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Determining The Estrogenic Activity Of BPA Replacements

Toxicology: Computer model identifies 11 bisphenol A substitutes predicted to have similar ability to bind to estrogen receptors

by Puneet Kollipara
September 16, 2015

Credit: Shutterstock
Many manufacturers have replaced bisphenol A, an endocrine disruptor, in products such as thermal receipt paper. But many of the alternatives also show estrogenic activity.
Credit: Shutterstock
Many manufacturers have replaced bisphenol A, an endocrine disruptor, in products such as thermal receipt paper. But many of the alternatives also show estrogenic activity.

Long used in polycarbonate plastics, epoxy resin food-can liners, and thermal receipt paper, bisphenol A (BPA) has become a poster child for endocrine disruptors—compounds that mimic or interfere with the body’s hormones, such as estrogens and androgens. Many manufacturers have replaced BPA with alternatives in recent years, but dozens of BPA substitutes lack data on their potential estrogenic activity. Now, a new computer model provides a way to determine whether a BPA substitute shows high potential to bind the estrogen receptor and requires further testing for its endocrine disrupting effects (Chem. Res. Toxicol. 2015, DOI: 10.1021/acs.chemrestox.5b00243).

Huixiao Hong of the Food & Drug Administration’s National Center for Toxicological Research and his colleagues developed a model that assesses how well a compound orients itself with the estrogen receptor, and then estimates binding affinity by calculating how energetically favorable the binding is. The researchers trained the model by running it on 18 BPA substitutes that already have estrogenic activity data and two reference compounds: BPA itself and 17β-estradiol, a key female sex hormone.

When the researchers ran the model on 27 BPA substitutes that lacked experimental data on estrogenic activity, the model identified 11 that met the criteria for binding to the receptor. Many compounds were predicted as better potential binders than BPA, including tetrabromobisphenol A, used in plastics and as a flame retardant, and bis-(3-allyl-4-hydroxyphenyl)sulfone, used in thermal receipt paper.

Binding the receptor alone isn’t sufficient to make the compound an endocrine disruptor, the researchers note. But they add that the findings do suggest the need for additional studies of these compounds’ safety.



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Robert Buntrock (September 24, 2015 10:15 PM)
Receptor binding is not a sufficient test. Binding constants, especially compared to estradiol, and dynamics of binding and half lives are also important. Also important are studies of "delivery" of any chemical to receptor in the body. Also test are needed for phytoestrogens, especially those in soy products which are encountered at levels far higher than BPA and similar compounds.
Jon Martin (October 1, 2015 12:26 PM)
The underlying story here is that the US and Canada need a more intelligent system of regulating and approving chemicals prior to their wide dispersal in the environment and widespread human exposure. Sure this study is not in itself proof that BPA-alternatives are dangerous at current exposure levels, but it points to a concern of endocrine disruption that cannot presently be refuted by any publicly available studies of mammalian development. By the time the proper studies are completed and published for BPS, a BPS-replacement will surely already be in use. The whole system seems dysfunctional. It's the same story with flame-retardants and perfluorinated compounds.
Mark S. (October 13, 2015 5:56 PM)
Agree completely. It's interesting that Europe seems to be ahead of the US in recognizing and banning industrially used materials that are deleterious to mammalian health.
Mike (September 25, 2015 11:55 AM)
The title "Determining The Estrogenic Activity Of BPA Replacements" is misleading because the article only describes research directed at *predicting* the estrogenic activity of BPA replacements. It's an important distinction. Computer models cannot be used to determine biological activity.

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