Is BPA making girls obese?

Exposure to bisphenol-A (BPA)-found in baby bottles, plastic containers, food and beverage cans, and dental sealants-may be contributing to the nation’s obesity epidemic. Researchers found recently that higher urine BPA levels are associated with overweight in young and adolescent girls, particularly those in the vulnerable 9- to 12-year-old age range.

Investigators from China conducted a study involving 1,326 children in grades 4 through 12 from 1 elementary, 1 middle, and 1 high school in Shanghai.

They found that those girls aged 9 to 12 years with urine BPA levels at 2 µg/L or higher (which was above the median for the population but less than the 90^th percentile) were more than twice as likely to be overweight (defined as >90^th percentile of age- and gender-specific population weight distribution) as those with urine BPA levels of <2 µg/L.

And the relationship was dose-dependent; the higher the BPA levels, the greater the risk of being overweight. Girls with urine BPA levels above the 90^th percentile were more than 5 times as likely to be overweight. The relationship did not exist in girls older than 12 years of age or in boys.

One of the reasons that BPA is an issue is that exposure is pervasive. The 2003-2004 National Health and Nutrition Examination Survey (NHANES III) conducted by the US Centers for Disease Control and Prevention (CDC) found detectable levels of BPA in 93% of 2,517 urine samples from people 6 years and older. And children tend to have higher levels than adults, either because of higher exposure, slower metabolism, or both.

Scientists know that exposure to BPA suppresses the release of adiponectin, a hormone that increases insulin sensitivity. Consequently, BPA could lead to insulin resistance and increased susceptibility to obesity and metabolic syndromes.

The CDC reports that almost 20% of all US children and adolescents are obese.