Environmentalists might believe that total elimination of risk that comes with pollution and other forms of environmental degradation is possible and even desirable, but economists argue that the benefits of risk elimination have to be balanced against the costs. Measuring risk is itself very complicated. Risk analysis in the case of pollution, for instance, involves determining the conditions of exposure, the adverse effects, the levels of exposure, the level of the effects, and the overall contamination. Long latency periods, the need to draw implications from laboratory studies of animal species, and the impact of background contamination complicate these efforts. Under these conditions, simple cause and effect statements are out of the question.

A cost-benefit analysis. (McGraw-Hill Inc. Reproduced by permission.)

The most that can be said in health risk assessment is that exposure to a particular pollutant is likely to cause a particular disease. Risk has...