SEATTLE - A new study cites a link between obesity and bisphenol A (BPA), a chemical found in food packaging such as plastics and aluminum cans.

Less than three months ago, a state law went into effect in Washington making it illegal to manufacture or sell sports bottles that contain BPA.

In the study, published in the September edition of the Journal of the American Medical Association, researchers found higher BPA levels in overweight teens and children. It doesn't prove that BPA causes obesity, but toxicologist Dr. Jennifer Lowry at Children's Mercy Hospitals and Clinics in Kansas City, Mo., says it's one example of why more research is needed.

"There are 80,000 chemicals that are regulated by EPA, and yet we only know maybe about 2,000 of them in any large degree, on the health effects that occur from them."

One concern about the latest findings is that many aluminum cans still contain BPA, and some families eat mostly canned foods for their convenience and low cost.

Dr. Garry Sigman, director of adolescent medicine at the Pediatric Weight Management Clinic at Loyola University in Maywood, Ill., says he'd still rather see parents keep serving up fruits and vegetables - even if they are from cans.

"We should try to give children more fruits and vegetables and help them learn to enjoy the tastes of those foods. Whether they come in cans or other forms, it's still going to be better in the long run."

Last year, the U.S. Food and Drug Administration chose not to ban BPA in food packaging, saying reasonable steps already are being taken to reduce its use. BPA has also been banned in baby bottles and toddlers' "sippy cups" in Washington and about a dozen other states because scientists say it interferes with hormones. The new study raises questions about its safety in products used by older children.

A summary of the study, from New York University School of Medicine, is online at jamanetwork.com.