Environmental exposure, species differences and risk assessment

Field observations and laboratory studies suggest that, under certain environmental conditions, xenobiotics such as DDT, polychlorinated biphenyls (PCBs), tetrachloro dibenzodioxin (TCDD), tributyltin (TBT) and nonylphenol (NP) may cause endocrine disrupting effects. Although there are specific examples of established or suspected endocrine-mediated effects in the environment, such effects cannot be considered of broad, general importance because of wide ecological and species differences. Such species differences may arise because of differences in the basic mechanisms of sex differentiation, differences in receptor structure and function and differences in metabolism. In some cases, natural hormones may be responsible for alleged adverse effects since, despite their minute concentrations, they are particularly potent. Additional in-depth comparative studies are required to assess more precisely the potential endocrine disrupting action of natural and synthetic chemicals in the environment and to develop effective screens for their detection.