National Toxicology Program scientists announced this week that Bisphenol A -- found in baby bottles, sippy cups and soup cans -- might pose health risks. The chemical, known as BPA, has been detected in as much as 90 percent of human urine.
The tentative conclusion is based on animal studies that showed high rates of breast cancer, prostate cancer, behavioral changes and early onset puberty among rat pups exposed to BPA. Particularly concerning is that the animals were exposed to levels comparable to likely human exposure.
"The fact that the levels are similar to what humans are exposed to is really the thing that drives the concern that we have," said John Bucher, associate director of the National Toxicology Program.
With little data available on its impact on humans, scientists still lack definitive proof that BPA is a toxin. In a report released on Wednesday by Bucher's agency, scientists called the chemical cause for "some concern." More research into its health effects is needed, the report says.
"But I always say when it comes to our children, some level of concern is high enough to take action," said Dr. Anila Jacob, senior scientist at Environmental Working Group, an environmental health research and advocacy group.
Walmart will only sell BPA-free bottles in stores starting early next year, the super chain said on Thursday. And Friday, the popular outdoor company Nalgene announced plans to start phasing out production of all polycarbonate containers containing BPA.
Meanwhile, storeowners in Canada will soon be pulling baby bottles and other plastic storage containers off the shelves, as the Canadian government is poised to take a more drastic step and declare BPA a toxic chemical.
Still unknown is whether the U.S. report will trigger any regulatory action.
BPA mimics the actions of estrogen, triggering the hormone receptors in the brain and inducing a hormonal response. In lab animals, the effects of BPA on the prostate and mammary glands puts the animals at higher risk for prostate and breast cancer, respectively. Developing fetuses, infants and children are believed to be the most at risk.
"What animal studies are showing is that when exposure occurs during the early stages of life... that can alter the animal's susceptibility to diseases later in life," Jacob said.
BPA has been used to make hard, clear, unbreakable plastic since the 1950s. As an alternative, parents can buy BPA-free or glass baby bottles and limit the use of canned foods and plastic.
"The science is changing rapidly," Bucher said. "It's a very complex database. There is lots and lots of research that needs to be done before we can fully understand where we are with this."