FDA Bans Three Arsenic Drugs Found in Poultry and Pig Feeds

In resolving a longstanding dispute, the Food and Drug Administration has announced that it will rescind approval for three of the four arsenic drugs that had been used in animal feeds at the request of the companies that market them.

The companies, Zoetis and Fleming Labs, already had largely withdrawn the three drugs from the market after recent studies showed levels of arsenic in chicken that exceeded amounts that occur naturally.

The compounds — roxarsone, carbarsone and arsanilic acid — have been used in 101 drugs added to feed for chickens, turkeys and pigs to prevent disease, increase feed efficiency and promote growth, according to the Center for Food Safety, which together with several other advocacy groups filed a petition almost four years ago seeking to ban the drugs in animal feeds.

“Zoetis withdrew roxarsone from the market voluntarily two years ago, and the companies have moved to withdraw the other two,” said Richard Sellers, vice president for feed regulation and nutrition at the American Feed Industry Association. “Now the F.D.A. is legally withdrawing their ability to market those drugs.”

The issue of arsenic in food has drawn increased public scrutiny since research last year by Consumer Reports found substantial arsenic levels in rice. Arsenic residue in rice often comes from the water used to grow it, and poultry feces are widely used as fertilizer for a variety of crops.

Pfizer, which spun its animal health division off as Zoetis this year, withdrew its roxarsone drug, 3-Nitro, from the market in 2011 after the F.D.A. found inorganic arsenic in chicken livers. “The product is no longer manufactured or used,” said Ashley Peterson, vice president of scientific and regulatory affairs at the National Chicken Council. “No other feed additives containing arsenic are currently used in broiler meat production in the United States.”

Nitarsone, the last of the four drugs the groups sought to ban from animal feeds, is the only known treatment for blackhead, or histomoniasis, a disease that can kill turkeys. Keith M. Williams, a spokesman for the National Turkey Federation, said nitarsone made from organic arsenic is used in the first six weeks of a turkey’s 20-week life span and that there is no other known treatment.

The F.D.A. said it would continue to study the effects of nitarsone.