Since the 1970s, the federal government has imposed progressively stringent regulations on the discharge of hazardous and toxic substances into the air, water, and soil in order to protect the public from the presumed health risks of exposure to these pollutants.¹ The acceptance of the precautionary principle by Congress and the courts in the 1970s has led the U.S. Environmental Protection Agency (EPA) and other agencies to base toxic pollutant standards on risk assessments. The use of risk assessments has been criticized from many perspectives. Opponents of stringent regulation have charged that these assessments represent bad or junk science because the data do not support the need for regulation. More moderate or rational critics question that economic benefits generated by standards compared to the costs of compliance. Environmentalists have argued that risk assessments use science to mask the hard policy and value choices involved in standard setting.² Until recently, however, all participants in the debate have accepted two common assumptions. First, there is some need to protect the population at large and specific sub-populations of at-risk groups, such as children, from the adverse affects of involuntary exposures to specific pollutants. The regulatory focus has been on the prevention of cancer, neurological disorders, and the impairment of male and female reproductive capacity. Second, it would be unfair and inefficient to shift the burden of protection to individuals for a wide variety of pollution risks.³ These assumptions are open to question in light of advances in genetic research.

Toxic pollution and hazardous substance regulation is not yet based on advances in our understanding of the relationship between human genetics and exposure to a potentially dangerous substance, but this could change in the future. Put differently, pollution regulation is not based on individual susceptibility to risk; it is based on group susceptibility. We do not base environmental and occupational health regulation on the possibility that substantial variability in risk exists among individuals within the protected class. We do base some standards on worst-case scenarios; for example, many risk assessments are based on worst-case individual susceptibility. This practice, however, is different from explicitly assuming that each member of a protected class has a different cellular response to exposure or ingestion. The reason is that society normally assumes that all exposures are involuntary, but this is not always the case. Air pollutants are the clearest example of involuntary exposure, but even in this case, those at risk could move to less polluted areas.