Medical study links BPA, kids’ obesity

Boston Herald ^ | September 19, 2012 | Christine McConville

[neverdem]

The BPA and body weight controversy heated up again yesterday, with a new Journal of American Medicine Association report that kids with lots of the controversial plastic chemical in their urine are more likely to be obese.

“Our study found ample evidence that BPA exposure makes fat cells bigger, reduces the function of a protein that protects from heart disease, and it disrupts the functional balance of testosterone and estrogen, which are important in maintaining caloric balance,” said New York University School of Medicine’s Dr. Leonardo Trasande, who traced the levels of Bisphenol A, also known as BPA, in 3,000 American children.

BPA is found in hard plastic food containers and soda cans, and on shiny credit card receipts.

Public health experts have argued that the chemical can alter a person’s metabolism.

Harvard School of Public Health’s Karin Michels, a BPA expert, said Trasande’s study is important because it adds to “evidence that is accumulating.”

Dr. Ana Soto of Tufts University’s Sackler School of Graduate Biomedical Sciences called its long-term implications chilling. “You can argue that the earlier you are exposed to this chemical, the more harm that can be done,” she said.

Critics at the American Chemistry Council, an industry trade group, pointed out that “the study measures BPA exposure only after obesity has developed.”

A spokesman added that attempting to link “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.”

[neverdem]

Association Between Urinary Bisphenol A Concentration and Obesity Prevalence in Children and Adolescents

Correlation is not causation, but epidemiology can generate testable hypotheses IMHO.

[Moltke]

Fat kids are fat because they eat more, hence they take in more BPA. No study needed.

[Sooth2222]

Since 1883, it's been the "Journal of the American Medical Association", not the "Journal of the American Medicine Association". Minor point, perhaps, but if the first sentence of the Boston Herald piece is wrong, one wonders what else the author has wrong about it. It would be best to read the original article (in JAMA, not in the Boston Herald) if this is a subject of interest.

[Stosh]

Fat kids have more body fat [duh], and have (by mass) a greater percentage of body fat.

BPA is a hydrophobic (water-adverse) compound; it will tend to concentrate in body fat.

What would be surprising is if fat kids did not have more BPA in their urine - there’s going to be an equilibrium between BPA in fat and BPA in the urine - if the BPA in fat is higher, the BPA in the urine will be higher as well.

First rule of scientific conclusions based on stats: correlation does not equal causation.

[neverdem]

"BISPHENOL A (BPA) IS USED TO manufacture polycarbonate resin"

That's the first string of text from the JAMA article. When I searched for it on Google, I got the abstract linked in comment# 1.

Here's another quote from the article:

"In bivariate analysis, urinary metabolites of other phenols were not associated with overweight or obesity (eTable 4) with the exception of urinary benzophenone level with obesity." (I'm a doc. I get a courtesy hard copy of JAMA. I don't subscribe.)

For the benefit of those without knowledge of organic chemistry, this is what these molecules look like in a standard notation. You start with benzene:

http://www.chemspider.com/Chemical-Structure.236.html?rid=c3984e58-c253-4f80-9b7f-f78b5e807876

Here's phenol:

http://www.chemspider.com/Chemical-Structure.971.html?rid=3da5b009-c6ff-49a6-8873-a31880cfa023

Here's bisphenol A:

http://www.chemspider.com/Chemical-Structure.6371.html?rid=97b539ca-dcb6-4641-a56e-820926726af0

Here's benzophenone:

http://www.chemspider.com/Chemical-Structure.2991.html?rid=a6724351-9bd0-4bfb-bebe-ca250a50f428

Get the picture? The hypothesis that BPA is an endocrine disruptor is definitely worth testing, IMHO.

[Stosh]

Not sure I’ve ever seen Lewis structures on FR before - that was pretty cool.

And you’re right that it does make sense to test BPA as an endocrine disruptor; among other things, it has a strong structural similarity to stilbene compounds that are known to behave in that way.

But it’s not like BPA hasn’t been studied in that context; on the contrary, it’s been studied to death, and it’s health effects continue to be studied. In that context, the European Union (about as anal as they come when it comes to chemical paranoia) has initiated yet another study of the compound, despite the fact that their latest study, probably the most extensive and rigorous ever carried out, demonstrated no reason for concern for BPA at levels commonly found in humans: http://www.efsa.europa.eu/en/topics/topic/bisphenol.htm

My major concern is that in just reading the headline to the article (which I’m prone to do, I must admit) it’s easy to fall into the trap of assuming that BPA ingestion will lead to obesity. I will compliment the poster for stating straight out that correlation doesn’t necessarily indicate causation, and your point on the value of investigating the health effects of BPA is a reasonable one - it’s just a question of how much study is enough, a point on which I believe reasonable people can disagree.

[neverdem]

http://www.rsc.org/chemistryworld/

Chemistry World links Chemspider near the top of the page. Chemspider gives structural formulas, molecular weight, isomers, etc. Thanks for the link.