Mercury is a persistent, bioaccumulative toxin that adversely affects human beings and wildlife. Mercury, like many such toxins, is a multimedia pollutant that can readily transfer among air, water, and soils, and thus crosses the boundaries of traditional regulatory programs. Mercury can also be transported long distances in the atmosphere, creating transboundary issues that are regional and global in scope. Human exposure to mercury is largely attributable to the consumption of contaminated fish, with women of childbearing age, infants, and children at greatest risk. Because mercury persists in the environment, the risk of neurological or other impairments can span generations. Mercury, largely from anthropogenic sources, enters aquatic systems through a variety of pathways including direct deposition from the atmosphere, runoff, and wastewater discharges.

Environmental pollution threatens public health. The search for solutions has advanced the frontiers of science and law. Efforts to protect the environment and public health begin with describing potential adverse consequences of human activities and characterizing the predicted risk. The National Environmental Policy Act requires the preparation of environmental impact statements to describe the effects of proposed federal projects and provide information for agency decisionmakers and the public.Risks to public health are particularly difficult to quantify because of uncertainty about the relation between exposure to environmental contamination and disease. Risk assessment is the current scientific tool to present estimates of risk. The methodology has created controversy, however, when underlying assumptions and uncertainties are not clearly presented. Critics caution that the methodology is vulnerable to bias. This Note evaluates the use of risk assessment in the environmental impact statement process and offers recommendations to ensure informed decisions.