title: Combined effects of estrogenic chemicals with the same mode of action using an estrogen receptor binding bioassay.
abstract: The increasing amounts of various estrogenic chemicals coexisting in the aquatic environment may pose environmental risks. While the concept of estradiol equivalent (EEQ) has been frequently applied in studying estrogenic mixtures, few experiments have been done to prove its reliability. In this study, the reliability of EEQ and the related model concentration addition (CA) was verified based on the two-hybrid recombinant yeast bioassay when all mixture components had the same mode of action and target of action. Our results showed that the measured estrogenic effects could be well predicted by CA and EEQ for all laboratory-made mixtures using two designs, despite the varying estrogenic activity, concentration levels and ratios of the test chemicals. This suggests that when an appropriate endpoint and its relevant bioassay are chosen, CA should be valid and the application of EEQ in predicting the effect of non-equi-effect mixtures is feasible.
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Yang
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: mamei@rcees.ac.cn.
authors.forename: Mei
authors.initials: M
authors.lastname: Ma
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: wangzj@rcees.ac.cn.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Wang
mesh_terms: D001681:Biological Assay; D004967:Estrogens / Q000737:chemistry* / Q000494:pharmacology*; D004997:Ethinyl Estradiol / Q000737:chemistry / Q000494:pharmacology; D008956:Models, Chemical; D011960:Receptors, Estrogen / Q000378:metabolism; D015203:Reproducibility of Results; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000494:pharmacology; D015003:Yeasts / Q000187:drug effects*
chemical_list: D004967:Estrogens; D011960:Receptors, Estrogen; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol
keywords: Concentration addition; Mixture toxicity; Mode of action; Two-hybrid yeast assay; Xenoestrogen