(CBS News) New research reports a link between the bisphenol A (BPA) chemical used in many types of food packaging and childhood obesity. The study found the link existed regardless of how many calories kids were taking in through their diets.
The study, published online Sept. 18 in the Journal of the American Medical Association, provides the first look at a nationally representative sample of U.S. children and teens, according to its authors. Lead researcher Dr. Leonardo Trasande, an associate professor in pediatrics and environmental medicine at NYU Langone Medical Center, told CBSNews.com that his study's findings lend support to efforts to get the chemical banned by the U.S. Food and Drug Administration (FDA).
BPA is a chemical used as protective linings in food packaging to prevent corrosion, and can leach into foods through packaging as well through tableware, food storage containers and plastic bottles. While BPA can be found in air and dust, according to Trasande, previous studies suggest 99 percent of BPA exposure in young children comes from their diets.
That's problematic because the chemicals have been tied to hormone-disrupting effects, including reproductive and neurological effects, and the researchers say children at a young age may be more prone to changes.The body excretes BPA through urination, but it can remain in fat deposits.
For the study, researchers examined the association between amounts of BPA in the bodies of more than 2,800 children and adolescents between ages 6 and 19 - as tested by urinary analysis - and body mass index (BMI), a measure for obesity. The children were part of the 2003-2004 National Health and Nutrition Examination Survey (NHANES) that measures children's behaviors and how it relates to their health.
Based on results from urine tests, the researchers divided the study participants into four groups, from lowest BPA exposure to the highest. After mathematically controlling for other contributing factors such as television viewing habits, caloric intake and socioeconomic status, the researchers found that only 10 percent of kids exposed to the lowest levels of BPA were obese, compared to more than 22 percent of kids who were exposed to the most BPA - a two-fold increase. Differences between the other groups were not statistically significant.
Trasande added that further analysis revealed the effect was only seen in white children and adolescents and not in Hispanic and black children studied, for unknown reasons. He also said his research found obesity was not linked to similar "phenol" chemicals used in sunscreens and soaps, such as triclosan.
Trasande noted that the study does not prove cause and effect and it may be that some factor of obesity causes children to store more BPA rather than the opposite. He said further studies that track children and adolescents for long periods of time are needed to provide additional answers to the role of BPA in causing obesity.
Linda Birnbaum, director of the National Institute of Environmental Health Sciences, who was not involved in the new study, told the Associated Press that the study raises some interesting questions but it's impossible to say BPA causes childhood obesity.
"It's a hypothesis that needs further exploration," she said.
Trasande said that based on his findings, it's too early to make clinical recommendations on certain foods to avoid, but did say aluminum canned food is one of the biggest sources of BPA in the food supply and fresh vegetables should be part of a healthy diet.
"BPA does not discriminate by can," he said.
He did however add that the findings lend support to intervention strategies, such as banning BPA from the lining of food packaging.
This past March, the FDA rejected a petition calling for the ban of BPA in all food and drink packaging.
"While evidence from some studies have raised questions as to whether BPA may be associated with a variety of health effects, there remain serious questions about these studies, particularly as they relate to humans," the agency said in its response at the time.
In July the FDA decided to formally ban BPA from baby bottles and sippy cups, which many companies had already been phasing out from their products after reported health risks. At the time, the agency said it "continues to support the safety of BPA for use in products that hold food."
A spokesperson for the Food and Drug Administration told CBSNews.com in an email that "FDA sees substantial uncertainties with respect to the overall interpretation of many published studies, and, particularly, their potential implications for human health effects of BPA exposure." The agency added that Trasande's study "will be considered in the FDA's ongoing evaluation of the safety of BPA."
Popular soup-maker Campbell's previously announced it would phase out BPA from its canned goods, saying the cans were safe, but would use alternative materials amid the national debate over the chemical's safety. Other companies like Eden Foods have already been using BPA-free packaging for its foods.
The American Chemical Council disputed the study's findings.
"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," the council said in a statement. "Due to inherent, fundamental limitations in this study, it is incapable of establishing any meaningful connection between BPA and obesity."
The National Institute of Environmental Health Sciences has more information on BPA.