Pfizer to suspend common chicken drug on arsenic concerns

Pfizer is putting one of its animal drugs out to pasture, at least for now. The company agreed to stop selling the poultry drug 3-Nitro in the U.S. after an FDA study found that it increased levels of inorganic arsenic in chickens, the agency said. The growth-promoting drug has been commonly used in poultry for decades.

While organic arsenic is found in the environment, it is a less toxic form than inorganic arsenic, which is a known carcinogen. The Pfizer drug contained organic arsenic that might be able to transmute into the inorganic form. "The levels we detected were very low," FDA Deputy Director Bill Flynn said (as quoted by Reuters), "but the fact that they represent an added source of human exposure to a carcinogen, and a source that's avoidable, led the FDA to take action."

Pfizer will continue selling 3-Nitro for 30 days, giving farmers a chance to find a substitute. As the New York Times reports, the drug kills intestinal parasites, boosts growth and makes meat look pinker. About 90 percent of the drug's sales are for use in chickens, it's also given to turkeys and pigs. As the NYT points out, environmentalists have been worried about the drug for some time, because of the potential for chicken waste, when used as fertilizer, could cause arsenic to leach into water supplies.

The sales suspension will allow Pfizer time to conduct its own "full scientific assessment" of the drug, Pfizer Animal Health's Scott Brown told the NYT. That assessment will also include another arsenic-based feed medicine called Histostat, which hasn't been studied by FDA and has not been suspended.

- get the release from FDA
- see the NYT coverage
- read the story from Reuters