Oct 10, 2019 7:00 AM

‘Forever Chemicals’ Are in Your Popcorn—and Your Blood

Food packaging can contain a group of chemicals called PFAS, which have been linked to immune, thyroid, kidney, and reproductive health problems.

Next time you pick up a pizza from your favorite pizzeria and toss the box in your front seat, think about why the grease doesn’t saturate through the cardboard onto your upholstery. Or when you hear popcorn bursting in a bag in your microwave, consider why the oil doesn’t ooze out and the paper doesn’t burst into flames, even when some kernels turn black.

The answer is likely to be PFAS. Per- and polyfluoroalkyl substances are a group of about 4,700 chemicals that make carpets and upholstery stain-resistant and help firefighters douse burning oil and gas. Some PFAS versions keep your burger from sticking to its fast-food wrapper and your salad from turning its fiber-based bowl into a soggy mess.

For years, scientists and environmental advocates have been sounding the alarm about these persistent “forever chemicals,” which break down very slowly and can contaminate groundwater and end up in rivers and oceans. PFAS chemicals, particularly those with long chains of carbon such as PFOA and PFOS, have been linked to immune, thyroid, kidney, and reproductive problems. PFOA, which has been designated as a possible carcinogen, has a half-life of 92 years in the environment and two to eight years in the human body.

As is so often the case with environmental issues, while steps have been taken to protect Americans from some PFAS chemicals, environmental health advocates and scientists say they don’t go far enough. Now a new study underscores that some common foods can ferry those chemicals into our bloodstream.

Researchers used interviews and biomonitoring data from almost 14,000 people, collected between 2003 and 2014, to build statistical models and find associations. From that federal data set, known as NHANES, they discovered that people who reported eating microwave popcorn had significantly higher levels of four types of PFAS chemicals, according to a study published in Environmental Health Perspectives. The more frequently people ate popcorn, the higher their level of PFAS chemicals in their blood samples.

The study also linked PFAS levels in blood to a diet high in shellfish, which can accumulate those chemicals from contaminated water. One limitation of the research: It measured PFAS chemicals used in past years, while current exposures are more likely to be versions that don’t persist as long in the blood—but are also less well-studied.

Virtually all Americans have detectable levels of PFAS in their blood. But the strongest association in the study revealed an antidote: The more often people ate at home, the lower their level of PFAS chemicals. “In the short term, it’s helpful to know some steps people can take,” says coauthor Laurel Schaider, a research scientist at Silent Spring Institute, the environmental research organization that performed the work. Ultimately, though, the solution to chemical exposure shouldn’t rely on consumer behavior, she says.

So add PFAS to the list of reasons it’s healthier to eat home-cooked food, but don’t despair too much about burgers, pizzas, and popcorn. Political pressure and consumer demand may force a change in food packaging, much the way public sentiment caused companies to remove BPA from plastic bottles and steel can linings.

BPA, or bisphenol-A, is a chemical that mimics estrogen and a component of polycarbonate plastics. In 1992, a Stanford University researcher accidentally discovered that BPA can migrate from a plastic container into its contents, such as food or water. Since then, hundreds of studies have analyzed its health effects, particularly focusing on the neurodevelopment of fetuses, infants, and young children. The NHANES data set revealed that 93 percent of Americans had detectable levels of BPA in their blood.

While the Food and Drug Administration reiterated that BPA was safe in food containers, consumers and local governments pushed back. By 2012, the FDA acknowledged that BPA was no longer used in baby bottles, sippy cups, and packaging of infant formula, and revoked its approval in those items.

The story of PFAS has begun to sound uncannily similar. Environmental advocates assert that PFAS chemicals may be worse than BPA because of the way they collect in our blood.

In 2019, the FDA analyzed 91 samples of food products for PFAS and found 14 with detectable levels. One item caught the eye of Maricel Maffini, a biologist who consults with environmental groups: chocolate cake with chocolate icing. It contained 17,640 parts per trillion of PFPeA, one of the many PFAS chemicals. By way of comparison, the EPA set a health advisory level of 70 parts per trillion for PFOA and PFOS in drinking water, although that standard doesn’t apply to food sources.

The FDA said none of the levels in its tests represented a health concern, “based on the best available current science.” There’s no regulatory limit for PFAS in food packaging, and the FDA has thresholds for safety only for PFOA and PFOS. More details may be yet to come; the FDA says it has established an internal work group to consider issues related to PFAS in food.

But the saga of BPA casts a shadow. Some of the substitutes for BPA turned out to be even more concerning. Evidence is emerging that “safer” PFAS versions aren’t actually safe either. After environmental contamination near manufacturing plants revealed significant health hazards, PFAS manufacturers eventually agreed to reduce and eventually eliminate PFOA, PFOS, and other PFAS chemicals that have long carbon chains.

Yet food packaging still sometimes contains them, along with the less persistent, short-chain form. A 2019 PFAS study on rats by the US Department of Health and Human Services’ National Toxicology Program showed that short-chain forms of PFAS had the same health effects related to the liver and thyroid as long-chain ones—although at higher doses.

“We need some testing of chemicals before they’re put out on the market instead of the whack-a-mole or the unfortunate substitution,” says Linda S. Birnbaum, who retired this month as director of the National Institute of Environmental Health Sciences and National Toxicology Program.

Part of the challenge is that tracking PFAS health effects takes years, notes Philippe Grandjean, an environmental health researcher at the University of Southern Denmark and at Harvard. He followed 490 children from birth to age 5 in the Faroe Islands, where PFAS exposure comes from marine food. He found that children with higher blood levels of PFAS had lower immunity after tetanus and diphtheria vaccination, based on their antibody response.

New forms of PFAS raise new questions, he says. “I’m not willing to put my grandchildren’s or the next generation of Americans at risk just because the compounds seem to be technologically useful,” says Grandjean.

That sentiment may be gaining ground. This year, Washington state and Maine passed laws banning the use of intentionally added PFAS chemicals in food packaging. In both states, the restrictions take effect in 2022 if safer alternatives are available. Bipartisan legislation currently in the US House of Representatives and Senate would, if passed, require the EPA to set national drinking water standards for PFOA and PFOS, increase monitoring and reporting of PFAS, and designate PFAS chemicals as hazardous substances, which would include them in the Superfund environmental cleanup program. In 2020, Denmark will become the first country to ban PFAS in food packaging.

Public awareness is likely to skyrocket in November when the Hollywood movie Dark Waters opens, starring Mark Ruffalo as a corporate lawyer who uncovers a hidden environmental disaster. It is based on the real-life story of PFOA contamination by chemical giant DuPont.

Lynn Dyer, president of the Foodservice Packaging Institute, asserts that the FDA-approved substances used in food packaging are safe. But she acknowledges that public opinion may put PFAS on the same trajectory as BPA. “If the customer says we don’t want PFAS in our packaging, then the packaging industry will design alternatives to meet the needs of their customers,” she says.

For now, though, old-fashioned wax paper might do the trick.