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PT07 Chemical and Biological Analysis of Endocrine Disrupting Compounds
(PT126) Impurities in industrial grade bisphenol A and their estrogenicity.
Terasaki, M1, Shiraishi, F2, Edmonds, J2, Morita, M2, Makino, M1, 1 University of Shizuoka, Shizuoka, Japan2 National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
ABSTRACT- Fifteen trace impurities, including a novel cyclohexene derivative, have been identified and quantified in a sample of an industrial grade of the estrogen-active compound bisphenol A. All of these compounds, like bisphenol A itself, possess phenolic hydroxyl groups para to other substituents and all thus also have the potential to mimic estradiol. The estrogencities of 9 synthetic and 3 commercially available compounds found as impurities were measured by yeast two-hybrid assays incorporating the human (hER) or medaka (mER) estrogen receptor and their toxicities determined in a photobacterium test. Seven impurities showed more potent activity than bisphenol A in an agonist assay for hER: 4,4′-(1,3-dimethylbutylidene) bisphenol was the most active among of impurities tested, and was 16 times as active as bisphenol A. Eleven impurities showed more potent activity than bisphenol A in an agonist assay for mER: 2-(2′-hydroxyphenyl)-2,4,4-trimethylchroman was the most active compound in this case, and was 31 times as active as bisphenol A. Para-cumylphenol and 2-(4′-hydroxyphenyl)-2,4,4-trimethylchroman were nearly equipotent and 18 times as active as bisphenol A. Potential metabolic transformation of each compound by exposure to rat liver S9 preparation showed reduced estrogenicities in assays using hER and mER. In the photobacterium test, all impurities exhibited weak toxicity. Published studies on the endocrine disrupting properties of bisphenol A have not considered these potentially active impurities but full assessment of the estrogenicity of bisphenol A as it is used commercially is now possible.
Key words: Impurities, Bisphenol A, Estrogenicity, Yeast two-hybrid assay
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