AbstractEnvironmental health science research, with its focus on fundamental science and disease prevention, is important for the development of rational and cost‐effective public health and regulatory policies related to environmental protection. Environmentally related diseases are preventable, yet they impose a major burden on society in terms of human suffering and costs related to health care. Similarly, the expenditure of hundreds of billions of dollars for regulatory compliance is a major economic concern. There is considerable debate regarding current regulatory risk assessment practices for environmental agents. Implicit in all risk assessment schemes is the need to extrapolate from high‐exposure studies to low‐exposure situations and from known risks in rodents to probable risks in people. Both extrapolations are fraught with uncertainties. These uncertainties are accommodated in risk‐assessment schemes by the incorporation of arbitrary “safety factors” and other default approaches. Since these factors are not derived experimentally, they may overestimate or under estimate actual risks. Risk‐assessment methodology, its relevance to the human condition, and its use in protecting human health will greatly improve when our expanding knowledge of the basic biology of environmental effects is incorporated into toxicological testing and risk‐assessment schemes. Moreover, exciting opportunities now exist to advance our understanding of the environmental and genetic bases of many common diseases and to design effective prevention and interventi on strategies to combat their development. This report discusses some of the current opportunities and challenges.© 1995 Wiley‐Liss, Inc