The common chemical bisphenol A (BPA), found in the lining of many aluminum cans and a variety of food packaging, may be adding to the obesity epidemic among children and teens, according to a new study.
Recently, the US Food and Drug Administration banned the use of BPA in baby bottles and sippy cups because of fears that it may cause developmental problems. BPA, however, remains in many products children and teens use daily, the study authors noted.
"BPA has been associated with adult obesity and heart disease," said lead researcher Dr Leonardo Trasande, an associate professor of pediatrics at New York University. These new findings "raise further questions about the need to limit BPA exposure in children," he said. "This is the first study to find an association of an environmental chemical with childhood obesity in a nationally representative sample."
BPA and obesity
The study also suggests that diet and exercise are not the only factors involved in the obesity epidemic, he said.
Trasande speculated that because BPA can act like oestrogen - a female hormone - it may have an effect on the body's hormones and fat cells, making them bigger.
Alternatives to BPA exist, he said. "This study raises the need to reconsider the decision not to ban BPA in aluminum cans and other food packaging," he said.
The report was published in the Journal of the American Medical Association.
How the study was done
Trasande's team looked at urinary levels of BPA in almost 2 900 children and teens who took part in the 2003-2008 US National Health and Nutrition Examination Surveys.
Comparing these urinary BPA levels with participants' weight, researchers found that about 10 percent of children with the lowest levels of BPA in their urine were obese, compared with more than 22 percent of those with the highest levels of BPA.
Additional analysis showed this connection was only significant for white children and teens. The findings were similar for boys and girls. The association was not connected to similar chemicals used in sunscreens, soaps and other products, the investigators found.
BPA is nearly everywhere, Trasande said. According to study background information, nearly 93 percent of Americans aged 6 and older have detectable BPA levels in their urine.
Another expert commented on the new findings, noting that they do not prove that the chemical causes obesity.
"Like all observational studies looking at associations, this one cannot prove cause and effect," said Dr. David Katz, director of the Yale University Prevention Research Center.
"It is possible that BPA is actually a cause of obesity. It could also just be a marker of, for instance, a diet made up of more processed foods that are the actual cause," he said.
It's also worth noting that obesity rates were substantial even among those in the study group with the lowest level of BPA exposure, Katz said.
Experts at odds
An industry spokesman said there's no tie between obesity and BPA and he discounted the new 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 under way to address this important national health issue," said Steven Hentges, of the Polycarbonate/BPA Global Group of the American Chemistry Council.
"Due to inherent, fundamental limitations in this study, it is incapable of establishing any meaningful connection between BPA and obesity," Hentges said. "In particular, the study measures BPA exposure only after obesity has developed, which provides no information on what caused obesity to develop."
Hentges added, "It is also relevant to note that dozens of studies have monitored the body weight of laboratory animals exposed to BPA. These studies found no consistent effect on body weight, indicating that BPA exposure is not likely to cause obesity."
However, Yale expert Katz said BPA might pose other health risks.
"BPA is a potential disrupter of hormones, and as such, it could plausibly contribute to obesity," Katz said. "A potential link to obesity simply adds to the list of potential indictments of this chemical. Whether this study is showing cause and effect or not, we seem to have ample information to reach a verdict: BPA ought to go."
Beware of BPA in baby bottles
To learn more about BPA, visit the U.S. Department of Health and Human Services.
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