Beware of BPA, study says

Bisphenol A (BPA), a chemical compound commonly found in plastics, may have long-term effects on fetal development, according to an article published by Yale School of Medicine researchers last month in the Journal of the Federation of American Societies for Experimental Biology. The results of the study come weeks after the Food and Drug Administration announced that exposure to BPA was of “some concern” to infants and children.

School of Medicine professor Hugh Taylor, the team’s leader, said researchers exposed mice fetuses to BPA for the time they were in the womb. The compound is found in many everyday objects, including hard plastic containers, the resin used to produce aluminum cans and certain dental fillings. Mice who were exposed to BPA in the womb were more sensitive to their body’s estrogen, which could render them infertile, Taylor said.

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The primary goal of the experiment was to determine whether a mother’s exposure to BPA can modify the offspring’s genes, said coauthor Jason Bromer, an associate with the Reproductive Science Center of New Jersey. Previous studies had determined that BPA could mimic certain properties of estrogen, a female sex hormone, but scientists were unsure of BPA’s long-term impact across generations, Taylor said.

Although the researchers did not formally examine the effects of increased sensitivity to estrogen, one possible implication of increased sensitivity to estrogen is infertility, Bromer said. If the gene needed for embryos to attach to a uterus does not function correctly, mothers will not be able to reproduce, Taylor said.

Bromer, who was a fellow at Yale during the study, said researchers now need to determine the levels of BPA exposure that are significant enough to impact fetal development.

While the experimenters purposefully introduced a high level of BPA into mice, researchers have yet to pinpoint the precise level needed to replicate the results with humans, Taylor said. But he added that people are already regularly exposed to BPA in plastics.

“You can measure [BPA] in 95 percent of humans, often in low amounts.” Taylor said. “Since it has a relatively short half-life, the fact that we can detect it in people shows that we are chronically exposed.”

The risk of BPA leaching out of plastics is higher before a plastic item has been washed for the first time or after it has been microwaved, Taylor said.

In addition to affecting fetal development, BPA has also been linked to obesity in other studies, Taylor said. But he added that people with the most exposure to BPA are likely to eat a lot of canned foods and therefore may be obese because of lifestyle choices rather than BPA exposure.

Bromer compared the effects of BPA with those of Diethylstilbestrol (DES), another chemical that mothers can pass on to their children. DES, which was once given to women as an estrogen supplement to prevent miscarriages, was discovered to cause health problems in children, including increased risk for breast cancer.

While pharmaceutical companies have since stopped producing medicinal DES, both Taylor and Bromer emphasized that BPA does not pose nearly as severe a health threat as other common chemicals such as nicotine or formaldehyde.

“It’s not causing cancer,” Taylor said. “But it’s good that society is able to debate these subtle problems.”

In March, the Environmental Protection Agency announced that it had added BPA to its list of “chemicals of concern.”

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