ADEQUACY OF REQUIRED REGULATORY HAZARD TESTING FOR THE DETECTION OF POTENTIAL HORMONAL ACTIVITY OF CROP PROTECTION CHEMICALS

The capacity of some synthetic chemicals, the so-called ''endocrine-di srupting chemicals,'' to alter hormonal activity, as well as the adequ acy of the testing of chemicals to evaluate this capacity, has been ca lled into question. Among the chemicals indicted have been certain cro p protection agents or pesticides. Crop protection chemicals rank amon g the most closely regulated and thoroughly tested chemicals in use in both the human health and environmental hazard areas. However, it has been proposed that in vitro and in vivo screening tests be used to id entify potential endocrine-active chemicals and to supplement or repla ce required regulatory bioassays. In vitro tests, such as receptor bin ding, examine a single chemical event, do not measure toxicity, post-r eceptor-mediated biological response, or the absorption, distribution, metabolism, and elimination of a chemical. Therefore, data derived so lely from such a limited testing technique should not be used as a bas is for selection of chemicals for making regulatory decisions. In vivo screening tests, such as the uterotrophic assay, which promise to pro vide a rapid answer to a targeted question, do not capture the complex ity of the biological response. As in the case with in vitro tests; re sults from a single in vivo test, such as a change in uterine weight, should not be used as a basis for regulatory decision making. Further, it has been suggested that such a screening battery should be put int o place for ecotoxicity testing. Yet it is well recognized that endocr ine-active chemicals that affect fish and wildlife in their natural ha bitat have been shown to cause similar adverse effects in laboratory t est animals. Therefore, these screening tests do not add value to the current regulatory test battery. Evidence is presented that demonstrat es that the regulatory safety assessment paradigm has a low likelihood of missing potential endocrine-active chemicals and has served societ y well.