The U.S. Food and Drug Administration (FDA) announced Wednesday that it has received a letter of commitment from Zoetis Animal Health that, by this coming fall, the company will suspend the sale of Histostat (nitarsone) and formally request that FDA withdraw approval for the drug by the end of the year. Nitarsone is the only arsenic-based animal drug that is currently approved for use in food animals. Nitarsone is approved for the prevention of blackhead disease (histomoniasis) in turkeys and chickens, but it is predominantly used in turkeys. The Center for Food Safety said Wednesday that it applauded FDA’s move. The agency agreed in 2013 to withdraw 98 of 101 arsenic-based animals drugs after CFS and eight other groups filed a lawsuit over the issue. “The withdrawal of these harmful feed additives is a major victory for consumers and the health of our food system. It is unfortunate that it took over 5 years of intense pressure from outside groups, yet in the end, we are pleased that FDA listened to our scientific objections and is now ridding arsenic from our meat supply,” said Paige Tomaselli, CFS senior attorney. The group says that arsenic is added to poultry feed to promote faster weight gain using less food and to create a “healthy color” in chicken and turkey meat. CFS notes that there is plenty of scientific evidence that organic arsenic compounds are toxic to both animals and humans. FDA stated in its Wednesday announcement that arsenic is present in the environment as a naturally occurring substance, or as a contaminant, and is found in water, air, soil, and food. Published scientific reports have indicated that organic arsenic, the less toxic form of arsenic present in the arsenic-based animal drugs, could transform into inorganic arsenic, a known carcinogen, the agency added. In 2011, Alpharma, then the sponsor of 3-Nitro (roxarsone), suspended marketing of that drug after an FDA study measured higher levels of inorganic arsenic in the livers of chickens fed roxarsone compared to those of untreated control chickens. In February 2014, FDA formally withdrew its approvals for three other arsenic-based animal drugs: roxarsone, arsanilic acid and carbasone. Zoetis and Fleming Labs had reportedly begun taking the drugs off the market after studies showed arsenic levels in chicken above naturally occurring levels. The agency has since completed additional studies that affirm the findings of its 2011 roxarsone study. Ownership of the roxarsone application subsequently changed to Zoetis, which continued the suspension from sale of 3- Nitro and ultimately withdrew the new animal drug application for that drug. On the same day, Zoetis and Huvepharma AD voluntarily withdrew all new animal drug approvals and supplements for 3- Nitro, as well as two other arsenical new animal drugs, arsanilic acid and carbasone, FDA stated. Zoetis holds three approved animal drug applications for nitarsone: Histostat-50 (approved for use in chickens and turkeys for prevention of blackhead), and two combination use approvals, BMD/Histostat and Albac/Histostat (approved for use in turkeys for prevention of blackhead). All three uses would cease to be marketed upon withdrawal of the nitarsone approval, FDA noted. Blackhead is a disease that occurs seasonally in certain parts of the country and is a cause of significant mortality in turkeys. Currently, nitarsone is the only animal drug approved for managing this disease in turkeys. Under the phase-out plan announced Wednesday, nitarsone will continue to be available for the 2015 season. FDA stated that this strategy allows affected producers the opportunity to consider alternatives for managing the disease in the future.