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22 November 2005 | Printer friendly

Low-dose Bisphenol A (BPA) linked to fetal brain damage

The chemical bisphenol A (BPA), widely used in products such as food cans, milk container linings, water pipes and even dental sealants, has now been found to disrupt important effects of estrogen in the developing brain, according to a report from Medical Research News, 2 December 2005. Scott Belcher PhD, who headed the research team at University of Cincinnati (UC), reports in two articles in the December 2005 edition of the journal Endocrinology that BPA shows negative effects in brain tissue "at surprisingly low doses."

The research was supported by funding from the National Institutes of Health and the Pediatric Brain Tumor Foundation. "These new studies are also the first to show that estrogen’s rapid signaling mechanisms are active in the developing and maturing brain in regions not thought to be involved with sexual differences or reproductive functions," Dr. Belcher said.

Although best known for its function as a female sex hormone, Dr. Belcher explained, estrogen also has very important roles in the developing brain of both males and females.

In the absence of estrogen, Dr. Belcher said, BPA alone was found to mimic the actions of estrogen in developing neurons, and very low doses of BPA completely inhibited the activity of estrogen. Because estrogen normally increases the growth and regulates viability of developing neurons, he said, these results support the idea that BPA may harm developing brain cells.

In fact, Dr. Belcher said, while high doses cause little effect, analysis of cellular and molecular markers of estrogen signalling revealed that near-maximal effects of BPA on rat brain neurons not only occurred "at surprisingly low" doses of 0.23 parts per trillion, they also happened in a matter of minutes.

"From other studies it’s clear that these low concentrations are in line with human fetal exposures, and at levels one might even see in the water supply," said Dr. Belcher.

This "low-dose" effect of BPA is troubling, Dr. Belcher points out, since its maximal effects occur at the level typical of human exposure. This means that the harmful effects of BPA could easily be missed using standard approaches for determining the risks of chemical exposure.

In the face of more than 100 studies published in peer-reviewed journals showing the detrimental effects of BPA, Dr. Belcher said, the chemical industry and federal regulatory agencies have resisted banning BPA from plastics used as food and beverage containers, despite the fact that plastics free of BPA and other toxic chemicals are available.


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