[Dr. De-Kun Li, a reproductive and perinatal epidemiologist at Kaiser Permanente in Oakland, California,] and colleagues studied 1,326 school-age children in Shanghai, China, and measured BPA levels in their urine. In girls ages 9 to 12, higher BPA urine levels were associated with a doubled risk of obesity. And as BPA urine levels increased, so did the girls' obesity risk - measured using their weight in reference to weight distribution in the population.
But strikingly, only girls in this age group were affected, the research showed. Neither girls outside of the 9-12 age range nor boys experienced a risk of being overweight or obese, even with high levels of BPA in their urine.
"Girls seem to be more sensitive to environmental impact, and we don't know exactly why," said Li, the lead study author.
Researchers do know BPA is an endocrine-disrupting chemical. It enters the body and mimics estrogen, the main hormone involved in female development.
When BPA acts like estrogen in young girls, it may accelerate the onset of puberty and cause weight gain – thus earning its "endocrine-disrupting" title.
"It is biologically plausible that BPA interferes with your normal hormone process - then your body gets screwed up," said Li.
In March, a study reported a link between BPA and childhood asthma, and last year, the FDA banned BPA from all baby bottles and sippy cups.
Image: Overweight girl, via Shutterstock