The Food and Drug Administration has raised its level of concern over the safety of bisphenol-A, or BPA, an industrial chemical found in baby bottles and the linings of canned goods and other consumer products. That is a welcome shift in attitude by an agency that seemed bent, during the Bush administration, on minimizing the potential for harm. But it sheds little light, for now, on how dangerous the chemical might be in the small amounts that leach out and are imbibed by infants and older people  or how rigorously it should be regulated.

In August 2008, the Bush-era F.D.A. released a draft report asserting that the small amounts of BPA that leach into milk or food are not dangerous. One month later, the National Toxicology Program, an interagency assessment group, came to a less reassuring conclusion. It expressed “some concern”  midway between “negligible concern” and “serious concern”  about the potential effects on the brain, behavior and prostate in fetuses, infants and children. Now the F.D.A. has also expressed “some concern” about the same risks.

Still, the message remained murky. Health officials said they have no proof that the chemical has harmed either children or adults. They have not taken any regulatory action to curb its use. Nor have they urged families to change their use of infant formula or foods because the benefit of good nutrition outweighs the potential risk from BPA exposure.

Instead, the two agencies will conduct crucial research on the safety of BPA over the next 18 to 24 months to reduce “substantial uncertainties” in assessing the risks of low-dose exposures. And the F.D.A. will seek more robust and flexible regulatory authority to clamp down on the chemical if the evidence warrants.