Miami (AFP) - Burgers, fries, tacos and pastries come wrapped in grease-proof paper and boxes that often contain non-stick chemicals that may be able to leach into food, US researchers said Wednesday.
The study in the journal Environmental Science and Technology Letters tested more than 400 samples from 27 fast food chains in the United States.
Almost half of paper wrappers and 20 percent of paperboard samples -- such as boxes for fries and pizza -- contained fluorine, a marker for highly fluorinated chemicals used in stain-resistant carpets, non-stick cookware and waterproof outdoor apparel.
"Wrappers for Tex-Mex food, desserts and breads were the most likely to contain fluorine," said the report.
The study did not show any specific harm to human health from exposure to these chemicals -- known as per- and polyfluoroalkyl substances (PFASs) -- in food wrappers.
But researchers warned that exposure to some PFASs has been associated with cancer, thyroid disease, immune suppression, low birth weight, and decreased fertility according to prior studies.
"These chemicals have been linked with numerous health problems, so it's concerning that people are potentially exposed to them in food," said lead author Laurel Schaider, an environmental chemist at the Silent Spring Institute.
"Children are especially at risk for health effects because their developing bodies are more vulnerable to toxic chemicals."
Six of the samples contained a long-chain PFAS called perfluorooctanoic acid (PFOA), also known as C8, even though several major US manufacturers agreed to stopping using C8 compounds in food packaging due to health hazards, after a 2011 US Food and Drug Administration review.
Researchers also detected some shorter-chain PFAS compounds, which have been increasingly used as replacements for the longer chain PFASs.
"The replacement compounds are equally persistent and have not been shown to be safe for human health," said co-author Arlene Blum, founder of the Green Science Policy Institute.
"That's why we need to reduce the use of the entire class of highly fluorinated compounds. The good news is there are non-fluorinated alternatives available."
About one in three American kids eat fast food every day.
The United States began phasing out certain PFASs in 2000, but other countries still produce them, and they tend to linger in the environment for long periods after being discarded in landfills.
Prior studies have shown that substances in food packaging can migrate into food.