Bisphenol A is used to line drinks cans and in tests affected the way genes work in the brains of laboratory rats.
May 28, 2013

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Bisphenol A is used to line drinks cans and in tests affected the way genes work in the brains of laboratory rats.

Researchers at Columbia University have found that bisphenol A (BPA), an endocrine disruptor found in many plastic products, has an effect on mice in utero. Male mice saw changes in their cortex while female mice saw changes in the hypothalamus region of the brain when their mothers were exposed to the chemical. The findings, published on Monday, note that low-dose, prenatal exposure to BPA causes changes to that could affect brain function and behavior. However, other scientists are skeptical that the findings will translate to humans because they believe a woman’s natural estrogen level would be high enough to counteract the effects of the BPA.


"At low doses, such as those considered safe for humans, mice exposed to bisphenol A (BPA) in utero showed sex-specific changes in their brains that could have affected social behaviors such as grooming and aggression, according to a study published yesterday (May 27) in Proceedings of the National Academy of Sciences.

Specifically, Frances Champagne from Columbia University in New York City and colleagues found changes in estrogen receptor expression in the cortex of male mice and in the hypothalamus of females whose mothers’ had been exposed to BPA. These expression changes were associated with epigenetic modifications to the genes coding for that receptor, which could have affected the animals’ social behavior.

In the paper, the authors write that “low-dose, prenatal BPA exposure induces lasting epigenetic disruption in the brain that possibly underlie enduring effects of BPA on brain function and behavior.”'

While previous studies on laboratory animals have also pointed to a possible link between BPA and ill health, the research was criticised by other experts for using very high doses of the chemical, which would not be relevant to levels of human exposure, and to injecting the substance rather than feeding it through the diet, which is how BPA enters the human body.

This latest study by Frances Champagne of Columbia University in New York,and published in the Proceeding of the National Academy of Sciences, used what scientists said were “environmentally relevant” doses of BPA, and were fed to the rats through their diet.

Not everyone agrees that the test results mean that comparable effects of bisphenol A could occur in humans, The Independent reports:

Professor Richard Sharpe of the Medical Research Council's Centre for Reproductive Health in Edinburgh said that although the study is well conducted there are still problems that make it difficult to extrapolate the findings to human health.

“Whilst these findings raise the possibility that comparable effects of bisphenol A could occur in humans, several factors suggest this is unlikely. First, the lowest dose used is still 10-20 times higher than normal human bisphenol A exposure,” Professor Sharpe said.

Another problem is that there were large variations in the results be[t]ween individual animals, making reproducible results questionable. A third issue was the suggestion that BPA works by interfering with the female hormone oestrogen, as oestrogen levels are much higher in pregnant women than in pregnant mice, Professor Sharpe said.

“If the effects described work through an oestrogen mechanism, they are unlikely to be human relevant because pregnancy levels of oestrogens in humans are far higher than in mice and would swamp any weak oestrogenic effects of bisphenol A,” he said.

While there are many products now available in the marketplace that are clearly labeled "BPA Free," I wish that I could tell you that they were safer, but because the U.S. system of regulating chemicals relies primarily on information supplied by a material's manufacturer, we know relatively little about these new plastics.

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