Three of four arsenic drugs used in animal feeds have been banned by the U.S. Food and Drug Administration.
The drugs -- roxarsone, carbarsone, and arsanilic acid -- were added to feed for chicken, turkeys and pigs to prevent disease and promote growth. However, recent studies showed levels of arsenic in chicken that exceeded amounts that occur naturally, The New York Times reported.
Nearly four years ago, the Center for Food Safety and several other advocacy groups filed a petition seeking to ban the four drugs in animal feed.
The fourth drug, nitarsone, is the only known treatment for blackhead (histomoniasis), a disease that can kill turkeys. The FDA said it will continue to study the effects of nitarsone, The Times reported.