|WIT's World Ecology Report - Vol. 08, No. 2 - Critical Issues in Health and the Environment (WIT, 1996, 16 pages)|
Jacobo Finkelman, MD
Pan American Center of Human Ecology and Health
Pan American Health Organization
World Health Organization
The close relationship between health and environmental conditions is drawn into focus by the critical socioeconomic changes that are affecting the developing countries. Because of the shortcomings in the fulfillment of basic sanitary needs, in many nations diarrheal and parasitic diseases are a leading cause of high mortality and morbidity among certain population groups, especially children and the aged. At the same time industrialization and urban growth have increased the health risk from exposure to toxic substances and hazardous wastes that are polluting the air, water, soil, and food.
The adverse effects of industrial activities on human health cover the spectrum from relatively high-level exposures of small populations in the occupational setting to usually lower level of exposure of the general public. While there are a few clear-cut cases, such as acute intoxications associated with exposure to pesticides, illness caused by long-term exposure to pollutants is often difficult to identify conclusively.
Diarrheal Diseases and Cholera Outbreaks
Diarrheal diseases constitute one of the most important health problems, affecting children in particular. The magnitude of the problem differs markedly from developing to developed countries. Among children under 1 year of age, mortality rates for diarrheal disease range from 0.5 per 100,000 live births in Canada to 967.3 per 100,000 live births in Nicaragua, a figure almost 2,000 times higher.
The mortality rate for diarrheal diseases other than cholera is declining in all developing countries, basically due to wide use of oral rehydration therapy.
Cholera is almost always introduced into new areas by infected travelers. However, within infected areas, disease is transmitted from person to person by contaminated food and water. An outbreak of cholera in Kinshasa, Zaire, which began this past February, has killed 27 people as of March 25 (Reuters). The epidemic has not spread to beyond the capital city as had been reported according to WHO'S representative in Zaire, but there were indications that the outbreak was not confined to poor areas. Illness, like pollution, knows no economic or national boundaries. The Joint Food and Agriculture Organization/World Health Organization (FAO/WHO) Expert Committee on Food Safety has stated that food-borne illnesses constitute the most widespread group of diseases in the world. According to published data, more than a billion cases of diarrheal diseases occurred in children under 5 years old, meaning that contaminated water and food were responsible for the high infant mortality recorded in the developing countries.
Disposal of untreated waste water constitutes a critical problem in all developing countries. The waste contaminates and damages water courses and groundwater, which are the sources of drinking water for large and small communities. In addition, this water is often used for bathing, recreation, irrigation, raising fish, thus further increasing the potential for health problems.
The large-scale use of untreated domestic sewage for irrigation is common in many arid and semiarid zones. High rates of enteritis, typhoid fever, and hepatitis occur as a result of the consumption of raw vegetables irrigated with untreated waste water.
As industrial activity in both developed and developing countries has increased, the potential for major catastrophes has also increased, and the number of significant accidents involving chemicals with serious health and environmental effects has been rising. Furthermore, particularly with the massive expansion in the availability and use of chemicals in developing countries, the number of poisonings of all types has increased, from household emergencies (children swallowing chemicals at home) to industrial devastation (production or storage plant explosions and product releases).
The most common chemical accidents in almost all countries involve flammable liquids and gases.
The large accidents, such as the massive release of industrial chemicals in Bhopal, India, in 1984 are usually the ones that attract the public's attention, but the most common accidents are the smaller ones that occur during the routine handling and transportation of chemicals.
Arsenic is a naturally occurring element that is widely distributed in the environment. All human beings are exposed to low levels of this element. Arsenic has been classified by the U.S. Environmental Protection Agency as a known human carcinogen when exposure occurs by inhalation and oral routes. In developing countries above-average levels of exposure are associated with ingestion of drinking water naturally contaminated with arsenic or by inhalation and ingestion of contaminated soil around copper smelters. Although treatment facilities have been introduced to reduce arsenic content in the drinking water supplied to the larger cities, many people continue to be exposed to unsafe levels of arsenic in their water.
Chronic exposure to arsenic in drinking water has been reported in Argentina. The estimated population at risk exceeds 1 million inhabitants, some of them living in small towns and villages scattered in large, semiarid territories. In Argentina chronic arsenic poisoning is a widespread public health problem, known since 1913. Cutaneous alterations (keratosis in palms and soles, melanoderma, and multiple epitheliomas) have been described.
Over the past years, air pollution, resulting from urban development and rapid industrialization, has become a major issue.
Adverse health effects have been associated with three types of air pollutants: 1) sulfur dioxide and particulates arising from the combustion of fossil fuels; 2) photochemical oxidants formed in the atmosphere from a complex chemical reaction between precursor hydrocarbon compounds and nitrogen oxides, which are largely related to such motor-vehicle emissions as carbon monoxide; and 3) a miscellaneous class of air pollutants such as hydrogen sulfide, lead, and cadmium, which are mostly emitted by such localized point sources as smelters, refineries, power plants, and manufacturing plants.
Air pollution has most severely affected the large metropolitan areas with concomitant increases in total suspended particulates (TSP) and sulfur dioxide (SO2). In many urban areas the mean annual TSP exceed 100 ug/m3: the WHO recommended value is 60 to 90 ug/m3. It is expected, as published in epidemiological studies that these exposures, adjusted for age, will be linked with about 6% of the reported mortality due to respiratory pathology. These pollution levels contribute to the increases of chronic cough among children and chronic bronchitis among the elderly.
Considering that the trend toward urbanization will not decline, and that it is closely linked with a continuous increase in the number of vehicles on the road and with local industrialization, it is very likely that efforts to control auto and industrial emissions will not be effective enough to reduce air pollution. On the contrary, there is a great chance that air quality in the large metropolitan areas will continue to decrease placing even more people at a higher risk.