Chemical BPA linked to obesity in children, teens

A new study has raised concerns that a chemical commonly found in aluminum cans, such as soda cans, may increase the risk of obesity in children and adolescents.

The chemical, called bisphenol A (BPA), is a low-grade estrogen that until recently was found in certain plastic bottles—typically marked with the number ‘7’ inside a recycling symbol.  Still used as an internal coating for aluminum cans, BPA acts as an antiseptic and helps prevent corrosion, according to manufacturers.

A 2003-2004 National Health and Nutrition Examination Survey (NHANES) found BPA exposure is “nearly ubiquitous” in the U.S. population, with 92.6 percent of people age 6 and older having detectable levels of BPA in their urine.  The survey also found that dietary sources appear to be responsible for 99 percent of BPA exposure.

Besides obesity, BPA exposure has also been associated with cardiovascular disease, breast cancer, prostate cancer, neurological disorders, diabetes and infertility.  The U.S. Food and Drug Administration (FDA) recently banned BPA from sippy cups and baby bottles – but did not extend the ban to other products.

“The FDA declined to ban [BPA] from aluminum cans, saying they wanted to wait for further evidence,” the study’s lead investigator Dr. Leonardo Trasande, associate professor of pediatrics and environmental medicine at the New York University School of Medicine, told FoxNews.com. “This study raises concerns about the need to reconsider that stance.”

The study looked at a sample of nearly 3,000 children and adolescents, between the ages of 6 and 19 years old, whose urinary BPA concentration had been measured in the 2003-2008 NHANES. Even controlling for gender, age and caloric intake, among other factors, the researchers still found a significant association between BPA levels and body mass.

The results indicated children with the highest levels of urinary BPA had 2.6 times higher odds of being obese than those with the lowest levels of the chemical.  Among children with the highest levels, 22.3 percent were obese compared to 10.3 percent of those with the lowest levels.

“We were especially concerned that children who ate too many calories might also ingest BPA,” Trasande said.  “But whether the children consumed an excessive amount of calories or a normal amount, BPA was still associated with obesity.”

According to Trasande, BPA is an endocrine-disruptor, which upsets the balance of estrogen and testosterone, and the signals critical for caloric and sodium balance in the body.  It also appears to have an impact on adiponectin, a protective factor against cardiovascular disease, as well as factors that regulate glucose and insulin.

The study found the association between obesity and BPA was only significant in white children and adolescents, suggesting certain groups may have a genetic predisposition, which makes  them more susceptible to the effects of BPA, Trasande said.

“We need to look at the effects of BPA in pregnancy to better tease out the findings from this study,” he said. “At the same time, this raises concerns of considering a broader paradigm in thinking about obesity.  Studies like this one increasingly suggest in addition to diet and physical activity, we must also consider environmental and chemical factors in obesity.”

In response to the study's findings, Steven Hentges of the Polycarbonate/BPA Global Group of American Chemistry Council, which represents chemical manufacturers, released a statement, saying: "Attempts to link our national obesity problem to minute exposures to chemicals found in common, everyday products are a distraction from the real efforts underway to address this important national health issue. Due to inherent, fundamental limitations in this study, it is incapable of establishing any meaningful connection between BPA and obesity."

The study will be published in the September 19 issue of the Journal of the American Medical Association.