An agent might disrupt the endocrine system by affecting any of the various stages of hormone production and activity, such as by preventing the synthesis of hormones, by directly binding to hormone receptors, or by interfering with the natural breakdown of hormones. A variety of chemicals, including certain pesticides, have been found to cause endocrine disruption in laboratory animal studies. Some scientists have hypothesized that effects seen in laboratory studies may also occur in human beings. With few exceptions, however, a causal relationship between exposure to a specific environmental agent and an adverse health effect in humans operating via endocrine disruption has not been established, according to the report. For example, conclusive evidence linking environmental exposure to endocrine disruptors with infertility or cancers of the breast or prostate is not available at this time.
Further research is needed before such effects can be either demonstrated or ruled out.
Information is particularly needed about potential risks to developing young, where in theory small disturbances could lead to profound and lasting effects. More information is needed about such potential effects and whether they could be occurring via endocrine disruption. The report finds that compelling evidence has accumulated that endocrine systems of certain fish and wildlife have been disturbed by chemicals that contaminate their habitats. Whether this endocrine disruption is confined to isolated areas or is representative of more widespread environmental conditions is not clear at present. Groups of organisms for which there is much evidence of endocrine disruption include snails, oysters, fish, alligators and other reptiles, and birds, such as gulls and eagles.