The report found fluorinated chemicals in one-third of the fast food packaging researchers tested.
These chemicals are favored for their grease-repellent properties.
Along with their use in the fast food industry, fluorinated chemicals -- sometimes called PFASs -- are used "to give water-repellant, stain-resistant, and non-stick properties to consumer products such as furniture, carpets, outdoor gear, clothing, cosmetics (and) cookware," according to a news release that accompanied the report.
"The most studied of these substances (PFOSs and PFOAs) has been linked to kidney and testicular cancer, elevated cholesterol, decreased fertility, thyroid problems and changes in hormone functioning, as well as adverse developmental effects and decreased immune response in children."
These are long-chain PFASs that have largely been phased out, in favor of shorter-chain compounds that are thought to have shorter half-lives in the human body, but these shortened forms have not yet been thoroughly studied.
As these chemicals are used in many everyday products, consumers are exposed to them frequently, and the same health effects may not be true for all of them.
Previous studies have shown that PFASs can migrate from food packaging into the food you eat, said Laurel Schaider
, a research scientist at the Silent Spring Institute
and one of the authors of the paper.
"These studies have found that the extent of migration depends on the temperature of the food, the type of food and how long the food is in contact with the paper," Schaider said. "And it depends on which specific chemical" is in the packaging.
What constitutes a bad (w)rap?
Scientists at the five institutions that collaborated on the report collected more than 400 samples of fast food packaging from 27 leading US chains.
The types of packaging were split into six categories: food contact paper (sandwich wrappers and pastry bags), food contact paperboard (boxes for fries or pizza), non-contact paper (outer bags), paper cups, other beverage containers (milk and juice containers) and miscellaneous (lids).
Food contact papers were divided into three subcategories: sandwiches, burgers and fried foods; Tex-Mex; and desserts and breads.
Food contact paper fared the worst, with 46% of all samples testing positive for fluorine. Food contact paperboard was next, at 20%, followed by other beverage containers at 16%. Non-contact paper, paper cups and miscellaneous all tested negative for fluorine.
The researchers did not provide any chain-specific data in order to compare fast food restaurants or determine which brands scored better or worse than average.
"For foodservice packaging that requires a barrier coating, 'short chain' fluorochemicals are used today, so it's no surprise that the study would find these chemicals," said Lynn M. Dyer, President of the Foodservice Packaging Institute
in the US. "These, like all packaging products, go through rigorous testing to ensure that they meet stringent US Food and Drug Administration regulations, providing the safe delivery of foods and beverages to consumers."
Dryer added, however, that "some fluorochemical-free products have been introduced since this study was conducted in 2014 and 2015," meaning there are now a greater numbers of options available for fast food chains to provide oil, grease and/or water resistance.
What's a consumer to do?
Short of asking that your next burger be served in between two lids, there isn't a whole lot you can do to avoid PFAS exposure once you've chosen to eat at a fast food restaurant.
"Unfortunately, for consumers, there's no easy way to tell -- just by looking at packaging -- whether or not it contains fluorinated chemicals," Schaider said. "For people who wish to reduce their exposure to these chemicals, they may be able to take some steps ... to reduce that migration from packaging into food -- for instance, by taking the food out of the packaging sooner rather than later."
You could also ask that your fries or dessert be served in a paper cup or a noncontact paper bag. This is the outer bag all your items are usually put into when you get your food.
More than anything, Schaider urges consumers to put pressure on their favorite fast food chains to switch to packaging that doesn't contain fluorinated chemicals.
"I think that this study provides yet another reason to support the idea that eating more fresh food and more home-cooked meals is better for our health," she said, "but it's hard to avoid the convenience of fast food, especially in people's busy lives."