Your fast food burgers or burritos may come wrapped in potentially dangerous chemicals, according to recent research.
The study in the journal Environmental Science and Technology Letters tested 400 container samples from 27 different fast food chains. Researchers detected fluorine in nearly half, including the four largest fast food chains in the U.S.
That's McDonald's, Starbucks, Chipotle Mexican Grill and Yum brands.
McDonald's tested 19 percent positive for potentially dangerous chemicals. Jimmy John's and Quiznos tested 100 percent positive.
The National Institute of Environmental Sciences said there is not enough data to know what the health risks are.
A McDonald's spokesperson told Bloomberg "the company's packaging is safe and contains materials that meet FDA standards."
Chipotle said their packaging complies with FDA requirements, but they are working to make products that are free of those potentially dangerous chemicals.
Quiznos responded to the study, saying they are looking into it.
Starbucks and Jimmy John's have not commented on the study.