Effects of Common Chemical BPA Span Generations

Bisphenol A, or BPA – a chemical that commonly leaches into food and drink from cans and plastic   containers – can alter the behavior of mice for generations after   exposure, research led by the University of Virginia School   of Medicine shows.

The researchers exposed female mice to the compound prior to and during   pregnancy, feeding them sufficient doses to create a BPA level in the   blood equivalent to what is typically found in humans. The researchers   then examined the genetic effects on subsequent generations. They found   that the initial BPA exposure continued to affect gene expression and   shape social behavior in the fourth generation – the last examined – though   there had been no additional exposure to the chemical.

The researchers believe BPA has trans-generational effects in people   the same as it does in mice. “Based on our data, and the results   from others, it is clear the effects of this chemical are going to be   with us for a long, long time,” said Emilie F. Rissman, the study’s   lead investigator and a professor of biochemistry and molecular genetics   at the School of Medicine.

BPA is an endocrine disruptor, meaning it interferes with the body’s   hormone system. The man-made chemical is commonly used in polycarbonate   plastics, and it is often found in can linings and food and drink packaging.   Because BPA is water-soluble, it can leach into food and drink, especially   when the container gets hot or if the food is acidic. This is the primary   way people are exposed to BPA.

A survey conducted by the Centers for Disease Control and Prevention   in 2003-04 found detectable levels of BPA in 93 percent of 2,517 urine   samples taken from Americans age 6 and older.

In examining the trans-generational effects of BPA, the researchers   looked at the social interactions between pairs of juvenile mice in the   generations after exposure to BPA. They evaluated the amount of time   the mice spent exploring their environment and the amount of time they   spent engaged in social activities. They also conducted targeted genetic   testing to determine BPA’s effects on genetic expression patterns in   the brain.

The researchers found that the mice exposed to BPA while in the womb   were less social than mice that had not been exposed. By the third subsequent   generation, the behavior had flipped: Mice descended from the BPA-exposed   mouse were more social than the control group.

The researchers’ conclusion: “Exposure to a low dose of BPA, only   during gestation, has immediate and long-lasting, trans-generational   effects,” they write in a paper published online in the journal   Endocrinology.

While the researchers believe BPA may have trans-generational effects   in humans as well, the effects may manifest differently.

“While we certainly observed behavioral changes that were passed   from generation to generation with subsequent exposure, I cannot say   for sure these effects would be the same in humans,” Rissman said. “However,   as fellow mammals with a 99 percent similarity in their genomes, mice   are a good laboratory model for investigations like these, which simply   cannot be done in people. While work in humans is correlational, it is   important and worth examination.”

The researchers next plan to examine the mechanism by which BPA is affecting   genes.

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