A guide to PFAS: From what forever chemicals are to how they can hurt you

Margaret Darby
·6 min read
A Burger King Whopper in a wrapper, left, rests next to a McDonald's Big Mac in a container, in Walpole, Mass., Wednesday, April 20, 2022. Food wrappers and packaging that contain “forever chemicals” that can harm human health are no longer being sold in the U.S., the Food and Drug Administration announced Wednesday, Feb. 28, 2024.
A Burger King Whopper in a wrapper, left, rests next to a McDonald's Big Mac in a container, in Walpole, Mass., Wednesday, April 20, 2022. Food wrappers and packaging that contain “forever chemicals” that can harm human health are no longer being sold in the U.S., the Food and Drug Administration announced Wednesday, Feb. 28, 2024. | Steven Senne

Discourse about “forever chemicals,” which are formally known as PFAS or per- and polyfluoroalkyl substances, is everywhere right now.

And so are the nearly indestructible man-made chemicals that the conversation is about.

So, why should you care?

Even a shallow dive into the topic of forever chemicals will tell you that they are embedded in dozens of everyday objects, from your raincoat to your frying pan. They’re even in the water you drink and the air you breathe.

Exposure to these chemicals is unavoidable, but research shows they can negatively impact your health, increasing a risk of developing certain cancers and potentially causing birth defects.

Here is a guide to forever chemicals, which includes a look at what PFAS are, where PFAS are found and why PFAS can be dangerous.

What are forever chemicals?

Forever chemicals, which are also known as per- and polyfluoroalkyl substances, or PFAS, are man-made chemical groups, per Harvard Health. They are called forever chemicals because they do not break down in our bodies or in the environment.

PFAS have a unique chemical structure, as Elsie M. Sunderland, an environmental chemist at Harvard who’s been studying PFAS for roughly a decade, explained to Vox.

“An organic molecule has bonds of carbon and hydrogen atoms. To make PFAS molecules, you replace the hydrogen with fluorine. So PFAS are molecules that have chains of fluorine-carbon bonds, and it’s incredibly difficult to break these bonds,” Sunderland told Vox.

“They are among the most persistent chemicals we’ve ever created. It takes a huge amount of energy to break down that carbon-fluorine bond.”

These chemicals have embedded themselves into our environment.

“Every raindrop has PFAS in it,” said Scott Belcher, an associate professor at North Carolina State University, per TIME. “It is really earth-shaking for me and eye-opening for folks.”

Forever chemicals are in our water, soil and air, according to the United States Environmental Protection Agency. They contaminate drinking water and sometimes fish and livestock are exposed to them through water and soil.

For some people, exposure to forever chemicals can lead to adverse health issues, such as kidney and testicular cancer, increased cholesterol, reduced response to vaccines, thyroid disease, infertility, reduced birth weight, birth defects and liver damage, per the CDC.

Your health outcomes depend on the type and length of exposure and your health history, among other factors, the CDC reported.

PFAS are not just in food — they are everywhere

Dental floss. Furniture. Cookware. Clothing. Water. Forever chemicals are not only found in some foods, they are in dozens of everyday objects.

“PFAS are man-made chemicals that have been used in industry and consumer products worldwide since the 1940s,” per the CDC’s Agency for Toxic Substances and Disease Registry. “They have been used to make nonstick cookware, water-repellent clothing, stain resistant fabrics and carpets, some cosmetics, some firefighting foams, and products that resist grease, water, and oil.”

According to the Wisconsin Department of Health Services, PFAS are commonly found in the following everyday objects:

  • Nonstick cookware.

  • Cleaning products.

  • Food packaging.

  • Tap water.

  • Water-resistant clothing, upholstery or carpet.

  • Electronics.

  • Wall paint.

  • Toilet paper.

  • Beauty products like shampoo and makeup.

  • Grease-resistant paper.

  • Dust.

The list goes on.

Due to their association with so many common objects, attempting to avoid these chemicals is pretty much futile. But there are simple lifestyle changes you can make to limit contact, experts say.

The National Resources Defense Council recommends taking these simple actions to manage exposure to forever chemicals.

  • Use a water filter.

  • Check clothing and beauty products for “PFOA-free” or “PFOS-free” tags.

  • Review lists of brands that make PFOA- and PFOS-free outdoor apparel and gear.

  • Replace nonstick pans with stainless steel pans or other alternatives.

  • Don’t heat up food that is in grease-resistant packaging.

  • Regularly dust surfaces in your home.

Does bottled water have PFAS?

Sometimes, even bottled water includes forever chemicals.

Regulations surrounding PFAS in water systems vary between states and cities, reports The Washington Post. Bottled water is typically safer than tap water but sometimes what you are getting is bottled tap water.

In a 2021 study published the journal Water Research and led by Johns Hopkins University, researchers found PFAS substances in 39 out of more than 100 bottled water brands tested. The study did not identify which brands were tested, but noted that bottles labeled as “purified” typically contained less PFAS.

Why are forever chemicals harmful?

Research has found that exposure to forever chemicals is associated with heightened risk of developing some cancers, liver damage, allergies, thyroid disease, asthma, higher cholesterol, reduced vaccine response, as well as infertility, low birthweight, birth defects, newborn death and delayed development, per Harvard Health.

This research is ”just the tip of the iceberg,” according to Carmen Messerlian, an epidemiologist who spoke with Harvard Health.

“This is only basically what we’ve been able to study. There’s probably a lot more impact. We just haven’t been able to do the science to be able to show it.”

Liver damage

Research published in the Journal of High Energy Physics said that people with higher than average exposure to PFAS are more likely to develop liver cancer.

“A really important part of the studies is actually being able to say that before these people got cancer, they had higher levels” of the chemicals, said Jesse Goodrich, an environmental epidemiologist and the lead author.

“And that helps us to determine that it’s more likely in this situation that it’s actually PFAS that are associated with the cancer as opposed to just some sort of random chance,” Goodrich said.

Goodrich and others believe more research needs to be done.

Thyroid cancer

A study published in eBioMedicine found a link between PFAS exposure and higher risk of thyroid cancer.

“With the substantial increase of thyroid cancer worldwide over recent decades, we wanted to dive into the potential environmental factors that could be the cause for this rise,” Maaike van Gerwen, a study co-corresponding author and an assistant professor and director of research in the department of otolaryngology/head and neck surgery at Mount Sinai Hospital’s Icahn School of Medicine in New York, said in a press statement.

“This led us to the finding that PFAS … may at least partially explain the rise of thyroid cancer and are an area we should continue to study further.”

Birth defects

A study from Environmental Health Perspectives found that 97% of the 300 pregnant women who took part had PFAS chemicals in their bodies. If an unborn child is exposed the these chemicals, it may complicate their health at birth.

A previous study published by the journal Environmental Health Perspectives found that exposure to forever chemicals while in the womb was associated with preterm birth, low birth weight, developmental delays, gestational diabetes, childhood obesity and birth defects.