Chemicals called perfluoroalkyl substances (PFAS) have been used for decades to make products more stain-resistant, waterproof or nonstick. They're used in cookware to keep food from clinging to pots and pans. They're incorporated into clothing to repel stains and water, used in foams to fight wildfires, and used in furniture and carpeting as protection from stains. PFAS are even used in fast food and other packaging to keep food from sticking.

These "forever chemicals" — so called because they persist in our bodies and the environment for years — are seemingly everywhere.

The list of health concerns about PFAS is long; the chemicals have been linked to high cholesterol, effects on the immune system, hormone disruption, low infant birth weights and even cancer, according to the U.S. Environmental Protection Agency (EPA). Yet U.S. production of these chemicals remains robust. There are at least 118 PFAS chemicals produced in volumes in excess of 25,000 pounds per year, according to a report from the Environmental Working Group (EWG). That’s an increase of more than 55% since 2002, according to an analysis of EPA data by Public Employees for Environmental Responsibility, or PEER. And new variations of these chemicals have been produced with EPA approval as recently as 2015.

The EPA currently recommends a maximum limit of 70 parts per trillion (ppt) of PFAS in water, although that limit is not mandatory, and many public health advocates argue it's too high anyway. The agency has faced growing pressure to crack down on PFAS pollution, and in February 2020, it announced plans to begin regulating two of the most notorious forever chemicals, PFOA and PFOS. That has drawn cautious praise from the EWG and others, although it could be years before any regulations are finalized. The EPA will have two years to set the new limits, The Hill reports, and then another 18 months to finalize the rules.

The prevalence of PFAS has also gotten the attention of the U.S. Food and Drug Administration (FDA), which confirmed in April 2019 that the chemicals have made their way into our food system. The warning was based on the initial findings of the agency's ongoing investigation of the chemicals and the U.S. food supply. The ongoing work is presented in an updated website the agency unveiled in 2019.

More recent lab tests commissioned by EWG found that dozens of cities across the U.S. have PFAS in their drinking water. Tap water samples in 43 of 44 cities detected the chemicals. The samples were taken from 31 states and Washington, D.C. Some of the highest PFAS levels were in water taken from major metro areas, including Miami, Philadelphia, New Orleans and the New Jersey suburbs of New York City.

"Our results are meant to highlight the ubiquity of PFAS and the vulnerability of the nation’s drinking water supply to PFAS contamination," the authors wrote in their report.

'We are decades behind in the research' on PFAS

hamburger fast food wrapped in paper Fast-food wrappers often contain PFAS because the chemicals can help prevent food from sticking. (Photo: Xanya69/Shutterstock)

"We are decades behind in the research because these compounds were first used in the 1950s and not much toxicology was done and there was no legislation," study co-author Philippe Grandjean, adjunct professor in the Department of Environmental Health at Harvard T.H. Chan School of Public Health, tells MNN. "They were just produced and applied and waste seeped out into the environment."

Because the chemicals have been used for decades in so many ways, they are ingrained in the environment, Grandjean says. A study published in Environmental Science & Technology Letters found that PFAS levels exceed recommendations in the drinking water supplies for at least 6 million Americans.

"Even if we do something about them now, this is a lasting problem and we will continue to be exposed," Grandjean says. "The greatest concentration is in polar bears, and they don't use sneakers or cookware."

The link between PFAS and obesity

One study suggests the chemicals may also make it tougher to keep off weight, and as Grandjean puts it: "This is just another nail to the coffin, so to speak."

The February 2018 study, published in the journal PLOS Medicine, found that higher levels of PFAS in the blood were associated with increased weight gain after dieting, particularly in women. The compounds are referred to as "obesogens" because they may upset normal metabolism and increase your risk for gaining weight the more you're exposed to them. The study found that people with higher concentrations of PFAS in their bodies also had a lower resting metabolic rate (RMR), meaning they burn fewer calories during normal daily activities.

"The potential endocrine-disrupting effects of PFAS have been demonstrated in animal studies, but whether PFAS may interfere with body weight regulation in humans is largely unknown," Gang Liu, lead researcher for the study and research fellow in the department of nutrition at Harvard T.H. Chan School of Public Health, tells MNN.

Researchers analyzed data from 621 overweight and obese people who took part in a two-year clinical trial conducted in the mid-2000s. The participants lost an average of 14 pounds in the first six months of the trial, but regained about six pounds over the next 18 months. The people who gained back the most weight had the highest concentration of PFAS, and the link was strongest among women.

"We found that all individual PFAS were significantly associated with more weight regain in women, but not in men, which was in agreement with some previous studies in which the intergenerational effects of PFAS on body weight were observed only in girls but not in boys," Liu says. "Although the reasons for these gender-specific findings are still unclear, accumulating evidence from experimental research suggests that PFAS are able to interfere with estrogen metabolism and functionalities."

Although the researchers say more studies are needed to confirm their findings, one thing seems clear.

"These findings suggest that environmental chemicals might play a role in the current obesity epidemic," the researchers conclude. "Given the persistence of these PFAS in the environment and the human body, their potential adverse effects remain a public health concern."

What you can do

water coming out of a faucet PFAS contamination in water supplies can vary widely from place to place. (Photo: Latte Art/Shutterstock)

To reduce your exposure to PFAS, Grandjean suggests calling your municipal water plant to make sure your water doesn't contain unacceptable levels of these compounds. (Although Grandjean points out he believes the EPA's "safe" limit of 70 parts per trillion is too high. As mentioned above, you can see how your city compares in the data from EWG.) He suggests drinking and cooking with bottled water or installing an activated carbon filter.

Cutting back on fast food may also decrease your exposure to the chemicals in the wrappers, as researchers from from the Silent Spring Institute and the University of Massachusetts Amherst discovered. (That move might also have the added benefit of helping you keep the weight off, too.) They looked at the association between PFSA serum levels and consumption of restaurant food and popcorn in a sample of Americans through the National Health and Nutrition Examination Survey and found that food is a major pathway for these chemicals to enter the body. The biggest culprit was microwave popcorn, as they described in a study published in Environmental Health Perspectives, and fast-food wrappers were also notable. The best solution for this problem, they wrote, was to eat at home more often, as that habit showed a notable decrease in the chemicals.

In addition, when shopping for everything from rain gear and waterproof shoes to carpeting and cookware, be informed, Grandjean says. Do your research, look for labels and ask if the products have been treated with PFAS.

Editor's note: This story has been updated since it was originally published in February 2018.

Mary Jo DiLonardo covers a wide range of topics focused on nature, health, science and anything that helps make the world a better place.

Why we can't run from 'forever chemicals'
Toxic compounds called PFAS have been linked to cancer and immune problems, and they may also make it tougher to keep off weight.