Chemical BPA linked to children's obesity

The chemical bisphenol-A, or BPA, has a long and controversial history.

Used to manufacture some plastics – like the kinds in soda or water bottles – and as an anti-corrosive in aluminum cans, BPA has been under fire for some time from consumer advocacy groups.

The FDA recently banned BPA in baby bottles and sippy cups after concerns were raised about potential side effects on the “brain, behavior, and prostate gland in fetuses, infants, and young children,” according to the FDA website.

Still, the organization has stood by the overall safety of the chemical; in March the FDA denied the Natural Resources Defense Council’s petition to ban BPA outright .

Now a new study published this week in the Journal of the American Medical Association is adding more fuel to the flames.  The paper shows an association between BPA levels in children’s urine and obesity prevalence.
BPA is known to disrupt your body’s metabolic mechanisms, according to the study authors, which could affect your body’s ability to control its weight.

A previous study linked the chemical to adult obesity; this new study is the first to suggest a link between BPA and children's obesity, according to lead author Dr. Leonardo Trasande.  He adds children are uniquely vulnerable to environmental chemicals.

“Pound for pound, they breathe more air, they eat more food and drink more water,” he said.  Children’s organs are still developing, “so early harmful exposure can have permanent and lifelong consequences.”

The study

Researchers analyzed data from more than 2,800 children aged 6 to 19 who participated in the National Health and Nutrition Examination Survey between 2003 and 2008.

The children were placed into four groups based on the amount of BPA found in their urine samples.

In the group with the lowest levels of BPA, slightly more than 10% of the children were obese. In the second group, the percentage jumped significantly.

“Children with highest levels (of BPA) had more than twice the odds of being obese,” said Trasande.

Interestingly, the researchers found the association between obesity and BPA levels was concentrated in the white study participants, not in other racial or ethnic subgroups and admit they can't explain why this is.

“We know of no behavior in obese white children that characteristically increases their BPA,” Trasande said, noting that the association could be caused by genetics.

Caveats

As the medical journal’s editor-in-chief Dr. Howard Bauchner said, “This paper is speculative.”

It’s difficult to prove that BPA causes obesity without dosing a group of people with a specific amount of the chemical and placing them in an environmental bubble – a study that would obviously raise huge ethical concerns.

Trasande said it is possible that the association is actually a reverse association, meaning instead of BPA causing obesity, obesity causes higher levels of BPA.

For instance, researchers speculate the fatty tissue in obese children might store more BPA and release the chemical more frequently, altering the amount collected.

It’s also possible, Trasande said, that obese children might have dietary habits that could create higher levels of BPA in their bodies.  They might be more likely to drink canned soda or drink from plastic bottles than their thinner counterparts.

Takeaway

Trasande said it’s too early to make any recommendations about reducing your child’s BPA levels in order to prevent obesity.

“It is fair to say that if you reduce a child’s food consumption from canned sources you would reduce a child’s BPA levels,” he said, but noted that the implications of doing so are not yet understood.

Going forward

Environmental chemicals like BPA are more likely to affect children before the age of 6, when they are still rapidly developing.  The authors believe longitudinal studies – where researchers would track the same variables over a longer period of time - are needed to determine stronger associations.