A new study in this week's Pediatrics medical journal suggests that prenatal exposure to bisphenol A (BPA), a chemical found in many products, including food and beverage containers, is linked to behavioral and emotional problems in 3-year-old children.
Some environmental and child health experts say the findings support the argument that BPA is harmful to children's development, a position that has been under debate for the past several years.
In the study, researchers from the Harvard School of Public Health, the Centers for Disease Control and Prevention, Cincinnati Children's Medical Center and several other institutions measured BPA levels in the urine of 244 women at different times during their pregnancies and in the urine of their children at one, two and three years of age.
They found BPA in more than 97 percent of the urine samples, and discovered an association between BPA exposure and subsequent behavioral problems.
"The results of this study suggest that gestational BPA exposure might be associated with anxious, depressive and hyperactive behaviors related to impaired behavioral regulation at three years of age," wrote the authors, led by Joe Braun, a research fellow at the Harvard School of Public Health in Boston.
The effects were especially strong among girls.
Despite the findings, the authors urge caution in their interpretation.
"There is considerable debate regarding the toxicity of low-level BPA exposure, and the findings presented here warrant additional research," they wrote.
Beginning in 2008, BPA emerged as a controversial chemical. Some studies have found a link between BPA, which disrupts hormone production, and neurological problems in children and lab animals, while other studies have not. Research has also found an association between between BPA and other medical conditions, such as breast cancer and heart disease.
U.S. government agencies, such as the Food and Drug Administration and the National Toxicology Program, recently said there is a "reason for some concern about the potential effects of BPA on the brain, behavior and prostate gland of fetuses, infants and children."
The FDA, however, said there are also "substantial uncertainties with respect to the overall interpretation of these studies and their potential implications for human health effects of BPA exposure."
Experts not involved in the study say the findings add to the mounting evidence that BPA can harm children's developing brains, although more research is needed to sort out how it affects development.
"Exposure to BPA and other chemicals prenatally is probably more harmful than in childhood, because there is much more vulnerability in the prenatal environment," said Dr. Philip Landrigan, director of the Children's Environmental Health Center at the Mount Sinai Medical Center in New York. "The brain is very vulnerable to things like BPA and it plays out in childhood. We see a reduction in intelligence and alterations in behavior."
He also explained that BPA mimics estrogen, which could explain why the behavioral effects were more pronounced in girls than boys.
Dr. Steven Lipshultz, chair of pediatrics at the University of Miami's Miller School of Medicine, said the behavior problems observed in the young study participants -- hyperactivity and poor behavioral inhibition -- are characteristics of attention deficit hyperactivity disorders, suggesting there could be a relationship between BPA and these disorders.
"These are very concerning findings," Lipshultz said. "We have certainly seen in the last 20 years a real increase in the diagnosis of children with attention deficit hyperactivity disorders to the point where right now, depending on which study you look at, between 8 and 11 percent of kids in the U.S. are diagnosed with them."
He added, "Is this because we are more aware of it or are there really environmental exposure that are changing how many kids have issues in this area?"
While they are concerned about the findings, Landrigan and Lipshultz say it's too early to say there's a cause-and-effect link between BPA and developmental problems in children.
"They can minimize consumption of canned food and avoid storing food in containers with BPA -- use glass or stainless steel."
But until additional research solidifies the association between BPA and developmental issues, the study authors say, "the benefits of such reductions are unclear."
The American Chemistry Council (ACC), a trade association representing American chemical companies, responded to the study by pointing out the authors themselves wrote, "the clinical relevance of these findings is unclear at this point."
Steven G. Hentges of the ACC's Polycarbonate/BPA Global Group also said other research funded by the U.S. Environmental Protection Agency and conducted by Pacific Northwest National Laboratory does not support this study's findings.
"Consistent with previous human and animal studies, the Pacific Northwest study ... indicates that, because of the way BPA is processed in the body, it is very unlikely that BPA could cause health effects at any realistic exposure level. Furthermore, regulators from Europe to Japan to the U.S. have recently reviewed hundreds of studies on BPA and repeatedly supported the continued safe use of BPA."