Potential human reproductive and developmental effects of endocrine active compounds (EACs) has become an area of increasingly greater concern to industry, special interest groups, toxicologists, and regulators alike.

These agents have been linked by some to a wide variety of adverse reproductive/developmental health outcomes in humans. See section on "health concerns"

While ample evidence from epidemiological studies has been brought forward in the literature which reveals that the prevalence rates for a number of adverse reproductive/developmental outcomes are indeed increasing, there is little credible evidence linking these changes with exposure to man-made chemicals in general let alone EACs in particular. See section on "Framework for assessing weight of evidence".

There is even some question as to whether there is a true change in prevalence for some of these outcomes such as infertility and prostate cancer. The reported changes maybe no more than an artifact of statistical reporting, improved diagnostic procedures, changes in medical management and heightened awareness by the community in general and the medical profession in particular.

In other cases meta-analyses of breast, ovarian, and endometrial cancer have failed to find a statistical association between the adverse outcome of concern and exposure to man-made chemicals (Adami et al., 1995; Houghton and Ritter, 1995).

Regardless, it is important to recognize that, the absence of evidence can not be construed as evidence of absence of an effect. The endocrine disrupter hypothesis, while intriguing, controversial and highly emotive, requires testing. This hypothesis, based on evidence from wildlife studies and reports of occupational exposure and animal experiments, is certainly plausible. However, demonstration that any of the above mentioned adverse outcomes are indeed mediated by man-made chemicals acting via an endocrine pathway has yet to be achieved. In addition to man-made chemicals alternative explanations must also be identified and investigated with equal vigor and determination as well. This is particularly important given the potential medical, legal, economic, social and ethical implications associated with any effects in the general population which could be induced by EACs.

Different groups have advanced various definitions of endocrine disrupters. While none has been universally accepted we propose the following definition of endocrine disrupters and potential endocrine disrupters developed by the International Program on Chemical Safety (IPCS; March, 1998):

" An endocrine disrupter is an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects in an intact organism, or its progeny, or (sub) populations."

"A potential endocrine disrupter is an exogenous substance or mixture that possesses properties that might be expected to lead to endocrine disruption in an intact organism, or its progeny, or (sub) populations."

These definitions include the important point that humans are exposed to mixtures of natural and anthropogenic chemicals. How such compounds interact is largely unknown.

See also under "What is an endocrine disruptor?" under Frequently Asked Question