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close this bookConducting Environmental Impact Assessment in Developing Countries (United Nations University, 1999, 375 p.)
close this folder9. Emerging developments in EIA
close this folder9.4 Environmental risk assessments
close this folder9.4.2 Terminology associated with ERA
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View the document9.4.2.1 Hazards and uncertainties

(introduction...)

Risk. The probability of an adverse effect, direct or indirect, on human health or the environment. It is, in fact, a combination of the probability of occurrence of an event and the possible extent of that event's adverse effects and consequences, in terms of human injury or adverse effects on the ecosystem. In a more mathematical sense, risk can be expressed as:

the probability of an event occurring × the seriousness of its consequences


Figure 9.3 Recommended risk assessment framework

Source: Environmental Risk Assessment for Sustainable Cities, Technical Publication Series [3], International Environmental Technology Centre, Osaka, 1996.

Hazard. The innate properties (biological, chemical, or physical) of a substance to cause harm.

Uncertainty. Doubt, lack of assurance as to the true value of a variable, considering all the possible values attributed to data or information.


Figure 9.4 Components of human health risk and ecological risk assessment

Source: Environmental Risk Assessment for Sustainable Cities, Technical Publication Series [3], UNEP International Environmental Technology Centre, Osaka/Shiga, 1996.

Assessment. Appraisal or evaluation in some prescribed endpoints in order to judge an activity.

Analysis. Detailed examination or thorough study in order to understand.

Exposure. The condition under which an organism comes into actual contact with a stressor. In site-specific considerations, the exposure value is substantially less than the quantity in the environment although sometimes it is assumed, under conservative assumptions, to be the amount of contaminant in the environment.

9.4.2.1 Hazards and uncertainties

The inquiry into the presence of hazards is also part of the preliminary assessment for EIA. It is by the explicit identification of significant uncertainties that the need to extend an EIA to include ERA is determined. Of course, if uncertainties can be resolved by readily acquiring more information, then the assessor should proceed to do so (Table 9.8).

Table 9.8 Major hazards associated with development projects

Types of project hazard

Toxic chemical

Flammable or explosive material

Highly reactive or corrosive material

Extreme conditions of temperature or pressure

Large mechanical equipment

Collision

Cement


X


X



Dam and reservoir




X

X


Fertilizer (N&P)

X

X

X

X

X


Hazardous materials handling, transport, and disposal


X


X


X

Highway

X

X



X

X

Iron and steel

X


X




Metal finishing

X


X




Pesticide

X

X





Petrochemical

X

X


X

X

X

Petroleum production and refining

X

X

X

X

X


Ports and harbours

X

X

X


X

X

Pulp and paper

X


X




Railroad

X

X



X

X

Smelting

X


X

X

X


Textiles

X

X





Thermal power


X


X

X


Waste management

X

X

X




The hazards of concern in economic development projects include:

• chemicals toxic to humans, animals, and plants;
• materials that are highly flammable or explosive;
• mechanical equipment, the failure of which would endanger persons and property;
• structural failure (e.g., dam or containment vessel);
• natural disasters that exacerbate technological hazards;
• ecosystem damage (e.g., eutrophication, soil erosion).

Examples of information about these hazards that, if uncertain, might trigger an ERA are:

• potential release of hazardous chemicals (rate and amount);
• accidental fires and explosions;
• transport and fate of pollutants in the environment;
• dilution-dispersion mechanisms and rates;
• exposure to toxins (who, how many, how much);
• dose-response predictions based on animal tests;
• failure rates of mechanical equipment or structures;
• human behaviour (errors by workers, public reaction);
• natural hazards (earthquake, tsunami, typhoon);
• alterations in drainage patterns, water table, vegetation, microclimate.

Uncertainties arise from:

• lack of understanding of important cause-effect relationships, lack of scientific theory (e.g., bioaccumulation of toxic chemicals in a food chain, pharmacokinetic mechanisms, reaction of crops to air pollutants);

• models that do not correspond to reality because they must be simplified and because of lack of understanding (see above);

• weaknesses in available data due to sampling and/or measurement problems, insufficient time-series of data, lack of replication;

• data gaps such as no measurements on baseline environmental conditions at a project site;

• toxicological data that are extrapolated from animals to humans and from high-dose experiments to low-dose exposures;

• natural variation in environmental parameters due to weather, climate, stochastic events;

• necessary assumptions on which estimates are based, and the sensitivity of the resulting estimates to changes in the assumptions;

• novelty of the project in terms of technology, chemicals, or siting, and lack of experience and historical data.