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BPA exposure linked to genetic changes that alter brain development

BPA is back in the news, now that a new study has linked the controversial chemical to potentially dangerous effects on a child's developing nervous system.

"Our study found that BPA may impair the development of the central nervous system, and raises the question as to whether exposure could predispose animals and humans to neurodevelopmental disorders," study author Dr. Wolfgang Liedtke, an associate professor of medicine and neurobiology at Duke University in Durham, N.C., said in a press release.

BPA, or bisphenol A, is widely available in consumer packaging, used to line aluminum cans to protect them from corrosion and also used in plastics such as bottles, tableware and food storage containers.

The chemical mimics estrogen in the body which in turn could disrupt the endocrine system (hormones), leading to negative health effects. Previous studies have linked BPA exposure to behavioral disorders, cancer, immune system problems and reproductive disorders, according to the researchers. Recent studies in children have tied BPA to risk for obesity, thyroid problems and kidney damage.

BPA is banned in the European Union and Canada, but the U.S. Food and Drug Administration (FDA) has only banned the chemical from for manufacturing of baby bottles and sippy cups as of July 2012.

For the new study, published online Feb. 25 in Proceedings of the National Academy of Sciences, researchers exposed nerve cells, or neurons, to BPA. The experiments were conducted in mice, rats and humans.

When neurons are developed, high levels of the ion chloride are present, but eventually chloride levels fall because a transporter protein called KCC2 "churns" it out of cells. Too much chloride in cells can damage nervous system pathways and disrupt the developing neuron's ability to move to where it needs to in the brain.

The researchers discovered when exposing the neurons to minute amounts of BPA, the gene that makes KCC2 shut down, which kept chloride longer in the neurons. They suspect the BPA made a different type of protein -- known as MECP2 -- more abundant in neurons, which in turn bound to KCC2 and shut it down.

That's important, scientists said, because it raises questions about whether BPA exposure could be linked to disorders such as the severe autism spectrum disorder Rett syndrome, which is characterized by mutations in a gene that makes MECP2. Rett syndrome is the most common cause of intellectual disability in girls, according to the researchers.

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"Our findings were established in rodent models and verified in human systems, an important validation step given health relevance of our findings and ongoing public concern about ubiquitous BPA exposure," wrote the researchers.

Liedtke added in a press release that more research is needed that focuses on what targets aside from KCC2 are affected by BPA, saying the new study "is a chapter in an ongoing story."

BPA expert Dr. Leonardo Trasande, an associate professor of pediatrics and environmental medicine at NYU Langone Medical Center in New York City, told that the new study is consistent with past research that found moms who had higher BPA levels in their urine had children who were more aggressive and hyperactive when compared to moms with lower BPA levels.

"The more recent study identifies a potential mechanism by which prenatal exposure to BPA may contribute to neurodevelopmental disability, and adds further scientific rationale for limiting exposure to this chemical in food and other routes of exposure," Trasande said in an email.

The American Chemistry Council, an industry group, says the weight of scientific evidence on BPA has been extensively evaluated by government and scientific bodies around the world, which have declared the chemical is safe as used.

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