BPA and BMI

Today a press release from the Journal of American Medical Association (JAMA) titled Higher Levels of BPA in Children and Teens Associated With Obesity, highlighted a new study titled Association Between Urinary Bisphenol A Concentration and Obesity Prevalence in Children and Adolescents. The paper found that children and adolescents who had higher concentrations of urinary bisphenol A (BPA), (that oft-maligned industrial chemical that is used in epoxy resins which serve as a protective lining [including protection from botulism!] in a variety of canned foods and beverages, and which is also found in a variety of other products), had significantly increased odds of being obese, and that children with the highest levels of urinary BPA had 2.6 times higher odds of being obese than those with the lowest measures of urinary BPA, and that among the participants with the highest levels of BPA, 22.3% were obese compared with 10.3% of the participants with the lowest levels. I don’t want to dispute the results of the study, but rather the conclusions and interpretation of the findings in the media.

Obligatory stock photo of a child drinking a soda that is required when writing about BPA.

In the press release, one of the authors notes that “Our findings further demonstrate the need for a broader paradigm in the way we think about the obesity epidemic. Unhealthy diet and lack of physical activity certainly contribute to increased fat mass, but the story clearly doesn’t end there.” The implication being that exposure to the chemical BPA, (and other environmental chemicals), is contributing to obesity. The authors note that 99% of children and adolescents’ exposure to BPA comes from dietary sources, such as aluminium cans that house high sugar sodas. In the actual paper, the authors note that “obese children may drink more canned or bottled beverages, or eat more canned food, and thus have higher urinary BPA levels” and that “explanations of the association cannot rule out the possibility that obese children ingest food with higher BPA content or have greater adipose stores of BPA“. Those facts are surprisingly missing in the press releases, and largely ignored in coverage of the story, such as in the CTV News article titled Study ties BPA in cans and bottles to childhood obesity, which later in the text notes that “the researchers were careful to point out that their findings don’t prove the cause of the higher rates of obesity, but only identified an apparent correlation to higher BPA level“. (See other examples of this linked at the end of this post).

Another interesting aspect of the study was the strength of the correlation when the results were analysed by race/ethnicity. When the authors did that, they found the distributions of urinary BPA concentrations differed by race/ethnicity, and that the only group for which the relationship between BPA and obesity held true, was non-Hispanic whites. Neither Hispanic, nor non-Hispanic black children and adolescents had a significantly increased risk of obesity with elevated concentrations of BPA, this is despite the high preponderance of elevated concentrations of BPA in non-Hispanic blacks. The authors struggle to reconcile this finding, speculating that obese whites have unique dietary behaviours that otherwise would result in differences in urinary BPA concentrations or that there are epigenetic factors responsible for the different effects observed in the racial/ethnic subgroups, both of these statements are made without any evidence to support this theory nor is a plausible mechanism suggested.

In the wake of this article The American Chemistry Council (ACC) released a statement calling the study speculative, and noting 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. Due to inherent, fundamental limitations in this study, it is incapable of establishing any meaningful connection between BPA and obesity.  In particular, the study measures BPA exposure only after obesity has developed, which provides no information on what caused obesity to develop.

I love that quote, and wish it got more attention. I agree that there needs to be some serious discourse on the causes, challenges, and possible solutions to the obesity epidemic, but I do not believe at this stage that should include passing the buck to chemicals, or as they are becoming increasing referred to as, obesogens. North Americans are not obese because of the chemicals we are exposed to, rather it is because of a severe imbalance in the number of calories taken in and those that are burned.

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4 thoughts on “BPA and BMI

  1. Pingback: Writing for Science: Beyond the Press Release | On a Quasi-Related Note

  2. Pingback: GET THE PLASTIC OUT OF YOUR BLOOD!!! : Dr. Pinna

  3. Pingback: Round-Up Ready: A Year in Blogging Edition | On a Quasi-Related Note

  4. Pingback: Higher levels of BPA in children and teens associated with obesity « Clinicalnews.org

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