The U.S. Food and Drug Administration on Friday downplayed the risk from contamination of the already recalled popular heartburn drug Zantac, and said its tests suggest it does not cause carcinogens to form in patients.

Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said in a statement that the levels of contamination it found in ranitidine - commonly known as Zantac - with the probable carcinogen N-nitrosodimethylamine (NDMA) "are similar to the levels you would expect to be exposed to if you ate common foods like grilled or smoked meats."

Still, the FDA released results of its testing on ranitidine products and showed that some versions of the drug had as much as nine times the regulator's "acceptable limit" for NDMA.

The FDA also said that tests it ran to simulate how Zantac reacts in users' stomachs and small intestines suggest it does not cause NDMA to form there. But the regulator said it still plans to test the drugs in human patients to fully understand whether it causes NDMA to form in users' bodies.

Zantac, sold over-the-counter in the United States by French drugmaker Sanofi SA, and some of its generic versions, have been recalled due to possible NDMA contamination of pills that had not yet been consumed. The FDA said earlier this month it found unacceptable levels of NDMA in drugs containing ranitidine.

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