An evaluation of endocrine modulators: implications for human health.

The potential health risk of a group of chemicals, popularly known as "endocrine disrupters," has generated considerable scientific debate and media attention. The endocrine disrupter hypothesis asserts that exogenous substances with estrogenic or other hormonally active properties may adversely affect human health. Proponents of this hypothesis have associated endocrine modulators with negative outcomes such as cancer in hormonally sensitive tissues and declining sperm counts in men. However, the available laboratory, wildlife, and epidemiological data do not provide consistent or convincing evidence that industrial chemicals suspected of modulating estrogenic pathways are related to adverse health effects in humans. Both public and private initiatives are investigating chemicals labeled as endocrine disrupters for their relative hormonal activity. Screening assays aimed at assessing the endocrine activity or potential of a variety of substances should not be confused with assessment of risk to humans, however. The latter entails not only hazard identification (the type of information that screening assays are designed to provide), but also critical factors such as exposure analysis, potency assessment, and dose-response for individual chemicals.