WEDNESDAY, June 12 (HealthDay News) -- There's fresh evidence that the chemical bisphenol A, or BPA, may play a part in childhood obesity.

BPA is a chemical that is widely used in food packaging. Government studies have shown that 92 percent of Americans have detectable levels of BPA in their bodies.

There's intense scientific interest in BPA because it is chemically similar to the hormone estrogen, and there's some concern that it may mimic estrogen's effects in the body, causing harm to the brain and reproductive organs, particularly in children.

Last year, the U.S. Food and Drug Administration formally banned BPA from baby bottles and sippy cups, though manufacturers had already stopped using it. The agency declined to ban it from other food containers, pending further research.

In a new study published online June 12 in the journal PLoS One, researchers measured BPA levels in the urine of more than 1,300 children in China and compared those levels to their body weights.

The study authors also asked the kids about other things that may influence body weight, such as how often they ate junk food, fruits and vegetables, how much exercise they got, whether their parents were overweight and how long they played video games, on average, each day.

After taking all those factors into account, the investigators found that girls aged 9 to 12 who had higher-than-average levels of BPA in their urine were about twice as likely to be obese as those with lower-than-average levels. The researchers didn't see the same association for boys or for older girls.

One explanation for the results may be that girls who are entering puberty are uniquely vulnerable to the effects of hormone-disrupting chemicals, said study author Dr. De-Kun Li, an epidemiologist at Kaiser Foundation Research Institute and the Stanford School of Medicine, in California.

"Human studies are starting to confirm animal studies that show BPA can disrupt energy storage and energy metabolism," said Li.

One of the most recent questions raised about BPA is whether or not it may be an obesogen, or a chemical that contributes to the development of obesity.