White children exposed to high levels of bisphenol A are five times more likely to be obese than children with low levels, according to a study published today in the Journal of the American Medical Association.
“This is a great example of a health study that is consistent with studies in animals, and it also confirms what we’ve seen in adult populations,” said Frederick vom Saal, a University of Missouri-Columbia professor who studies bisphenol A (BPA) but was not part of the new study. “That gives the findings much greater weight and strengthens this link we keep seeing between BPA and obesity.”
Traces of BPA – used in some canned food and beverages, paper receipts and dental sealants – are found in virtually every U.S. adult and child.
In the study of body mass and BPA data from 2,838 youths aged 6 to 19, only white children were found to have significant increases in obesity prevalence as their BPA levels increased. Those with the highest concentrations in their urine were five times more likely to be obese than children with the lowest levels.
Black children with higher BPA levels were 1.25 times more likely to be obese than those with lower levels, which the scientists said is not statistically significant. Hispanic children had the same rates of obesity at the highest and lowest levels.
“Neither Hispanic (Mexican American and other Hispanic) or non-Hispanic black children had a significantly increased risk of obesity with elevated concentrations of urinary BPA,” the authors wrote in the journal article.
It is unclear why BPA levels were so strongly associated with obesity in white children.
“There were no dietary differences specific to whites,” said Dr. Leonardo Trasande, an associate professor in pediatrics, environmental medicine and health policy at NYU’s School of Medicine who was lead author of the paper. “It is possible that there is some genetic interaction that may be specific to the (white) population ... but we don’t know.”
It’s also possible, he said, that higher rates of obesity in the Hispanic and black children – 23 and 24 percent, respectively, compared with 15 percent of white children – made it more difficult to tease out a link between the chemicals and obesity in those groups.
Representatives of the chemical industry said the study had too many weaknesses to prove a connection.
Steven Hentges, from the American Chemistry Council's Polycarbonate/BPA Global Group, said that 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 median BPA urinary concentration for children in the study was 2.8 nanograms per milliliter, slightly higher than the median for U.S. adults, according to a 2008 national survey by the Centers for Disease Control and Prevention. The highest group of children had concentrations at least double that.
Experts suspect that diet is the most frequent route of exposure for children. One study of 257 preschoolers in North Carolina and Ohio found that 99 percent of BPA exposure was through food. But national data is lacking and it is hard to pinpoint exposure since the chemical is in many plastics and other products.
The study adds to the evidence that certain industrial chemicals – called obesogens – may be in part spurring the obesity problem in the U.S.
“People are always told if you just stop eating or exercise more, you will lose weight. But there may be more to it … and I think there is,” said Retha Newbold, a visiting scientist at National Institute of Environmental Health Sciences who specializes in BPA and other endocrine disrupting chemicals.