Concern arose after reproductive and developmental effects were reported in laboratory animals. BPA is considered to be "weakly" estrogenic, so researchers are investigating its effect on infant development and hormone-related diseases like breast and prostate cancer.

Within days of the NIH's recent National Toxicology Program report, the Canadian government, based on its own risk assessment, began moving toward a ban of baby bottles with BPA.

Wal-Mart, among other stores, has begun pulling baby bottles with BPA from the shelves; a spokesman said the company expects all of its baby bottles to be BPA-free early next year.

Playtex Infant Care is distributing one million free no-BPA "Playtex Drop-Ins Original Nurser Systems" bottle liners. "While U.S. and worldwide regulatory bodies continue to deem the ingredient safe," the company says, "we are listening to consumer concerns."

Following California, New Jersey legislators have introduced bills banning BPA in toys and child-care products.

The chemical industry has cricticized many of these moves.

"Although I'm sure their intention is to do things that are good for their customers, they're not going to improve health or safety of their customers by taking these products off the shelves," says Steven Hentges, executive director of the American Chemistry Council's Polycarbonate/BPA Global Group.

"We believe BPA is safe for use, based on many scientific reviews," says Hentges, who was authorized to speak for manufacturers of BPA.

There's also the matter of replacing it. "If we want to not use BPA, we will not have polycarbonate plastics. That becomes a real big challenge," he says. "You will find no alternatives that have been tested so well as bisphenol A."

Meanwhile, the research continues.

The National Institute of Environmental Health Sciences, one of the major funders of BPA studies, has given Roberts a three-year, $150,000 grant to study its effect in a new area, the immune system.

"So from that standpoint, it's a unique grant that's very valuable," says Jerrold Heindel, an institute program official. "Her results will be important to help us determine if there should be concerns."

In her Collegeville lab, Roberts and her research students are looking at cathepsins - enzymes that act like small scissors, cutting to pieces whatever is brought into a body's infection-fighting white blood cell. Some pieces return to the cell surface and become potential flags for the immune system.

Basically, if the cathepsins do their job differently than they are supposed to, the immune response may be faulty.

So Roberts and her students have been injecting Cheerios-shaped cereal with BPA and feeding it to mice. Later, they collect and analyze the mice's white blood cells.

While results are preliminary, she believes she's seeing problems.

Roberts is applying for more grants to continue her enzyme work. She also hopes to start an outreach program in the area, educating mothers about BPA and how to avoid it.

"Do I think more science needs to be done? Always," the biologist says.

Adds Roberts the mother: "I have two little kids at home. I want to make sure they're healthy and growing up the best they can."