WASHINGTON - The U.S. Food and Drug Administration announced last week that it would not ban the use of bisphenol A (BPA) in food packaging, but rather that it would continue to study the health effects of the chemical.

The decision rejects a petition by the Natural Resources Council (NRC), an environmental group, to ban the chemical in food and beverage containers immediately, though leaves the door open for 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."

The agency said NRC did not present compelling scientific evidence to justify new restrictions on the chemical. Dosing methods in some studies, for example, did not reflect how a person would ingest the chemical, the FDA said. And it said the sample sizes of the research were not large enough to provide convincing 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.

The Natural Resources Defense Council expressed frustration and impatience with the FDA??s announcement. "We always support more research but we also wonder, when is enough enough?" said Dr. Sarah Janssen, a senior scientist with the NRC. "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 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."