June 28, 2011

Male Mice Exposed To BPA Act More Feminine

According to a new study, male mice that were exposed as babies to Bisphenol A (BPA) acted more like females and were seen as less desirable mates.

The study said the findings could have implications for how BPA, which is a common chemical in canned foods and plastic containers, may affect human development and behavior.

"The BPA-exposed deer mice in our study look normal; there is nothing obviously wrong with them. Yet, they are clearly different," lead author Cheryl Rosenfeld at the University of Missouri-Columbia said in a statement.

"Females do not want to mate with BPA-exposed male deer mice, and BPA-exposed males perform worse on spatial navigation tasks that assess their ability to find female partners in the wild."

Mother deer mice were fed a diet with levels of BPA that were proportional to the amount the U.S. government considers safe for pregnant women to ingest.

The lab mice were fed this diet for two weeks prior to breeding and throughout lactation.

The offspring were fed a BPA-free diet and their behaviors were monitored into adulthood.

The male mice that were exposed to BPA showed less ability to navigate a maze safely.  This skill is well developed only in male mice because females do not seek out mates.

"The untreated mice quickly learned the most direct approach to finding the correct hole, while the exposed males appeared to employ a random, inefficient trial and error strategy," said the study authors said in a statement.

Scientists found that females preferred chemical-free males by a factor of two to one.

"These findings presumably have broad implications to other species, including humans, where there are also innate differences between males and females in cognitive and behavioral patterns," Rosenfeld said in a statement.

"Whether there are comparable health threats to humans remains unclear, but there clearly must be a concern."

The U.S. Food and Drug Administration said it had "some concern" with BPA, which has been used in packaging since the 1960s.

The European Union and Canada have banned the use of BPA in baby bottles.  However, the study said there is no scientific consensus on the dangers BPA poses.

The study was published in the Proceedings of the National Academy of Sciences.


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