both elderly and weak, died. No pudding was available for testing. However, it was known that the pudding, amounting to 225 servings, was refrigerated in one large container until dinner.

Question 2. What is a possible source of contamination? Was it food poisoning? What could have been done to prevent this?

The local health officials confirmed that 91 of the patients had been infected by Salmonella enterititis, another common cause of foodborne disease. Given the incubation period of 12 - 36 hours for the disease, the tapioca pudding immediately fell under suspicion because the sick persons ate it and because it was made from raw eggs, which may have carried the organism. While the cook at the hospital had also fallen ill, it is likely that he was a victim rather than the cause as he had also eaten the pudding and was otherwise healthy at the time of the dinner.

Although no pudding was available for testing, the officials found out that the pudding was prepared and stored refrigerated in one large container until dinner. The heating of large quantities of thick foods, like pudding, frequently leads to “false boiling” when only the bottom layer is at the boiling point. The temperature in other parts of the pan did not get high enough to destroy the Salmonella. Thick food should be stirred thoroughly in order to make sure that all parts reach at least 70° C. A food thermometer is a useful tool in commercial kitchens.

The other problem was that, when the pudding was placed in the refrigerator, the refrigerator had insufficient capacity to rapidly cool the large quantity of hot pudding. Consequently, the temperature of the pudding was not cold enough during storage to prevent the growth of the surviving organism (below 10° C). This is a common problem when foods prepared in large amounts are not cooled properly. Commercial kitchens should be equipped with refrigerators with sufficient capacity. In addition, large quantities of food may be placed in shallow pans to promote more rapid cooling.

Salmonella enterititis is an emerging pathogen that may contaminate the egg prior to shell formation. As a result, there is no means to identify contaminated eggs. Consequently, all eggs must be handled as if they were contaminated. This means that they should be stored at low temperature and be thoroughly cooked to destroy any contamination. In addition, recipes with raw eggs should be avoided unless pasteurized eggs are used.

What causes food poisoning

These two incidents describe typical cases of foodborne illness. Food poisoning usually results from eating foods containing large numbers of harmful bacteria that infect the lining of the digestive tract or release toxins into it (i.e. infections), or from eating foods in which bacteria have previously produced toxins (i.e. intoxications).

Proper hygienic practices are important in the preparation, cooking and storage of foods. Since bacteria depend on moisture to move about, it is vital that their paths be blocked. Hand-washing will help prevent the spread of bacteria to goods or from one food to another. Making sure kitchen utensils, containers and work spaces are thoroughly cleansed, especially those that have been in contact with raw meat and poultry, will also help stop cross-contamination.

Ultimately, adequate cooking and avoidance of time-temperature abuse are the most important factors in preventing foodborne illness.

Case No. 3: A gift of fresh fish in Fiji

A man had very good luck fishing on the reef and offered to share some of the catch with his neighbours. The fish were nice and fresh, but about one hour after eating them, one person noticed a numbness of her lips and tongue. Soon other people also showed signs of illness, such as nausea, vomiting, headache and dizziness. Some people noticed that cold drinks felt hot, and hot water felt cold. Two people were hospitalized with irregular heartbeats. After several days, the signs of poisoning subsided, but for some people symptoms of weakness and dizziness persisted for several weeks.

Question 3. What was the cause of this illness? How could have it been prevented?

The people were made ill by ciguatoxin which is caused by the consumption of tropical and subtropical marine finfish which live near reefs. The fish become toxic when they feed on a naturally occurring algae which contains the toxin. As the toxin is not harmful to fish, the fish can accumulate high levels of it. The toxins are passed up the food chain so that larger predatory fish have high levels in their meat. Examples of fish which have been associated with ciguatoxin poisonings include barracuda, snapper, grouper, sea bass and king fish. The reversal of the sensations of hot and cold is a characteristic symptom but it is not always present.

The rapid growth (“blooming”) of algae which produce the toxin is difficult to predict but is usually associated with disturbances in the reef caused by natural forces (e.g. typhoons) or human disturbances (e.g. construction). Afflicted persons should seek medical assistance immediately and local health authorities should take action to warn the public to avoid eating the type of fish implicated in the investigation.

Case No. 4. The good mother in Tanzania

Salome’s child was now nearly 5 months old and it was time to introduce food other than breast milk into the diet. She had heard that nutritious and inexpensive weaning food could be made from local foods and she wanted to make sure that her child would grow and thrive. Following the advice in the nutrition literature she had be given, she faithfully prepared the recipe for a follow-up food using boiled sorghum as the base. At first, her child loved the new solid food and clearly was eating more and more. However, it was difficult and time-consuming work so she started making larger batches so that she needed to prepare it only once a day. She carefully covered it with cloth gauze to protect it from flies. Subsequently, her child started to experience periodic episodes of diarrhoea and after a few months the child started to show signs of growth faltering.

Question 4. What might be the reason for growth faltering in this case? How could it be avoided?

The preparation of large amounts of weaning food which was subsequently allowed to stand at ambient temperature resulted in the growth of pathogens to infectious levels. Contamination of food has been estimated to be the cause of up to 70% of episodes of diarrhoea in children under the age of 5. WHO has estimated that worldwide there are 1500 million such episodes resulting in the deaths (usually from dehydration) of over 3 million children a year. In addition, episodes of diarrhoea result in growth faltering and stunting and make the child more susceptible to a range of other infectious diseases.

This problem could be avoided by making small batches of weaning food so that it is freshly prepared before each meal. Alternatively, a recipe based on fermentation could be used to extend the safe “shelf life” of the food. In recognition of the general problem, WHO has prepared a brochure entitled Basic principles of the preparation of safe food for infants and young children. These principles include:

1. Cook food thoroughly.
2. Avoid storing cooked food.
3. Avoid contact between raw foodstuffs and cooked food.
4. Wash fruits and vegetables.
5. Use safe water.
6. Wash hands repeatedly.
7. Avoid feeding infants with a bottle.
8. Protect foods from insects, rodents and other animals.
9. Store non-perishable foodstuffs in a safe place.
10. Keep all food preparation premises meticulously clean.

All of these principles should be observed in preparing food for infants and young children as they are well known to be highly susceptible to diarrhoeal diseases and the dangers of dehydration.

7.2. Problem-solving exercise: Pesticide poisoning - an outbreak among antimalarial workers1

1 From: Problem-based training exercises for environmental epidemiology, revised version. Geneva, World Health Organization, 1998 (Document WHO/EHG/98.1).

Prepared by Linda Rosenstock, revised by Steven Markowitz*

* Dr. Linda Rosenstock, Director, National Institute of Occupational Safety and Health, USA

Dr. Steven Markowitz, Division of Environmental and Occupational Medicine, Mt. Sinai School of Medicine, New York, NY, USA

Adapted from: Jeyaratnam J. Pesticide poisoning among antimalarial workers.

In: Teaching epidemiology in occupational health. NIOSH/WHO, 1987.

Time: 3 hours

Objectives:

At the end of the exercise, students will be able to:

1. Establish a case definition.

2. Understand the basic principles of study design, sampling, nonparticipant bias and routes of exposure.

3. Identify strategies to prevent recurrence of epidemics.

Procedures:

1. This is an unfolding exercise in seven parts, designed to mirror the real-life conditions of an environmental health practitioner in the field. Students are asked to analyse the information as it becomes available and to draw conclusions. If all parts of the exercise are distributed simultaneously, students should be instructed to work page by page and not to look ahead. Otherwise each part can be distributed separately. The decision to proceed to the next part can be made jointly by the students and instructor. Report-back sessions can take place after each part or at the conclusion of the entire exercise.

2. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

3. Distribute the exercise and review the participants’ tasks.

4. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 17), flip chart, coloured markers.

Case scenario, Part I

You are a medical officer recently appointed to take charge of a large malaria control programme. You learn that a suspected increase in the number of pesticide poisonings started soon after the beginning of the last spraying season.

Question 1. How would you proceed to investigate this situation? What more would you like to know before getting started?

Participants should raise questions about what the “suspicion” of the epidemic is based on. Students should ask about:

- person, time and place;

- types of pesticide poisonings;

- sources of information, including ones useful in epidemiological surveys-case registries, hospital records, outpatient records, workplace records, individuals (parents, employers, community residents, health care workers);

- new work exposures or work processes that may have occurred.

Case scenario, Part II

You learn that the pesticide malathion (an organophosphate) has replaced DDT this spraying season because the mosquito had become resistant to DDT and because malathion is an effective pesticide, that is thought to be relatively safe for human use on the basis of much experience, including field trials in Nigeria and Uganda.

You learn that there are about 7700 antimalaria workers, making up 1100 teams of seven workers each (5 spraymen, 1 mixer, 1 supervisor). In addition to the reported increase in illness (which suggested organophosphate poisoning), five deaths have occurred-two in mixers and three in spraymen. It is thought that one of the three brands of malathion was associated with the most severe illness (used by three of the five who died). It is also reported that the illness was more common on Friday and Saturday than on Sunday.

Question 2. What appears to be the main exposure problem in the episode described?

Malathion, an organophosphate pesticide that was believed to be relatively safe, has caused unexpected episodes of poisoning, including deaths. The problem is serious, unexplained and needs prompt attention.

Question 3. How can you plan organizationally to investigate this outbreak?

The study population is large. Are locally available resources sufficient to undertake the study? Use this as an opportunity to discuss resources, including outside assistance. In this case the study was undertaken in collaboration with WHO and the Centres for Disease Control and Prevention, USA.

Question 4. What case definition of “poisoning” would you suggest (use Table 1)?

Review the importance of case definition for proceeding with a formal study. The type of definition will vary according to the data available (e.g. questionnaire surveys will by definition rely on interview responses and not actual laboratory data). There is a trade-off between broad case definitions that will include all cases but also non-cases, and narrow case definitions that will include fewer non-cases but also fewer cases. A case definition should be based on knowledge about symptoms, signs and laboratory findings, but depends on the feasibility of data collection.

The case definition used in this study is given in Part III.

Table 1. Symptoms of organophosphate poisoning

Mild poisoning

headache
nausea
dizziness
anxiety, irritability

Moderate poisoning

muscle twitching,tremor
sweating, salivation
blurred vision
vomiting, diarrhoea, abdominal pain
chest tightness, wheezing

Severe poisoning

pulmonary edema
bradycardia (slow heart rate)
or tachycardia (fast heart rate)
confusion
seizures, coma
involuntary defecation, urination

Question 5. Why are there more symptoms on Friday and Saturday than on Sunday?

Why does there appear to be a problem with a pesticide that has apparently been safely used in other antimalaria programmes?

In this case study, workers were off work on Sunday. The increased number of cases at week’s end reflected the cumulative exposure to the pesticide (and progressive decrease in cholinesterase levels).

Particular properties of the pesticide itself, or the way it is being used, need to be considered as reasons for the outbreak. Students should also be encouraged to maintain scepticism about past reports of chemical safety. The chemical may not be as safe as advertised.

Case scenario, Part III

The occurrence of cases of poisoning has been confirmed. Cases occur predominantly towards the end of the working week. You decide to study it further with a questionnaire survey.

You define a case as:

- occurring in a member of a spraying team;
- having at least four of the following five symptoms (blurred vision, dizziness, nausea, vomiting, abdominal pain).

You decide to interview a random sample (10%) of all the antimalaria workers to ask them about their past and present symptoms and their exposures at work.

Question 6. What type of epidemiologic study is this survey?

This is a cross-sectional study - at one point in time subjects will be investigated and exposures and effects will be assessed.

Question 7. What are the advantages and weaknesses of:

- this study design?
- this case definition?
- this sampling strategy?

Issue

Advantages

Disadvantages

a) Cross-sectional study design

Relatively inexpensive; easy

Selection bias - many affected workers may no longer be working and therefore are unavailable to participate in study

Recall bias - relies on memory of symptoms in the course of an epidemic

b) Case definition

Easy to elicit (symptoms only); cases are likely to be true cases because definition is relatively narrow

Subjective only; may miss milder cases Symptoms are not specific for pesticide poisonings

c) Sampling strategy

Easy to perform; random; not influenced by investigator

May not be representative; may not be large enough to study subgroups

Case scenario, Part IV

You interview 79% of those targeted in your sample. Your main findings are shown in Table 2.

Table 2. Number of acute poisonings during recent spray season

Number in sample

Number interviewed

% response

Number with at least 1 episode of poisoning

% poisoned


(a)

(b)

(b/a)

(c)

(c/b)

Spraymen

550

425

77

174

41

Mixers

110

86

78

33

38

Supervisors

110

95

86

19

20

Total

770

606

79

226

37

Question 8. What do you think about the overall response rate of 79%? How could the non-responders affect your assessment of the problem?

The overall response rate (79%) is reasonably good. Non-responders could lead to underestimation or overestimation of the problem, depending on whether they were more or less frequently ill than responders.

Question 9. On the basis of these questionnaire results, how might you estimate the total number of workers with at least one episode of poisoning within the whole population of 7700 antimalaria workers during the recent spraying season?

Estimates derived from study results are as follows:

Total at risk

Percent poisoned

Estimated number poisoned

Spraymen

5500

41%

2255

Mixers

1100

38%

418

Supervisors

1100

20%

220

Total

7700

38%

2893

Optional: students may be encouraged to consider the role of participant/nonparticipant bias. For example, for spraymen only:

- if you assume that the survey is biased to find all sick (i.e. only those who were sick agreed to participate), then none of 125 not interviewed is sick, so the number of sprayman poisoned = 174/550 = 32%, extrapolated from the sampled group to the 5500 at risk (1740 poisoned);

- if you assume that the survey is biased to miss those who are sick (i.e. all 125 not interviewed are sick), then the total number of poisoned sprayman equals 299 (174 + 125) = 299/550 = 54%, extrapolated to 5500 at risk (2970 poisoned).

No matter what the magnitude and direction of the bias here, there is a major problem of poisoning.

Question 10. What would you do next?

Despite potential problems with the accuracy of the estimate, the problem is clearly significant, and further details about pesticide exposure are needed.

Case scenario, Part V

You now know that there has been a major outbreak (epidemic) of poisonings, having estimated a total of 2893 (38%) of workers with at least one episode of pesticide intoxication. Sprayers and mixers are at highest risk. Observations of spray teams showed problems such as:

- working in clothes wet from pesticides;
- direct pesticide contact with skin due to mixing with bare hands;
- leaking spray cans.

Skin patch samples confirm that there is high skin exposure, particularly for mixers and sprayers (about 10-20 times higher than for supervisors). Airborne estimates of malathion exposure to sprayers were obtained by standard methods and were determined to be low (3% of recommended US standards).

Question 11. What seems to be the most important route of exposure?

Airborne exposures are low for all. Skin exposures are high, and there is a crude dose-response effect to support the importance of this route of exposure.

Question 12. How could you study whether poor work practices and faulty equipment explain the epidemic? What are other possible explanations? How would you measure individual exposure more specifically?

Although poor work practices are present, they cannot be assumed to be the total explanation. The pesticide has been used in other settings where such practices are likely to have existed without this apparent extent of problems and the study has not shown the relationship between work practices and illness at the level of the individual workers. Other possibilities are that the pesticide may be more toxic than suspected, or that it is absorbed more than usual.

Studies to explore exposure-effect relationships at the level of the individual should be considered. Blood cholinesterase levels can be used to measure exposure.

Case scenario, Part VI

You conclude that factors other than poor work practices contribute to the epidemic. The workers themselves suggest that there are more problems among those using one or two malathion brands (out of three brands used). But a lot of workers use more than one brand in any given day. You collect blood and measure cholinesterase levels in a small sample of workers in the three job categories who used only one brand on the day of tests.

Your findings are shown in Table 3.

Table 3. End-of-day cholinesterase levels and mean % change
(from morning to end of day)

End-of-day levels*

Mean % change

Malathion Brand

Supervisors

Mixers

Sprayers

Supervisors

Mixers

Sprayers


(N=22)

(N=21)

(N=102)

Brand 1

0.62

0.58

0.58

+5.9

-0.8

-3.1

Brand 2

0.59

0.34

0.38

+3.2

-20.1

-11.2

Brand 3

0.59

0.39

0.24

+0.2

-39.2

-46.7

*Normal range: 0.53 - 0.93

Question 13. What do you think about these results? Is any brand safe? Which brand(s) might be causing the epidemic? Why might there be differences between brands?

All groups of workers have low cholinesterase levels, even at the beginning of the day (e.g. supervisors’ cholinesterase levels do not change during one day but the mean is at the low level of the normal range, suggesting cumulative overexposure; only the mean is given, so even some supervisors will probably be definitely abnormal). Brands 2 and 3 are worse than Brand 1 for mixers and sprayers, who are likely to have larger exposures to any given brand than supervisors. Differences might be due to different concentrations of malathion, different concentration of other toxic components, or different properties such as greater skin absorption.

Case scenario, Part VII

Analysis of the chemicals in the three pesticide preparations showed Brands 2 and 3 had a much higher concentration of toxic breakdown products (formed when the main chemical, malathion, is degraded). This breakdown was thought to be due to different “chemical carriers” (believed to be non-toxic). You conclude that use of Brands 2 and 3 was the main cause of the epidemic, but you are also concerned about problems with poor work processes, faulty equipment and inadequate protective clothing.

Question 14. Name at least three things you would do now to deal with the epidemic.

Actions will include:

- product substitution (remove Brands 2 and 3, consider other products);

- change in work practices, including worker education, provision of better equipment and protective clothing;

- pesticide surveillance (disease registry programme);

- improved medical treatment for cases.

Question 15. You learn that there may be a problem with children in the community becoming ill. How would you investigate this?

Consider how this might be explored (e.g. questionnaire and laboratory surveys to assess the nature and extent of the problem).

7.3. Problem-solving exercise: Toxic encephalopathy from a seafood toxin

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Time: Two 2-hour sessions, allowing time for independent study.

Objectives:

At the end of the exercise, students will be able to:

1. Understand and apply the material on food quality criteria/assurance in Sections 7.3 and 7.4 of the textbook.

2. Describe investigative approaches that may be required in an episode of food poisoning to identify an unknown natural toxin and what actions might need to be taken to protect the public.

3. Identify the local public health practices that ensure food safety.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. Distribute the exercise and review the participants’ tasks.

3. Brainstorm a list of the issues raised in the case study with the entire group. Alternatively, this can be done in small groups. This helps to establish the existing knowledge of members of the group and to identify special resource persons within the group.

4. Following the small group work, reconvene the groups and invite a response from one group to the first question (or from the designated group if questions were assigned to a specific group). Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 18), flip chart, coloured markers.

Case scenario

In late 1987, a mysterious and serious outbreak of food poisoning occurred in Canada. Symptoms of the poisoning included vomiting and diarrhoea, followed in some cases by confusion, memory loss, disorientation and even coma. Two elderly patients died and in some other severely affected cases the neurological symptoms still persist. Epidemiologists from Health and Welfare Canada soon attributed the illnesses to restaurant meals of cultured blue mussels (Mytilus edulis L.). Using the Association of Official Analytical Chemists’ mouse bioassay for “red-tide” paralytic shellfish poison (PSP), Health and Welfare Canada and Fisheries and Oceans scientists demonstrated that the mussels contained toxic material. Furthermore, they were able to trace the problem to mussels harvested from a specific area of eastern Prince Edward Island. All the Deputy Ministers of Health of the 10 Canadian Provinces were notified by telex of the recommendation to take Prince Edward Island mussels off the shelves in retail stores and to remove them from restaurants. Consumption was to be stopped. Statistical analysis of the mussel distribution records and reported cases showed that for each symptomatic case some 500 people ate the contaminated mussels without any toxic consequences.

Subsequently, a team of scientists using suitable chemical separation, analytical techniques and the mouse assay, established that a neuroexcitatory amino acid, domoic acid, was the probable toxic agent. It was shown that the diatom Nitzschia pungens (an alga) was the source of this compound. Mussels feed on plankton, of which Nitzschia pungens became a significant component during an algal bloom in the waters off the eastern coast of Prince Edward Island. When the toxic bloom waned early in 1989, shellfish were found to contain low levels (<20 mg/g) of domoic acid and distribution for human consumption was again allowed. No further illnesses were documented.

Question 1. Identify, without detailed discussion, important issues highlighted in the case scenario. (Do this in a group setting with a recorder at the blackboard or flip chart.)

Possible major issues are (in random order):

- domoic acid is a naturally occurring food toxin;
- is there a safe level?
- why were some individuals not affected?
- what is PSP?
- food safety surveillance;
- emergency response by public health authorities;
- need for an investigative team of medical specialists and scientists;
- need for bioassays and analytical methods;
- mechanism of action of domoic acid;
- rules of evidence.

Some of these issues are pursued in more detail in subsequent questions.

Question 2. What is paralytic shellfish poisoning (PSP)? Can domoic acid poisoning be distinguished from it?

The etiologic agent of PSP is saxitoxin, which is a relatively heat-stable alkaloid produced in plankton species (specifically, dinoflagellates of the genera Gonyaulax and Pyrodinium). It is found in mussels, cockles, clams, soft shell clams, butter clams, scallops and shellfish broth; bivalve mussels are the most common vehicles (Kotsonis et al., 1996). Saxitoxin is a neurotoxin that blocks neural transmission at the neuromuscular junction. Symptoms include tingling or burning numbness around lips and fingertips, ataxia, giddiness, staggering, drowsiness, throat dryness, incoherent speech, aphasia, rash, fever and respiratory paralysis (Kotsonis et al., 1996). Saxitoxin does not have emetic nor hypothermic action. Death occurs infrequently.

By contrast, domoic acid poisoning referred to as “neurovisceral toxic syndrome” is characterized by several of the following acute symptoms: nausea, vomiting, neurogenic gastric distress, gastric bleeding, diarrhoea, dizziness, confusion, weakness, lethargy, somnolence, headache, coma and seizures. A chronic consequence can be severe short-term memory deficit, devoid of dementia, which resolves very slightly and very slowly over time (Perl et al., 1990).

Question 3. Discuss possible mechanisms of action of domoic acid.

Domoic acid is an amino acid and an analog of glutamate, which is recognized as an excitatory amino acid. Domoic acid passes freely into certain regions of the brain that are not protected by the blood-brain barrier. There it interacts with specific neuronal receptors (specifically N-methyl-D-aspartate, NMDA, or kainic acid, KA, receptors). The apparent consequence of this action is hypervulnerability to overstimulation (excitotoxic degeneration). Domoic acid is believed to activate KA receptors. Seizure-mediated brain damage ensues (Olney, 1990; 1994).

Question 4. From the information given, do you expect there to be a safe intake level of domoic acid?

The fact that only one in 500 individuals eating the contaminated mussels became ill suggests that there is a safe level for most individuals. Interestingly, most people who become seriously ill had some underlying condition such as renal disease, liver failure, atherosclerosis or diabetes (Hynie et al., 1990). Further, studies in mice have indicated a four- to five-fold variability in dose response. It is important to emphasize that susceptibility (inherited or acquired) to toxicants is very important in occupational, environmental and public health settings.

The amount of domoic acid consumed by individuals was calculated to be as much as 5 mg/kg or 6 mg/kg body weight based on domoic acid levels in mussels of 960 to 1280 mg/g (ppm). Such levels produced vomiting in cynomolgus monkeys and are 10-fold higher than the amounts given as an anthelmintic (remedy for intestinal worms) in Japan.

Question 5. Suggest how one might determine quantitatively the concentration of domoic acid in mussel tissue.

Since domoic acid is an organic compound, some form of chromatography will be needed to separate/isolate it for quantitative determination. The following procedure was found to be adequate, with a detection limit of 1 mg/g (º mg/kg or ppm). The Association of Official Analytical Chemists’ procedure for the isolation of saxitoxin was employed. Mussel tissue (50 g) was boiled gently for five minutes in 0.1 N HCl, followed by cooling and centrifuging. An appropriately diluted aliquot of the supernatant was analysed by high-performance liquid chromatography (HPLC). Detection was by UV absorption spectrometry (Iverson et al., 1989). Purified domoic acid isolated from mussels and characterized by spectroscopic techniques (Wright et al., 1990) served as the analytical standard. Any analytical chemistry textbook featuring instrumental analysis can provide additional details about HPLC and spectrometric detection.

Question 6. Are you convinced there was enough evidence to assign the blame to domoic acid as the causative agent?

The evidence may be itemized as follows (Wright et al., 1990; Hynie et al., 1990; Teitelbaum et al., 1990):

- Two localized sources of the contaminated mussels were established.

- The mussels from the two sources had the highest domoic acid content.

- Extracts were toxic in an official mouse test, with a response different from PSP (respectively, death in 30 minutes, preceded by typical scratching, compared to paralysis-type death in 15 minutes).

- Extracts from contaminated mussels had the same toxicologic outcome in rodents as did pure domoic acid added to non-toxic extracts.

- The neuropathology of the four patients who died in the outbreak was specific and strikingly similar to the findings in experimental animals poisoned by domoic acid.

- The action of domoic acid as an agonist of kainic acid in experimental systems provides an underlying molecular mechanism for the toxic effects.

- Unfortunately, since the investigators did not know exactly what they were looking for during the outbreak, urine or faeces samples were not collected for domoic acid analysis.

- Estimated intakes are qualitatively consistent with doses producing effects in animal models and appear to be higher in magnitude than doses reported with no effects in humans being treated for intestinal worms.

- The variability in human responses was reflected in animal experiments and the individuals affected appeared to be especially susceptible.

Although not absolute, the evidence of domoic acid as the putative agent is convincing to very convincing.

Question 7. Assess the role of the interdisciplinary investigative team.

It is clear from the details in the scenario and answers to the previous questions that, without the investigative team, the relatively quick action of the health authorities would have been delayed considerably and it would not have been possible to collect the evidence of causation.

Question 8. Suggest preventive actions to avoid future incidents.

Steps were taken to prevent the recurrence of domoic acid poisoning by shellfish consumption. Sacks of mussels are now labelled with respect to time and place of harvesting and the absence of domoic acid is confirmed by the mouse bioassay and HPLC before commercial distribution. These actions have been effective.

Question 9. Discuss the broad area of food safety in public health. In your discussions, highlight the status and practices of the following aspects in your geographical region: (i) regulatory authority; (ii) setting of food safety standards; (iii) routine food inspection/surveillance; (iv) emergency response capacity.

It is suggested that Sections 7.3 and 7.4 of the textbook be consulted as background. Students are encouraged to consult the local public health office and other appropriate local sources to obtain the information needed for an informed discussion/debate. Individual presentations about investigative projects are another approach.

Selected references

Hynie I, Hockin J, Wright J, Iverson F. Panel discussion: evidence that domoic acid was the cause of the 1987 outbreak. Can. Dis. Wkly. Rep. 1990; 16S1E:37-40.

Iverson F, Truelove J, Nera E, Tryphonas L, Campbell J, Lok E. Domoic acid poisoning and mussel-associated intoxication: preliminary investigations into the response of mice and rats to toxic mussel extract. Food Chem. Toxicol. 1989; 27:377-384.

Kotsonis FN, Burdock GA, Flamm WG. Food toxicology. In: Casarett & Doull’s Toxicology, 5th ed. The Basic Science of Poisons (CD Klaassen, ed.). New York, McGraw-Hill, 1996, pp. 909-949.

Olney JW. Excitotoxicity: an overview. Can. Dis. Wkly Rep. 1990; 16S1E:47-58.

Olney JW. Excitotoxicity in foods. Neurotoxicology 1994; 15:535-544.

Perl TM, Brd L, Kosatsky T, Hockin JC, Todd ECD, Remis RS. An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid. N. Engl. J. Med. 1990; 322:1775-1780.

Perl TM, Teitelbaum J, Hockin J, Todd ECD. Panel discussion: definition of the syndrome. Can. Dis. Wkly. Rep. 1990; 16S1E:41-45.

Teitelbaum JS, Zatorre RJ, Carpenter S, Gendron D, Evans AC, Gjedde A, Cashman NR. Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. N. Engl. J. Med. 1990; 322:1781-1787.

Wright JLC, Bird CJ, deFreitas ASW, Hampson D, McDonald J, Quilliam MA. Chemistry, biology, and toxicology of domoic acid and its isomers. Can. Dis. Wkly. Rep. 1990; 16S1E:21-26.

Learner, peer and problem evaluation

Formative evaluation

Make sure there is plenty of opportunity for feedback by the participants concerning how they felt about their own participation and contributions and that of the instructor/facilitator and fellow learners. This should be done after each group session, but especially at the close of the last one. Are the group sessions or classes stimulating? Is self-directed learning encouraged? Do the students feel that their group is approaching the problem and the stated objectives effectively. Were the objectives met? Is the problem as presented relevant and how can it be improved? Is the workload being shared?

Summative evaluation

Two suggestions seem relevant. First, test the response of individual students (orally or in writing) to a food poisoning episode. Test for knowledge, application of knowledge, judgement and decision-making. The scenario might contain more than one part, as in the modified essay questions (MEQs) approach (see Problem-solving Exercise 6.1 for more details). Second, have individual students prepare an investigative/critical assessment of a specific aspect of food safety in their own community, such as one of the issues suggested in Question 9. Performance in an oral presentation might be combined with the mark achieved on the investigative report.

7.4. Problem-solving exercise: Hazard assessment in food production2

2 Based on: J. de Vries et. al, Food safety and toxicity workbook. Heerlen, Open University, 1994

Prepared by Theo de Kok*

* Dr Theo de Kok, Faculty of Natural Sciences, Open University, Heerlen, Netherlands

Time: Two 1-hour sessions, allowing time for independent study

Objectives:

At the end of the exercise students will be able to:

1. Identify and discuss critical control points in food processing.

2. Explain the origin of bacterial contamination of food items.

3. Indicate possible health effects of bacterial food contamination.

4. Discriminate between foodborne infections and food poisoning.

5. Describe possible chemical changes that nutrients may undergo leading to the formation of toxic products during storage, processing, manufacturing and preparation of foods.

Procedures:

1. Introduce the exercise and review its objectives. Divide your class into small groups (5-8 persons). Instruct participants to identify a chairperson and a recorder.

2. Let each group define its own approach to the problem posed. The role of the tutor is to visit all groups and ensure that each group:

- formulates a clear problem definition;
- conducts brainstorming to generate potential answers to the questions;
- prepares a list of specific study objectives for independent study;
- prepares a list of sources of additional information to be consulted (databases, libraries, specialists, etc.).

3. Reconvene the groups after 1-3 days. Invite one group to report back on the information gathered. Ask for comments from the other groups and reports on any responses which were different from those of group one. Alternatively, you may ask each group to give a short summary of its findings and have a plenary discussion about the key elements in the exercise.

Materials:

Problem-solving exercise (Annex 19), flip chart, coloured markers.

Exercise: Hazard assessment in food production

You are a health inspector who is visiting a food processing plant that produces infant food on a large scale. The product of the production line you are working on today is a drum-dried and spray-dried infant food, based on rice, maize, starch, coconut oil, sugar milk and a number of supplements. The flow diagram of the process given to you by the director is shown in Figure 1.


Figure 1 - Flow diagram for drum- and spray-dried rice-based infant foods

Based on your visit to the plant and interviews with staff and employees, you identified a number of critical control points. Table 1 lists the critical control points and the hazards involved.

Table 1 Analysis chart of the process of spray-drying rice-based infant food and control points

Critical control

Description

Hazard

1. Dispersal

Addition of hot water.

Bacterial proliferation ccurs over time

2. Mixing

The solution is mixed in stir tank.

As above.

3. Belt mixer

To achieve the required mixing of all ingredients.

As above.

4. Drum dryer

Evaporation of water by a Drum Dryer (DD)
The dryer works at 150 oC
The product reaches...oC

The products leaving DD meet the current of air caused by the extractor. Microorganisms may be transferred to the product. Bacterial proliferation occurs over time in plant and environment.

5. Prebreaker

The sheet form of the products is reduced to pieces.


6. Sacks

The product is put in sacks.

Contamination of sacks.

7. Dry-mixing

Addition of other ingredients to the semi-finished product.

Pathogens in milk and fruit powders (raw materials).

8. Grinding

The dry mixture is ground by milling.

Contamination from mill.

9. Pneumatic transport trolley tanks pneumatic transport

Pneumatic transport of product, then stored in trolley tanks until transferred to sprat dryer by pneumatic transport

During these operations the product can be contaminated by trolley-tanks as these are transferred from one building to another. Contact with air can introduce microorganisms

10. Spray dryer
Fluid bed

Water is added to the dry mixture; this is then treated In a spray dryer with a fluid bed.

Atomizer rotor is subject to bacterial growth.

11. Packaging

Product placed in sachet of impermeable nitrogen flushed laminate before heat sealing. Sealed sachet placed in a box.

Packaging material can be contaminated. Contamination (pathogens) from the environment. Product residues in filler can contaminate fresh product as it is filled.

It is your task to write a report on the safety of the foods produced by this plant. The following questions may give some guidance in doing so.

Question 1. Describe when and how the microbial hazards may give rise to toxin formation, thus resulting in poisoning of the infant that consumes the food.

As can been seen in Table 1, microbial hazards may occur at each stage of the process. Several steps allow bacterial proliferation over time (especially steps 1-3 since the product still has a high water content).

Rice flour, maize oil, maize starch and soya flour may contain 100-500 ng of mycotoxins per g of the product.

Question 2. What could be the cause of mycotoxin formation in the flow of oil and starch products, and what types of mycotoxins may be formed under which conditions?

The main problems can be expected as a result of the harvest and oil production conditions. Water activity and hygienic GMP (good manufacturing practice) during production, handling, transport and storage are especially important. In the flow of oil products, hydrophobic toxins like aflatoxin and ochratoxin can be expected. The critical water activity is 0.80 for mould growth and 0.83 for toxin formation.

Question 3. What options are there to prevent mycotoxin formation?

There are several options:

- the application of a GMP protocol preventing mould infection of the products and the equipment;

- the use of a quick-drying procedure down to aw = 0.80 (preventing mould growth);

- the use of a fast oil (maize) production processing technique with a CCP examining mould growth and mycotoxin formation.

Question 4. Is it possible to inactivate the mycotoxins that have already been formed in the products, either chemically or physically?

In practice, it appears to be difficult to detoxify a mycotoxin-containing product. Thus, once a product is contaminated, it has to be eliminated from the process.

Question 5. Staphylococcus aureus enterotoxin may have been formed in the milk before it was dried (e.g. 1 ng per g dried milk powder). Is it possible that children show S. aureus poisoning after consuming 250 g of the contaminated product?

These children will probably show no effects, as the milk powder is diluted before it is used in the preparation of food. The concentration of the S. aureus toxin may thus remain far below the toxic intake level of 1?g per 100 g food (for adults).

Question 6. Is it likely that children fall ill after consuming the product in case it is contaminated with 104 viable Bacillus cereus spores per g and the product was left at 20° C for 16 hours?

Yes, the B. cereus spores may germinate, multiply and produce their toxins up to a toxic level within 16 hours at 20° C.

Before use, the infant food is reconstituted by adding 90 g tap water to 10 g of the dried powder containing 10% w/w of milk powder.

Question 7. Describe the toxicological hazards (other than microbiological) that may be associated with this infant formula. Take the whole sequence of production into account from raw material to the consumer (e.g. origin, level, hazards, possible avoidance/elimination).

Study hint: take the following points into account

· Regarding the raw materials:

- excess vitamin A/D;
- antinutritive substances (soy);
- lipid oxidation and its products;
- contaminants (e.g. heavy metals, PCBs, dioxin, nitrate, packing materials);
- additives.

· Regarding the food processing:

- lipid oxidation (minerals, oxygen, heat treatment);
- Maillard reactions (depending on conditions, spray-drying versus drum-drying);
- maintenance or loss of nutritional value depending on the processing conditions;
- contamination from the equipment;
- oxidative and thermal degradation of proteins (drum-drying).

· Regarding packaging/storage:

- contamination.

Suggested references

Hazard analysis critical control point system, concept and application. Report of a WHO Consultation with the participation of FAO. Geneva, World Health Organization, 1995 (Document WHO/FNU/FOS/95.7).

Application of risk analysis to food standards issues. Report of the joint FAO/WHO expert consultation. Geneva, World Health Organization, 1995 (Document WHO//FNU/FOS/95.3).

J. de Vries et al. Food safety and toxicity. CRC press, 1997.

8.1. Round robin on human settlements and urbanization

Time: 1 hour

Objectives:

At the end of the exercise, students will be able to:

1. Identify key environmental health hazards associated with housing or urbanization, the health effects caused by these hazards and potential solutions.

2. Review categorization of environmental health hazards.

Procedures:

(Note to instructor: The exercise is based on categorizing environmental health hazards in housing or urbanization (as biological, chemical, physical, mechanical or psychosocial) and their health effects, along with a primary or secondary measure for their prevention.)

1. Ask one student to name a biological hazard associated with housing or urbanization and to state the health effects of the hazard.

2. Ask a second student to give two primary or secondary prevention measures for the hazard mentioned by the first student.

3. Ask a third student to name a chemical hazard associated with housing or urbanization and to state the health effects of the hazard. Student four gives a primary or secondary prevention measure for the hazard.

4. Proceed as above for the physical, mechanical and psychosocial hazards. Move along rapidly. If one student does not have an answer, proceed to the next.

5. Summarize key hazards mentioned, their effects and potential solutions.

Materials:

Flip chart (you may want to record hazards and prevention measures as they are mentioned), coloured markers, tape.

8.2 Worksheet questionnaire: Health effects of motor vehicle air pollution

Prepared by Ellie Schindelman and David Calkins1

1 From: Motor vehicle air pollution: teacher’s guide. Geneva, World Health Organization, 1996 (Document WHO/EHG/96.16).

Time: 1-2 hours

Objectives:

At the end of the exercise, students will be able to:

1. Describe how motor vehicles cause air pollution.
2. List the pollutants and health risks associated with motor vehicle air pollution
3. Describe who is at risk from motor vehicle air pollution.
4. Describe the main health effects of specific pollutants.

Procedures:

1. Use the attached worksheet to introduce lecture information in a participatory format and as a catalyst for group discussion. During the first 10 minutes of the session, invite students to answer the questions by themselves (or in pairs). Explain that the worksheet is not a test and that no one will see their answers. Encourage participants to guess at the answers if they are not sure of them.

2. The body of the lecture is a review of the questionnaire. Read each potential response and ask students for a show of hands indicating agreement. Encourage students with different responses to justify their answers.

3. Conclude with the correct information and elaborate further, if desired. Then proceed with the next question.

Materials:

Flip chart, coloured markets, tape, worksheet questionnaire (Annex 20).

Motor Vehicle Air Pollution
Health Effects Worksheet

Instructions: Circle all the correct answers or fill in the blanks.

Note to teacher: This version of the worksheet contains the answers. A copy for use by participants is provided in Annex 20.

Question 1. Motor vehicles become a source of air pollution as a result of:

(a) refueling losses
(b) evaporative emissions
(c) exhaust emissions
(d) crank case losses
(e) reckless driving (wrong answer).

Question 2a. What is smog? (not multiple choice)

Smog is a pollutant primarily made up of ground-level ozone. While ozone in the stratosphere protects human health and the environment, ground-level ozone is the most harmful ingredient in smog. Ozone is not directly emitted - it results from a combination of other pollutants and sunlight.

Question 2b. How is smog produced?

(a) power generating plants (wrong answer)
(b) reaction of hydrocarbons and nitrogen oxides with sunlight
(c) automobile exhausts
(d) acid rain (wrong answer).

Explanation:

Acid rain is a combination of pollutants from many sources: smoke stacks, cars, paints, solvents. Wind blows smog-forming pollutants away from their sources; smog-forming reactions take place while pollutants are in the air; pollutants “cook” in the sky, especially if it is sunny and warm. It takes several hours to cook up smog.

Additional information about smog:

What determines where smog goes and how bad it is?

- Weather and topography; temperature inversions.
- When winds are calm, smog can stay in place for days at a time.

How much smog is caused by motor vehicles?

In the United States, motor vehicles:

- are responsible for up to half of smog-forming VOCs (volatile organic compounds) and nitrogen oxides;

- release more than 50% of hazardous air pollutants;

- release up to 90% of the carbon monoxide in the air.

The amount of smog from motor vehicles depends on many factors in the particular area/country.

Question 3. What are the main pollutants from motor vehicles?

(a) carbon monoxide
(b) nitrogen oxides
(c) ozone
(d) particulate matter
(e) lead
(f) benzene
(g) carbon dioxide (wrong answer)
(h) sulfur dioxide (wrong answer)
(i) acid aerosols
(j) halogenated hydrocarbons (wrong answer).

Question 4. What factors affect the composition of motor vehicle exhaust emissions?

(a) fuel type and quality
(b) geographical factors (wrong answer)
(c) maintenance of vehicle
(d) age of vehicle
(e) speed of vehicle (wrong answer)
(f) type and operating condition of engine
(g) use of emission control device.

Question 5. Which population groups may be especially susceptible to adverse health effects from motor vehicle pollution?

(a) children
(b) people who live at high elevations
(c) people who smoke
(d) people with asthma
(e) people with cardiovascular disease
(f) elderly people
(g) people with respiratory disease.

Note: there are no wrong answers.

Question 6. Which groups of people have an increased chance of exposure to motor
vehicle air pollution?

(a) traffic police
(b) pedestrians (it depends)
(c) people who live on highly trafficked streets
(d) parking garage attendants
(e) toll-booth workers at bridges or tunnels
(f) subway passengers (wrong answer)
(g) people who drive buses, taxis, trucks
(h) urban roadside street vendors
(i) gasoline station workers
(j) people who work in urban centres.

Question 7. True or false: Fuels in developing countries often have a high lead and
sulfur content. T F

True

Additional information

Additional issues related to fuels used around the world are:

- leaded gasoline
- diesel (high sulfur, especially in developing countries)
- ethanol blends (increased volatility)
- butane components added to enhance octane increase volatility
- methanol
- natural gas
- LPG (liquid petroleum gas)
- fuel volatility affects evaporative emissions.

Question 8. True or false: All motor vehicles are equally polluting. T F

Why or why not?

False. Factors affecting how polluting a vehicle may be:

- age of vehicle
- catalytic converters
- fuel injection and ignition systems
- two-stroke engines (motorcycles/mopeds), HC (hydrocarbons) emitted from lubricating oil
- diesel trucks and buses (sulfur, exhaust odours)
- maintenance.

Question 9. Which motor vehicle air pollutants can adversely affect the respiratory
tract?

(a) nitrogen oxides
(b) ozone
(c) lead (wrong answer)
(d) sulfur oxides
(e) particulate matter
(f) carbon monoxide (wrong answer).

Additional information

A. Nitrogen dioxide (NO2)

- An irritant gas absorbed into the mucosa of the respiratory tract. When inhaled, 80-90% of NO2 can be absorbed.

- Health effects vary from a mild inflammatory response to bronchitis and bronchial pneumonia. NO2 is linked with increased susceptibility to respiratory infection, increased airway resistance in asthmatics and decreased lung function.

B. Ozone

- Primary target organ is the lungs. Ozone exposure produces cellular and structural changes, causing a decrease in the lung’s ability to perform normal functions.

- The main ingredient of smog is ozone. Many persons exposed to smog suffer eye irritation, coughs and chest discomfort, headaches, upper respiratory illness and increased frequency and severity of asthma attacks.

- In Los Angeles, air pollution from ozone and particulate matter affects 13 million residents up to 17 days per year. Achieving the U. S. EPA’s National Ambient Air Quality Standards may save 1600 lives per year.

C. Sulfur dioxide and particulate matter

- These are only a minimal part of automotive emissions but they react and may have a synergistic effect with other pollutants from motor vehicles.

- Inhaled sulfur dioxide is absorbed in the nose and upper respiratory tract where it has an irritant effect. It then enters the lungs where it can be absorbed into the blood and body.

- In the United States, 8% of non-smoking cancer risk is due to fine particulate matter from diesel trucks, buses and automobiles.

- Particulate matter is thought to be the main cause of excess mortality observed during the London and New York smog episodes of the 1950s and 1960s (this smog was caused by coal combustion, but effects are expected to be similar from smog caused by motor vehicle emissions).

Question 10. Which substances in motor vehicle emissions can produce toxic
systemic effects?

- carbon monoxide
- lead.

A. Carbon monoxide


- Rapidly absorbed in lungs and taken up in blood, carbon monoxide impairs the oxygen-carrying capacity of the blood so that less oxygen gets to the heart, brain or fetus.

- Health effects: low levels can cause headaches, fatigue, slow reflexes.

- People with previous cardiovascular disease (weak hearts) constitute the most sensitive group.

- Large numbers of sensitive people experience adverse health effects at 15ppm (8-hour average).

B. Lead

- Most lead is in fine particles.

- Lead affects many different systems (central nervous system, cardiovascular, endocrine, reproductive).

- Lead is an important problem for young children as it can impair learning ability, behaviour, intelligence and fine motor coordination.

Question 11. Which substances in motor vehicle emissions have a potential
carcinogenic effect?

(a) lead (wrong)
(b) sulfur oxides (wrong)
(c) ozone (wrong)
(d) benzene.

Additional information:

- Benzene is a constituent of crude oil.
- In Europe, benzene is present in petrol (5-16%); in the United States, less than 1.5-2%.
- 50% of inhaled benzene is absorbed and distributed to fat-rich tissue such as bone marrow.
- There are toxic effects on the central nervous system, and immunological effects.
- Benzene is a known human carcinogen; there is no safe level for airborne benzene.

Question 12. True or false: Noise pollution can cause physical, physiological and
psychological effects. Why or why not? T F

True. Noise can cause physical, physiological and psychological effects.

- Direct effect: sound waves act physically against the ear drums and damage them.

- There is no real potential for damage to hearing from road traffic noise (except possibly young children and people with previous hearing impairment).

- Indirect effects: noise can induce physiological change through nerve impulses to the central nervous system, eventually causing damage.

- Reactions are complex and include sleep disturbance and effects on performance. Blood pressure may be affected.

- Noise can also be a major annoyance, creating stress and anxiety.

Question 13. How is human exposure to motor vehicle air pollution measured?

- by ambient air quality data from fixed stations (gives an overview);

- by personal monitors (self-use in a population sample);

- by technicians using personal monitors to measure concentration in selected micro-environments.

Note to teacher: The following are points to consider for your conclusion:

- Motor vehicles account for half the emissions that cause smog, all the carbon monoxide in city centres, more than 25% of fine particulates, and more than half the toxic air pollutants.

- Motor vehicle emissions are a major source of adverse health effects. Ongoing studies continue to show adverse effects at lower and lower levels.

- Why is air pollution from developing countries particularly important to address?

1. There is a large proportion of motorcycles and three-wheeled vehicles, especially in Asia.

2. Some countries have large fleets of two-stroke vehicles (e.g. in eastern Europe).

3. The high proportion of buses, taxis and trucks is often mixed with tractors and slow-moving non-motorized vehicles. Many countries have large fleets of trucks and buses with poor fuel economy and high emissions of CO (carbon monoxide), HC (hydrocarbons), and NOx (nitrogen oxides).

4. There is a higher average age of the vehicle fleet and a very low scrappage rate due to moderate climate, the high cost of vehicle ownership, import duties and excise taxes. Older vehicles may have inadequate exhaust controls and may be poorly maintained.

5. There may be insufficient urban road space and ineffective traffic management, causing slow travel speeds and traffic congestion.

6. Strict emission control laws and regulations are lacking.

8.3. Problem solving exercise: Building a healthy city - the case of Managua, Nicaragua

Prepared by Merri Weinger

Time: 3 hours

Objectives:

At the end of the exercise, students will be able to:

1. Understand the basic principles of the World Health Organization’s Healthy Cities Programme.

2. Recognize the important impact that physical, social and economic environments have on health status in urban settings.

3. Appreciate the need for intersectoral collaboration and community participation to create physical and social environments that support health.

4. List the key steps in implementing a Healthy Cities project.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. Distribute the exercise and review the participants’ tasks. The case scenario is very brief. Instruct students that they can also draw on their knowledge of typical urban problems in health and environment, including those in their own cities.

3. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

4. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 21), flip chart, coloured markers.

Case scenario

Adapted from an article by Francoise Barten and Angel Sanchez

At present, Nicaragua is one of the poorest countries in Latin America. The dislocation caused by the low-intensity war during the last decade led to massive migration from the countryside. The population of the capital, Managua, more than doubled in three years. Today, roughly one-third of the country’s population lives in Managua. This rapid and uncontrolled growth of the city, combined with a lack of urban planning and increased demand on urban services, has contributed to a crisis situation, with increasing social inequalities and the political polarization of society.

Between 1987 and 1994, poverty in Managua increased from 30% to 72.5% and extreme poverty from 15% to 50% - mainly among female-headed households. Unemployment stands at a staggering 62% and malnutrition in children at 68%, while domestic violence and drug abuse among school-aged youth are rapidly rising. The 270 squatter settlements constitute the most unhealthy environments of the city, and more than 300 polluting industries are located in low-income areas. Waste is dumped at 310 illegal sites throughout the city, causing serious health hazards.

Among other health problems, the city faces serious epidemics of malaria and dengue. In spite of declining health status, the public health budget was reduced by 50% in recent years.

Question 1. What are some of the key health, environmental and social problems likely to be faced by the city of Managua?

Students should summarize the problems listed in the exercise and also try to suggest others on the basis of their experience and the information provided. For example: poor housing, overcrowding, unemployment, malnutrition, domestic violence, drug abuse, air and water pollution, potential exposure to hazardous waste, high rates of communicable diseases, high infant mortality rates, shorter life expectancy for adults, poor access to health care, lack of access to effective solid waste management and sanitation, higher crime rates, stress.

Question 2. Your task is to work with an intersectoral group in Managua to develop a municipal action plan to address some of these problems.

a. Who should be part of this working group and how do you propose to establish it?

The working group might include representatives from local government agencies (health, environment, social services, etc.), nongovernmental organizations, community groups, universities and training institutions. This core group of individuals initiates the process, begins to build public support and contacts other groups and individuals who may be interested in participating.

Healthy Cities projects often appoint an advisory group to provide the leadership and legitimacy needed for health advocacy and for the mobilization of people and resources to bring about health improvements. In addition to those mentioned above, potential members may be: city councillors responsible for social services; senior managers of the primary health care system or network of health centres of the city; the mayor; representatives from business, industry, labour and professional organizations; religious leaders, etc.

A workshop or seminar is an excellent means of initiating a Healthy Cities project and building a core group of activists. In Managua, more than 30 organizations participated in a workshop convened to explain the concept and approach of a Healthy Cities project and to identify current contributions to urban health development which could contribute to the initiative. It soon became clear that many different institutions, municipal agencies, community bodies and nongovernmental organizations were making various separate efforts, often in the same areas of Managua.

b. You would like to ensure that the community is involved in developing the plan. What is your strategy for raising awareness about the project and fostering community participation?

Open meetings, workshops and seminars can be helpful in informing the community about the project. As the project develops, community members can be asked to participate in committees to address particular issues, such as water and sanitation, health conditions in markets, clinic services, etc. A visible and accessible office makes a valuable contribution to the project. Several cities have set up Healthy Cities store-fronts at street level that encourage visitors to drop in. These provide information on environment and health care.

Other strategies for fostering community participation include: gaining the commitment of community leaders, providing training for community participants, publishing stories and reports about the project in local media, organizing public campaigns on specific projects (e.g. vaccination, street cleaning), and inviting the community to participate in gathering information about health problems in their neighbourhoods.

c. Which problem would you make first priority and how would you go about making this decision?

A good first step is to collect and analyse all existing reports on environment and health. In addition, it is often helpful to conduct a survey or study to identify the city’s main environmental health problems as a basis for prioritization. In Managua, the School of Public Health, in collaboration with WHO and the United Nations Development Programme (UNDP) undertook a field study based on direct consultations with the public. The information provided helped to set the agenda for their municipal action plan.

This information is generally presented to the working group and the community. Emphasis is placed on the contribution that problems make to the burden of ill-health. Priority problems can then be identified through group discussion and collective decision-making. It is common for communities to give high priority to access to clean water and sanitation.

d. What are the objectives of your action plan?

Objectives will be:

- to create conditions that promote health in settings such as the home, school, neighbourhood, market, workplace and city at large;

- to improve the performance of the municipality both in provision of services and in supporting local community initiatives that promote health;

- to identify health education and other health-related activities which can be incorporated into the agenda of municipal agencies working at community level in water, sanitation, solid waste, housing, education, social services, etc.;

- to facilitate community participation in the health-related activities outlined in the plan.

e. What are the key components of your municipal action plan?

Key components will be:

- background information which describes and quantifies the social, economic and environmental health problems and conditions in the city;

- prioritization of problems based on their contribution to the burden of ill-health;

- existing municipal agencies and organizations including NGOs and international agencies that can potentially contribute to solving health problems;

- potential mechanisms for participating partners to work in a more coordinated manner in addressing problems;

- priority actions and programmes, including setting of targets, timetable and evaluation plans.

f. What kind of activities might be included in the plan?

Activities might include: health education on nutrition and sanitation; collaboration with the university, water and housing authorities to improve conditions in the squatter communities (e.g. street drainage, tree planting, installation of household water connections, installation of drinking-water and washing stations, community-based management of waste collection, construction of sewerage and stabilization ponds, etc.); improved access to maternal and child health services; youth recreation or job development programmes, etc.

g. On the basis of the activities outlined above, which agencies might take the lead in implementing the plan?

Leadership should reflect intersectoral collaboration and should include community participation.

Selected references

Barten F, Sanchez A. Towards a Healthier Managua. World Health, January-February 1996.

Price C, Tsouros A (eds.). Our cities, our future: policies and action plans for health and sustainable development, 2nd edition. Copenhagen, WHO Regional Office for Europe, 1996.

Von Schirnding Y. Intersectoral action for health: addressing health and environment concerns in sustainable development. Geneva, World Health Organization, 1997 (Document WHO/PPE/PAC/97).

Building a healthy city: a practititioner’s guide. Geneva, World Health Organization, 1995 (Document WHO/EOS/95.10).

9.1. Introductory exercise: Health and energy

Time: 1 hour

Objectives:

At the end of the exercise, students will be able to:

1. List examples of energy sources in specific country settings.

2. Identify the health effects associated with common energy sources, and name potential alternatives.

Procedures:

1. Divide class into small groups. Ask each group to answer the following questions which are listed on the blackboard or flip chart (20 minutes):

What energy sources are used in your jurisdiction?
What are these sources used for?
What are the advantages of each of the energy sources used?
What are the health effects associated with each of these energy sources?
What energy sources could be used?
Why are these alternative energy sources not currently in use in this jurisdiction?

2. Invite reports from each group. Discuss and summarize responses.

Materials:

Flip chart (you may want to record energy sources as they are mentioned), coloured markers, tape.

9.2. Problem-solving exercise: Nuclear energy - a safe alternative?

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Time: Two 2-hour sessions, allowing time for independent study.

Objectives:

At the end of the exercise, students will be able to:

1. Understand the basic principles of health physics (nature and sources of ionizing radiation, measurement and detection of ionizing radiation, chronic health effects of exposure, possibility of heritable consequences).

2. Explain the background exposure to ionizing radiation experienced by the general public.

3. Appreciate the advantages/disadvantages of both major and minor energy sources and understand the impact of their use on society, human health and the environment.

Procedures:

(Note to instructor: This exercise requires substantial study by participants which can be done both in the classroom and at home. Divide the workload of retrieving and reviewing the references among the class members. A general issue-generating session is recommended to provide a context for addressing the questions posed below (see item 4). Review of Chapter 9 and Section 2.4.3 is, of course, a prerequisite.)

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. Distribute the exercise and review the participants’ tasks.

3. Brainstorm a list of the key issues raised in the case study. Alternatively, this can be done in the small groups. This helps to establish the existing knowledge of members of the group and to identify special resource persons within the group.

4. Following the small group work, reconvene the groups and invite a response from one of the groups to the first question (or from the designated group if questions were assigned to a specific group). Ask whether other groups have any different responses. Summarize, and if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 22), flip chart, coloured markers.

Case scenario

Concern about the prevalence of childhood cancer around a nuclear installation was broadcast on a national television programme. An ad hoc committee was set up by the Ministries of Health, Labour and Environment. It initiated two epidemiologic studies: a retrospective cohort study of the workers at the plant, and a case-control study of leukemia and lymphoma among young people living in the vicinity of the plant. The installation consists of four reactors, a spent-fuel reprocessing unit, various waste treatment plants, and a fast-reactor fuel-fabrication plant.

The study of workers’ mortality included all persons first employed before 1976, followed up until 31 December 1983. Deaths from all causes and cancer were somewhat lower than expected based on the general population mortality rates of the province. However, there were positive associations between accumulated radiation dose and death rates from bladder cancer, multiple myeloma, leukemia and haematopoietic neoplasms. These were not statistically significant when exposure up to the time of death or up to two years previously was considered. Nevertheless, when exposures recorded in the 15 years before death were ignored, these associations, with the exception of that for leukemia, became significant (p < 0.05). The observed association of radiation with bladder cancer has not been found in previous studies, but the findings for myeloma have been reported before for radiation workers.

In the second study, all identified cases of leukemia and lymphoma among individuals born in the region and diagnosed at ages under 25 were compared with controls matched by sex and date of birth and selected from the same birth register as the cases (eight controls were taken for every case). The startling and significant finding (p < 0.05) was that paternal external radiation dose at work during the 6 months before conception (> 10 mSv) or total occupational life-time dose before conception (> 100 mSv) was associated with a raised incidence of leukemia and non-Hodgkin’s lymphoma among children of employees of the nuclear complex. Other than antenatal abdominal X-ray examinations, for which there was a non-significant positive (p > 0.05) association, and maternal age, no other risk factors were correlated with the observed incidence of leukemia and lymphoma. This study is based on 46 cases of leukemia and 20 cases of lymphomas.

Chapter 2 Questions

1. Discuss the fundamental properties of ionizing radiation, including the types and their sources.

Ionizing radiation exists as either particles or electromagnetic waves. Particles (e.g. alpha, beta, neutrons, protons) have finite mass and some are charged. By contrast, ionizing electromagnetic waves (i.e. gamma radiation and X-rays) have no charge or mass, move at the speed of light and have very short wavelengths. Ionizing radiation is capable of physically knocking electrons out of biomolecules, including DNA, thereby inducing direct molecular damage, and of generating tissue-damaging radicals. Radicals are atoms or molecules with unpaired electrons in their valence shells, which causes them to be very chemically reactive. Examples are the hydroxyl radicals from water and lipid peroxyl radicals from membranes. For additional details see Sections 2.4.3 and 2.4.4 and Box 2.7 of the textbook.

2. How is radiation measured and in what units? Distinguish between absorbed dose, equivalent dose and effective dose in your answer.

Joule: A joule is a unit of work and equals 0.24 gram-calories. It is also the amount of work produced in one second by one watt. One joule (J) is equal to 107 ergs.

Electron Volt: The electron volt (eV) is a unit of energy. Chemical bonds are the order of a few electron volts, while nuclear decay energies normally involve thousands (keV) or millions (MeV) of electron volts of energy.

Curie (Ci): The curie is defined as 3.7x1010 disintegrations per second. More common are the submultiples millicurie (1 mCi = 10-3 Ci) and microcurie (1 mCi = 10-6 Ci).

Becquerel (Bq): The becquerel has replaced the curie as the fundamental unit of activity. It is defined as one disintegration per second. Its common multiples are:

kilobecquerel (kBq = 103 Bq)
megabecquerel (MBq = 106 Bq)
gigabecquerel (GBq = 109 Bq)
terabecquerel (TBq = 1012 Bq)

Thus:

1 Ci = 37 GBq
1 mCi = 37 MBq
1 mCi = 37 kBq

The amount of X- and gamma-radiation that causes ionization in air is measured in roentgens (R). The absorbed dose of 1 rad is that which results from the absorption of 1R of ionizing radiation deposited in any medium, typically water or tissue. The SI unit is 1 gray = 1 J/kg (º 100 rads, an older unit). The equivalent dose is the product of the absorbed dose in grays and the radiation weighing factor (RWF), which is a measure of the biological damage it can inflict, and depends on the radiation type. The RWF value is 1.0 for beta particles, as well as X- and gamma-radiation; it is 20 for alpha particles and ranges from 5-20 for neutrons, depending on their kinetic energy. The SI unit is the sievert (Sv) = dose in grays x RWF (or rem = dose in rads x RWF). For all practical purposes rads, rems and roentgens can be used interchangeably when dealing with X- or gamma-rays. The effective dose takes into account the different sensitivities of organs to ionizing radiation; it corresponds to the sum of the product of the equivalent dose and the tissue weighting factor (TWF) for all the organs or tissues exposed. Values of TWF are: 0.20 (gonads), 0.12 (red bone marrow, colon, stomach, lung), 0.05 (thyroid, bladder, breast, oesophagus, liver), 0.01 (skin and bone surface), 0.05 (remainder).

Personal exposure measurement devices include film badges or nuclear emulsion monitors (for X-rays, gamma rays, beta particles and neutron radiation), thermoluminescent dosimeters and ionization dosimeters. A scintillation counter or gamma counter can be used to measure radioisotopes in urine specimens or in tissues from target organs (e.g. thyroid). Environmental or area monitoring devices include the Geiger-Mcounter, ionization chamber and scintillation detector. The specific choice depends on the type and energy of the radiation to be detected.

3. Are the health effects reported for the workers and the young people in the case scenario consistent with exposure to ionizing radiation? What are the routes of exposure?

Exposure is either external, when the radiation source is outside the body, or internal, when the radiation is emitted within the body (after ingestion/absorption of radioactive substances).

A perusal of the health effects known to be associated with exposure to ionizing radiation, as described in Section 2.4.3 and Table 2.9 of the textbook, makes it clear that the reported bladder cancer and the neoplastic changes in the haemopoietic system and lymphoid tissues are recognized risks and thus constitute probable outcomes. At the molecular level, ionizing radiation induces direct and indirect damage in DNA that can lead to permanent changes it (i.e. mutations). As indicated in some detail in the answer to Question 1 (Part II) of Problem-solving Exercise 2.4, mutations can bring about the genetic alterations that lead to cancer.

In women exposed during pregnancy, increased incidences of miscarriages, stillbirths and neonatal deaths have been reported (Pope and Rall, 1995). Children exposed in utero have shown an excess of congenital defects, especially interference with the development of the nervous system (Ikenoue et al., 1993). Risk of the development of leukemia in children after birth is also known (Gardner, 1991). Although heritable defects due to exposure of the mother and/or father before conception have not been evident in atomic bomb survivors, no a priori reason exists to conclude that humans are exempt from genetic defects induced in germ cells (Pope and Rall, 1995).

4. Assuming that the implied link between paternal exposure and leukemia and lymphoma in children of the exposed workers is real, what underlying pathological mechanism is implied?

The development of leukemia and lymphoma in children of fathers exposed to ionization prior to conception implies that one of the genetic events at the gene or chromosome level required in the development of malignancy has occurred in the germ cell and is inherited. This would constitute an increased probability that the offspring will contract childhood leukemia.

There has been considerable debate on whether the above hypothesis has merit. Most geneticists and radiobiologists consider that the levels of occupational (external) exposure recorded (c.f. the case scenario) are too low for genetic damage to male germ cells to occur. This conclusion is based on experience among Japanese survivors of atomic explosions (Garner, 1991; Doll et al., 1994). In addition, the contribution of inherited mutations to the development of childhood leukemia is estimated to be low (~5%) compared to other cancers (Doll et al., 1994). However, a recent review of childhood leukemia cases in England, Scotland and Wales (excluding the cases in the case scenario) suggests that paternal preconception exposure to radionuclides (i.e. source of ionizing radiation is internal) is a more likely risk factor of childhood cancer than exposure to external radiation (Sorahan and Roberts, 1993).

5. What are the allowable occupational exposure limits for external ionizing radiation in the jurisdiction in which you live?

Dose limits will vary from jurisdiction to jurisdiction. The International Commission on Radiological Protection (ICRP) recommended the following guidelines in 1991: for stochastic effects (e.g. cancer and genetic damage; see textbook Sections 2.4.3, 9.5.2 and 9.5.3), 50 mSv is the annual effective dose limit, with 100 mSv as the 5-year cumulative effective dose; for nonstochastic effects (e.g. lens cataracts and fertility impairment), the annual equivalent dose limit to the lens of the eye is 150 mSv and 500 mSv to skin, hands and feet.

In December 1984, Stanley Watras, a worker at the Limerick nuclear power plant in Pennsylvania, USA, began setting off radiation alarms when he entered the plant on a Monday morning.

6. Interpret this incident.

The cause was traced to excessive radon gas levels in his home. He had worked in his basement all weekend. Measured levels were found to be 500 times the level at which the US EPA currently recommends remediation [4 pCi/L or (4x10-12)(3.7x1010 disintegrations per second)/L=0.15 Bq/L]. The source of the radon came from the surrounding soil/rocks. Elevated radon levels in homes, especially in basements where radon gas leaks since it is dense, occur in areas with significant deposits of granite, uranium, shale and phosphate - all high in radium content, which is an alpha particle emitter yielding radon (also an alpha emitter).

The ICRP recommends the following annual dose limits for the public (excluding medical and natural background exposures): 1 mSv (effective dose for stochastic effects); 15 mSv (equivalent dose to lens of the eye) and 50 mSv (equivalent dose to skin, hands and feet) for nonstochastic effects. By comparison, the mean annual dose of radiation received in Britain is in the order of 2-5 mSv, of which 87% is from natural sources with half of that from radon; cosmic radiation is another significant source. The rest comes from man-made sources: 12% of medical origin and 1% from nuclear fall-out and inadvertent occupational sources. The corresponding North American average background radiation is estimated at 2.6 mSv.

Chapter 9 Questions

1. Energy is necessary for daily survival and provides heat for warmth, working and manufacturing, or power for transport and mechanical work. Energy fosters activity. Ensuring an adequate, safe and environmentally-sound energy supply is a big challenge. Compare the four major energy sources (biomass fuels, fossil fuels, hydroelectric power, nuclear power) in terms of developmental costs, safety, environmental impact, social impact and renewability.

Individual or group presentations might be considered. A well-informed discussion or debate format would also be appropriate.

2. Discuss the feasibility of alternative energy sources, highlighting those of special relevance to your own region.

Again a discussion or debate seems suitable. Use the material in Section 9.6 and Table 9.7 as the starting point. Also explore ways to conserve energy.

3. With special reference to The Chernobyl Accident Case Study (see Box 9.3 of the textbook), develop arguments for and against the statement that the operation of nuclear power plants should be discontinued as it does not adequately ensure the protection implied in Article 3 of the UN Declaration of Human Rights that “everyone has the right to life, liberty and security of person.”

Potential answers are summarized on the chart that follows.

Factor

Biomass fuelsa

Fossil fuelsb

Hydroelectric power

Nuclear power

Developmental costs

Retrieval low (except transport); commercial production moderate; regeneration low to moderate

Search for and retrieval high; processing high (oils) or low (gas, coals)

Construction high (dams, generators); maintenance low

Construction and maintenance high

Safety

Acute and chronic effects of smoke serious: respiratory irritation/disease; acute poisoning (carbon monoxide); reduced air quality; risk of fires (see Tables 9.2 and 9.3)

Chronic respiratory disease (coal mining; oil refineries); acute poisoning (gases); reduced air quality; industrial transport accidents/fires (see Tables 9.4 and 9.5)

Construction accidents; threat of dam breakage; spread of parasitic diseases; mercury contaminated fish (see Section 9.4)

Construction accidents; proper safety precautions, monitoring and maintenance are essential; occupational cancers (see Section 9.5 and Table 9.6)

Environmental impact

Deforestation; generation of greenhouse gases; air pollution; erosion; global climate effects

Significant release of greenhouse gases and other gaseous pollutants; global climate effects

Flooding of lands; negative effects on wildlife and watersheds; impact on species diversity

Contamination of cooling waters with radioactive substances (e.g., tritium); storage of spent fuel not sustainable; disaster if meltdown (due to improper maintenance or use)

Social impact

Impact greatest on females (gathering and use often “women’s work”; labour intensive); loss of tillable land; health costs

Health costs; smell of refineries unpleasant; devaluation of property; labour intensive

Relocation, often of native peoples; land loss; generates few jobs

Low impact if no accident; disaster if not operated safely; perceived risk is great, causing anxiety

Renewability

Potentially renewable with revegetation/reforestation

Non-renewable (limited reserves)

Renewable if water source is plentiful

Non-renewable (limited reserves)

a Includes: wood, logging wastes, animal dung, vegetation, agricultural wastes.
b Includes: coal, oil and natural gas.

Nuclear power and right to life, liberty and security of person

A. Arguments for closing

Reason

· If not operated/constructed properly/safely, a Chernobyl may arise and emissions may not meet regulations.

· Threatens life and security; evacuation would affect liberty.

· If no emergency procedures are in place (e.g. evacuation of workers and general population; disaster modelling).

· Threatens all three.

· If plutonium is generated/used (a component of nuclear weapons).

· Threatens all three.

· If no fuel reprocessing is done.

· Long-term storage is a possible threat to future security.

· If workforce is not educated/trained.

· Operation errors can result in accidents/meltdown (e.g. Chernobyl; Three Mile Island)

· If there is no right-to-know policy.

· Perceived risk affects “security of person”.

B. Arguments against closing

Reason

· No significant air pollution (SO2, CO2, organic compounds, etc.).

· Environmentally friendly; a cleaner and healthier environment.

· Creates jobs.

· In mining, refining of uranium; operation of power plant.

· May be the only economic source of energy available to a region.

· Economically attractive since oil would need to be imported; energy is the engine of society.

· An interim source of energy (limited reserves).

· Buys time to find and establish long-term sources of energy.

Selected references

Doll R, Evans HJ, Darby SC. Paternal exposure not to blame. Nature 1994; 367:678-680.

Gardner MJ, Snee MP, Hall AJ, Powell CA, Downes S, Terrel JD. Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria. Br. Med. J. 1990; 300:423-429.

Gardner MJ. Childhood cancer and nuclear installations. Public Health 1991; 105:277-285.

Gibbons J H, Blair P D, Gwin H L. Strategies for energy use. Sci. Amer. 1989; 261 (Sept.):136-143.

Hle W. Energy from nuclear power. Sci. Amer. 1990; 263 (Sept.):137-144.

Harley NH. Toxic effects of radiation and radioactive materials. In: Casarett & Doull’s Toxicology, 5th ed. The Basic Science of Poisons (CD Klaassen, ed.). New York, McGraw-Hill, 1996, pp 773-800.

Ikenoue T, Ikeda T, Ibara S, Otake M, Schull WJ. Effects of environmental factors on perinatal outcome: neurological development in cases of intrauterine growth retardation and school performance of children perinatally exposed to ionizing radiation. Environ. Health Perspect. 1993; 101 (Suppl. 2):53-57.

OECD/NEA. Chernobyl ten years on. Radiological and health impact. An assessment by the NEA Committee on Radiation Protection and Public Health, November 1995. OECD Nuclear Energy Agency.

Ogilvy-Stuart AL, Shalet SM. Effect of radiation on the human reproductive system. Environ. Health Perspect. 1993; 101 (Suppl. 2):109-116.

Pope AM, Rall DP. Environmental medicine. Washington, DC, National Academy Press, 1995, pp. 639-700.

Sali D, Cardis E, Sztanyik L, Auvinen A, Bairakova A, Dontas N, Grosche B, Kerekes A, Kusic Z, Kusoglu C, Lechpammer S, Lyra M, Michaelis J, Petridou E, Szybinski Z, Tominaga S, Tulbure R, Turnbull A, Valerianova Z. Cancer consequences of the Chernobyl accident in Europe outside the former USSR: A review. Int. J. Cancer 1996; 67:343-352.

Shcherbak YM. Ten years of the Chernobyl era. The environmental and health effects of nuclear power’s greatest calamity will last for generations. Sc. Amer. 1996; 274 (April):44-49.

Smith PG, Douglas AJ. Mortality of workers at the Sellafield plant of British Nuclear Fuels. Br. Med. J. 1986; 293:845-854.

Sorahan T, Roberts PJ. Childhood cancer and paternal exposure to ionizing radiation: preliminary findings from the Oxford survey of childhood cancers. Amer. J. Ind. Med. 1993; 23:343-354.

Learner, peer and problem evaluation

Formative evaluation

Make sure there is plenty of opportunity for feedback by the participants concerning how they feel about their own participation and contributions and that of the instructor/facilitator and fellow learners. This should be done after each group session, but especially at the close of the last one. Are the group sessions or classes stimulating? Is self-directed learning encouraged? Do they feel that the group is approaching the problem and the stated objectives effectively. Were the objectives met? Is the problem as presented relevant and how can it be improved?

Summative evaluation

An assessment of the factual knowledge associated with the Chapter 2 questions might best be achieved by short answer questions (SAQs) or multiple choice questions (MCQs). For guidance on how to construct these, see Exercise 2.4. It is suggested that the student evaluation related to Chapter 9 questions be an essay. It is important to specify the format and length, to help students in setting achievable objectives, and to assist in defining the scope of the chosen topic. Assistance in the professional use of references (both in the text and in preparing the list) is also urged.

10.1. Problem-solving exercise: Occupational exposure to inorganic lead

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Time: Two 1-2 hour sessions, with independent study.

Objectives:

At the end of the exercise, students will be able to:

1. Define and explain hazard identification, dose-response relationships, exposure assessment, risk characterization, NOAELs and LOAELs, risk management, environmental controls, threshold limit values (TLVs), and the principles of occupational health surveillance/monitoring.

2. Understand the need for a preventive approach to protect workers’ rights to a clean working environment and for workers’ participation in planning environmental control or health surveillance programmes.

3. Appreciate the long-term social and economic benefits of a clean working environment.

4. Promote worker education and training in health and safety and the promulgation of air and related exposure regulations.

Procedures:

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. Distribute the exercise and review the participants’ tasks.

3. Brainstorm a list of the key issues raised in the case study with the entire group. Alternatively this can be done in small groups. This helps to establish the existing knowledge among members of the group and to identify resource persons.

4. Following small group work, reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize, and if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered. Possible answers to the questions are provided below. These answers are not all-inclusive. Instructors are encouraged to develop alternative responses and intervention strategies that are appropriate to the local situation.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 23), flip chart, coloured markers.

Case scenario

To assess lead exposure in the Jamaican lead-acid battery manufacturing industry, three separate plants were surveyed. Of the 42 personal breathing-zone air samples collected, 38 exceeded the OHSA (US Occupational Health and Safety Administration) regulated permissible exposure level (PEL) of 50 mg/m3 (range 30-5300 mg/m3) and nine samples exceeded 500 mg/m3. The air samples were collected on mixed cellulose-ester filters using a flow rate of 2 L/min for the duration of the work-shift. Twenty-eight percent of the workers had blood levels exceeding 2.90 mmol/L (60 mg/dL). More specifically, in Plant B, the geometric mean of the air lead levels was 233 mg/m3, with 60% in the range 50 to 200 mg/m3 and the remaining 40% exceeding 500 mg/m3. The distribution of the measured blood-lead levels in the same plant was: 9% < 1.93 mmol/L (<40 mg/dL), 17% between 1.93 to 2.85 mmol/L (40-59 mg/dL), 57% in the range 2.90-3.81 mmol/L (60-79 mg/dL), and 17% above 3.86 mmol/L (80 mg/dL).

In a recent critical assessment of the literature, IPCS (1995) suggests the following NOAEL blood-lead levels for biochemical or health effects of lead exposure in adults: 1.20 mmol/L (25 mg/dL, men) and 0.96 mmol/L (20 mg/dL, women) for haem synthesis depression measured by zinc protoporhyrin (ZPP), also referred to as erythrocyte protoporhyrin (EP); 2.16 mmol/L (45 mg/dL) in men and 1.68 mmol/L (35 mg/dL) in women for urinary excretion of ALA (aminolaevulinic acid); < 0.48 mmol/L (10 mg/dL) for learning and behavioural effects in children; 2.40 mmol/L (50 mg/dL) for anaemia; 1.44 mmol/L (30 mg/dL) for reduction in peripheral nerve conduction velocity; 1.92 mmol/L (40 mg/dL) for sensory motor function impairment; 1.68 mmol/L (35 mg/dL) for alterations in the autonomic nervous system function; and 2.88 mmol/L (60 mg/dL) for risk of nephropathy. The blood-lead/air-lead relationship in occupational settings is curvilinear, having slopes between 0.00096 and 0.0038 mmol/L (0.02 and 0.08 mg/dL) per mg/m3 air. WHO (1980) recommends that air levels should not exceed 30-60 mg/m3; in most other jurisdictions, threshold limit value-time-weighted average (TLV-TWA) values of 100 to 150 mg/m3 are recommended (Saryan and Zenz, 1994).

Review questions

Chapter 3 Questions

1. In terms of hazard identification, succinctly state what we know about the adverse health effects of lead.

The exposure in the case scenario is to inorganic lead. This grouping includes lead metal fumes, lead binary compounds such as oxides or sulphides, ternary compounds such as sulphates and phosphates, water-soluble lead salts (e.g. chloride, nitrate, acetate). The majority of the lead compounds have lead in the +2 oxidation state. Organometallic lead compounds (organic lead) are characterized by the lead-carbon bond. The prime example is the gasoline additive tetraethyllead [Pb(CH2CH3)4]. In alkyl lead compounds, lead is in the +4 oxidation state. By contrast to inorganic lead compounds, organometallic lead compounds are soluble in organic solvents and biologically speaking are lipid (fat) soluble.

Inorganic lead compounds are systemic poisons (IPCS, 1995). Acute effects include abdominal pain (colic), encephalopathy (degenerative brain disease), haemolysis and acute renal failure. Chronic effects are manifested as fatigue, weakness, muscle and joint pain, anaemia, peripheral nervous system disturbances (neuropathy), central nervous system (CNS) effects (including neurobehavioural disturbances), gout and kidney alterations. Reproductive and developmental effects have also been documented. Lead is readily transferred across the placenta. Of great concern are the learning and behavioural deficits observed in young children, even for low-level exposures. Contaminated soils or lead-containing paints are frequent sources of inorganic lead for children. The symptomatology associated with exposure to alkyl lead compounds is somewhat different than for inorganic lead intoxication. Symptoms comprise fatigue and lassitude, headache, nausea and vomiting, neuropsychiatric complaints (memory loss, difficulty in concentrating) and, if severe, delirium seizures and coma.

Perhaps short student presentations would be an effective way to summarize the health effects of lead.

2. Based on the biological exposure indices or NOAELs provided in the case scenario, what are the likely shapes of the dose-response curves (i.e. effect versus lead in blood)?

A “threshold response” such as that depicted in Figure 3.12 is predicted.

3. Are the threshold values in agreement with those indicated in Figure 3.10? Give reasons for any discrepancies.


Threshold (mg Pb/L)

Effect

Scenario

Figure 3.10

haem synthesis (ZPP)

200 (females), 250 (men)

£50

urinary ALA

350 (females), 450 (men)


anaemia

500

750

peripheral nerve conduction

300

300

sensory motor function

400


autonomic nervous system

350


nephropathy

600


cognitive and behavioural

£100

£100

effects in children



The differences in these threshold evaluations probably reflect the number of published studies reviewed to obtain the data depicted in the figure. The lead value of <50 mg/L for increases in ZPP probably refers to children. IPCS (1995) suggests that 0.72 mmol/L (150 mg/L) is the NOAEL for excess ZPP formation in children. In spite of these discrepancies, it is clear that lead is a very potent systemic poison.

4. Comment on the exposures experienced by the workers.

As indicated in the case scenario, TLV-TWA values vary between 30 and 150 mg/m3. The American Conference of Governmental and Industrial Hygienists (ACGIH) in its 1995-1996 TLV-TWA listing has set it at 50 mg/m3 for elemental and inorganic lead compounds; the previous value was 150 mg/m3. The reason for this change is that lead compounds have been designated as animal carcinogens. Clearly, some of the workers in the scenario are exposed to air-lead levels that are too high by most international standards.

5. In your opinion, are the workers at risk? Justify your answer. Can you characterize this risk?

Taking Plant B as the example, it is clear that the air levels of lead exceeded all international standards. A similar picture emerges by comparing the blood-lead values with the NOAEL values. In terms of risk characterization, up to 90% of the workers may be expected to have enhanced risk for measurable biochemical, haematological or neurological changes; about 60% of the workers may be considered at risk for kidney damage.

6. Do you believe the workers are subjected to a risk high enough to warrant work refusal?

Certainly the workers with blood-lead levels exceeding 3.86 mmol/L (80 mg/dL) would be removed from work in most jurisdictions. For example, this is warranted in the USA if three blood samples exceed 2.90 mmol/L (60 mg/dL); in the Province of Ontario, Canada, removal is required for levels > 3.38 (70 mg/dL) in the case of male workers and 1.90 mmol/L (40 mg/dL) for females of childbearing age.

7. Clearly lead is a systemic poison. Explain why the total (inhalable) lead levels are measured rather than the respirable fraction?

Total inhalable lead levels are relevant for a systemic poison like lead. Some absorption can take place directly through the tissues of both the upper and lower respiratory tract. In addition, the upper respiratory tract is cleared by cilial action (including the nasal passages and bronchial epithelium), which results in swallowing or rejection by coughing/spitting. Of course, the amount swallowed will contribute significantly to the total amount absorbed.

Chapters 4 and 10 Questions

1. Would you recommend that the workers in the case scenario should be issued personal protection equipment? If so, what would you recommend?

Personal protective equipment should be issued to some workers since their exposure is at levels above the TLV-TWA of many jurisdictions; personal protection is usually mandated for occasional brief exposures above the TLV-TWA or for emergencies. For example, in the USA, NIOSH prescribes the following respirators: (i) half-mask, air-purifying respirator equipped with high-efficiency filters for air-lead levels not exceeding 500 mg/m3 which corresponds to 10 x PEL; (ii) full facepiece, air-purifying respirator with high-efficiency filters for air-lead levels not exceeding 2500 mg/m3 (50 x PEL); (iii) for levels not in excess of 50,000 mg/m3 (1000 x PEL), any powered, air-purifying respirator with high-efficiency filters or half-mask supplied-air respirator operated in positive-pressure mode. It is further specified that full facepiece protection is required if the lead aerosols cause eye or skin irritation at the use concentrations and that a high efficiency particulate filter means it is 99.97% efficient against 0.3 mm size particles (Saryan and Zenz, 1994). It should be emphasized that personal protective equipment is for use when the engineering control measures fail to provide a safe working environment. Respirators are not to be substituted for technical control measures and are not to be regarded as the primary method of protection.

2. What additional information do you need to know about the plant and workers before an environmental control programme can be considered?

Before an environmental control programme can be implemented, more needs to be known about the physical characteristics and dimensions of the plant (including workroom ventilation), the manufacturing process, and the operational details (number of employees, job classifications, daily production, number of shifts etc.).

To make the discussion more realistic, a number of the students might consult the references that deal with exposures of lead-acid battery workers (i.e. Awad El Karim et al., 1986; Matte et al., 1989; and especially Caplan et al., 1979). Briefly, a lead matrix or grid is cast and a paste, primarily composed of lead, lead oxide, sulphuric acid, water and expanders, is pressed into and onto the grids at the pasting machine. The pasted grids or plates pass through an oven to dry the surface to prevent sticking. Curing follows, with the plates stacked on racks. Subsequently, plates are parted as they are produced in pairs. Parted plates are arranged to form elements (alternating negative or positive plates with an inert separator between them) by hand or machine and are then welded to form groups. A common feature of battery plants is the transfer of grids, plates, elements or groups between steps of the process, on racks or pallets (i.e. platforms). Often the employees transfer the plates by hand between the racks and work stations. Lead dust is the most significant health exposure (Caplan et al., 1979).

3. Discuss the control options that might be considered or implemented to decrease workers’ exposure?

As mentioned in answer to Question 1, it is important to stress that personal protection is not an acceptable substitute for proper ventilation and containment. Personal protection is only an interim measure. The control options are administrative controls (change procedures, establish work rules) and engineering controls (e.g. install a suitable ventilation system, limit lead exposures). Ventilation by diluting contaminated air with uncontaminated air is not as satisfactory for health hazard control as local exhaust ventilation, in which contaminants and process emissions are captured prior to their escape into the workplace environment.

4. What is a TLV-TWA? Would the promulgation of such an inorganic air-lead standard help? What about BEIs?

The TLV-TWA used in western countries is the time-weighted average concentration for a normal 8-hour workday and a 40-hour work week, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect. BEIs, biological exposure indices, are reference values intended as safety guidelines in biological monitoring to evaluate the existence of potential health hazards in the practice of industrial hygiene. Biological monitoring consists of an assessment of overall exposure to chemicals by measuring the appropriate parameter in biological specimens collected from the worker at specified times. Blood and urine are the usual body fluids collected. The concentration of the contaminant in these fluids is often a suitable indicator of exposure. The measurement of metabolites that reflect biochemical changes or tissue injury are also possible, such as ZPP in blood or ALA or enzymes in urine.

There is no doubt that the implementation of a suitable TLV-TWA would protect the worker.

5. Design a risk management package that includes air monitoring, biological monitoring and medical surveillance for use after the appropriate control measures have been put into place.

In the short term, routine and rather frequent personal air measurements should help to identify the exposure associated with various components of the plant operations or specific jobs. Collection should be over an entire shift and, if possible, on two to three consecutive days for individual workers. Adjustments to the engineering controls may be necessary to keep exposures within accepted ranges. The frequency of air measurements can probably be reduced when designing a long-term monitoring programme. Of all the biochemical parameters that can be measured, blood-lead concentration appears to be the most effective index of exposure. Consequently, periodic (e.g. twice per year) assessment of blood-lead levels is warranted. The frequency of such measurements should be increased in cases where the levels give an indication of unwanted lead exposure (e.g. > 1.93 mmol/L or > 40 mg/dL), and increased to monthly assessments during medical removal from exposure (e.g. for levels > 2.90 mmol/L or > 60 mg/dL). Medical examination might be done when any blood-lead level exceeds 1.93 mmol/L (40 mg/dL), prior to assignment in an area where lead levels are around the TLV-TWA, or as soon as possible if a worker develops any signs or symptoms of lead intoxication. Worker personal hygiene also needs to be optimized.

6. Does the risk management package suggested adhere to the principles of occupational health surveillance stated in Table 10.5?

The workers must be involved in the planning and acceptance of the monitoring programme. Appropriate worker training sessions should be implemented to explain the programme objectives and the health implications associated with exposure to lead. Baseline levels of blood-lead should be obtained. Each worker should be informed of his or her individual result; only group test results, without personal identifiers, should be posted or reported to ensure workers’ confidentiality.

7. Debate workers’ rights and responsibilities using the present scenario as a basis for discussion.

In the planned debate, the following workers’ rights might be considered: (i) the right to participate or be part of identifying and resolving workplace health and safety concerns; (ii) the right to know about potential hazards; (iii) the right to refuse work that is believed to be dangerous, without penalty or discrimination; (iv) the right of certified “safety and health” personnel to stop the work. No doubt the acceptance or manner of implementation of such rights will vary between jurisdictions. Responsibilities are usually not identified formally. Nevertheless, they should be part of your debate/deliberations.

Selected references

American Conference of Governmental Industrial Hygienists. 1995-1996 threshold limit values and biological exposure indices. Cincinnati, OH, ACGIH, 1995.

Awad El Karim MA, Hamed AS, Elhaimi YAA, Osman Y. Effects of exposure to lead among lead-acid battery factory workers in Sudan. Arch. Environ. Health 1986; 41: 261-265.

Caplan KJ, Knutson GW. Experimental analysis of lead-in-air sources in lead-acid battery manufacture. Am. Ind. Hyg. Assoc. J. 1979; 40: 637-643.

International Programme on Chemical Safety. Environmental Health Criteria No. 165. Inorganic lead. Geneva, World Health Organization, 1995.

Matte TD, Figueroa JP, Burr G, Flesch JP, Keenlyside RA, Baker EL. Lead exposure among lead-acid battery workers in Jamaica. Am. J. Ind. Med. 1989; 16: 167-177.

Saryan LA, Zenz C. Lead and its compounds. In: Occupational medicine, 13th ed. (C Zenz, OB Dickersen, E P Horvath Jr., eds.). St. Louis, Mosby, 1994, pp. 506-541.

Recommended health-based limits in occupational exposure to heavy metals. Report of a WHO Study Group. (Technical Report Series, No. 647). Geneva, World Health Organization, 1980.

10.2. Discussion starter on occupational hazards1

1 Based on “Women’s job ghettoes - the fish-processing industry” in Women, health and environment. Geneva, World Health Organization, 1994 (Document WHO/EHG/94.11), pp. 117 - 119.

Prepared by Merri Weinger

Time: 1 hour

Objectives:

At the end of the exercise, students will be able to:

1. Identify how occupational hazards affect women in particular ways.

2. Use gender as a critical category to analyse and propose potential solutions for occupational health hazards.

Procedures:

1. As mentioned in the review of selected teaching methods in Part I, the discussion starter can take a variety of forms such as role-play, case study, picture, or video. This exercise demonstrates a scripted role-play of a conversation among workers at a fish factory. Ask for three volunteers and invite them to come to the front of the room to read their lines.

Role-play


Maria: Did you hear about Catherine? She’s still off work with those pains in her wrist. She may lose her job.

William: It didn’t sound that serious to me. I think she just wanted some time off.

Maria: It is serious. She’s been to the doctor several times, but he’s not sure what it is.

William: That’s because it’s all in her head.

Anna: Why doesn’t she just change jobs?

Maria: What else could she do? All the better jobs around here are done by men.

William: She’d better figure it out soon. She can’t stay off work forever.

2. Facilitate a discussion on the scenario portrayed in the role-play using the following guidelines. Your leading questions to participants follow the acronym SHOWeD described on page 8. Some potential responses are listed below each question.

See:

What do you see here? What are the issues being raised?

Some ideas might be the expression of different attitudes about the illness of a co-worker, the problems faced by a woman worker, her lack of options, and a lack of compassion for her problems.

Happening:

What’s really happening here? How do each of the characters feel? What about William?

Cynical, lacking in compassion, skeptical about the illness of his colleague, reflecting “traditional” attitudes about women and work, representing the views of management.

What about Maria?

Compassionate, concerned about her friend, conscious of the problems and the apparent lack of options available to her co-worker.

What about Anna?

Perhaps a bit na, unaware of her own lack of mobility and that of her co-worker, and looking for an easy solution to a complicated problem. She may not acknowledge the health problem of her co-worker.

Our:

Does this situation seem familiar? How is it similar? How is it different?

Encourage participants to share similar or different experiences.

Why:

Why is............. such a problem?

Name the problem identified during the discussion. For example, it may be discrimination against women, lack of options for women, occupational hazards and their effect on women, or lack of understanding about certain occupational health problems. Discuss the causes of the problem (e.g. social, political, cultural, institutional, etc.).

Do:

What can you do about it?

Discuss short-term and long-term action strategies. Some could be adopted immediately; others would require long-term institutional changes.

3. Conclude the discussion. Review the issues that have been raised about occupational hazards and their effects on women. Acknowledge the important role of values and attitudes in determining outcomes and action (e.g. the pervasive attitude that women workers are complainers, unequal to the task, hysterical, and so on).

10.3. Lecture/demonstration on personal protective equipment and methods for atmospheric monitoring

Time: 1 hour

Objectives:

At the end of the exercise, students will be able to:

1. List the main types of personal protective equipment used to prevent exposure to occupational hazards, as well as their advantages and disadvantages.

2. List the main methods for atmospheric monitoring, plus their advantages and disadvantages.

Procedures:

1. Bring to the classroom samples of protective work clothing and equipment for a particular work environment and display them in front of the class. (For example, for agricultural workers with exposure to pesticides, bring several types of respirator, gloves, hat, overalls, boots.) Display samples of both adequate and inadequate equipment to provide more of a challenge to students.

2. Introduce the following scenario.

“You are a farmworker who will be manually applying pesticides using a backpack sprayer. You need to get dressed for work. The temperature today is 90° F.”

Invite a volunteer to select from the equipment displayed and dress for work. Ask for comments from the class and the volunteer.

3. Follow with a discussion of appropriate protective clothing and equipment, attitudes toward utilizing equipment, level of personal comfort and compliance, and implications for development of control strategies.

4. Demonstrate equipment for air monitoring (e.g. monitor carbon dioxide in the classroom), noise monitoring, etc. Utilize the demonstration to initiate discussion of the different atmospheric monitoring techniques and their advantages and disadvantages.

Alternatively, ask for students to volunteer to track down and bring in equipment to demonstrate and discuss.

Materials:

Sample protective clothing and equipment, sample monitoring equipment.

11.1. Question “can” (sample terms and concepts)1

1 Definitions can be found in the text

(Note to instructor: For guidelines on how to conduct the “Question Can” exercise, see page 32.)

Global ecological changes

Greenhouse effect

Refugees

Fossil underground water

Geneva Protocol

Arthropod-borne viral diseases

Guerrilla warfare

Ecological succession

Ecological vandalism

Biodiversity

Ozone depletion

Acid precipitation

Scorched-earth strategies

The Basel Convention

Hague Declaration

Post traumatic stress syndrome

Nuclear winter

Natural disasters

Land mines

Global warming

Stratosphere

Algal biotoxins

Tropospheric ozone accumulation

Tickborne diseases

Montreal Protocol

Desertification

Bio-prospecting


12.1 Problem-solving exercise: Ethical analysis for decision-making in environmental health

Prepared by Dr Colin L. Soskolne, Lee E. Sieswerda*

* Dr Colin L. Soskolne, Professor and Director of Graduate Training, Department of Public Health Sciences, University of Alberta, Edmonton, Alberta, Canada

Lee E. Sieswerda, B.Ed., Graduate Student

Time: One 3-hour block

Objectives:

At the end of the exercise, students will be able to:

1. Apply ethical principles as aids to effective and defensible decision-making.

2. Recognize that the perspectives of all stakeholders (i.e. participants, investigators, sponsors and others) are necessary to provide a fair assessment of any epidemiological study.

3. Recognize issues of confidentiality and disclosure.

4. Implement procedures that provide for accountability and minimize unethical behaviour, or the perception of unethical behaviour, with regard to confidentiality and disclosure in epidemiological studies.

Procedures:

(Note to instructor: This exercise has three parts: a short background section on ethics theory, a case study with associated questions, and a final comment and set of questions. The background material in Part I should be distributed early so that students can read it before the class. The proposed answers should not be considered as the only correct answers. An answer given by a student is correct if it can be justified to any reasonable person.)

1. Introduce the exercise and review its objectives. Divide participants into small groups (4-6 persons). Instruct participants to identify a chairperson and a recorder.

2. Distribute Part II of the exercise and instruct the groups to discuss the issues and formulate answers to the questions by drafting consensus statements along with the underlying rationale behind them.

3. Reconvene the groups and invite a response from one group to the first question. Ask whether other groups have any different responses. Summarize and, if necessary, expand on the participants’ responses and proceed to Question 2. Allow a different group to initiate the discussion and continue in this way until all questions have been answered.

4. Distribute Part III and follow the same procedures.

5. Summarize the results, emphasizing key messages.

Materials:

Problem-solving exercise (Annex 24), flip chart or overhead projector, transparencies, coloured markers.

Part I: Definitions relevant to ethical issues in public health services

Deontology: This is a class of theories known as duty-based ethics. The scientific ethic is a duty-based ethic that specifies the duties of scientists, including their obligations to the participants of research, to society at large, to colleagues, and to the sponsors of their research. Scientists are expected to subscribe to the values of science which, in essence, include the pursuit of truth. This is most assured when scientists are impartial (i.e. objective) in their research.

Utilitarianism: This theory requires that the greatest good be done for the greatest number of people. The utilitarian approach is consistent with the values to which public health professionals have subscribed for many years.

Principle-based ethics: Moral reasoning in the health sciences can be conceived of as using the principles of beneficence, non-maleficence, autonomy and justice. There can often be tensions between the different principles. When this happens, consideration of which principles are contravened and which are given priority characterizes the nature of the ethical dilemma. An example follows the definitions of the principles below.

Beneficence: This principle requires people to maximize benefits to others. It is closely related to the utilitarian ethic. In public health, the principle of beneficence requires that more good than harm be accomplished through public health action.

Non-malficence: This principle requires that people do not harm one another. It is related to the principle of beneficence. There is, however, a subtle but material distinction between the non-infliction of harm and the requirement to do good.

Respect for automomy: This is the principle requiring respect for individual self-determination. Autonomy manifests itself in many ways, but an instructive example is the requirement to obtain prior informed consent from research participants whenever feasible. Honesty in informing potential research participants of potential risk and harm demonstrates respect for their right to self-determination.

Justice: This principle is also known as equity. It requires that potential risks and benefits be evenly distributed among people in the community.

Egalitarianism: Complimentary to the utilitarian ethic is the egalitarian ethic which assumes that community members are equally important. It upholds the principle of solidarity and measures the well-being of the group by the standard of the least well-off in the group. Its success is determined on the basis of equity in the distribution of harm and benefit associated with public health actions.

Libertarianism: In contrast to egalitarianism, this ethic holds that the individual is more important than the community. Under libertarianism, the just society protects the rights of property and liberty, allowing persons to improve their circumstances on their own initiative. According to libertarian theory, social intervention in the market undermines justice by placing unwarranted constraints on individual liberty. Hence, libertarians hold the view that taxation for the redistribution of wealth is coercive and, therefore, inappropriate. Consequently, health care is not a right under this conception and privatization in the health care system is a protected value. Libertarianism has less utility within public health because it makes the greatest good for the greatest number of people less attainable.

Because public health interventions can impact on vested interests, the public health professional has to remain aware of the pressures that could be brought to bear on his or her recommendations in support of health policy. Ethics guidelines can be helpful in public health decision-making and should be seen as a means to achieving a balanced dialogue on a contentious issue.

Part II: Case scenario

(Note: Information in this case study was derived from published media reports and court documents. The names of individuals and corporations used in this case study are a matter of public record.)

As countries become more environmentally aware, governments have legislated programmes and directives to limit the amount of environmentally hazardous material to which people are exposed. The main targets for this legislation are the large petroleum refining and chemical manufacturing companies. These companies are very careful to adhere to the strict regulations within their own countries but may not abide by these high standards when company operations are established in other countries where legislation may not be as strict. This type of behaviour constitutes a double standard that may pose an ethical dilemma for the employees of the company in the country with the stricter rules. While the country in which the subsidiary company is operating may not have standards as strict as those of the country where the parent company is located, the danger of exposure to the chemical of concern for any other population is just as great as that of the population in the country of the parent company. Employees who are concerned about the health of the public in the less developed/regulated country may be fired with impunity if they voice opposition to their company’s application of different standards which would place at risk the health and/or lives of people in the country with less strict regulations. In several states in the USA, these employees are now protected by so-called “whistleblower laws”. In New Jersey, this legislation is called the Conscientious Employee Protection Act, and protects employees who act in the public interest from employers who see such acts as counter to their business interests.

Dr Peter Smith was employed as the director for environmental health and toxicology for the American-owned Petroil Oil Corporation. In addition, Smith ran, in his own time, a scientific publishing company. From time to time, Smith’s roles would overlap. Such overlap was seen by Petroil as adding to the company’s prestige and was well-known to Petroil.

In September, 1989, Smith was sent to Thailand to speak at a symposium on gasoline health risks which was also attended by executives of the Petroil-owned affiliate, Petroil Oil and Gas Thailand (POGT) and Thai government officials. In Smith’s presentation, he reported that the level of benzene in gasoline that Petroil was selling in Thailand was 2.5-3.5 times that permitted in the USA, but noted that this was well below the Thail government’s legislated level. After he had given his presentation, Smith was said to have been approached by one of the POGT executives who informed him that the level of benzene in gasoline sold by POGT was actually in excess of even the Thai standard. Smith’s figures had, in fact, been on the low side.

Benzene is a gasoline additive used as a blending agent to improve engine performance. It is also a very toxic and carcinogenic agent (a leukemogen) and has been targeted in recent years by US environmental law. Currently in the USA, any products containing more than 5% benzene must be labelled “danger” and “poison” with a skull and crossbones symbol. In 1989, maximum allowable benzene levels in US gasoline were in the 1.5-2% range. The US Environmental Protection Agency now limits levels to 1%. In the company’s Thai operation, levels were said to be in excess of 5%.

Smith informed the POGT executive that the levels were extremely high and hence very dangerous. He strongly advised the executive to reduce the benzene levels or to stop selling the gasoline. The executive is on record as having stated that upgrading the refineries (built during World War II) to provide lower benzene levels would cost Petroil hundreds of millions of dollars.

On returning to the US after the symposium, Smith was denied access to the toxicology laboratory and was informed that he had been placed on “special assignment indefinitely”. Petroil executives alleged that he had used Petroil resources and employees for his publishing business. Smith sued Petroil for wrongful dismissal under New Jersey’s whistleblower law (i.e. the Conscientious Employee Protection Act).

In court testimony, Petroil stated that it was unable to produce documents which would have cleared Smith of any wrongdoing because these documents were “eaten” and/or “defecated” upon by mice. In addition, many exculpatory (i.e. exonerating) statements about Smith were excluded from Petroil’s investigative report. Petroil’s security manager admitted that he had omitted several statements from his report that would have been exculpatory for Smith. Petroil executives also acknowledged that the company had gained prestige from Smith’s publishing activities and that many Petroil scientists had published in Smith’s journals. Despite these admissions from Petroil, Smith was fired in November 1989. The company denied that he had been fired for voicing concerns over the benzene levels in the Thai gasoline. They launched a smear campaign to discredit Smith, claiming that he had appropriated Petroil funds and employees’ time for his publishing company.

Question 1.

a) Is it the responsibility of companies from more environmentally regulated countries to protect the citizens of other countries by enforcing the strict environmental standards of the more regulated country on their operations in the less regulated country? Use ideas from egalitarianism and libertarianism to help formulate your answers.

Aside from ethics, there are conventions and treaties that would directly influence decisions in this regard. From an egalitarian point of view, equity is very important. The egalitarian believes that people have responsibility for one another and hence would not believe that companies should endanger lives, whatever the nationality of those endangered.

A libertarian, on the other hand, believes that the marketplace should dictate environmental regulations, not a sense of global responsibility.

b) If so, should these standards be enforced even if the facilities in the less regulated country are unable to meet these higher standards? Should the company insist that inadequate facilities be upgraded, possibly at the company’s expense?

This depends on the level of development of the less regulated country. There must be a balance of benefit and harm. Certainly from an egalitarian perspective, the decision on permissible levels of pollution should be made by a group of people representing various interests.

c) If not, what number of expected deaths could be considered an unacceptable risk to the population of the less regulated country? Who decides what that level is?

This is question of risk assessment and deciding upon acceptable levels of risk. The decision must be made considering questions of equity and whether or not the risk is voluntary (e.g. wearing seatbelts, participating in a dangerous sport) or involuntary (e.g. job depends upon accepting the exposure, invisible ambient air contaminants such as benzene), among other things. The question of who decides is once again difficult. Egalitarians would suggest that everyone should have a voice in the decision and that the risks and benefits should be distributed evenly throughout the population. The libertarian believes that the market should dictate.

Question 2. Would Petroil’s decision not to upgrade its Thai plant result in more good than harm? Identify the stakeholders involved in this decision and what they have to gain or lose.

· Dr. Smith: professional integrity, research funding, compensation for job loss and potential loss of profits to his publishing company.

· Thai public: Protection from unsafe levels of benzene, potential increased risk of cancer.

· Thai leukemia patients (if any attributable to benzene exposure): potential compensation for their illness.

· Company owner/shareholders: profits, reputation.

· Company workers: potential employment losses if Petroil were to suffer financial losses.

· Media: sell more copies through sensationalist stories.

· Government: seen by the public as protecting the public interest versus the industry’s interest.

Question 3. Discuss how the introduction of whistleblower laws may help to prevent negligent and unethical behaviour on the part of corporate executives/employers. Do you believe that such legislation is appropriate in view of the lengths to which Petroil demonstrated that it would go to protect its interests? What distinctions are there between law and professional codes of conduct and would codes be sufficient to prevent unethical behaviour?

By protecting employees, a whistleblower law allows employees who wish to protect the public interest to avoid harsh consequences. The students may wish to think of examples where a whistleblower law would and would not be appropriate. Professional codes of conduct are far less enforceable than laws, and are regulated by peers, not by outside parties. In general, such codes have been seen as sufficient to keep professionals on the right track. However, when undue pressure is brought to bear, such as the loss of one’s livelihood, many people are unable to resist violating their profession’s codes. It is generally believed that such violations of professional ethics occur more often in profit-making corporations than in academic settings. Corporations should respect the obligations of employees who belong to a professional group. Any professional group granted the relative autonomy to self-regulate has a “social contract” that requires it to protect the public interest.

Question 4. How tenacious should Dr Smith have been in making his point that people should not be subjected to poisonous levels of a substance regardless of whether they are American or Thai citizens? Were his actions justifiable? Use the principles of beneficence, non-maleficence, autonomy and justice to help formulate your answers. How typical is the fortitude demonstrated by Dr Smith?

While in theory any employee should be able to voice concerns when the public interest is at risk, it is often not possible for people who cannot afford to lose their jobs. It is often even less possible to litigate against a major corporation. Dr Smith was well-established, well-respected, and the owner of a publishing company. His relatively secure position enabled him to proceed with his litigation. In thinking about the defensibility of his actions, students might consider the following:

Beneficence/non-maleficence: Smith acted in the interests of minimizing harm to the Thai population. He did not, however, maximize benefits to his employer.

Respect for autonomy: By “going public”, Smith respected the right of the public to know about harm to which they may be exposed. Petroil, in all likelihood, felt that Smith had not respected its right to determine its own actions.

Justice: Justice requires that risks and benefits be evenly distributed within the community. Smith clearly believed that far more benefits were accruing to Petroil and far more risk was being assumed by the Thai public.

Question 5. How common do you think instances analogous to the firing of Dr Smith are in industry, government and academia? On what basis? How might one obtain a more precise estimate of the prevalence of such disciplinary action? What might some of the difficulties be in conducting a study to obtain such estimates?

It is difficult to obtain estimates for the prevalence of professionals fired for attempting to protect the public interest at the expense of their employers. The major hurdle is to identify the victims and to verify that they were indeed fired on those grounds. Individuals who are fired for favouring public over private interests may not even know why they were fired. Also, an individual who is fired may have a somewhat biased perspective of the event.

Question 6. Should employees be permitted, or even encouraged, to hold more than a single job? At what stage would the holding of more than one job constitute a conflict of interests for the employee?

The holding of several jobs or roles is very common, especially among highly qualified individuals. Problems can be minimized when both the employer and the employee approach one another with openness and the employee receives the employer’s sanction to hold more than one job. Both the employer and the employee should consider potential for conflicting interests and take steps at the contracting phase to avoid them. In addition, some kind of suitable oversight may help to arbitrate when conflicts do arise.

Part III: Resolving the issues

The jury awarded Smith US$3.4 million in compensatory damages and US$3.5 million for punitive damages in March 1994. The trial judge allowed only half of the jury’s award, saying that the compensatory damages were inapplicable because the whistleblower law was not valid outside the USA.

Both sides appealed the ruling - Petroil against the heavy punitive damages, and Smith for reinstatement of the full award.

In June 1996, a three-judge appellate court ruled in Smith’s favour, stating that he had identified a “clear mandate for public policy” under the whistleblower law. In its decision, the panel wrote that Smith’s concerns with “professional negligence” and “professional ethics” were justified as Petroil had defied its own policy to apply “health standards of developed countries in the absence of local regulations”. Smith’s lawyer said that the decision will serve as a warning to American oil companies not to ignore the health of customers abroad. He further predicted that US companies would no longer be able to apply the double standard of abiding by strict regulations set by federal and state environmental laws within the USA while allowing hazardous levels to exist elsewhere. A further award of approximately US$3 million was granted by the court in interest payments and additional legal fees. The decision was being appealed by Petroil to the State Supreme Court at the time this case study went to press.

Question 1. Is there a point at which ethics and law interact in the above case study? What arguments might Petroil invoke in its further appeal against the decision to the State Supreme Court? How do you think the court will decide? Discuss.

Under the libertarian view, Petroil should have the right to hire and fire as it pleases without the interference of governments. There may be treaties and conventions to which Petroil may appeal. However, unless there was compelling new evidence, a constitutional challenge, or some reason for mistrial, the State Supreme Court would be likely to find in favour of Smith.

Question 2. Leaving the legal aspects aside and concentrating on ethics, do you think that the court made the correct decision? How does your ideological perspective (i.e. libertarian, egalitarian, etc.) affect your judgement of the court decision?

One’s judgement is driven by one’s ideological perspective which is rooted in a set of values. For example, the values of the egalitarian would require that equity prevail and be operationalized through respect for persons at every level of deliberation. On the other hand, the values of the libertarian would require that the interests of individuals (e.g. the investigators and/or the employer) take precedence over those of amorphous groups such as society or the public.

Question 3. Do you think that this case will substantially affect the operation of multinational corporations? Why?

Precedence is an important part of law, and with this precedent, corporations may be more conscientious in not polluting because of the risk that an employee might “blow the whistle”. This case has received a lot of media attention in North America and Thailand and may lead to the strengthening of professional organizations, and hence to even more protection for professionals. One potentially negative consequence of this decision is the possibility that corporations may move their head offices to less regulated countries in order to avoid litigation in more regulated countries.

Question 4. List examples of standards of practice to which scientists must always adhere regardless of their affiliation with any government, corporation or academic institution.

Examples include telling the truth, avoiding conflicting interests, being objective, avoiding partiality, conducting scientifically appropriate analyses, and attempting to publish methods and results.

12.2. Action planning exercise

Time: 1-1½ hours

Objectives:

At the end of the exercise students will be able to:

1. Develop short-term and long-term action plans aimed at reducing the negative impact of environmental factors on health and well-being. Actions may include awareness-raising, investigation/research, and specific projects in areas related to health, environment and development.

Procedures:

1. Brainstorm a list of potential activities to reduce environmental health problems and promote health and well-being. These may include literature searches for supporting data/information (particularly local initiatives or prevention efforts in countries with similar problems), interviews with health professionals and policy-makers, involvement in ongoing activities of local groups and organizations, development of further studies and development of educational programmes.

2. (Optional) Incorporate discussion of obstacles and resources for action planning, as shown in Exercise 12.3.

3. Ask participants to work independently or in groups to prioritize target groups for activities (based on risk, need, interest, etc.), and contents of activities. Indicate whether any preliminary investigations or studies must be conducted.

4. Once priority areas have been established, instruct participants to use worksheets to independently plan follow-up activities that they will undertake at the end of the course or after the workshop. Establish a target date by which all follow-up activities should be completed. Participants should designate their target population, rationale for their selection, objectives and estimated timeline for implementation.

5. (Optional) Make a copy of the plans that participants hope to undertake. These can serve as a useful evaluation tool to assess participants’ increase in knowledge and analysis, and to measure the overall effectiveness of the course or workshop. Inform participants if you intend to retain copies of their plans for evaluation and follow-up.

6. When plans are complete, ask each participant to briefly present his or her future programme. Post these on flip chart paper with the following suggested headings: name, region, target audience, topic, specific plans. Record each participant’s proposal. Highlight opportunities for collaboration and sharing of materials.

Materials:

Worksheets for distribution in class, flip chart.

Individual action planning worksheet

(Note to instructor: This worksheet can be adapted in various ways according to the type of activity and the time available. For example, if time is limited, participants can be asked simply to identify their area of focus, target group, objectives and the first step in their implementation plan.)

Instructions:

Develop a plan of action which you will undertake to identify, control and prevent environmental health problems.

Topic or area of focus

Prioritize one area for action planning, such as:

- education and training (e.g. planning a workshop, course, seminar, or study group;

- research (e.g. carrying out a literature search, interviews);

- investigating existing or missing legislation, policies, procedures;

- organizational development (e.g. establishing departments, committees, interdisciplinary working groups);

- participation in ongoing activities of local groups and organizations.

Goals

1. What are your short-term goals in the area you selected? For example, what can be done now to raise awareness and strengthen education, training and research on environmental health with the current levels of expertise and resources?

2. What are your longer-term goals? (These may require additional planning or research.) For example, what can be done to better utilize environmental risk data in advocacy for improved health policies and legislation; and how can you educate health professionals, policy-makers and the general public on their role in identifying, preventing and controlling environmental health problems?

Action steps

What action steps would you recommend in support of the activities selected?

1. What is your target population and why have you selected it? (For example, is selection based on exposure to risk, lack of prior attention to this kind of problem, interest in the issue, ability to finance or some other reason?)

2. What are your specific plans?

3. Outline the steps needed to implement your plan of action.

4. What human and financial resources are needed and how do you propose to obtain them?

5. With whom do you plan to collaborate?

6. What is your timeline? For example, what do you hope to accomplish in the next month, 6 months, 1 year, 5 years?

7. What obstacles are you likely to encounter in trying to implement this activity and how do you propose to overcome them?

8. Which of the above steps can realistically be achieved in the next 3-6 months?

12.3. Promoting activities to identify, control and prevent environmental health problems: Identifying obstacles and resources

(Prioritising/planning exercise)

Time: ½-1 hour

Objectives:

At the end of the exercise, students will be able to:

1. Analyse potential problems in implementing action strategies on environmental health issues, and identify their causes and potential solutions.

2. Identify resources to support initiatives in environmental health.

Procedures:

1. Ask all participants to identify one or, if the group is small, two obstacles that they may face in applying what they have learned about environmental health problems and promotion outside the course or workshop. Participants should write each obstacle in large print on a piece of paper, using a coloured marker. (The writing should be large enough for everyone to read when the paper is posted at the front of the class. The key is to use few words and big letters.)

2. Ask for a volunteer to read out his or her obstacle and pass the piece of paper to the front of the room for posting. Then call for obstacles with a similar theme, posting each piece of paper under the previous one to create a vertical column. A new column is created for each new theme. By proceeding in this manner, a visual representation of the most pressing problems is created. The longest list usually reflects the problem of greatest concern.

3. Summarize the prioritized obstacles. Discuss causes and potential solutions. Focus on obstacles of which the solution would have the greatest positive impact.

4. Brainstorm a list of institutional, national and international resources for activities related to health and environment.

Materials needed:

Coloured markers, tape, pieces of paper or stiff cards (preferably coloured), board for posting the cards.

1. Pre-workshop questionnaire

Workshop on basic environmental health

Please complete this questionnaire to help us in our workshop planning.

We request that you forward completed questionnaires by __________ to _____________:

1.Family name:

First name:

2. Position or function within your institute:

3. Department/Institution:

Address:

Telephone:

Telefax:

4. List any courses in environmental health and epidemiology that you have taken. Include university courses (undergraduate and/or postgraduate), short courses and workshops. Describe the target population for these educational activities (e.g. environmental health students, government officials, health personnel, community residents, etc.).

Educational programme

Target population

______________________________________________________________________________
______________________________________________________________________________

5. What knowledge and skills would you like to acquire at this workshop?

______________________________________________________________________________
______________________________________________________________________________

6.Can this knowledge and these skills be applied in your work or other activities?
If so, how?

______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________

2. Selected bibliography

Abbatt FR. Teaching for better learning. Geneva, World Health Organization, 1992.

Guilbert JJ. Educational handbook for health personnel. (WHO Offset Publication No. 35.) Geneva, World Health Organization, 1987.

Motor vehicle air pollution: teacher’s guide: one week training workshop. Geneva, World Health Organization, 1996 (Document WHO/EHG/96.16).

Problem-based training exercises for environmental epidemiology. Instructor’s guide and exercises for students, 2nd ed. Geneva, World Health Organization, 1997 (Document WHO/EHG/97.6).

Shannon S, Norman G. Evaluation methods: a resource handbook. Hamilton, Ontario, McMaster University, 1995.

Sims J, Weinger M. Women, health and environment: a teacher’s guide. Geneva, World Health Organization, 1995 (Document WHO/EHG/95.1).

Wallerstein N, Rubenstein H. Teaching about job hazards. Washington, DC, American Public Health Association, 1993.

Yassi A, Kjellstr, de Kok T, Weinger M. Teaching basic environmental health in universities utilising an interdisciplinary holistic approach and interactive learning methods. Ecosystem Health. Vol 3(3) 1997: 143-153

References on participatory teaching methods

Mandel S. Technical presentation skills. Crisp Publications, Inc., 95 First St., Los Altos, CA 94022, USA, 1988.

Risk mapping: a group method for improving workplace health and safety. Labor Occupational Safety and Health (LOSH) Program of the UCLA Center for Occupational Health and the Center for Labor Research and Education, Institute of Industrial Relations, 1001 Gayley Ave., Los Angeles, CA 90024-1478, USA, 1996.

Silberman M. Active training: a handbook of techniques, designs, case examples, and tips. Lexington Books (McMillan, Inc.), 855 Third Ave, New York, NY 10022, USA, 1990.

Srinivasan L. Bridging the gap: a participatory approach to health and nutrition education. Save the Children, 54 Wilton Road, Westport, CT 06880, USA, 1982.

Srinivasan L. Tools for community participation: a manual for training trainers in participatory techniques. PROWWESS/UNDP Technical Series, 304 E. 45th St., 12th Floor, New York, NY 10017, USA, 1990.

Teaching techniques for labor education. AFL-CIO Department of Education and George Meany Center for Labor Studies, Labor Institute of Public Affairs, 815 16th St., N.W., Room 206, Washington, DC 20006, USA, 1993.

Visualization in participatory programmes: a manual for facilitators and trainers involved in participatory group events. UNICEF, P.O. Box 58, Dhaka 1000, Bangladesh, 1993.

Werner D, Bower B. Helping health workers learn. Hesperian Foundation, P.O. Box 1692, Palo Alto, CA 94302, USA, 1984.

3. Teaching methods chart

Teaching methods

Strengths

Limitations

Objectives achieved

Lecture

Presents factual material in direct and logical manner.
Contains experiences which inspire.
Stimulates thinking to open a discussion.
Suits large audiences.

Experts may not always be good teachers.
Audience is passive.
Learning difficult to gauge.
Needs clear introduction and summary.
Needs time and content limits to be effective.

Knowledge

Worksheets and questionnaires

Allow people to think for themselves without being influenced by others in discussion.
Individual thoughts can then be shared in small or large groups.

Can be used only for short period of time.
Handout requires preparation time.

Knowledge
Attitudes

Brainstorming

Listening exercise that allows creative thinking for new ideas.
Encourages full participation because all ideas are equally recorded.

Can become unfocused.Needs to be limited to 10-15 minutes.

Knowledge
Attitudes

Planning deck

Can be used to quickly catalogue information.
Allows students to learn a procedure by ordering its component parts.
Group planning experience.

Requires planning and creation of multiple planning decks.

Knowledge

Audiovisual materials (films, slide shows, etc.)

Entertaining way of teaching content and raising issues.
Keeps audience’s attention.
Effective for large groups.

Too many issues often presented at one time to have a focused discussion.
Discussion will not have full participation.

Knowledge

Problem-solving exercises

Develops analytic and problem-solving skills.
Allows for exploration of solutions.
Allows students to apply new knowledge and skills.

People may not see relevance to their own situation.
Cases and tasks for small groups must be clearly defined to be effective.

Knowledge
Social action
Attitudes

Role-play session

Introduces problem situation dramatically.
Develops analytical skills.
Provides opportunity for people to assume roles of others.
Allows for exploration of solutions.

People may be too self-conscious.
Not appropriate for large groups.

Social action
Attitudes

Report-back session

Allows for large group discussion of role-plays, case studies, and small group exercise.
Gives people a chance to reflect on experience.

Can be repetitive if each small group says the same thing.
Instructors should prepare questions to focus discussion so as to avoid repetition.

Social action
Knowledge

Prioritizing and planning activity

Ensures participation by students.
Provides experience in analysing and prioritizing problems.
Allows for active discussion and debate.

Requires a large wall or blackboard for posting.
Posting activity should proceed at a lively pace to be effective.

Social action

Hands-on practice

Provides classroom practice of learned behaviour.

Requires sufficient time, appropriate physical space, and equipment.

Behaviour

Source: Adapted from Labor educator’s health and safety manual, Labor Occupational Health Program, University of California, Berkeley, CA, USA.

4. Student’s version: Problem-solving exercise: The impact of chistosomiasis haematobium on women in Cameroon1

1 Anthology on women, health and environment. Geneva, World Health Organization, 1994 (Document WHO/EHG/94.11), pp.9 - 11

Exercise

In a village in Cameroon, 76% of the population is affected by schistosomiasis, with slightly more women infected than men. The disease is contracted by the passage of the parasite Schistosoma haematobium through the skin in water. The effects of the disease can include iron deficiency and anaemia if the infection reaches a level sufficient to cause loss of blood in the urine. The infection results in loss of appetite, fatigue and weakness, along with impaired ability to carry out domestic, agricultural and parental duties.

Other potential effects include genital lesions, as well as reproductive disorders which are particularly devastating for women in the community. Marriage opportunities for those affected may be diminished since potential suitors must be informed of the infection. Many believe that the infection is a venereal disease. Married women who are infected are forbidden sexual contact until they are cured and may even be evicted from the household.

Women’s infection rates are linked to their domestic and agricultural responsibilities which include collecting water, bathing children, laundering, cleaning utensils, preparing and washing foodstuffs, and farming, all of which involve regular and prolonged exposure to infected water. Inadequate sanitation and waste disposal facilities, lack of basic amenities and lack of awareness concerning sources of infection and transmission are other causal factors.

Few villagers can afford the medication needed to treat the infection. Women in particular are disinclined to seek treatment, not only because of financial limitations but also because of the social stigma associated with the disease. Its persistent recurrence fosters the belief that schistosomiasis responds neither to traditional nor western medicine. For these reasons, it is likely that urinogenital schistosomiasis infections in women are significantly underreported.

Your task is to analyse this public health problem and identify potential solutions.

Question 1. What are the environmental issues or problems facing women in this case?

Question 2. What are the health effects of these problems?

Question 3. What are the underlying causes of these problems?

a. Is this problem related to women’s status in society?

b. Is the problem due to women’s exposure to a certain hazard through performing obligatory tasks?

c. Do biological or physiological factors play a role in this problem?

d. Do women suffer more from the health problem once it occurs, such as through lack of awareness of its impact on them, social stigmatization or lack of access to treatment?

Question 4. What other information do you need to fully assess the situation?

What kind of health information is already available?

Is it gender-sensitive?

For what reasons have other groups (adolescent males) mostly been targeted for study?

Why is it thought that these groups are most at risk?

Given their traditional roles, has sufficient attention been given in the past to women’s potential exposure?

Question 5. How would you go about investigating this problem in detail?

a. What cultural/gender issues need to be considered in planning further investigations/studies?

In the society under investigation, what work or other activities done by women are likely to expose them to the same or greater risks than other population groups?

What is the regularity and duration of women’s exposure, during all their roles and responsibilities, compared with that of other groups at risk?

Does exposure to this risk affect women’s ability to perform their roles in other spheres?

What kind of measures could be taken to ascertain whether women are unwilling or unable to report this disease?

b. Whom would you involve in your investigation team?

Question 6. What can be done about the problem?

a. What prevention measures or campaigns would you recommend?
b. Why and how would you involve women in your prevention efforts?
c. Why and how would you involve men in your prevention efforts?

5. Student’s version: Problem-solving exercise: Environmental estrogens

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Background

Steroid hormones are essential for the growth, differentiation and function of many tissues in both animals and humans. The International Agency for Reasearch on Cancer (IARC) (1987) designates steroidal estrogens as used in estrogen replacement therapy as carcinogenic to humans. The risk of endometrial and breast cancers is increased. Environmental estrogens (xenoestrogens) bind to estrogen receptors and have estrogenic activity in model systems. As illustrated in Box 2.1, this group of chemicals includes nonsteroidal estrogens, polycyclic aromatic hydrocarbons, DDT, and a number of PCBs (congeners that have two adjacent nonsubstituted carbon atoms on at least one of the biphenyl rings, including a para position). In addition to being suspected of acting as promoters in the development of estrogen-mediated cancers in humans (Davies et al., 1993), such xenoestrogens are believed to disrupt the immune, nervous and endocrine systems (McLachlan, 1993; EHP, 1995). Considerable and convincing evidence exists that reproductive and developmental processes are impaired in wildlife (such as birds, fish, reptiles and mammals (Colborn and Clement, 1992; Colborn et al., 1993). Comparable causal links in humans are less convincing and still speculative, such as the role of xenoestrogens in an apparent decline in semen quality over the past 50 years (Sharpe and Skakkebaek, 1993; Carlsen et al., 1995; Sate, 1995). The evidence for the involvement of environmental estrogen mimics in the etiology of breast cancer is explored in the present case scenario.

Case scenario, Part I

In a recent prospective cohort study investigating the role of endogenous hormones and environmental factors in cancer development, 58 women with a diagnosis of breast cancer 1-6 months after they entered the cohort (14 290 participants from New York City, 80% Caucasian) were compared to 171 controls selected from the same cohort and matched for menopause status and age. Sera, taken at the time of enrolment between 1985 and 1991 when attending a mammography screening clinic, were analysed for a metabolite of DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane], namely DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], and total PCBs (polychlorinated biphenyls). Limits of detection were 1 µg/L for DDE and 2 µg/L for total PCBs based on three times the standard deviation of the results from the lowest quality-control serum pool standard over the course of the analyses (n=18). DDE was 35% higher in patients than in control subjects (p=0.031), while PCBs were 15% higher (p=0.058). After adjustment for first-degree family history of breast cancer, lifetime lactation and age at first full-term pregnancy, conditional logistic regression analysis showed a four-fold increase in relative risk of breast cancer for an elevation of serum DDE concentrations from 2.0 ng/mL (10th percentile) to 19.1 ng/mL (90th percentile) (p=0.0037 for trend). Other potential confounders considered, but with no effect, were: body mass index, age at menarche, history of benign breast tissue, history of tobacco smoking and/or alcohol drinking, and race. The corresponding association for PCB levels was not significant (p=0.16). It was concluded that environmental chemical contamination with organochlorine residues may be an important etiological factor in breast cancer.

Chapter 2 Questions

1. In simple terms, describe how estrogens regulate the growth, differentiation or function of cells.

2. DDE and PCBs are persistent organic pollutants (POPs). What is meant by this?

3. How is DDT converted to DDE?

4. What is the likely source or exposure route of the organochlorines?

5. Comment on the use of serum PCB and DDE levels as measurements of exposure.

6. From the toxicokinetic perspective, does it make sense that duration of lactation is an important determinant in the study? Explain.

Chapter 3 Questions

1. The study considered in the scenario is a case-control study nested within a prospective cohort study. What are the salient features of these two types of epidemiologic study?

2. What are confounders?

3. Has selection bias been avoided?

4. What are the known risk factors for breast cancer?

5. Apply the rules of causation outlined in Table 3.3 to the study at hand.

6. Comment on the authors’ overall conclusion. Is it valid?

Case scenario, Part II

Two of the investigators of the study described in Part I, participated in a second study conducted in California (Krieger et al., 1994; also see Wolff and Toniolo, 1995). Again the hypothesis tested was that exposure to organochlorines is a risk factor for breast cancer. Study subjects belonged to a cohort of 57 040 women (46 629 white, 8123 black and 2288 Asian) who took a multiphasic health examination between 1964 and 1971, independent of concern about risk of breast cancer. Follow-up was conducted through December 31, 1990 to identify those with histopathologically confirmed primary breast cancer six or more months after their multiphasic examination. From among the women who developed breast cancer (1805 white, 230 black and 62 Asian), a random sample of 50 women in each racial/ethnic group was selected, as were equal numbers of controls matched according to race/ethnicity, date of joining the medical care programme, year of multiphasic examination and age at that time, and length of follow-up. Matched analyses found no difference in DDE or total PCBs, although organochlorine levels were significantly higher (p<0.05) among black and Asian women compared to white women. The mean differences (95% confidence intervals) for DDE were 11.0 (4.3, 17.6) ug/L in the black women and 12.6 (4.3, 17.6) ug/L in the Asian women and, respectively, 0.8 (0.2, 1.4) ug/L and 1.4 (0.8, 1.9) ug/L for PCBs. The detection limits were as stated in Part I. These ethnic differences persisted even after adjusting for available confounders: age at and year of medical examination, body mass index, educational level, poverty level, place of birth (United States or elsewhere), pregnancy history (ever or never). Multivariate analysis showed the absence of a significant association (p<0.05) between exposure to organochlorines and breast cancer, regardless of length of follow-up, year of diagnosis and menopausal status. The conclusion was that the data do not support the hypothesis that exposure to DDE and PCBs increases risk of breast cancer.

Chapter 2 Questions

1. What do we know about the molecular basis of cancer?

2. Do you have any analytical concerns about the PCB and DDE measurements reported in Parts I and II?

3. Does the estrogen hypothesis make biological sense to you (e.g. in terms of nutrition or physiology)?

Chapter 3 Questions

1. Is there room for an environmental risk factor to explain breast cancer?

2. Does the “xenoestrogen hypothesis” of breast cancer make epidemiological sense? Return to your previous deliberations concerning the rules of causation. You might also consider that epidemiological studies of individuals occupationally exposed to much higher concentrations of PCBs or DDT/DDE do not show a higher incidence of breast cancer (IARC, 1987; Safe, 1995).

3. IARC (1987) designates DDT as Group 2B and PCBs as Group 2A carcinogens. Do the results of the two studies discussed suggest that these classifications ought to be upgraded? Justify your answer?

Selected references

Callahan R, Campbell G. Mutations in human breast cancer: an overview. J. Natl. Cancer Inst. 1989; 81:1780-1786.

Carlsen E, Giwercman A, Keiding N, Skakkebaek NE. Declining semen quality and increasing incidence of testicular cancer: is there a common cause? Environ. Health Perspect.1995; 103 (Suppl. 7):137-139.

Colborn T, Clement C (eds.). Chemically induced alterations in sexual and functional development: the wildlife-human connection. New Jersey, Princeton Scientific Publishing Co., 1992.

Colborn T, von Saal FS, Soto AM. Developmental effects of endocrine-disrupting chemicals in wildlife and humans. Environ. Health Perspect. 1993; 101:378-384.

Cooper GM. Oncogenes, 2nd ed. Boston, Jones and Bartlett, 1995.

Davies DL, Bradlow HL, Wolff M, Woodruff T, Hoel DG, Anton-Culver H. Medical hypothesis: xenoestrogens as preventable cause of breast cancer. Environ. Health Perspect.1993; 101:372-377.

Estrogens in the environment. Special issue, Environ. Health Perspect. 1995; (Suppl. 7): 1-178.

Goldstein JL, Brown MS. Genetic aspects of disease. In: Harrison’s principles of internal medicine, 13th ed. (KJ Isselbacher, JB Martin, E Braunwald, AS Fauci, JD Wilson DL Kasper, eds). New York, McGraw-Hill, 1994, pp 339-349.

Hendersen IG. Breast cancer. In: Harrison’s principles of internal medicine, 13th ed. (KJ Isselbacher JB Martin E Braunwald AS Fauci JD Wilson DL Kasper, eds). New York, McGraw-Hill, 1994, pp 1840-1850.

Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7. Overall evaluation of carcinogenicity: an updating of IARC monographs Vols 1 to 42. Lyon, International Agency for Research on Cancer, France, 1987.

Krieger N, Wolff MS, Hiatt RA, Rivera M, Vogelman J, Orentreich N. Breast cancer and serum organochlorines: a prospective study among white, black, and Asian women. J. Natl. Cancer Inst. 1994; 86:589-599.

McLachlan JA. Functional toxicology: a new approach to detect biologically active xenobiotics. Env. Health Perspect. 1993; 101:386-387.

Safe SH. Environmental and dietary estrogens and human health: is there a problem? Environ. Health Perspect. 1995; 103:346-361.

Sharpe RM, Skakkeback NE. Are estrogens involved in the falling sperm counts and disorders of the male reproductive system. Lancet 1993; 341:1392-1395.

Wolff MS, Toniolo PG. Environmental organochlorine exposure as a potential etiologic factor in breast cancer. Environ. Health Perspect. 1995; 103 (Suppl. 7):141-145.

Wolff MS, Toniolo PG, Lee EW, Rivera M, Dubin N. Blood levels of organochlorine residues and risk of breast cancer. J. Natl. Cancer Inst. 1993; 85:648-652.

6. Dose-response/dose-effect curves: Transparencies

The figures on the following pages are designed to be photocopied and used in conjunction with Exercise 3.2: The Relationship Between Dose and Health Outcome: Dose-Response Versus Dose-Effect. Place each figure on the overhead screen with the title covered. After students have described the curve, confirm the correct response and reveal the title.


Figure 1 - Dose-Response Relationship

WHO 98024


Figure 2 - Dose-effect Relationship

WHO 98025


Figure 3 - Dose-Response Curve for Various Health Effects of Lead in Children

WHO 98026


Figure 4 - Dose-Response Between Occupational Sound Levels and Percentage of Workers with Impaired Hearing for Different Age Groups

WHO 98028


Figure 5 - Dose-Response Relationship Between Speed and Risk of Injury for Seat Belt Use and Non-use

WHO 98029


Figure 6 - Dose-Response Relationship Between Noise Level and Annoyance

WHO 98030

7. Student’s version: Problem-solving exercise: Emergency response to a PCB fire

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

A. General instructions

The problem scenario will be given to you in three consecutive parts.

Part I consists of a vignette.

Part II provides factual information to help you to understand the problem better.

Part III gives you the outcome. The decision to proceed to the next stage should be made jointly by students and instructor.

B1. Response to a PCB-fire emergency (Part I)

Your group has been appointed to coordinate the emergency and follow-up responses to a fire that is burning out of control at a PCB warehouse in a community north-east of the city of Montreal, Quebec, Canada. The cloud of smoke and soot can be seen a long distance away and is moving in a north-westerly direction. In its path are three towns (total population of approximately 4000), interspersed with farmland (livestock, dairy and crop farms). Fire-fighters are at the scene.

Question 1. What are the PCBs and what hazards do they pose to human health? What information retrieval sources are you going to consult? Remember, immediate answers are required.

Question 2. What immediate actions should be taken and who should be involved?

B2. Response to a PCB-fire emergency (Part II)

Ministry of Environment records show that 500 drums (~100,000 litres) of a dielectric fluid called “askarel”, containing up to 70% PCBs, were stored in the warehouse.

PCBs have the formula C12H10-nCln with n=1 to 10; they constitute a family of 209 compounds called congeners that are characterized by different halogenation and phenyl-ring substitution patterns. PCBs mixed with mineral oil are used as insulating fluids, coolants and lubricants in high temperature electrical equipment. Pyrosynthetic products of PCBs include polychlorinated dibenzofurans (PCDFs) and dibenzodioxins (PCDDs). The Canadian Environmental Contaminants Act limits the use of PCBs, although their continued presence in equipment built before 1 July 1980 is permitted. These regulations also limit the concentration of PCBs in equipment offered for sale or in material released into the environment to 50 parts per million by weight. Further, the release from any one piece of equipment is limited to 1gm per day. Approved methods for the destruction of PCBs are slowly becoming available.

Acute exposure to PCBs (as well as PCDFs and PCDDs) results in a clinical syndrome of “PCB poisoning” characterized by skin abnormalities (chloracne) and oculodermatological symptoms, mucosal surface irritation, abnormal liver function, elevated serum triglycerides and peripheral neuropathy. Non-specific symptoms include excessive fatigue, anorexia and weight loss. Long-term concerns, based on the Yusho (Japan) and Yu-Cheng (Taiwan) epidemics caused by accidental ingestion of rice oil contaminated with PCBs and minor amounts of PCDFs, are reproductive and non-permanent developmental effects in infants, and cancer. These concerns are accentuated by the aftermath of the release of PCDDs in a 1976 explosion in a chemical plant near Seveso, Italy. The International Agency of Research on Cancer (IARC) lists PCBs as Group 2A carcinogens (limited human and sufficient animal evidence); TCDD (2,3,7,8-tetrachlorodibenzo-para-dioxin) is assigned to Group 2B (inadequate human evidence, but sufficient animal evidence). PCBs, PCDFs and PCDDs are believed to act as environmental estrogens or antiestrogens (see Exercise 2.4). They are considered to act as endocrine-disrupting contaminants in wildlife species and humans. The quantitative analysis of air, water and biological samples for these compounds requires considerable expertise and sophistication.

Question 3. Should the inhabitants of the three towns be evacuated? Who should make that decision?

Question 4. What measures should be implemented for environmental monitoring, biological monitoring and health effects monitoring? Who ought to be involved in such programmes? What group of individuals is likely to be at highest risk?

B3. Response to a PCB-fire emergency (Part III)

Residents of the nearby towns were evacuated immediately by the authorities and emergency accommodation was arranged. Specific instructions for evacuees and people living in neighbouring districts were made available through the Ministries of Agriculture (concerning consumption of local vegetables, milk, meat, etc.), Health, and Environment and via 24-hour telephone hotlines. It was strongly recommended that breast-feeding be stopped. Fire-fighters and others who were heavily exposed were given immediate medical attention, monitoring and psychological support (debriefing, counselling if required). A detailed questionnaire issued to 5000 persons was used to assess the probability of exposure. An ad hoc panel was convened, including local, national and international experts. Three task-groups were formed. Task-group I initiated and supervised the collection and analysis of environmental samples (air, dust on interior and exterior surfaces, soil, water, vegetation), as well as biological samples (e.g. serum levels of PCBs in most heavily exposed groups and in maternal milk). The environmental data was employed by task-group II in risk assessment calculations and in determining when to allow people to return home. Task-group III determined what short-term and long-term medical and psychosocial actions were needed for the exposed population and emergency respondents.

About 8% of the PCBs stored in the warehouse were actually burned. Harmonization and quality control of the analytical laboratories identified some aberrant methodologies which were corrected. In most of the environmental samples, PCBs were below the threshold of detection. Because some dust droplets were found that were contaminated with PCBs, dioxins and furans, all the homes and cars in the affected area were washed (special instructions were given). Although local vegetables were only minutely contaminated, an embargo was placed on this year’s crop of produce. No traces of contaminants were found in blood, milk and faeces of animals tested. Milk from the area was allowed to go for pasteurization two weeks after the exposure. Government compensation for losses was made available. The determination of PCDDs, PCDFs and planar PCB congeners (the most toxic group) in breast milk during the first three days showed no elevation. Women were reassured and breast-feeding was resumed. Breast milk analyses during the subsequent weeks and months confirmed the initial conclusion of negligible exposure. Although 5000 people in all were medically examined and tested, only some of the fire-fighters, police and emergency respondents who participated in containment and clean up had higher-than-average liver enzyme levels in their sera. These latter individuals also showed some symptoms of the PCB poisoning syndrome, had evidence of mild elevation of serum PCBs, and will be subjected to long-term follow-up. These findings indicated improper protection when on emergency duty. Psychosocial impact assessments will also be pursued for at least six months. Quantitative risk calculations confirmed that, other than the “heavily exposed” groups, the general public were not at risk and would not be resettled provided the required precautionary measures were followed. The evacuation decision was judged to be justified.

Question 5. In your assessment, were the actual emergency responses and follow-up adequate?

Question 6. What risk communication issues can you identify?

Question 7. What follow-up measures do you recommend?

Selected references

Axelson O. Seveso: disentangling the dioxin enigma. Epidemiology 1993; 4:389-392.

Dewailly E, Tremblay-Rousseau H, Carrier G, Groulx X, Gringras S, Boggess K, Stanley J, Weber JP. PCDDs, PCDFs and PCBs in human milk of women exposed to a PCB fire and of women from the general population of the Province of Quebec, Canada. Chemosphere 1991; 23:1831-1835.

Hay A. What caused the Seveso explosion? Nature 1978; 273:582-583.

Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7. Overall evaluation of carcinogenicity: an updating of IARC monographs, Vols 1 to 42. Lyon, International Agency for Research on Cancer, 1987.

International Programme on Chemical Safety. Environmental health criteria No.88. Polychlorinated dibenzo-para-dioxins and dibenzofurans. Geneva, World Health Organization, 1989.

International Programme on Chemical Safety. Environmental health criteria No.140. Polychlorinated biphenyls and terphenyls (2nd edition). Geneva, World Health Organization, 1993.

James RC, Busch H, Tamburro CH, Roberts SM, Schell JD, Harbison RD. Polychlorinated biphenyl exposure and human disease. J. Occup. Med. 1993; 35:136-148.

Kimbrough RD. Polychlorinated biphenyls (PCBs) and human health: an update. CRC Crit. Rev. Toxicol. 1995; 25:133-163.

Swain WR. Effects of organochlorine chemicals on the reproductive outcome of humans who consumed contaminated Great Lakes fish: an epidemiologic consideration. J. Toxicol. Environ. Health. 1991; 33:587-639.

U.S. Public Health Service. Toxicological profile for 2,3,7,8-Tetrachlorodi-benzo-p-dioxin. Atlanta, GA, Agency for Toxic Substances and Disease Registry, 1989 (Document ATSDR/TP-88/23).

U.S. Public Health Service. Toxicological profile for selected PCBs (Aroclor -1260, -1254, -1248, -1242, -1232, -1221, and -1016), Atlanta, GA, Agency for Toxic Substances and Disease Registry, 1989 (Document ATSDR/TP-88/21).

8. Student’s version: Problem-solving exercise: Mercury poisoning in the Amazon

Adapted by A. Yassi, D. Mergler and E. Nieboer*

* Dr Annalee Yassi, Occupational and Environmental Health Unit, University of Manitoba, Winnipeg, Canada

Dr Donna Mergler, Universitu Quc ontr (UQAM), Canada

Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Gold mining in Brazil has been associated with a wide variety of concerns, especially contamination of the environment with mercury (Pfeiffer et al., 1993). Most of Brazil’s gold is produced by non-organized prospectors called garimpeiros. After gravimetric preconcentration, amalgamation is carried out by passing a water slurry of the ground ore over mercury-coated copper plates to which the gold particles adhere. Periodically, the gold-mercury amalgam is scraped off. The gold itself is recovered by heating, which is carried out by distillation in the local towns, in huts beside the river, or by driving off the mercury to the air by direct heating at river banks without any containment or personal protection. There are approximately 1 million garimpieros in the Brazilian Amazon, generating the release annually of about 130 tons of mercury to the environment; of this, it is estimated that 65-83% is released to the atmosphere and the remainder to soils or rivers (Pfeiffer et al., 1993).

Metallic mercury in the environment is transformed after oxidation into methylmercury by the activity of bacteria present in soil, sediments and suspended particulates in water. Organic mercury is highly assimilable into the trophic chains where it can be biomagnified a million-fold between initial transformation and the ultimate predatory species. (You will learn more about biomagnification in Chapter 7.) Fish with mercury concentrations exceeding the 0.5 mg/gm concentration limit proposed as safe for human consumption by IPCS in 1976, have been caught downstream from the gold mining area (Malm et al., 1990).

On the Tapajos river system where extensive gold mining efforts have focused (see Box 11.5 in the textbook), a physician working in the area became concerned. He was assessing the effect of mercury vapour on gold miners and his positive findings led him to wonder whether the communities living downstream of the gold mining activities might be at risk from methylmercury exposure. Both psychological and neurological symptoms are associated with chronic exposure to mercury vapour (IPCS, 1991). Acute inhalation results in interstitial pneumonitis. Mercury concentrations in whole blood reflect current and recent exposures to inorganic mercury (usually experienced as mercury vapour). The time required for the lowering of inorganic mercury in the blood compartment by a factor of 2 (t½) is 3 days, with a minor decay component characterized by t½ = 30 days. Methylmercury poisoning results in a neurological disorder called Minamata disease, which first occurred in the 1950s following mercury contamination of Minamata Bay, Japan (IPCS, 1990; see boxes 4.9 and 7.5 in the textbook). The exposure levels in that situation, however, were thought to be considerably higher. Total mercury level in hair and whole blood constitute good exposure indices to methylmercury. On average, the hair-to-blood concentration ratio observed is 250 (IPCS, 1990; Akagi et al., 1995). In both matrices, it is present primarily as the alkyl compound. National health agencies use 10-20 mg/g total mercury in hair (equivalent to 40-80 mg/L in whole blood) as the maternal concentration range for which some risk exists of neurological/developmental effects in neonates, with 6 mg/g in hair and 20 mg/L in whole blood as having no adverse effect or safe levels. For methylmercury, t½ values for its removal are 45-70 days for the whole-body, blood or hair compartments.

Question 1. What do you know about mercury poisoning (refer to Chapters 2 and 9 if necessary).

Question 2. What types of environmental and health assessment studies might be carried out? (Review Chapter 3 if necessary.)

Question 3. Should developed countries be involved in this sort of problem assessment?

Question 4. What professionals (disciplines) should be involved? Who else should participate?

Question 5. What questions might the villagers have?

Question 6. Should the details of the results be shared with villagers? How might this be achieved?

Question 7. Based on the information provided, estimate the dose (risk) ratio.

Question 8. Should a follow-up study be planned? Should the villagers be part of this decision?

Question 9. What should the UQAM/Brazilian team say now?

Question 10. What might be some short-term solutions and what might they tell the community now?

Question 11. What occupational and environmental preventive measures might be implemented. Use the perspectives “at the source”, “along the path” and “at the person” in your deliberations. Environmental, biological and health effects monitoring, as well as alternative gold extraction procedures, should be considered.

Question 12. How is it useful to link occupational and environmental health here? (You may wish to review the section in Chapter 1 that addressed this.)

Question 13. Is this problem a local one? Could it happen in developed countries? Is there a reason for global concern about mercury contamination?

Selected references

Akagi H, Malm O, Branches FJP, Kinjo Y, Kashima Y, Guimarases JRD, Oliveira RB, Haraguchi K, Pfeiffer WC, Takizawa Y, Kato H. Human exposure to mercury due to gold mining in the Tapajos River Basin, Amazon, Brazil: Speciation of mercury in human hair, blood and urine. Water Air Soil Pollut. 1995; 80: 85-94.

Cohn JG. Stern EW. Gold and gold compounds. In: Kirk-Othmer encyclopedia of chemical technology, 4th ed., Vol. 12 (JI Kroschwitz, M Howe-Grant, eds.). New York, Wiley, 1994, pp. 738-767.

International Programme on Chemical Safety. Environmental Health Criteria No. 101. Methylmercury. Geneva, World Health Organization, 1990.

International Programme on Chemical Safety. Environmental Health Criteria No. 118. Inorganic mercury. Geneva, World Health Organization, 1991.

Lebel J, Mergler D, Lucotte M, Amorim M, Dolbec J, Miranda D, ArantG, Rheault I, Pichet P. Evidence of early nervous system dysfunction in Amazonian populations exposed to low-levels of methylmercury. Neurotoxicol. 1996; 17: 157-168.

Malm O, Pfeiffer WC, Souza CMM, Reuther R. Mercury pollution due to gold mining in the Madeira River Basin, Brazil. Ambio 1990; 19: 11-15.

Nriagu JO, Pfeiffer WC, Malm O, de Souza CMM, Mierle G. Mercury pollution in Brazil. Nature 1992; 356: 389.

Pfeiffer WC, Lacerda LD, Salomons W, Malm O. Environmental fate of mercury from gold mining in the Brazilian Amazon. Environ. Rev. 1993; 1: 26-37.

Wheatley MA. The importance of social and cultural effects of mercury on aboriginal peoples. Neurotoxicol. 1996; 17: 251-256.

9. Student’s version: Introduction to risk communication

Instructions: Please complete this questionnaire.

1. Communicating with the public about health risks is more likely to alarm people unduly than keeping quiet.

Agree________

Disagree________

Why?

2. We should not go to the public until we have solutions to occupational or environmental health problems.

Agree________

Disagree________

Why?

3. The best way to determine which hazards or risk situations require scientific attention is to listen to those affected by the occupational or environmental problems (e.g. workers or community members).

Agree________

Disagree________

Why?

4. Environmental health issues are too difficult for the public to understand.

Agree________

Disagree________

Why?

5. If we could explain risks clearly enough, people would accept them.

Agree________

Disagree________

Why?

6. I see risk communication as an important part of the environmental health specialist’s job.

Agree________

Disagree________

Why?

(Adapted from Hance, Chess and Sandman, Improving dialogue with communities: a short guide for government risk communication. Environmental Communication Research Program, Rutgers University, New Brunswick, NJ, 1988.)

10. Sample risk communication scenario

Prepared by Merri Weinger

Representatives of the Department of Health in Mexico will be attending a meeting with the community in the town of San Cristobal de las Casas, Chiapas. The purpose of the meeting is to address concerns about the proposed construction of a gas plant in the community. What follows is a list of the arguments, both supporting and opposing the construction of the plant, which will probably be raised in the meeting.

The job of the presenters is to inform the community about the utility of the plant, explain potential health risks, and anticipate and address any concerns.

Issues

Supporting construction of the plant (Agency perspective)

1. The community needs gas for domestic and commercial use, as well as for industry.

2. Gas is a source of combustion that offers no risk when handled with caution.

3. In the 45 years that gas has been distributed, there have been 14 accidents inside the country’s gas plants that have not affected the neighbouring residents.

4. Gas is not toxic. Its combustion produces a clean flame.

5. The plant’s equipment complies with national and international safety standards.

6. The fire prevention system within the plant has been improved.

7. Gas plants are equipped with an emergency response plan, a security manual and trained personnel.

8. The Department of Health is vigilant in monitoring gas plants and in enforcing health and safety standards.

Opposing construction of the plant (Community perspective)

1. We don’t want to risk an explosion like the one that happened in San Juan Ixhuatepec.

2. Gas is dangerous and toxic.

3. Since the odour of the gas is so strong, it seems there will be an explosion any minute.

4. The gas cylinders are in very bad condition.

5. There are other dangerous industries in our community and we don’t want any more.

6. If the plant explodes, the town will be destroyed.

11. Student’s version: Worksheet for community involvement scenario

Instructions

You will be representing the Department of Health in the upcoming meeting and are preparing your presentation to the community. Using your list of tips for community involvement and the list of arguments supporting and opposing the solid waste landfill, please respond to the following questions in your small group.

1. As you see it, what is the problem represented in this scenario? What is the goal of your presentation?

2. Who do you think will attend the meeting and what are their primary concerns?

WHO

CONCERNS

Think about the potential target audience(s) listed above as you respond to the following questions:

3. How would you explain the utility of the facility?

List three concepts or ideas you want to make sure you get across.

4. How would you explain the health risk of the solid waste facility?

List three concepts or ideas you want to make sure to get across.

5. What is the agency’s plan of action that you will be presenting to the community?

List three concepts or ideas that you want to make sure to get across.

6. What obstacles might you encounter during the meeting and what will you do about them?

7. Can you think of any ways to prevent such a situation from becoming controversial in the future?

12. Student’s version: Problem-solving exercise: Epidemic asthma2

2 From: Problem-based training exercises for environmental epidemiology. Geneva, World Health Organization, 1997 (Document WHO/EHG/97.6, revised version).

Prepared by: Ruth A. Etzel*

* Dr Ruth A. Etzel, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA

Part I

Barcelona is a city of 1.7 million situated on the Mediterranean Sea.

During the last week of January 1986, several physicians contacted public health authorities to report an increase in the number of persons who had come to the emergency rooms of the four large urban hospitals seeking medical care for acute severe asthma. Specifically, on Tuesday 21 January 1986 a total of over 130 people had sought care at these hospitals for difficulty in breathing. Most of these people were thought to be suffering asthma attacks. The attacks struck very suddenly and caused such severe problems that 10% of the patients required ventilatory support and 2% died.

Question 1. What is asthma?

Question 2. Is this an epidemic of asthma? What further information do you need?

Question 3. Review of the hospital records reveals that the four hospitals treated 288 persons with asthma during January 1986. Now can you determine if this is an epidemic?

Question 4. Develop a preliminary case definition.

Table 1. Number of persons over 14 years of age who presented with acute asthma to the city’s four hospital emergency rooms in the previous year (1985).

Month

Number

Month

Number

Month

Number

January

199

May

165

September

181

February

146

June

128

October

166

March

180

July

138

November

182

April

155

August

124

December

147

Question 5. Do you now have sufficient information to determine if there is an epidemic of asthma?

Table 2. Number of persons over 14 years of age who presented with acute asthma to the city’s four hospital emergency rooms in January 1986.

Day

Number

Day

Number

Day

Number

Day

Number

Day

Number

1

5

8

9

14

6

20

11

26

8

2

8

9

7

15

7

21

96

27

8

3

8

10

9

16

6

22

9

28

7

4

5

11

9

17

7

23

4

29

3

5

5

12

5

18

4

24

0

30

8

6

4

13

8

19

9

25

8

31

2

7

4

Question 6. Using the attached graph paper, draw a bar chart of the data tabulated above in Table 2. What additional information does the bar chart provide?


Figure


Figure 1. Number of persons seen in emergency rooms during January with acute asthma, Barcelona, 1986

Question 7. What other information would be useful to characterize the epidemic?

Question 8. On the attached city map, using dots, show the geographic distribution of the place of onset of illness (Table 3) for the 96 persons who came to the emergency rooms with acute asthma on 21 January. What does this distribution suggest?


Figure 2 City map

Question 9. Using the attached graph paper, draw a bar chart of the cases by hour of occurrence (Table 3). What hypotheses are suggested?


Figure

Table 3. Data regarding age, sex, time and place of onset of illness, for each of the persons who came to the emergency room with acute asthma on 21 January 1986.

Age

Sex

Time of onset

Place of onset (Region)

41

F

10:55

4

28

M

12:50

2

27

M

13:40

2

40

F

12:00

3

30

F

13:25

2

19

F

02:20

3

17

F

11:05

2

40

M

17:15

1

28

M

13:50

2

49

M

17:10

1

47

F

14:30

1

29

M

11:10

2

28

F

14:30

2

38

M

11:35

1

49

F

18:20

3

59

M

22:10

6

39

M

11:25

1

40

M

11:05

1

59

M

21:20

3

41

M

11:08

10

10

M

23:15

7

27

F

12:05

2

27

M

12:40

2

20

F

09:25

8

27

M

11:40

2

18

F

12:30

2

30

M

12:15

2

48

M

16.50

2

30

F

12:25

2

29

F

13:20

2

37

M

12:17

1

38

M

12:35

1

39

M

12:25

1

40

M

12:05

1

37

F

11:30

1

41

M

12:08

10

40

M

19:15

6

37

M

10:17

1

38

M

10:35

1

38

F

10:45

1

39

F

10:25

1

39

M

10:25

1

40

M

10:05

1

15

F

23:25

6

18

M

00:50

3

70

M

15:15

2

18

F

00:30

7

50

M

11:15

2

40

M

10:00

3

41

M

10:08

10

28

F

13:30

2

48

F

16:30

1

29

M

13:10

2

30

M

13:15

2

27

F

14:05

2

57

M

14:40

2

28

M

14:50

2

30

F

11:25

2

29

F

14:20

2

29

M

14:10

2

50

M

14:15

2

30

F

14:25

2

41

M

12:55

4

40

F

15:25

2

57

F

15:05

2

47

M

15:40

2

58

M

15:50

2

41

F

11:50

4

48

F

15:30

2

69

M

15:10

2

40

F

15:25

2

27

F

13:05

2

47

M

16:50

2

89

M

12:10

2

49

F

15:20

2

29

F

12:20

2

19

F

17:20

1

67

F

12:30

1

40

F

17:25

1

29

F

11:20

2

78

F

11:30

2

68

M

12:45

1

19

F

12:25

1

38

M

18:50

1

48

F

18:30

10

37

M

11:17

1

49

M

19:10

3

38

F

11:45

1

40

F

19:25

7

59

M

11:25

1

60

M

11:00

3

19

M

05:10

3

20

M

06:15

8

47

M

15:30

1

67

M

16:40

2

28

M

11:50

2


Figure 3. Hourly distribution of admissions

Part II

In your discussions with emergency room personnel, you learn that this is not the first time that the hospitals have been overwhelmed with patients suffering from acute asthma attacks. You are told that “asthma epidemic days” have occurred on 12 other occasions during the past two years.

Noting the clustering of asthma emergency room visits in space and time, you request data on air pollution in the city during the past two years. For Tuesday 21 January, air pollution levels were below normal for the city. The 24-hour average level of sulphur dioxide was 54 mg/m2 and that of black smoke was 98 mg/m3. The highest hourly mean for nitrogen dioxide was 10 ppb. Twenty-four hour pollen and spore counts were also below average for that time of year. Meteorological data showed high atmospheric pressure and stagnancy of the air with very low wind speed.

Question 10. What conclusions can you draw from this information?

Since many persons reported that they were affected in the centre of the city, near the waterfront, you decide to find out more information about the activities there. You learn that the following eight products were loaded or unloaded from barges and boats in the harbour during the past two years:

coal

cotton

gasoline

soybeans

fuel oil

coffee

corn

butane.

Question 11. How would you use this information to further explore this problem?

You ask for the dates on which each of these products were loaded or unloaded from barges or boats. This information is shown in Table 4.

Table 4

Days product is handled
(Loaded or unloaded)

Days product is NOT handled
(Loaded or unloaded)

Asthma epidemic days

Asthma epidemic days

Product

NO

YES

NO

YES

Coal

196

4

521

9

Fuel Oil

150

3

567

10

Gasoline

180

2

537

11

Cotton

399

7

318

6

Coffee

300

5

417

8

Corn

135

1

582

12

Soybeans

249

13

468

0

Butane

140

1

577

12

Question 12. Using the information in Table 4, complete the tables on the following pages and calculate the risk ratios. Optional: calculate the confidence interval (C.I.) for each table, using the formulas presented in class discussion. Also, the computer software EPIINFO may be demonstrated to calculate confidence intervals.

Question 13. How do you interpret the risk ratios and confidence intervals you have calculated?

Question 14. Now substitute a 1.0 for the 0 in cell B (soybeans) and re-calculate.

Question 15. How would you proceed from here?


Figure 4. Risk ratios and confidence intervals based on Table 4.

Risk ratio and 95% C.I. calculations were made using the EPI INFO software package, Version 5. USD, Inc., Stone Mountain Georgia, USA, 1990.

95% C.I. are exact confidence intervals.

Part III

Question 16. Develop a strategy for prevention of asthma epidemics in the city.

Question 17. How would you assess the costs of this prevention strategy compared to the costs of the emergency visits for asthma attacks?

Based on a report by Anto JM et al. Community outbreaks of asthma associated with inhalation of soybean dust. New England journal of medicine, 1989, 320(17): 1097-1102

For further study of methodology for epidemiologic studies of asthma, the following review article is recommended: Anto JM, Sunyer J. Epidemiologic studies of asthma epidemics in Barcelona. Chest, November 1990 (Supplement): 185s-189s.

13. Student’s version: Problem-solving exercise: AECI/MACASSAR sulfur fire

Prepared by Stuart A. Batterman*

* Dr. Stuart Batterman, Department of Environmental and Industrial Health, School of Public Health, Ann Arbor, Michigan, USA

Part I

After several days of brush fires in the vicinity, a huge stockpile of sulfur caught fire late on a Saturday afternoon. The stockpile site belonged to AECI, the largest manufacturer of chemicals and explosives in South Africa.

Due to strong and persistent winds, the fire cannot be extinguished and a total of about 7000 tons of sulfur has already burned. While the fire site is several kilometres away from large population areas, the township of Macassar (population 40000) is 2.5 km downwind, and many suburbs of Cape Town (population 1.5 million) are 10-30 km distant. From about 21:00 on Saturday to 01:00 on Sunday morning, the most intense period of burning, the prevailing winds blow to the west-north-west.

Symptoms among residents in the vicinity of Macassar increase in prevalence and intensity up to midnight and beyond. Residents, mostly black, working class and poor, report a number of irritative effects (e.g. burning and irritation of eyes, nose and throat, coughing, shortness of breath, chest pain, stomach cramps and vomiting). Figure 1 shows the general area.


Figure 1. Map showing portions of Western Cape Province.

The smaller inset map shows a 6 km x 6 km region near the fire. “F” = fire site; “M” = sites of existing continuous SO2 monitoring instruments; heavy dots = farms visited after the fire to investigate vegetative damage; shaded areas are mountains and/or nature preserves.

Question 1. What happens when sulfur burns? What are appropriate protective levels for the resulting toxic gases? Can occupational and ambient air standards be used?

Question 2. What immediate steps should be taken to protect public health? What would you recommend?

Question 3. What information is needed to assess the situation and confirm your decision?

Part II

On early Saturday evening, residents of Macassar were told to stay indoors and to close doors and windows. Due to high winds (8-12 m/s), fire-fighting efforts were ineffective and the fire intensity increased. Macassar was directly downwind. Because the wind direction did not vary from about 20.00 to 01.00 in the morning, concentrations in even well sealed homes increased and exposures were prolonged. Residents began to experience increasingly intense discomfort, eye and skin irritation, breathing difficulty, gastrointestinal cramps and respiratory distress. Shortly after midnight, an evacuation of the town was attempted in a chaotic operation. Between 3000 and 5000 residents were moved to a shopping mall in Firgrove about 5 km distant. Most left after midnight. Despite this effort, approximately nine deaths occurred, including two men (both asthmatics) driving in opposite directions along a highway. In addition, between 1000 and 2000 people visited emergency respiratory clinics that were set up soon afterwards near the affected community, and approximately 15 people were later diagnosed with chronic asthma-like respiratory disease. The chemical company sponsored several emergency actions, including setting up local clinics where some health services (e.g. spirometry) were provided in the days and weeks after the fire.

Question 4. What information, if any, should be obtained from evacuees?

Question 5. What concerns might you have for the health of the evacuees?

Question 6. How might company sponsorship of the clinics affect their credibility and utilization?

Part III

In the days and months following the fire, a moderate amount of sampling and analysis was performed to investigate impacts related to the fire. Many residents suffering symptoms made repeat visits to local clinics. Symptom information was collected for about 1000 individuals, and spirometry was done on several hundred. Additional analysis was focused on ecological impact (e.g. impact on vineyards some 10-25 km distant).

Approximately one year later, the duration and extent of exposures on the nearby population were estimated using dispersion modelling. Using the best available data, air concentrations were predicted for each hour of the fire. Figure 2 depicts a Gaussian plume model imposed on a photo of the fire taken on Sunday morning (winds had considerably decreased and much of the fire was out by this time). The plume has Gaussian profiles, depicting the spread of pollutants in the crosswind and vertical dimensions.

Some of the dispersion model results are displayed in Figure 3 using “isopleths” or lines of equal concentrations (like contour maps). The maximum one hour concentration ranged from about 10 to 200 ppm, and much of the area was exposed to 100 ppm for one hour. Thus, levels appear to have approached or exceeded the IDLH value. Firgrove (where Macassar evacuees were accommodated) was in a relatively low concentration area. Note that the maximum hourly concentrations are not necessarily coincident in time, i.e. one cannot tell from the map what hour the exposure occurred. The second highest hourly concentrations ranged from 10 to 40 ppm, and the 24-hour averages were from 1 to 15 ppm. These estimates indicate that concentrations in the Macassar community exceeded by 20-1000 times levels designed to be protective of health.


Figure 2. Depiction of the plume resulting from the fire.

The plume width and plume height follow Gaussian curves which are adjusted in practice (but not in the figure) to match characteristics of the fire’s plume. Such models allow concentrations to be estimated at many locations.


Figure 3. Isopleths showing the maximum 1 hour SO2 concentrations in ppm in the Macassar area.

The modelled area is 6 x 6 km, with the sulfur fire located in the south-east corner and designated “F”. The complex pattern results from wind shifts over the fire; most of the time, winds blew to the west-north-west.

Question 7. What is air quality dispersion modelling? What information is required?

Question 8. How can a modelling analysis be used?

Question 9. What are some of the uncertainties in dispersion modelling and the exposure assessment? What data would be useful?

Selected references

Documentation of the threshold limit value, 4th ed. Cincinnati, OH, American Conference of Governmental Industrial Hygienists, 1980, pp. 377-378.

Batterman S. An Evaluation of SO2 concentrations resulting from the AECI Fire. Report to the Legal Resources Centre, Cape Town, South Africa, 26 Jan. 1997.

Industrial Source Complex Dispersion Model, version 93109. US Environmental Protection Agency Research Triangle Park, NC, 1993.

Nappo C J et al. l982. The workshop on the representativeness of meteorological observations, June l98l. Bull. Amer. Meteor. Soc. 1982, 63(7):761-764.

Newhouse MT, Dolovich M, Obminski G, Wolff RK. Effect of TLV levels of S02 and H2504 on bronchial clearance in exercising man. Arch. Environ. Health 1978, 33:24-32.

On-Site meteorological program guidance for regulatory modeling applications. US Environmental Protection Agency, Research Triangle Park, NC, June 1987, revised 1996.

White N. A survey of the health effects on helderbug community of smoke exposure from a sulfur fire. Cape Town, University of Cape Town, 1996.

14. Student’s version: Problem-solving exercise: Water for Tonoumassť, a village in Togo

Prepared by Evert Nieboer and Annalee Yassi*

* Dr Annalee Yassi, Occupational and Environmental Health Unit, University of Manitoba, Winnipeg, Canada

Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Adapted with permission from Water for TonoumassCarleton (Ontario, Canada); Local Committee of CUSO

A. General instructions

The case scenario has two parts. The decision to proceed to Part II should be made jointly by students and instructor. Both parts are followed by questions related to the material covered in Chapter 1 and Chapter 6 of the text.

B. Case scenario, Part I

Togo is a long and narrow country in Africa that stretches 580 km north from the Gulf of Guinea. It is flanked by Ghana on the west and Benin on the east. It has an average rainfall of 100 cm/year which is considerably less than that received in other tropical areas. The United Nations classifies Togo as a “least developed country”. Tonoumasss a village of about 100 inhabitants located 50 km or so north of the coastal capital of LomThe surrounding area is a mixture of forested land (teak, mahogany, bamboo) and agricultural land (small farms growing coffee, cacao and cotton). Regionally, about 18% of the people have access to safe drinking-water. Fetching water is considered “women’s work”. Women spend 1-4 hours daily in the wet season (March to July) and as much as 8 hours in the dry period (December to March) in walking the 15 km to the nearest river. While there, they wash the family’s clothes and carry about 15 litres of water back to the village. Housework, child care, farming and handicraft production/sale needs to be taken care of after arriving home about midday. The water they collect is rarely safe. Drinking it can lead to a parasitical disease caused by the guinea worm, as well as typhoid, hepatitis, schistosomiasis, dysentery and other intestinal infections. As a result, up to 40% of the children die before the age of five. Those that survive miss a lot of school because of chronic illness. The ability of adults to work is also affected by parasitic disease and repeated infections. Not surprisingly, back ailments are prevalent among women.

Chapter 1 Questions

1. Meeting human survival needs is consistent with the UN Universal Declaration of Human Rights (1948). What obstacles exist in rural Togo in achieving this priority?

2. From the perspective of the WHO definition of health, what is the health status of the Tonoumassillagers?

3. Discuss the interaction between human activity in Tonoumassnd the biological environment.

4. Poverty is considered the greatest risk factor of poor health and a major obstacle to resolving environmental health problems. Discuss this in the context of Tonoumass

5. Do you consider the women of Tonoumasss a “vulnerable group” in terms of susceptibility to poor health? Explain.

Chapter 6 Questions

1. Review the causes of the diseases mentioned.

2. What categories of communicable diseases linked to water appear to be involved in the case scenario?

3. The small wet season in the period September to December is disappearing in the maritime region of Togo. Within the context of the causes of water scarcity, what might be the cause? Is this development consistent with global trends?

4. Would water treatment have helped the Tonoumassater problem? What might have been done?

5. What options other than water treatment might be considered?

C. Selected references

Canadian Universities Services Overseas. Water for TonoumassThe story of a village in Togo. Ottawa, Carleton Local Committee of CUSO, 1988.

Isselbacher KJ, Martin JB, Braunwald E, Fauci AS, Wilson JD, Kasper DL. Harrrison’s principles of internal medicine, 13th ed. New York, McGraw-Hill, 1994 pp 485-938.

Tin UU, Lun Wai U, Ba Tun U, Mya Win U, Thein Dan U, Than Sein U. “We want water, not gold.” World Health Forum 1988; 9:519-525.

Our planet, our health, Geneva, World Health Organization, 1992, pp 106-144.

The International Drinking Water Supply and Sanitation Decade. Review of regional and global data (as at 31 December 1983). Geneva, World Health Organization, 1994 (Offset Publication No. 92).

D. Case scenario, Part II

During the 1980s, the Government of Togo with the help of Canadian Universities Services Overseas (CUSO) initiated a rural water supply project. The village of Tonoumassecame aware of this through a female extension officer and, because there was dissatisfaction with the lack of water, appointed a committee. One of the requirements of the project was that at least half of the committee members should be women. The men grumbled and predicted failure, but grudgingly went along with the idea. Although pump installation was free, the villagers had to agree to clean the installation site, provide materials and labour for the concrete apron, send two people to learn how to maintain the pump, and to pay for all future repairs. A formal agreement was signed in a public ceremony in the presence of high-ranking government officials.

Tonoumassillagers chose to set up a collective farm plot and required each family to contribute a day’s work per week. Sales of produce from this venture were 10 times more than was needed to cover the pump maintenance costs. Consequently, the village had a fund that could be used for other community improvements. Effectively this constituted the first local taxes Tonoumassver raised.

In eight general meetings for villagers and project managers (mostly female), rural extension workers and trained villagers took time to explain the connection between clean water and sanitary conditions and good health (including use of covered water containers, curtailment of the soiling of houses and yards, and a general programme to keep the village clean). A reduction in illness became apparent soon after the pump was installed and the concomitant improvements were made.

An interesting aside concerns respect for religion and culture. After consulting the spirits of the dead, village elders agreed with the modern-day technicians about the location of the water source and the placement of the pump.

Chapter 1 Questions

1. Was the requirement of female membership of the project committee a reasonable one?

2. Discuss the required contribution to the collective farm plot in terms of individual versus community initiatives/rights.

3. Empowerment is an important motivational principle. What was its role in the pump project and how was it achieved?

4. To what extent did the principle that community decision-making needs to integrate ecological, cultural, health, technical and economic dimensions apply to Tonoumass

5. The ability to respond to community environmental health problems is said to depend on economic prosperity. Was that the only determinant in the pump project?

6. How did the pump project make life better in Tonoumass/BLOCKQUOTE>

Chapter 6 Questions

1. What criteria were used in selecting the site for the pump?

2. Why is adequate sanitation crucial to a safe local water supply?

3. Suggest some routine monitoring to test for indicator organisms in the well water.

4. Outline strategies, other than improving sanitation services, for safeguarding the water supply.

15. Student’s version: Problem-solving exercise: Water availability and Trachoma1

1 Based in part on a report by West S et al. Water availability and trachoma. Bulletin of the World Health Organization, 1989, 67(1): 71-75.

Prepared by Nancy V. Hicks*

* Dr Nancy Hicks, former consultant, WHO

Part I

A major cause of blindness in developing countries is trachoma resulting from repeated infections. Lack of water and increasing distance from the home to the water source has been reported to be associated with the disease, which can be hyperendemic in dusty, dry regions. However, the association is not entirely borne out by the results of all studies.

You are the epidemiologist for a region of 20 villages where the incidence of trachoma is very high. Before promoting increased water supplies as an effective method for preventing trachoma, you decide to investigate the impact of distance to water supply on the prevalence of trachoma and on water use habits among families in your region. You are concerned that factors other than water availability may influence water use for hygiene purposes.

You decide to conduct a risk factor survey for trachoma among a random sample of 20 villages. Interviews (using a pre-tested structured questionnaire) will be conducted by trained local women.

Question 1. Devising items for an epidemiological questionnaire is not always straightforward. For example, you are interested in knowing the time needed to walk one way to a water source. However, in pretesting your questionnaire, you discover that this is difficult to communicate in the interview. How would you creatively deal with this problem in terms of the characteristics of the population that you might be working with?

Part II

A preliminary summary of your study data indicate that 389 households are located less than 30 minutes from the nearest water supply, 844 are within ½-2 hours, and 705 are more than 2 hours away. In the first group of 389 households, 148 households have no children with trachoma, 97 households have at least one child with trachoma, and in 144 households all children are affected. In the second group of 844 households, 228 have no children with trachoma, 202 households have at least one child with trachoma, and in 414 households all children are affected. In the third group of 705 households, 204 households have no children with trachoma, 148 households have at least one child with trachoma, and in 353 households all children are affected.

Question 2. Presenting study findings in a clear and concise way is very important. Construct a tabular presentation of your data. In addition to absolute numbers of children in each category, include a column with the corresponding percentages.

Question 3. Now, give an interpretation of your data.

Part III

Table 1 below presents the results of logistic regression (a statistical procedure that calculates the association of a particular risk factor with the outcome while controlling for the influence of other variables). (You are now a statistics expert!)

Table 1. Results of logistic regression analysis of the association between trachoma in the household by time (distance) to water source, quantity of household water, and other factors

Variable

Odds ratio

95% confidence interval

Time to water source:


0.5-2 hours

1.45

1.08-1.95


>2 hours

1.37

1.01-1.87

Quantity of water


Medium

1.01

0.76-1.35


High

0.84

0.61-1.15

No. of children


2

2.49

1.93-3.23


³3

5.16

3.63-7.37

Herding cows

1.85

1.35-2.56

House with a metal roof (vs. flat or thatched)

0.63

0.47-0.86

Traditional religion (vs. Christian or Muslim)

1.71

1.28-2.30

Sleeping next to a cooking fire

1.48

1.14-19.20

Presence of unclean faces:


some children

1.30

0.82-2.08


all children

1.70

1.22-2.35

Question 4. How do you interpret the study results in Table 1?

Part IV

Table 2. Distribution of children with clean faces, according to the time (distance) to the water source and the quantity of household water

Percentage of households with children

N

All clean

Some clean

All not clean

Time to water source:*


<30 minutes

386

15

16

70


0.5-2 hours

831

11

14

75


>2 hours

691

10

9

81

Quantity of water


High

577

10

16

74


Medium

815

12

12

76


Low

516

12

10

78

* c2 = 21.85; P = 0.01

Question 5. Give an interpretation of the data in Table 2.

Question 6. Comment on the way these data were gathered.

Question 7. What are your overall conclusions from this study?

Question 8. How will these study findings influence your opinion concerning increased and closer water supplies as an effective public health intervention for preventing trachoma and blindness?

16. Student’s version: Typical cases of foodborne diseases

Prepared by Gerald Moy*

* Dr Gerald Moy, Scientist, World Health Organization

Cases 1 and 2 are adapted from Food safety: it’s all in your hands: Ministry of National Health and Welfare, Canada, 1993.

Instructions:

Working in your small group, read the following cases and respond to the questions.

Case No. 1: The long-remembered wedding feast in Peru

It was to be the happiest day of Magda’s life. Relatives and friends from both sides of the family would be coming over for a lavish wedding feast. Her mother had worked late into the night preparing her best dishes for the guests. She finally went to bed at 04:00 in the morning after making sure that the food was attractively arranged on the tables. The next day was hot (over 30° C) but everyone enjoyed the good food. However, later that night, many people who attended the wedding started to experience severe stomach pains, nausea, vomiting and, in some cases, diarrhoea. While Magda felt fine, her new husband became so sick he had to go to the hospital.

What might have caused the illness?

What could have been done to prevent it?

Case No. 2: Deadly dessert in Canada

One September evening, patients at a hospital in Scarborough, Ontario, were served tapioca pudding for dessert. Later the next day, patients began showing the symptoms of food poisoning (cramps, chills, vomiting, diarrhoea). In all, 103 patients became ill and two of these, both elderly and weak, died. No pudding was available for testing. However, it was known that the pudding, amounting to 225 servings, was refrigerated in one large container until dinner.

What is a possible source of contamination?

Was it food poisoning? What could have been done to prevent this?

Case No. 3: A gift of fresh fish in Fiji

A man had very good luck fishing on the reef and offered to share some of the catch with his neighbours. The fish were nice and fresh, but about one hour after eating them, one person noticed a numbness of her lips and tongue. Soon other people also showed signs of illness, such as nausea, vomiting, headache and dizziness. Some people noticed that cold drinks felt hot, and hot water felt cold. Two people were hospitalized with irregular heartbeats. After several days, the signs of poisoning subsided, but for some people symptoms of weakness and dizziness persisted for several weeks.

What was the cause of this illness?

How could have it been prevented?

Case No. 4. The good mother in Tanzania

Salome’s child was now nearly 5 months old and it was time to introduce food other than breast milk into the diet. She had heard that nutritious and inexpensive weaning food could be made from local foods and she wanted to make sure that her child would grow and thrive. Following the advice in the nutrition literature she had be given, she faithfully prepared the recipe for a follow-up food using boiled sorghum as the base. At first, her child loved the new solid food and clearly was eating more and more. However, it was difficult and time-consuming work so she started making larger batches so that she needed to prepare it only once a day. She carefully covered it with cloth gauze to protect it from flies. Subsequently, her child started to experience periodic episodes of diarrhoea and after a few months the child started to show signs of growth faltering.

What might be the reason for growth faltering in this case?

How could it be avoided?

17. Student’s version: Problem-solving exercise: Pesticide poisoning - an outbreak among antimalarial workers

Prepared by Linda Rosenstock, revised by Steven Markowitz*

* Dr. Linda Rosenstock, Director, National Institute of Occupational Safety and Health, USA

Dr. Steven Markowitz, Division of Environmental and Occupational Medicine, Mt. Sinai School of Medicine, New York, NY, USA

Adapted from: Jeyaratnam J. Pesticide poisoning among antimalarial workers. In: Teaching epidemiology in occupational health. NIOSH/WHO, 1987.

Part I

You are a medical officer recently appointed to take charge of a large malaria control programme. You learn that a suspected increase in the number of pesticide poisonings started soon after the beginning of the last spraying season.

Question 1. How would you proceed to investigate this situation? What more would you like to know before getting started?

Part II

You learn that the pesticide malathion (an organophosphate) has replaced DDT this spraying season because the mosquito had become resistant to DDT and because malathion is an effective pesticide that is thought to be relatively safe for human use on the basis of much experience, including field trials in Nigeria and Uganda.

You learn that there are about 7700 antimalaria workers, making up 1100 teams of seven workers each (5 spraymen, 1 mixer, 1 supervisor). In addition to the reported increase in illness (which suggested organophosphate poisoning), five deaths have occurred - two in mixers and three in spraymen. It is thought that one of the three brands of malathion was associated with the most severe illness (used by three of the five who died). It is also reported that the illness was more common on Friday and Saturday than on Sunday.

Question 2. What appears to be the main exposure problem in the episode described?

Question 3. How can you plan organizationally to investigate this outbreak?

Question 4. What case definition of “poisoning” would you suggest (use Table 1)?

Table 1. Symptoms of organophosphate poisoning

Mild poisoning

headache
nausea
dizziness
anxiety, irritability

Moderate poisoning

muscle twitching, tremor
sweating, salivation
blurred vision
vomiting, diarrhoea,
abdominal pain
chest tightness, wheezing

Severe poisoning

pulmonary edema
bradycardia (slow heart rate)
or tachycardia (fast heart rate)
confusion
seizures, coma
involuntary defecation,
urination

Question 5. Why are there more symptoms on Friday and Saturday than on Sunday?

Why does there appear to be a problem with a pesticide that has apparently been safely used in other antimalaria programmes?

Part III

The occurrence of cases of poisoning has been confirmed. Cases occur predominantly towards the end of the working week. You decide to study it further with a questionnaire survey.

You define a case as:

- occurring in a member of a spraying team;
- having at least four of the following five symptoms (blurred vision, dizziness, nausea, vomiting, abdominal pain).

You decide to interview a random sample (10%) of all the antimalaria workers to ask them about their past and present symptoms and their exposures at work.

Question 6. What type of epidemiologic study is this survey?

Question 7. What are the advantages and weaknesses of:

- this study design?
- this case definition?
- this sampling strategy?

Part IV

You interview 79% of those targeted in your sample. Your main findings are shown in Table 2.

Table 2. Number of acute poisonings during recent spray season


Number in sample

Number interviewed

% response

Number with at least 1 episode of poisoning

% poisoned


(a)

(b)

(b/a)

(c)

(c/b)

Spraymen

550

425

77

174

41

Mixers

110

86

78

33

38

Supervisors

110

95

86

19

20

Total

770

606

79

226

37

Question 8. What do you think about the overall response rate of 79%? How could the non-responders affect your assessment of the problem?

Question 9. On the basis of these questionnaire results, how might you estimate the total number of workers with at least one episode of poisoning within the whole population of 7700 antimalaria workers during the recent spraying season?

Question 10. What would you do next?

Part V

You now know that there has been a major outbreak (epidemic) of poisonings, having estimated a total of 2893 (38%) of workers with at least one episode of pesticide intoxication. Sprayers and mixers are at highest risk. Observations of spray teams showed problems such as:

- working in clothes wet from pesticides;
- direct pesticide contact with skin due to mixing with bare hands;
- leaking spray cans.

Skin patch samples confirm that there is high skin exposure, particularly for mixers and sprayers (about 10-20 times higher than for supervisors). Airborne estimates of malathion exposure to sprayers were obtained by standard methods and were determined to be low (3% of recommended US standards).

Question 11. What seems to be the most important route of exposure?

Question 12. How could you study whether poor work practices and faulty equipment explain the epidemic?

What are other possible explanations? How would you measure individual exposure more specifically?

Part VI

You conclude that factors other than poor work practices contribute to the epidemic. The workers themselves suggest that there are more problems among those using one or two malathion brands (out of a total of three brands used). But a lot of workers use more than one brand in any given day. You collect blood and measure cholinesterase levels in a small sample of workers in the three job categories who used only one brand on the day of tests.

Your findings are shown in Table 3.

Table 3. End-of-day cholinesterase levels and mean % change (from morning to end of day)


End-of-day levels*

Mean % change

Malathion Brand

Supervisors
(N=22)

Mixers
(N=21)

Sprayers
(N=102)

Supervisors

Mixers

Sprayers

Brand 1

0.62

0.58

0.58

+5.9

-0.8

-3.1

Brand 2

0.59

0.34

0.38

+3.2

-20.1

-11.2

Brand 3

0.59

0.39

0.24

+0.2

-39.2

-46.7

*Normal range: 0.53 - 0.93


Question 13. What do you think about these results? Is any brand safe? Which brand(s) might be causing the epidemic? Why might there be differences between brands?

Part VII

Analysis of the chemicals in the three pesticide preparations showed Brands 2 and 3 had a much higher concentration of toxic breakdown products (formed when the main chemical, malathion, is degraded). This breakdown was thought to be due to different “chemical carriers” (believed to be non-toxic). You conclude that use of Brands 2 and 3 was the main cause of the epidemic, but you are also concerned about problems with poor work processes, faulty equipment and inadequate protective clothing.

Question 14. Name at least three things you would do now to deal with the epidemic.

Question 15. You learn that there may be a problem with children in the community becoming ill. How would you investigate this?

18. Student’s version: Problem-solving exercise: Toxic encephalopathy from a seafood

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada


Case scenario

In late 1987, a mysterious and serious outbreak of food poisoning occurred in Canada. Symptoms of the poisoning included vomiting and diarrhoea, followed in some cases by confusion, memory loss, disorientation and even coma. Two elderly patients died and in some other severely affected cases the neurological symptoms still persist. Epidemiologists from Health and Welfare Canada soon attributed the illnesses to restaurant meals of cultured blue mussels (Mytilus edulis L.). Using the Association of Official Analytical Chemists’ mouse bioassay for “red-tide” paralytic shellfish poison (PSP), Health and Welfare Canada and Fisheries and Oceans scientists demonstrated that the mussels contained toxic material. Furthermore, they were able to trace the problem to mussels harvested from a specific area of eastern Prince Edward Island. All the Deputy Ministers of Health of the 10 Canadian Provinces were notified by telex of the recommendation to take Prince Edward Island mussels off the shelves in retail stores and to remove them from restaurants. Consumption was to be stopped. Statistical analysis of the mussel distribution records and reported cases showed that for each symptomatic case some 500 people ate the contaminated mussels without any toxic consequences.

Subsequently, a team of scientists using suitable chemical separation, analytical techniques and the mouse assay, established that a neuroexcitatory amino acid, domoic acid, was the probable toxic agent. It was shown that the diatom Nitzschia pungens (an alga) was the source of this compound. Mussels feed on plankton, of which Nitzschia pungens became a significant component during an algal bloom in the waters off the eastern coast of Prince Edward Island. When the toxic bloom waned early in 1989, shellfish were found to contain low levels (<20 mg/g) of domoic acid and distribution for human consumption was again allowed. No further illnesses were documented.

Question 1. Identify, without detailed discussion, important issues highlighted in the case scenario. (Do this in a group setting with a recorder at the blackboard or flip chart.)

Question 2. What is paralytic shellfish poisoning (PSP)? Can domoic acid poisoning be distinguished from it?

Question 3. Discuss possible mechanisms of action of domoic acid.

Question 4. From the information given, do you expect there to be a safe intake level of domoic acid?

Question 5. Suggest how one might determine quantitatively the concentration of domoic acid in mussel tissue.

Question 6. Are you convinced there was enough evidence to assign the blame to domoic acid as the causative agent?

Question 7. Assess the role of the interdisciplinary investigative team.

Question 8. Suggest preventive actions to avoid future incidents.

Question 9. Discuss the broad area of food safety in public health. In your discussions, highlight the status and practices of the following aspects in your geographical region: (i) regulatory authority; (ii) setting of food safety standards; (iii) routine food inspection/surveillance; (iv) emergency response capacity.

Selected references

Hynie I, Hockin J, Wright J, Iverson F. Panel discussion: evidence that domoic acid was the cause of the 1987 outbreak. Can. Dis. Wkly. Rep. 1990; 16S1E:37-40.

Iverson F, Truelove J, Nera E, Tryphonas L, Campbell J, Lok E. Domoic acid poisoning and mussel-associated intoxication: preliminary investigations into the response of mice and rats to toxic mussel extract. Food Chem. Toxicol. 1989; 27:377-384.

Kotsonis FN, Burdock GA, Flamm WG. Food toxicology. In: Casarett & Doull’s Toxicology, 5th ed. The Basic Science of Poisons (CD Klaassen, ed.). New York, McGraw-Hill, 1996, pp. 909-949.

Olney JW. Excitotoxicity: an overview. Can. Dis. Wkly Rep. 1990; 16S1E:47-58.

Olney JW. Excitotoxicity in foods. Neurotoxicology 1994; 15:535-544.

Perl TM, Brd L, Kosatsky T, Hockin JC, Todd ECD, Remis RS. An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid. N. Engl. J. Med. 1990; 322:1775-1780.

Perl TM, Teitelbaum J, Hockin J, Todd ECD. Panel discussion: definition of the syndrome. Can. Dis. Wkly. Rep. 1990; 16S1E:41-45.

Teitelbaum JS, Zatorre RJ, Carpenter S, Gendron D, Evans AC, Gjedde A, Cashman NR. Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. N. Engl. J. Med. 1990; 322:1781-1787.

Wright JLC, Bird CJ, deFreitas ASW, Hampson D, McDonald J, Quilliam MA. Chemistry, biology, and toxicology of domoic acid and its isomers. Can. Dis. Wkly. Rep. 1990; 16S1E:21-26.

19. Student’s version: Problem-solving exercise: Hazard assessment in food production

Prepared by Theo de Kok*

* Dr Theo de Kok, Faculty of Natural Sciences, Open University, Heerlen, Netherlands

Case scenario

You are a health inspector who is visiting a food processing plant that produces infant food on a large scale. The product of the production line you are working on today is a drum-dried and spray-dried infant food, based on rice, maize, starch, coconut oil, sugar milk and a number of supplements. The flow diagram of the process given to you by the director is shown in Figure 1.


Figure 1. Flow diagram for drum- and spray-dried rice-based infant foods

Based on your visit to the plant and interviews with staff and employees, you identified a number of critical control points. Table 1 lists the critical control points and the hazards involved.

Table 1 Analysis chart of the process of spray-drying rice-based infant food and control points

Critical control

Description

Hazard

1. Dispersal

Addition of hot water.

Bacterial proliferation ccurs over time

2. Mixing

The solution is mixed in stir tank.

As above.

3. Belt mixer

To achieve the required mixing of all ingredients.

As above.

4. Drum dryer

Evaporation of water by a

The products leaving


Drum Dryer (DD)
The dryer works at 150 oC
The product reaches...oC

DD meet the current of air caused by the extractor. Microorganisms may be transferred to the product. Bacterial proliferation occurs over time in plant and environment.

5. Prebreaker

The sheet form of the products is reduced to pieces.


6. Sacks

The product is put in sacks.

Contamination of sacks.

7. Dry-mixing

Addition of other ingredients to the semi-finished product.

Pathogens in milk and fruit powders (raw materials).

8. Grinding

The dry mixture is ground by milling.

Contamination from mill.

9. Pneumatic transport trolley tanks pneumatic transport

Pneumatic transport of product, then stored in trolley tanks until transferred to sprat dryer by pneumatic transport

During these operations the product can be contaminated by trolley-tanks as these are transferred from one building to another. Contact with air can introduce microorganisms

10. Spray dryer
Fluid bed

Water is added to the dry mixture; this is then treated In a spray dryer with a fluid bed.

Atomizer rotor is subject to bacterial growth.

11. Packaging

Product placed in sachet of impermeable nitrogen flushed laminate before heat sealing. Sealed sachet placed in a box.

Packaging material can be contaminated. Contamination (pathogens) from the environment. Product residues in filler can contaminate fresh product as it is filled.

It is your task to write a report on the safety of the foods produced by this plant. The following questions may give some guidance in doing so.

Question 1. Describe when and how the microbial hazards may give rise to toxin formation, thus resulting in poisoning of the infant that consumes the food.

Question 2. What could be the cause of mycotoxin formation in the flow of oil and starch products, and what types of mycotoxins may be formed under which conditions?

Question 3. What options are there to prevent mycotoxin formation?

Question 4. Is it possible to inactivate the mycotoxins that have already been formed in the products, either chemically or physically?

Question 5. Staphylococcus aureus enterotoxin may have been formed in the milk before it was dried (e.g. 1 ng per g dried milk powder). Is it possible that children show S. aureus poisoning after consuming 250 g of the contaminated product?

Question 6. Is it likely that children fall ill after consuming the product in case it is contaminated with 104 viable Bacillus cereus spores per g and the product was left at 20° C for 16 hours?

Question 7. Describe the toxicological hazards (other than microbiological) that may be associated with this infant formula. Take the whole sequence of production into account from raw material to the consumer (e.g. origin, level, hazards, possible avoidance/elimination).

Study hint: take the following points into account

· Regarding the raw materials:

- excess vitamin A/D;
- antinutritive substances (soy);
- lipid oxidation and its products;
- contaminants (e.g. heavy metals, PCBs, dioxin, nitrate, packing materials);
- additives.

· Regarding the food processing:

- lipid oxidation (minerals, oxygen, heat treatment);
- Maillard reactions (depending on conditions, spray-drying versus drum-drying);
- maintenance or loss of nutritional value depending on the processing conditions;
- contamination from the equipment;
- oxidative and thermal degradation of proteins (drum-drying)

· Regarding packaging/storage:

- contamination.

Suggested references

Hazard analysis critical control point system, concept and application. Report of a WHO Consultation with the participation of FAO. Geneva, World Health Organization, 1995 (Document WHO/FNU/FOS/95.3).

Application of risk analysis to food standards issues. Report of the joint FAO/WHO expert consultation. Geneva, World Health Organization, 1995 (Document WHO//FNU/FOS/95.3).

J. de Vries et al. Food safety and toxicity. CRC press, 1997.

20. Motor vehicle air pollution health effects worksheet

Circle all the correct answers or fill in the blanks.

1. Motor vehicles become a source or air pollution as a result of:

(a) refueling losses
(b) evaporative emissions
(c) exhaust emissions
(d) crank case losses
(e) reckless driving

2 a. What is smog?

2 b. How is smog produced?

(a) power generating plants
(b) reaction of hydrocarbons and nitrogen oxides with sunlight
(c) automobile exhausts
(d) acid rain

3. What are the main pollutants from motor vehicles?

(a) carbon monoxide
(b) nitrogen oxides
(c) ozone
(d) particulate matter
(e) lead
(f) benzene
(g) carbon dioxide
(h) sulfur dioxide
(i) acid aerosols
(j) halogenated hydrocarbons

4. What factors affect the composition of motor vehicle exhaust emissions?

(a) fuel type and quality
(b) geographical factors
(c) maintenance of vehicle
(d) age of vehicle
(e) speed of vehicle
(f) type and operating condition of engine
(g) use of emission control device

5. Which population groups may be especially susceptible to adverse health effects from motor vehicle pollution?

(a) children
(b) people who live at high elevations
(c) people who smoke
(d) people with asthma
(e) people with cardiovascular disease
(f) elderly people
(g) people with respiratory disease

6. Which groups of people have an increased chance of exposure to motor vehicle air pollution?

(a) traffic police
(b) pedestrians
(c) people who live on highly trafficked streets
(d) parking garage attendants
(e) toll booth workers for bridges or tunnels
(f) subway passengers
(g) people who drive buses, taxis, trucks
(h) urban roadside street vendors
(i) gasoline station workers
(j) people who work in urban centres

7. True or false: Fuels in developing countries often have a high lead and sulfur content.

T

F

8. True or false: All motor vehicles are equally polluting.

T

F

Why or why not?

9. Which motor vehicle air pollutants can adversely affect the respiratory tract?

(a) nitrogen oxides
(b) ozone
(c) lead
(d) sulfur oxides
(e) particulate matter
(f) carbon monoxide

10. Which substances in motor vehicle emissions can produce toxic systemic effects?

11. Which substances in motor vehicle emissions have a potential carcinogenic effect?

(a) lead
(b) sulfur oxides
(c) ozone
(d) benzene

12. True or false:Noise pollution can cause physical, physiological and psychological effects.

T

F

Why or why not?

13. How is human exposure to motor vehicle air pollution measured?

21. Student’s version: Building a healthy city - the case of Managua, Nicaragua

Prepared by Merri Weinger

Case scenario by Francoise Barten & Angel Sanchez*

* From: Barten F, Sanchez A. Towards a healthier Managua. World Health. 1996; 1:16.

At present, Nicaragua is one of the poorest countries in Latin America. The dislocation caused by the low-intensity war during the last decade led to massive migration from the countryside. The population of the capital, Managua, more than doubled in three years. Today, roughly one-third of the country’s population lives in Managua. This rapid and uncontrolled growth of the city, combined with a lack of urban planning and increased demand on urban services, has contributed to a crisis situation, with increasing social inequalities and the political polarization of society.

Between 1987 and 1994, poverty in Managua increased from 30% to 72.5% and extreme poverty from 15% to 50% - mainly among female-headed households. Unemployment stands at a staggering 62% and malnutrition in children at 68%, while domestic violence and drug abuse among school-aged youth are rapidly rising. The 270 squatter settlements constitute the most unhealthy environments of the city, and more than 300 polluting industries are located in low-income areas. Waste is dumped at 310 illegal sites throughout the city, causing serious health hazards.

Among other health problems, the city faces serious epidemics of malaria and dengue. In spite of declining health status, the public health budget was reduced by 50% in recent years.

Question 1. What are some of the key health, environmental and social problems likely to be faced by the city of Managua?

Question 2. Your task is to work with an intersectoral group in Managua to develop a municipal action plan to address some of these problems.

a. Who should be part of this working group and how do you propose to establish it?

b. You would like to ensure that the community is involved in developing the plan. What is your strategy for raising awareness about the project and fostering community participation?

c. Which problem would you make first priority and how would you go about making this decision?

d. What are the objectives of your action plan?

e. What are the key components of your municipal action plan?

f. What kind of activities might be included in the plan?

g. On the basis of the activities outlined above, which agencies might take the lead in implementing the plan?

Selected references

Barten F, Sanchez A. Towards a Healthier Managua. World Health, January-February 1996.

Price C, Tsouros A (eds.). Our cities, our future: policies and action plans for health and sustainable development, 2nd edition. Copenhagen, WHO Regional Office for Europe, 1996.

Von Schirnding Y. Intersectoral action for health: addressing health and environment concerns in sustainable development. Geneva, World Health Organization, 1997 (Document WHO/PPE/PAC/97).

Building a healthy city: a practititioner’s guide. Geneva, World Health Organization, 1995 (Document WHO/EOS/95.10).

22. Student’s version: Problem-solving exercise: Nuclear energy - a safe alternative?

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

Case scenario

Concern about the prevalence of childhood cancer around a nuclear installation was broadcast on a national television programme. An ad hoc committee was set up by the Ministries of Health, Labour and Environment. It initiated two epidemiologic studies: a retrospective cohort study of the workers at the plant, and a case-control study of leukemia and lymphoma among young people living in the vicinity of the plant. The installation consists of four reactors, a spent-fuel reprocessing unit, various waste treatment plants, and a fast-reactor fuel-fabrication plant.

The study of workers’ mortality included all persons first employed before 1976, followed up until 31 December 1983. Deaths from all causes and cancer were somewhat lower than expected based on the general population mortality rates of the province. However, there were positive associations between accumulated radiation dose and death rates from bladder cancer, multiple myeloma, leukemia and haematopoietic neoplasms. These were not statistically significant when exposure up to the time of death or up to two years previously was considered. Nevertheless, when exposures recorded in the 15 years before death were ignored, these associations, with the exception of that for leukemia, became significant (p < 0.05). The observed association of radiation with bladder cancer has not been found in previous studies, but the findings for myeloma have been reported before for radiation workers.

In the second study, all identified cases of leukemia and lymphoma among individuals born in the region and diagnosed at ages under 25 were compared with controls matched by sex and date of birth and selected from the same birth register as the cases (eight controls were taken for every case). The startling and significant finding (p < 0.05) was that paternal external radiation dose at work during the 6 months before conception (> 10 mSv) or total occupational life-time dose before conception (> 100 mSv) was associated with a raised incidence of leukemia and non-Hodgkin’s lymphoma among children of employees of the nuclear complex. Other than antenatal abdominal X-ray examinations, for which there was a non-significant positive (p > 0.05) association, and maternal age, no other risk factors were correlated with the observed incidence of leukemia and lymphoma. This study is based on 46 cases of leukemia and 20 cases of lymphomas.

Chapter 2 Questions

1. Discuss the fundamental properties of ionizing radiation, including the types and their sources.

2. How is radiation measured and in what units? Distinguish between absorbed dose, equivalent dose and effective dose in your answer.

3. Are the health effects reported for the workers and the young people in the case scenario consistent with exposure to ionizing radiation? What are the routes of exposure?

4. Assuming that the implied link between paternal exposure and leukemia and lymphoma in children of the exposed workers is real, what underlying pathological mechanism is implied?

5. What are the allowable occupational exposure limits for external ionizing radiation in the jurisdiction in which you live?

6. In December 1984, Stanley Watras, a worker at the Limerick nuclear power plant in Pennsylvania, USA, began setting off radiation alarms when he entered the plant on a Monday morning. Interpret this incident.

Chapter 9 Questions

1. Energy is necessary for daily survival and provides heat for warmth, working and manufacturing, or power for transport and mechanical work. Energy fosters activity. Ensuring an adequate, safe and environmentally-sound energy supply is a big challenge. Compare the four major energy sources (biomass fuels, fossil fuels, hydroelectric power, nuclear power) in terms of developmental costs, safety, environmental impact, social impact and renewability.

2. Discuss the feasibility of alternative energy sources, highlighting those of special relevance to your own region.

3. With special reference to The Chernobyl Accident Case Study (see Box 9.3 of the textbook), develop arguments for and against the statement that the operation of nuclear power plants should be discontinued as it does not adequately ensure the protection implied in Article 3 of the UN Declaration of Human Rights that “everyone has the right to life, liberty and security of person.”

Selected references

Doll R, Evans HJ, Darby SC. Paternal exposure not to blame. Nature 1994; 367:678-680.

Gardner MJ, Snee MP, Hall AJ, Powell CA, Downes S, Terrel JD. Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria. Br. Med. J. 1990; 300:423-429.

Gardner MJ. Childhood cancer and nuclear installations. Public Health 1991; 105:277-285.

Gibbons J H, Blair P D, Gwin H L. Strategies for energy use. Sci. Amer. 1989; 261 (Sept.):136-143.

Hle W. Energy from nuclear power. Sci. Amer. 1990; 263 (Sept.):137-144.

Harley NH. Toxic effects of radiation and radioactive materials. In: Casarett & Doull’s Toxicology, 5th ed. The Basic Science of Poisons (CD Klaassen, ed.). New York, McGraw-Hill, 1996, pp 773-800.

Ikenoue T, Ikeda T, Ibara S, Otake M, Schull WJ. Effects of environmental factors on perinatal outcome: neurological development in cases of intrauterine growth retardation and school performance of children perinatally exposed to ionizing radiation. Environ. Health Perspect. 1993; 101 (Suppl. 2):53-57.

OECD/NEA. Chernobyl ten years on. Radiological and health impact. An assessment by the NEA Committee on Radiation Protection and Public Health, November 1995. OECD Nuclear Energy Agency.

Ogilvy-Stuart AL, Shalet SM. Effect of radiation on the human reproductive system. Environ. Health Perspect. 1993; 101 (Suppl. 2):109-116.

Pope AM, Rall DP. Environmental medicine. Washington, DC, National Academy Press, 1995, pp. 639-700.

Sali D, Cardis E, Sztanyik L, Auvinen A, Bairakova A, Dontas N, Grosche B, Kerekes A, Kusic Z, Kusoglu C, Lechpammer S, Lyra M, Michaelis J, Petridou E, Szybinski Z, Tominaga S, Tulbure R, Turnbull A, Valerianova Z. Cancer consequences of the Chernobyl accident in Europe outside the former USSR: A review. Int. J. Cancer 1996; 67:343-352.

Shcherbak YM. Ten years of the Chernobyl era. The environmental and health effects of nuclear power’s greatest calamity will last for generations. Sc. Amer. 1996; 274 (April):44-49.

Smith PG, Douglas AJ. Mortality of workers at the Sellafield plant of British Nuclear Fuels. Br. Med. J. 1986; 293:845-854.

Sorahan T, Roberts PJ. Childhood cancer and paternal exposure to ionizing radiation: preliminary findings from the Oxford survey of childhood cancers. Amer. J. Ind. Med. 1993; 23:343-354.

23. Student’s version: Problem-solving exercise: Occupational exposure to inorganic lead

Prepared by Evert Nieboer*

* Dr Evert Nieboer, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada

A. Case scenario

To assess lead exposure in the Jamaican lead-acid battery manufacturing industry, three separate plants were surveyed. Of the 42 personal breathing-zone air samples collected, 38 exceeded the OHSA (US Occupational Health and Safety Administration) regulated permissible exposure level (PEL) of 50 mg/m3 (range 30-5300 mg/m3) and nine samples exceeded 500 mg/m3. The air samples were collected on mixed cellulose-ester filters using a flow rate of 2 L/min for the duration of the work-shift. Twenty-eight percent of the workers had blood levels exceeding 2.90 mmol/L (60 mg/dL). More specifically, in Plant B, the geometric mean of the air lead levels was 233 mg/m3, with 60% in the range 50 to 200 mg/m3 and the remaining 40% exceeding 500 mg/m3. The distribution of the measured blood-lead levels in the same plant was: 9% < 1.93 mmol/L (<40 mg/dL), 17% between 1.93 to 2.85 mmol/L (40-59 mg/dL), 57% in the range 2.90-3.81 mmol/L (60-79 mg/dL), and 17% above 3.86 mmol/L (80 mg/dL).

In a recent critical assessment of the literature, IPCS (1995) suggests the following NOAEL blood-lead levels for biochemical or health effects of lead exposure in adults: 1.20 mmol/L (25 mg/dL, men) and 0.96 mmol/L (20 mg/dL, women) for haem synthesis depression measured by zinc protoporhyrin (ZPP), also referred to as erythrocyte protoporhyrin (EP); 2.16 mmol/L (45 mg/dL) in men and 1.68 mmol/L (35 mg/dL) in women for urinary excretion of ALA (aminolaevulinic acid); < 0.48 mmol/L (10 mg/dL) for learning and behavioural effects in children; 2.40 mmol/L (50 mg/dL) for anaemia; 1.44 mmol/L (30 mg/dL) for reduction in peripheral nerve conduction velocity; 1.92 mmol/L (40 mg/dL) for sensory motor function impairment; 1.68 mmol/L (35 mg/dL) for alterations in the autonomic nervous system function; and 2.88 mmol/L (60 mg/dL) for risk of nephropathy. The blood-lead/air-lead relationship in occupational settings is curvilinear, having slopes between 0.00096 and 0.0038 mmol/L (0.02 and 0.08 mg/dL) per mg/m3 air. WHO (1980) recommends that air levels should not exceed 30-60 mg/m3; in most other jurisdictions, threshold limit value-time-weighted average (TLV-TWA) values of 100 to 150 mg/m3 are recommended (Saryan and Zenz, 1994).

B. Review questions

Chapter 3 Questions

1. In terms of hazard identification, succinctly state what we know about the adverse health effects of lead.

2. Based on the biological exposure indices or NOAELs provided in the case scenario, what are the likely shapes of the dose-response curves (i.e. effect versus lead in blood)?

3. Are the threshold values in agreement with those indicated in Figure 3.10? Give reasons for any discrepancies.

4. Comment on the exposures experienced by the workers.

5. In your opinion, are the workers at risk? Justify your answer. Can you characterize this risk?

6. Do you believe the workers are subjected to a risk high enough to warrant work refusal?

7. Clearly lead is a systemic poison. Explain why the total (inhalable) lead levels are measured rather than the respirable fraction?

Chapters 4 and 10 Questions

1. Would you recommend that the workers in the case scenario should be issued personal protection equipment? If so, what would you recommend?

2. What additional information do you need to know about the plant and workers before an environmental control programme can be considered?

3. Discuss the control options that might be considered/implemented to decrease workers’ exposure?

4. What is a TLV-TWA? Would the promulgation of such an inorganic air-lead standard help? What about BEIs?

5. Design a risk management package that includes air monitoring, biological monitoring and medical surveillance for use after the appropriate control measures have been put into place.

6. Does the risk management package suggested adhere to the principles of occupational health surveillance stated in Table 10.6?

7. Debate workers’ rights and responsibilities using the present scenario as a basis for discussion.

C. Selected references

American Conference of Governmental Industrial Hygienists. 1995-1996 threshold limit values and biological exposure indices. Cincinnati, OH, ACGIH, 1995.

Awad El Karim MA, Hamed AS, Elhaimi YAA, Osman Y. Effects of exposure to lead among lead-acid battery factory workers in Sudan. Arch. Environ. Health 1986; 41: 261-265.

Caplan KJ, Knutson GW. Experimental analysis of lead-in-air sources in lead-acid battery manufacture. Am. Ind. Hyg. Assoc. J. 1979; 40: 637-643.

International Programme on Chemical Safety. Environmental Health Criteria No. 165. Inorganic lead. Geneva, World Health Organization, 1995.

Matte TD, Figueroa JP, Burr G, Flesch JP, Keenlyside RA, Baker EL. Lead exposure among lead-acid battery workers in Jamaica. Am. J. Ind. Med. 1989; 16: 167-177.

Saryan LA, Zenz C. Lead and its compounds. In: Occupational medicine, 13th ed. (C Zenz, O B Dickersen, E P Horvath Jr., eds.). St. Louis, Mosby, 1994, pp. 506-541.

Recommended health-based limits in occupational exposure to heavy metals. Report of a WHO Study Group. (Technical Report Series, No. 647). Geneva, World Health Organization, 1980.

24. Student’s version: Ethical analysis for decision-making in environmental health

Prepared by Dr Colin L. Soskolne, Lee E. Sieswerda*

* Dr Colin L. Soskolne, Professor and Director of Graduate Training, Department of Public Health Sciences, University of Alberta, Edmonton, Alberta, Canada

Lee E. Sieswerda, B.Ed., Graduate Student

Part I: Definitions relevant to ethical issues in public health services

Deontology: This is a class of theories known as duty-based ethics. The scientific ethic is a duty-based ethic that specifies the duties of scientists, including their obligations to the participants of research, to society at large, to colleagues, and to the sponsors of their research. Scientists are expected to subscribe to the values of science which, in essence, include the pursuit of truth. This is most assured when scientists are impartial (i.e. objective) in their research.

Utilitarianism: This theory requires that the greatest good be done for the greatest number of people. The utilitarian approach is consistent with the values to which public health professionals have subscribed for many years.

Principle-based ethics: Moral reasoning in the health sciences can be conceived of as using the principles of beneficence, non-maleficence, autonomy and justice. There can often be tensions between the different principles. When this happens, consideration of which principles are contravened and which are given priority characterizes the nature of the ethical dilemma. An example follows the definitions of the principles below.

Beneficence: This principle requires people to maximize benefits to others. It is closely related to the utilitarian ethic. In public health, the principle of beneficence requires that more good than harm be accomplished through public health action.

Non-maleficence: This principle requires that people do not harm one another. It is related to the principle of beneficence. There is, however, a subtle but material distinction between the non-infliction of harm and the requirement to do good.

Respect for autonomy: This is the principle requiring respect for individual self-determination. Autonomy manifests itself in many ways, but an instructive example is the requirement to obtain prior informed consent from research participants whenever feasible. Honesty in informing potential research participants of potential risk and harm demonstrates respect for their right to self-determination.

Justice: This principle is also known as equity. It requires that potential risks and benefits be evenly distributed among people in the community.

Egalitarianism: Complimentary to the utilitarian ethic is the egalitarian ethic which assumes that community members are equally important. It upholds the principle of solidarity and measures the well-being of the group by the standard of the least well-off in the group. Its success is determined on the basis of equity in the distribution of harm and benefit associated with public health actions.

Libertarianism: In contrast to egalitarianism, this ethic holds that the individual is more important than the community. Under libertarianism, the just society protects the rights of property and liberty, allowing persons to improve their circumstances on their own initiative. According to libertarian theory, social intervention in the market undermines justice by placing unwarranted constraints on individual liberty. Hence, libertarians hold the view that taxation for the redistribution of wealth is coercive and, therefore, inappropriate. Consequently, health care is not a right under this conception and privatization in the health care system is a protected value. Libertarianism has less utility within public health because it makes the greatest good for the greatest number of people less attainable.

Because public health interventions can impact on vested interests, the public health professional has to remain aware of the pressures that could be brought to bear on his or her recommendations in support of health policy. Ethics guidelines can be helpful in public health decision-making and should be seen as a means to achieving a balanced dialogue on a contentious issue.

Part II: Case scenario

(Note: Information in this case study was derived from published media reports and court documents. The names of individuals and corporations used in this case study are a matter of public record.)

As countries become more environmentally aware, governments have legislated programmes and directives to limit the amount of environmentally hazardous material to which people are exposed. The main targets for this legislation are the large petroleum refining and chemical manufacturing companies. These companies are very careful to adhere to the strict regulations within their own countries but may not abide by these high standards when company operations are established in other countries where legislation may not be as strict. This type of behaviour constitutes a double standard that may pose an ethical dilemma for the employees of the company in the country with the stricter rules. While the country in which the subsidiary company is operating may not have standards as strict as those of the country where the parent company is located, the danger of exposure to the chemical of concern for any other population is just as great as that of the population in the country of the parent company. Employees who are concerned about the health of the public in the less developed/regulated country may be fired with impunity if they voice opposition to their company’s application of different standards which would place at risk the health and/or lives of people in the country with less strict regulations. In several states in the USA, these employees are now protected by so-called “whistleblower laws”. In New Jersey, this legislation is called the Conscientious Employee Protection Act, and protects employees who act in the public interest from employers who see such acts as counter to their business interests.

Dr Peter Smith was employed as the director for environmental health and toxicology for the American-owned Petroil Oil Corporation. In addition, Smith ran, in his own time, a scientific publishing company. From time to time, Smith’s roles would overlap. Such overlap was seen by Petroil as adding to the company’s prestige and was well-known to Petroil.

In September, 1989, Smith was sent to Thailand to speak at a symposium on gasoline health risks which was also attended by executives of the Petroil-owned affiliate, Petroil Oil and Gas Thailand (POGT) and Thai government officials. In Smith’s presentation, he reported that the level of benzene in gasoline that Petroil was selling in Thailand was 2.5-3.5 times that permitted in the USA, but noted that this was well below the Thail government’s legislated level. After he had given his presentation, Smith was said to have been approached by one of the POGT executives who informed him that the level of benzene in gasoline sold by POGT was actually in excess of even the Thai standard. Smith’s figures had, in fact, been on the low side.

Benzene is a gasoline additive used as a blending agent to improve engine performance. It is also a very toxic and carcinogenic agent (a leukemogen) and has been targeted in recent years by US environmental law. Currently in the USA, any products containing more than 5% benzene must be labelled “danger” and “poison” with a skull and crossbones symbol. In 1989, maximum allowable benzene levels in US gasoline were in the 1.5-2% range. The US Environmental Protection Agency now limits levels to 1%. In the company’s Thai operation, levels were said to be in excess of 5%.

Smith informed the POGT executive that the levels were extremely high and hence very dangerous. He strongly advised the executive to reduce the benzene levels or to stop selling the gasoline. The executive is on record as having stated that upgrading the refineries (built during World War II) to provide lower benzene levels would cost Petroil hundreds of millions of dollars.

On returning to the US after the symposium, Smith was denied access to the toxicology laboratory and was informed that he had been placed on “special assignment indefinitely”. Petroil executives alleged that he had used Petroil resources and employees for his publishing business. Smith sued Petroil for wrongful dismissal under New Jersey’s whistleblower law (i.e. the Conscientious Employee Protection Act).

In court testimony, Petroil stated that it was unable to produce documents which would have cleared Smith of any wrongdoing because these documents were “eaten” and/or “defecated” upon by mice. In addition, many exculpatory (i.e. exonerating) statements about Smith were excluded from Petroil’s investigative report. Petroil’s security manager admitted that he had omitted several statements from his report that would have been exculpatory for Smith. Petroil executives also acknowledged that the company had gained prestige from Smith’s publishing activities and that many Petroil scientists had published in Smith’s journals. Despite these admissions from Petroil, Smith was fired in November 1989. The company denied that he had been fired for voicing concerns over the benzene levels in the Thai gasoline. They launched a smear campaign to discredit Smith, claiming that he had appropriated Petroil funds and employees’ time for his publishing company.

Question 1. a) Is it the responsibility of companies from more environmentally regulated countries to protect the citizens of other countries by enforcing the strict environmental standards of the more regulated country on their operations in the less regulated country? Use ideas from egalitarianism and libertarianism to help formulate your answers.

b) If so, should these standards be enforced even if the facilities in the less regulated country are unable to meet these higher standards? Should the company insist that inadequate facilities be upgraded, possibly at the company’s expense?

c) If not, what number of expected deaths could be considered an unacceptable risk to the population of the less regulated country? Who decides what that level is?

Question 2. Would Petroil’s decision not to upgrade its Thai plant result in more good than harm? Identify the stakeholders involved in this decision and what they have to gain or lose.

Question 3. Discuss how the introduction of whistleblower laws may help to prevent negligent and unethical behaviour on the part of corporate executives/employers. Do you believe that such legislation is appropriate in view of the lengths to which Petroil demonstrated that it would go to protect its interests? What distinctions are there between law and professional codes of conduct and would codes be sufficient to prevent unethical behaviour?

Question 4. How tenacious should Dr Smith have been in making his point that people should not be subjected to poisonous levels of a substance regardless of whether they are American or Thai citizens? Were his actions justifiable? Use the principles of beneficence, non-maleficence, autonomy and justice to help formulate your answers. How typical is the fortitude demonstrated by Dr Smith?

Question 5. How common do you think instances analogous to the firing of Dr Smith are in industry, government and academia? On what basis? How might one obtain a more precise estimate of the prevalence of such disciplinary action? What might some of the difficulties be in conducting a study to obtain such estimates?

Question 6. Should employees be permitted, or even encouraged, to hold more than a single job? At what stage would the holding of more than one job constitute a conflict of interests for the employee?

Part III: Resolving the issues

The jury awarded Smith US$3.4 million in compensatory damages and US$3.5 million for punitive damages in March 1994. The trial judge allowed only half of the jury’s award, saying that the compensatory damages were inapplicable because the whistleblower law was not valid outside the USA.

Both sides appealed the ruling - Petroil against the heavy punitive damages, and Smith for reinstatement of the full award.

In June 1996, a three-judge appellate court ruled in Smith’s favour, stating that he had identified a “clear mandate for public policy” under the whistleblower law. In its decision, the panel wrote that Smith’s concerns with “professional negligence” and “professional ethics” were justified as Petroil had defied its own policy to apply “health standards of developed countries in the absence of local regulations”. Smith’s lawyer said that the decision will serve as a warning to American oil companies not to ignore the health of customers abroad. He further predicted that US companies would no longer be able to apply the double standard of abiding by strict regulations set by federal and state environmental laws within the USA while allowing hazardous levels to exist elsewhere. A further award of approximately US$3 million was granted by the court in interest payments and additional legal fees. The decision was being appealed by Petroil to the State Supreme Court at the time this case study went to press.

Question 1. Is there a point at which ethics and law interact in the above case study? What arguments might Petroil invoke in its further appeal against the decision to the State Supreme Court? How do you think the Court will decide? Discuss.

Question 2. Leaving the legal aspects aside and concentrating on ethics, do you think that the court made the correct decision? How does your ideological perspective (i.e. libertarian, egalitarian, etc.) affect your judgement of the court decision?

Question 3. Do you think that this case will substantially affect the operation of multinational corporations? Why?

Question 4. List examples of standards of practice to which scientists must always adhere regardless of their affiliation with any government, corporation or academic institution.

25. Sample evaluation questionnaire

Workshop on teaching approaches for environmental health, Cape Town, South Africa

Please complete the following evaluation questionnaire. Your comments will assist us in planning future workshops.

I.

Teaching processes/contents

Definitely yes




No, not at all








A.

In general, were you satisfied with the presentation and explanations of the instructors?
If not, please explain:

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B.

More specifically, were you satisfied with the presentation and explanations of the following instructors’ topics?













Teaching approaches
Merri Weinger

5

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Issues in Environmental Health
Annalee Yassi

5

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3

2

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Identifying hazards
Annalee Yassi

5

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3

2

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Risk assessment
Risk management
Annalee Yassi

5

4

3

2

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Use of audiovisuals and discussion starters
Merri Weinger

5

4

3

2

1







Air quality
Annalee Yassi

5

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3

2

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Water and health
Ilse Wilson

5

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Food safety and nutrition
Brian Delcarme

5

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Urbanization
John Seager

5

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2

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Industrial pollution Simphiwe Mbuli
Annalee Yassi

5

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3

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Energy and health
Annalee Yassi

5

4

3

2

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Global health problems
Annalee Yassi

5

4

3

2

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Preparing case studies
Merri Weinger

5

4

3

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Evaluation
Merri Weinger

5

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C.

Were you satisfied with the handouts?

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4

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If not, please explain:













D.

Considering your previous background, was the academic level of the course









1.

Too low

___






2.

About right

___






3.

Too advanced

___













E.

Which of the topics were most interesting to you?

Please list.













F.

Which of the topics were least interesting to you?

Please list.













II.

Teaching materials: Basic Environmental Health text








A.

Is the content suitable for your teaching?








Yes, very suitable

No, not suitable at all

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If the content was not suitable, please comment on how you would like it to be changed.








B.

Which topics from the text would you be most likely to teach after the workshop? For which audience (s)?

TOPIC

AUDIENCE








C.

For the audience you have in mind













(please name:____________________________________________), the level was:








Too advanced






Just right






Too basic













c.

Which topics should be added to the text or given more space?



d.

Which topics should be deleted from the text or given less space?



e.

Were the examples appropriate?


If not, please comment on how they should be changed.



III.

Educational gains



A.

At the beginning of the workshop, you indicated your expectations.



1.

Which of them have been satisfied?



2.

Which of them have not been satisfied and should be considered for future training programmes?



B.

Did you learn any new skills or concepts in the workshop?

Definitely yes




No, not at all



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If so, which? Please list:








C.

Can these skills be applied in your work?

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If so, which? Please list:








IV.

Organization and logistics













A.

Were you satisfied with the course organization and leadership?

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B.

Were you satisfied with travel and lodging?

5

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If not, please explain:








V.

Recommendations for the future













A.

As a result of this workshop, what new activities do you plan to undertake?








B.

What are your suggestions for future workshops?








C.

Other comments or suggestions?