That's not okay with Sen. Chuck Schumer, D-N.Y., who on Sunday called on the FDA to ban the substance.
"McDonald's bread is so full of azodicarbonamide so that billions and billions served could really be billions and billions served toxic chemicals," Schumer told Newsday, adding that the chemical is banned "in most of the developed world."
Last week, Subway announced that it would stop using azodicarbonamide to make its bread after Vani Hari, an activist known for her blog Food Babe, earned 57,000 signatures on a petition calling on the restaurant chain to reform its recipe and "stop using dangerous chemicals."
The World Health Organization has linked the chemical to allergies, asthma and other respiratory issues, but the chemical is legal in the U.S. and Canada.
Jeff Stier, the head of risk analysis at the National Center for Public Policy Research, a conservative think-tank in Washington, thinks the outcry is an overreaction.
"[Schumer] is allowing the Food Babe to dictate policy based on the notion that the chemical also appears in yoga mats, therefore it is harmful," Stier told ABC News. "Is he saying we shouldn't trust the FDA's food scientists?"
McDonald's spokesperson Lisa McComb pointed out that the version of the chemical used for industrial purposes is different than the variety used and approved for food production.
"Just to give an analogy that might make sense, there is salt to de-ice your driveway and salt you use in the kitchen. They are both sodium chloride," McComb said.