Chemists dispute BPA link to obesity

The research, presented at a media briefing organised by the Journal of the American Medical Association, studied BPA in urine and body mass index for 2,838 people aged from six to 19. It was led by Dr Leonardo Trasande of the New York School of Medicine, New York City.

Trasande’s team claimed the findings suggested a plausible link between exposure to BPA and childhood obesity.

However, a statement issued by Steven Hentges, of the ACC’s Polycarbonate/BPA Global Group, called the work “a distraction from the real efforts”​ to tackle obesity.

‘Fundamental limitations’​​

“Due to inherent, fundamental limitations in this study, it is incapable of establishing any meaningful connection between BPA and obesity,” said Hentges.​

“In particular, the study measures BPA exposure only after obesity has developed, which provides no information on what caused obesity to develop.​

“The authors themselves state: ‘Obesity develops over time, and causation cannot be inferred from a cross-sectional association of urinary BPA concentration ...’ The authors further state that their work is ‘at best hypothesis-generating,’ indicating that this study is speculative and might, at most, be the basis for conducting additional studies.”​

‘No consistent effect on bodyweight’​​

Hentges said “dozens of studies”​ monitoring the body weight of lab animals exposed to BPA had found “no consistent effect on body weight”.​

He also cited research funded by the Environmental Protection Agency and conducted by scientists at the US government’s Pacific Northwest National Laboratory, Centres for Disease Control and Prevention and Food and Drug Administration.

This study indicated that because of the way BPA was processed by the body, it was “very unlikely that BPA could cause health effects at any realistic exposure level”,​ he said.

Regulators from Europe to Japan and the US had recently reviewed hundreds of studies on BPA and repeatedly supported its continued safe use, said Hentges.

2.6 times higher odds of obesity​

Trasande’s team divided urine samples taken into four categories and discovered that the people providing samples with the highest BPA content had 2.6 times higher odds of obesity.

They also found obesity was not associated with exposure to other phenols, such as sunscreens and soaps.

“To our knowledge this is the first report of an association of an environmental chemical exposure with childhood obesity in a nationally representative sample,”​ the researchers wrote.

Source: Journal of the American Medical Association, September 19, 2012;308[11]:1113-1121

http://jama.jamanetwork.com/article.aspx?articleid=1360865​

Authors: Leonardo Trasande, MD, MPP; Teresa M. Attina, MD, PhD, MPH; Jan Blustein, MD, PhD