[2015 Jan] The FDA Admits That Prior to 2011 Over 70% of U.S. Chickens Contained Cancer-Causing Arsenic  Prior to 2011, the cancer-causing toxic chemical Roxarsone, which in high doses could kill you, was being added to chicken feed on purpose, giving store-bought chicken the illusion of healthy coloring and plump appearance. Shockingly, this was the case with more than 70 percent of all U.S. chickens!