The capacity of numerous chemicals released into the environment to disrupt the development and function of the endocrine system of wildlife and humans is drawing the attention of scientists. Many of these chemicals may bind to estrogen receptors and thus evoke estrogenic effects in wildlife and humans. Early evidence that estrogenic chemicals could pose a threat to human health during development came from studies of diethylstilbestrol used to prevent (unsuccessfully) premature birth and spontaneous abortion. Laboratory experiments have demonstrated that exposure of animals to sex hormones during perinatal life can cause permanent and irreversible alterations of the endocrine and reproductive systems as well as the immune system, nervous system, bone, muscle, and liver in both sexes. Synthetic compounds and natural chemicals in the environment are now known to have potential disrupting effects on fetal development and reproductive system, acting as estrogens, antiestrogens, antiandrogens, thyroactive or antithyroid agents. Such chemicals may contribute to an increase in human testicular cancer and a progressive fall in sperm count, which appear to parallel an accumulation of estrogenic compounds in the environment over the past 50 years. Environmental chemicals are also suspected to play a causative role in alteration of endocrine and sexual development in various species of wildlife. Analyses of transgenerational effects of xenobiotic agents are needed in order to allow potential dangers to human and wildlife population to be estimated and confronted.
