The U.S. Food and Drug Administration announced Friday that it would not ban the use of bisphenol A, also known as BPA, in food packaging but said it would continue research on the health effects of the widely used chemical.

Although it rejected a petition by an environmental group to outlaw the compound in food and beverage containers, the agency did not close the door on future regulation. “This is not a final safety determination on BPA,” FDA spokesman Douglas Karas said. “There is a commitment to doing a thorough evaluation of the risk of BPA.”

Scientists are still working to determine what effects BPA, which mimics estrogen in the body, has on human health once ingested.

They know that it is metabolized quickly and that it has been shown to have negative effects in mice, including developmental and reproductive abnormalities, precancerous changes in the prostate and breasts, and other health problems. In epidemiological studies, researchers have reported correlations between BPA levels in people and higher risk of ailments including cardiovascular disease, diabetes and liver problems.

The FDA said the scientific evidence presented in the Natural Resources Defense Council’s 2008 petition “was not sufficient to persuade” the agency to prohibit BPA in food packaging. Dosing methods in some research studies, for example, did not reflect how a person would ingest the chemical, the agency said. It also took issue with sample sizes, which it said were not large enough to provide confidence in results.

“FDA is performing, monitoring and reviewing new studies and data as they become available, and depending on the results, any of these studies or data could influence FDA’s assessment and future regulatory decisions about BPA,” wrote David Dorsey, the agency’s acting associate commissioner for policy and planning.

Dr. Sarah Janssen, a senior scientist with the Natural Resources Defense Council, said, “We always support more research but we also wonder, when is enough enough?.... What the FDA is saying is: We’re going to keep studying it and in the meantime you’re going to still eat it and then maybe later we’ll tell you it’s not safe.”

Steven Hentges of the American Chemistry Council, a trade group that represents manufacturers, said in a statement that the FDA decision “again confirms that BPA is safe for use in food-contact materials, as it has been approved and used safely for four decades.”

First made more than a century ago, BPA is used to manufacture polycarbonate plastic for shatter-resistant food containers, sports safety equipment, eyewear and other products. It is used in epoxy resin as a protective coating for food and beverage packaging to prevent it from reacting with the contents. And it is present on many types of sales receipts, from which it rubs onto people’s hands.

Residual BPA can migrate from containers into food, and the FDA agreed with the defense council “that most infants, children and adults are exposed to low levels of BPA through the diet.”

Manufacturers have stopped using BPA in baby bottles and sippy cups sold in the U.S. because of customer concerns and bans in some states. The chemistry council has petitioned the FDA to prohibit use of the chemical in those products to create a national standard, Hentges said.

Linda S. Birnbaum, director of the National Institute of Environmental Health Sciences at the National Institutes of Health, said that the agency was funding experiments to address lingering doubts about BPA.

“Our grantees have published nearly 100 papers since January 2010. Nothing has been published that says there isn’t any problem here,” she said. “On the other hand, there are still a lot of outstanding questions.”

For instance, she said, “We want to have some surety that if BPA is removed from products, that what is put in its place is not a problem as well.”

bettina.boxall@latimes.com

eryn.brown@latimes.com