Mechanisms of action and suspected effects of xenohormones

During the last few years, several chemical compounds that are environmental pollutants have been shown to display xenohormonal activity, and have been called endocrine disrupters. In particular, several pesticides and herbicides bind the estrogen receptor and activate oestradiol-dependent gene promoters. It has been suggested that these compounds could account for the increase in both the male reproductive disorders as well as the incidence of testicular cancer. This hypothesis which remains controversial, is strenghthened by the well known toxic effects in human and in animals of the drug diethyl stilbestrol, an estrogen mimetic. Xeno-estrogens could act during fetal life by altering the organogenesis of the reproductive system or by disrupting the gonadotropin-steroid hormones feedback loop. Other xenobiotics could act through their anti-androgenic activity Or by modifying the metabolism or the half-life of the steroid hormones. Since endocrine disrupters could prove to be harmful to man and animals, several in vivo or in vitro tests have been developped to assay for their functional activity.