March/April 1995 Issue #32


Western industrial countries use a process called "risk assessment" when evaluating environmental hazards. In theory, risk assessment is a highly objective scientific tool for environmental decision making. In practice however, risk assessment can be politicized. It can involve confusing and controversial assumptions, and it often contains a significant degree of uncertainty. This issue of ECOLOGIA Newsletter attempts to examine and clarify some of the issues surrounding the practice of risk assessment. In addition, examples will show the range of uses and abuses of risk assessment today.

Defining Risk and Risk Assessment

Risk assessment is a formal scientific process for calculating the probability and degree of harm that will result from exposure to an environmental hazard. Clinical, laboratory, and field evidence is used to produce statistical projections which estimate the harm associated with exposure to chemical compounds or radiation. Risk assessments attempt to examine the various pathways of pollutants into the environment or into humans. Risk assessment also considers the dilution, natural degradation, or dispersal of pollution in the environment in the calculation of probable doses.

Risk assessment leads policy makers to conduct environmental impact assessments for new technologies or substances specific to each site, or for each medium (food, water, air) rather than establishing fixed and universal standards for emission and exposure. Thus as a result of risk assessment, higher lead emissions may be allowed at a rural facility where no other lead emissions are present than would be allowed at an identical facility in a polluted urban area where too much lead risk is already present.

In theory this process allows for flexibility in emission control strategies. It provides for the consideration of economic factors such as the cost of antipollution control programs. The goal is to avoid unnecessary expenditures where they would not result in a significant reduction of risk.

Risk assessment can allow policy makers to ask and answer the difficult question, "Where can I get the most benefit (reduction of risk) with a limited amount of money?"

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