VALIDATION AND APPLICATION OF A RAPID IN-VITRO ASSAY FOR ASSESSING THE ESTROGENIC POTENCY OF HALOGENATED PHENOLIC CHEMICALS

The E-Screen assay serves as an in vitro tool for the detection of est rogenic activity of chemicals and extracts of environmental samples. B ased on the induction of proliferation in human estrogen receptor-posi tive MCF-7 breast cancer cells we could substantially simplify the ass ay. As one important step of validation we applied the modified assay for testing nine known xenoestrogens. We could confirm the results of other groups assuring the reproducibility of the E-Screen assay. The r esults provide evidence that the E-Screen assay is suitable for determ ination of estradiol equivalency factors (EEFs) for environmental estr ogens to rank their estrogenic potency relative to the natural estroge n 17 beta-estradiol. Further, we used the optimized proliferation test to screen nine halogenated phenolic compounds for their possible estr ogenic potency. Three widely applied chemicals expressed a weak recept or-mediated estrogenic activity: the flame retardant Tetrabromo-Bisphe nol-A, the disinfectant 4-chloro-3-methylphenol, and the herbicide edu ct 4-chloro-2-methylphenol. Their estrogenic potencies were five to si x orders of magnitude lower than that of 17 beta-estradiol. (C)1998 El sevier Science Ltd. All rights reserved