There is a great concern about the effects of exposures to hazardous substances on human health. A basic understanding of the cellular, molecular and biochemical processes that are affected by the exposures can enhance the scientific base used in the decision process. A major component of the SBRP-funded research effort is directed towards improving the understanding of health effects from exposures to contaminants. Given this role, the Program has invested heavily in health effects research including basic mechanistic studies, toxicological investigations, as well as biomarker development and molecular epidemiology studies. The advances made in these studies can assist remedial project managers and other decision-makers in protecting the environment and meeting the public health needs of the communities affected by Superfund sites.