Researchers at Johns Hopkins University said they found levels of arsenic in chicken that exceeded amounts that occur naturally, and warned that they could lead to a small increase in the risk of cancer for consumers over a lifetime.

The levels were well below danger levels set in federal safety standards, though the researchers pointed out that those were first established in the 1940s. And the chicken samples tested were from 2010 and 2011, before sales of the drug that researchers say was a major driver of the elevated arsenic levels, roxarsone, were suspended.

A spokeswoman for the chicken industry said the levels found by researchers were low, but the researchers contend that the elevated levels are important because the Food and Drug Administration has not banned the drug, and it is still being sold abroad.

The issue of arsenic in food has drawn public attention since research last year by Consumer Reports found substantial arsenic levels in rice. Arsenic residue in rice often comes from water used in farming.