What we know about the health risks of "forever chemicals"

• While it’s possible to reduce your exposure to PFAS with lifestyle and health changes, the nature of these chemicals, their pervasiveness, and the way they leach into the environment means it’s likely impossible to avoid them entirely
• PFAS have been linked to multiple types of cancer, obesity, liver damage, fertility issues, and immunosuppression
• The FDA eliminated the use of these chemicals in food applications as of February 2024, but they’re still allowed in nonstick cookware, and lingering stock of PFAS-treated food packaging may still be on the market 
• Quantity of exposure matters, but the chemicals are odorless, tasteless, and colorless, meaning it’s difficult to assess one’s lifetime exposure 

What are forever chemicals? 

Per- and polyfluoroalkyl substances, or PFAS, are a group of nearly 15,000 synthetic chemicals used in a wide variety of products worldwide since the 1950s. The carbon-fluorine bonds that define this class of chemicals are particularly strong, which means the chemicals do not degrade easily, leading to the nickname “forever chemicals.”  

Common sources of exposure 

Unsurprisingly considering the vast number of compounds in this class of chemicals, PFAS are used in a vast array of products, from firefighting foam, to stain repellent fabric and carpeting, to waterproofing, to nonstick cookware. Jet engines, cosmetics, medical devices, and industrial equipment all rely on the compounds. Until recently, they were used in dozens of food packaging products, including microwave popcorn bags, takeout containers, and fast food wrappers. The FDA discontinued their use in food packaging at the end of February, but older stock of all these products will take some time to make its way out of the supply chain. 

However, even without significant direct exposure, most of us are currently exposed to PFAS. Since they take hundreds (or possibly thousands) of years to degrade, they often leach into soil and water sources, meaning they show up in the food and water supply. The chemicals are colorless, tasteless, and odorless, meaning there’s no simple way to know if you’ve encountered PFAS in the food, water, or air without testing. 

One study found PFAS in the blood of 97% of adult Americans^[1], and they have been found in the blood of newborn babies, in creatures ranging from polar bears to plankton, and in regions as remote as Siberia.^[2] 

PFAS and cancer 

PFAS have been implicated in a variety of cancers, including: 

• Kidney cancer
• Thyroid cancer and non-Hodgkin lymphoma
• Testicular cancer
• Pancreatic cancer
• Childhood leukemia
• Breast and reproductive cancers
• Prostate cancer
  

The mechanisms for how these chemicals lead to cancer aren’t well understood, in part because there are still few rigorous studies of the chemicals’ effects in the human body. Moreover, the studies which exist tend to focus on a handful of the compounds. Though links to breast and reproductive cancers are still tenuous, there is biologic evidence of endocrine disruption from the chemicals^[3], a known risk for these types of cancers. A recent study by the Yale School of Public Health additionally shows evidence that PFAS caused cancer cells to migrate, which implies the chemicals might also speed metastasis of cancer, regardless of the type.^[4]

Currently, kidney cancer and testicular cancer show the strongest evidence of a causal relationship. The National Cancer Institute’s Division of Epidemiology and Genetics is currently running studies on several different types of cancer in an effort to better understand the chemicals and their risks. 

Despite limited evidence, in 2023 the International Agency for Research on Cancer (IARC) officially designated the most studied chemical in the PFAS family, perfluorooctanoic acid (PFOA), as carcinogenic. 

Additional health problems linked to PFAS

PFAS have also been linked to several additional health problems. All of these health concerns raise your overall cancer risk. 

Obesity - A recent study from the University of Rhode Island^[5] found that higher concentrations of PFAS in the blood correlated with significant increase in weight gain across five different diets, leading the researchers to postulate that the chemicals alter metabolism. Previous studies have tied PFAS with childhood obesity and an increase in cholesterol in children. 

Liver damage - A National Institute of Environmental Health Sciences review of 111 studies on how PFAS affect the liver^[6] showed that elevated levels of three PFAS commonly found in people corresponded with elevated levels of liver enzymes that indicate damage to the organ. Rodent studies also linked the chemicals to steatosis, the first stage of non-alcoholic fatty liver disease (NAFLD). Both liver damage and NAFLD increase the risk for liver cancer.

High blood pressure - A large population study^[7] showed a small but significant increase in both diastolic and systolic blood pressure amongst heavily exposed young adults. While the size of the increase may not seem alarming, the range of health problems that high blood pressure can contribute to make the potential ramifications significant

Fertility and reproductive health - Exposure to PFAS has been linked to both reduced fertility and delayed onset of puberty in girls. Both these results may have to do with endocrine disruption caused by the chemicals.^[8][9] 

Weakened immune system - PFAS have been shown to cause immune suppression, significantly reducing the efficacy of vaccination. Particularly when considering the wide variety of preventable diseases that can cause significant and widespread inflammation–a known risk for cancer–this finding could have wide-ranging implications. 

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How can you reduce your exposure to PFAS? 

PFAS are used so widely, and have been in use for so long, that they’ve made it to the furthest corners of the globe. Because of their persistent nature and ability to contaminate soil and drinking water, it’s functionally impossible to completely protect yourself against the substances. 

The amount of exposure to PFAS is an important factor in how they act in the human body–the observed increase in cancers and other health problems in human studies have mainly been in populations with significant exposure, either through majorly contaminated water sources or daily contact with the chemicals in a career capacity (firefighters working with PFAS-containing fire suppressant foams, for example). 

That said, we’re only just beginning to understand the ways they operate in the human body, and it’s likely any exposure carries some health risk. An apt comparison might be smoking versus second- or thirdhand smoke exposure–one carries much more risk, but it’s best to avoid them all. Fortunately, there are certain steps you can take to reduce your exposure and mitigate your risk from PFAS: 

1. Replace your nonstick pans
   While the FDA claims^[10] that the risk posed by nonstick pans is low if they’re used properly, the coating on nonstick pans will eventually chip or flake, and the PFAS it contains can then make their way into your food. Stainless steel pans have no such coating, and ceramic coating on pans acts as a natural nonstick with none of the dangerous chemicals. 
2. Consider changing your diet
   While it’s likely most foods contain some level of PFAS, some foods have been shown to have higher concentrations^[11] on average. A recent paper showed that individuals with higher tea, pork, nut and seed butter, sports drinks, processed meat, and bottled water intake had higher concentrations of PFAS in their body. The association was strongest with tea and pork. Individuals who consumed more takeout food likewise showed higher concentrations of PFAS. Seafood has also been shown to contain high levels of PFAS, particularly shellfish, including shrimp and lobster.^[12] Conversely, a high fiber diet has been shown to be protective against some of the negative effects of PFAS exposure in early studies.^[13] 
3. Invest in a quality water filter
   The Environmental Working Group^[14] (EWG) says that more than 200 million Americans might be drinking PFAS-contaminated water, and multiple large-scale studies of the chemicals’ effects were the result of known contamination of drinking water. Some water filters can remove the chemicals, however. The EWG has tested several and picked their favorites. And if you’re unsure about the safety of your water, the EWG’s interactive map can give you more insight. 
4. Check whether your personal products are safe
   The EWG has also created a searchable database of thousands of consumer cosmetic products, and has rated them for overall safety. With over 15,000 potential chemicals to consider, it’s simpler and more effective than checking individual labels. ‍
5. Look for PFAS-free products
   ‍While it’s not always possible to find a PFAS-free alternative, many products are advertising their avoidance of the chemicals to consumers. If a product label exists, look for “fluoro” or “perfluoro” in the names of any ingredients or component parts–these are likely PFAS. Fabrics that promise to be waterproof or stain resistant–and which don’t specifically state they’re PFAS-free–probably contain PFAS. If you menstruate, consider a medical-based silicone period cup; PFAS (as well as lead, arsenic, and other toxic chemicals) have been detected in a wide swathe of sanitary napkins and tampons.^[15]

PFAS have been linked to a wide range of health risks, and should be avoided whenever possible. Lifestyle and dietary changes can significantly reduce your exposure.