By Ariel Schwartz

According to the CDC, African Americans have a 51% higher obesity rate and Hispanics have a 21% higher obesity rate than whites in the U.S. You might correctly presume that this has something to do with lifestyle differences--diet and physical activity, mostly. But there's another, less obvious factor in play: chemicals.

The scientific community has found increasing evidence that pthalates, a group of industrial chemicals found in everything from pharmaceuticals to personal care products, can increase obesity risk (much like the estrogen-mimicking compound BPA, which we've also discussed).

In a study published this week in Environmental Health Perspectives, researchers examined urinary pthalate concentrations and body mass of 2,884 ethnically diverse children between ages six and 19 that participated in a National Health and Nutrition Examination Survey. They discovered that there is also a link between race and ethnicity, pthalates, and childhood obesity. Specifically, they found an association with the kind of pthalates (called low-molecular weight pthalates) commonly found in cosmetics, lotion, and creams with increased body mass among African American children--but not with Hispanics or whites. How can this be?

In the past, studies have shown that ethnic groups have varying urinary pthalate concentrations. "There exists the possibility of disproportionate consequences of that exposure," explains Dr. Leonardo Trasande, the lead author of the study and a pediatrician. That part is obvious enough. But the reasons behind why African Americans are more heavily exposed to pthalates aren't entirely clear.

One clue: a different study showed that an increased use of personal care products is associated with higher levels of those low-molecular weight pthalates (so maybe African Americans tend to use personal care products differently), but "there's only so far we can take this line of thinking," says Trasande. "We can't say for certain that an increase in exposure is linked to effect. There's also the possibility that predispositions can trigger effects."

Regardless of the reason, pthalate exposure is a real problem. Trasande and his colleagues write an increase in pthalate exposure could lead to a 1.7 pound increase in body weight, as well as increased chances of being both overweight and obese. It might not sound like much, but that's no trivial amount of weight. "Many risk factors for childhood obesity are in that range," says Trasande.

Since we don't know exactly African-Americans have higher levels of urinary pthalate concentrations, there isn't much we can do about--except to regulate pthalates for everyone. FDA, it's your move.

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