Investigations of environmental pollution by endocrine-disrupting chemicals are now in progress. Up to now, several in vitro bioassays have been developed for evaluation of the endocrine disruptive activity; however, there is still a lack of comparative studies of their sensitivity. In this work comparison of the estrogen screening assay based on beta-galactosidase expression and a bioluminescent estrogen screen revealed differences in the sensitivity and specificity of the two tests. With the beta-galactosidase screen a slight estrogen-like activity of Delor 103, a commercial mixture of PCB congeners, and a fungicide triclosan was measured whereas no activity was detected using the bioluminescent assay. A bioluminescent androgen test negated previously suggested androgenic potential of triclosan. Further, this work demonstrates the androgenic activity of Delor 103, with an EC(50) value of 2.29 x 10(-2)mg/L. On the other hand, chlorobenzoic acids (CBAs), representing potential PCB degradation metabolites, exhibited no androgenic activity but were slightly estrogenic. Their estrogenicity varied with their chemical structure, with 2,3-CBA, 2,3,6-CBA, 2,4,6-CBA and monochlorinated compounds exhibiting the highest activity. Thus the results indicated possible transitions of the hormonal activity of PCBs during bacterial degradation.

Laboratory of Environmental Biotechnology Institute of Microbiology Academy of Sciences of the Czech Republic Vídenská 1083 CZ 142 20 Prague Czech Republic

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