Right now, you likely have something unnatural lurking inside your body. It was made by a large corporation and could potentially harm you.

That something is called PFAS.

Known colloquially as “forever chemicals,” PFAS — short for per- and polyfluoroalkyl substances — are a large group of chemicals that make certain products nonstick or stain resistant. Research indicates that these chemicals can be dangerous. Exposure to PFAS is linked to cancers, weakened immune systems among children, weight gain, and a wide range of other health problems.

PFAS are a public health concern, according to the Centers for Disease Control and Prevention. Yet companies are still producing them.

What’s especially alarming is that nearly all Americans have some amount of PFAS in their blood, no matter how healthy they might be. “We’re really seeing PFAS absolutely everywhere,” said Elsie M. Sunderland, an environmental chemist at Harvard who’s been studying PFAS for roughly a decade.

These chemicals are in all kinds of consumer products, from clothes to fast food, where they help repel oil and water. They also contaminate the water we drink and, in some places, even the air we breathe, Sunderland said. Earlier this summer, the Environmental Protection Agency published an advisory that suggests even tiny amounts of PFAS in drinking water may pose health risks.

The good news is that there are ways to avoid exposure, such as by using a water filter, Sunderland said. And new research suggests there might be a simple approach to destroy them in the environment.

To understand what these chemicals really are and how they might affect our bodies, I chatted with Sunderland, an expert on the topic. Our conversation has been edited for length and clarity.

Explain it like I’m 5: What are PFAS?

Benji Jones

How would you explain PFAS to a 5-year-old?

Elsie M. Sunderland

They are chemicals that we add to everyday products, such as our rugs, our fast-food packaging, and our cosmetics. Those chemicals repel oil and fat, and they are very profitable. And it turns out that when humans ingest them — either through their diet or water — they can cause some bad health effects.

Benji Jones

How would you explain them to a college student?

Elsie M. Sunderland

The chemical structure of PFAS is one thing that differentiates them from other chemicals.

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.

Benji Jones

Why are they called “forever chemicals”?

Elsie M. Sunderland

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.

[The term “forever chemicals” is also a play on words: The “f” in “forever” comes from “fluorine” and the “c” in “chemicals” comes from “carbon.” The Harvard researcher Joe Allen coined the term “forever chemicals” in a 2018 op-ed in the Washington Post.]

PFAS are absolutely everywhere — in fast-food wrappers, water, and even the air

Benji Jones

Where do PFAS come from?

Elsie M. Sunderland

The companies 3M, DuPont, and Chemours. Chemical companies make PFAS and sell them to other companies that use them in an incredibly diverse array of products. They’re really in everything: furniture, rugs, textiles, outdoor gear, paper packaging, food packaging.

They’re mainly used as surfactants — they repel oil and water. So when you have a spill on your furniture, and want to keep it clean, then PFAS are often added.

[DuPont has had a complicated history of mergers, acquisitions, and divestments, including spinning off its chemicals business in 2015 into what’s now known as the Chemours Company. In a statement to Vox, DuPont spokesperson Daniel Turner said, “the company has established a set of commitments to take responsible action related to PFAS.” You can read DuPont’s full statement regarding PFAS here.]

[3M spokesperson Sean Lynch told Vox that PFAS are important materials that can be used and manufactured safely. “3M is taking proactive steps to reduce our reliance on persistent materials through innovation.” You can read 3M’s full statement here.]

[Cassie Olszewski, a spokesperson at Chemours, said “the world depends on our products, and we are committed to manufacturing these essential chemistries responsibly.” Here’s the company’s full statement.]

Benji Jones

How do these chemicals contaminate the environment?

Elsie M. Sunderland

A major source of community contamination across the US has been a product called aqueous film-forming foam, or AFFF, which suppresses oil-based fires. The military actually requires AFFF at bases and they’ve used it for decades during training exercises [to put out purposefully set fires]. It’s 8-10 percent PFAS by weight, which is incredibly high. So you just need a tiny quantity of that to contaminate drinking water.

Bastiaan Slabbers/NurPhoto via Getty Images

If you’re trying to save a life during a fire, maybe you’d want to have AFFF, if you don’t have an effective alternative. The problem is that the military has used huge quantities of it for training. It contaminated the groundwater in all of these communities next to military bases. There are more than 600 known sites like this across the country.

[In a statement to Vox, the Department of Defense acknowledged that PFAS are a national problem and said it’s committed to protecting human health. “The Department prioritizes resources and addresses sites where risk to human health is the highest,” Defense officials said. Peter Hughes, a spokesperson for the department, also shared a memo from April 2022 that details a new policy that restricts the use of AFFF for training. You can read the complete statement here and the new AFFF policy here.]

Benji Jones

What consumer products expose us to PFAS?

Elsie M. Sunderland

One of my undergrads did a day in the life of a Harvard student and tested things around campus. She found PFAS in her Doc Martens, in the carpet, in the furniture’s upholstery, in shower curtains. It’s also in cosmetics like lotions and mascaras. Eye drops actually have it.

And if you’re into outdoor activities there are a ton of them. They’re in ski waxes and bike chain oils and outdoor clothing.

Benji Jones

What’s the likelihood that if I grab a burger at a fast-food joint I’m going to be exposed to PFAS?

Elsie M. Sunderland

Very high. But we should be able to fix that problem relatively quickly. A few US states are now banning PFAS in food packaging.

Benji Jones

Are there also PFAS in our drinking water? That seems particularly scary and unavoidable.

Elsie M. Sunderland

Almost everybody has some PFAS in their drinking water. And if you’re actually measuring what’s in your blood, 98 percent to 99 percent of people have PFAS in their bodies, so it’s literally in everybody.

Matthew Hatcher/Bloomberg via Getty Images

PFAS get into drinking water when they are released to the environment from sources such as firefighting foam use at airports and military bases, manufacturing sites, and waste disposal sites such as wastewater treatment plants and landfills. Some PFAS precursors are also transported in the atmosphere and when they break down and can be deposited onto soils and surface waters, eventually entering groundwater as well.

Benji Jones

Are they in the air, too?

Elsie M. Sunderland

It is in the air. There’s a plastic manufacturer in New Hampshire, for example, that has volatile emissions. You can see it in the soils surrounding the plant. Factories like these don’t emit the PFAS that people are concerned about — chemicals like PFOS or PFOA — but they emit compounds that degrade into them.

It’s also important to consider the indoor environment, because it’s on furniture and other things. Inhalation is actually another way it can enter your body.

What PFAS do to your body, at different levels of exposure

Benji Jones

Should we be worried about our exposure?

Elsie M. Sunderland

The people who should be most worried are those who are inadvertently exposed to those really contaminated sites. They have more severe problems — things like cancer. There’s been some sort of statistical association between PFAS and every major organ system in the body, which is not comforting. You name the disease and you can find an association.

In children, PFAS exposure has been associated with a decline in antibody production in response to routine vaccination. That’s an indicator of whole immune health. There are a bunch of studies showing increase in severity of Covid-19 with higher levels of exposure to certain PFAS. It’s also been linked to diabetes and the ability to lose weight.

Another really sad impact is related to breastfeeding. PFAS can interfere with fat metabolism. Anecdotally, there are a lot of reports of women who aren’t able to continue breastfeeding their children because they lack the [breast milk] supply.

Benji Jones

How do PFAS impact our body at lower levels of exposure, which an average American might experience?

Elsie M. Sunderland

Exposure to PFAS may do nothing or it may do something. The question is how meaningful is that risk relative to all the other risks you undertake. It’s not going to kill you immediately. And there’s a lot of evidence showing that some people are more sensitive to exposures to environmental chemicals than others.

A new advisory for drinking water from the EPA essentially says that any level of exposure to these chemicals is going to cause some health impacts. I agree with that.

Benji Jones

Why are these chemicals, specifically, so harmful to us?

Elsie M. Sunderland

Their half-lives [i.e., how long they take to decompose] are very long, so they accumulate in your body. They look like phospholipids [a kind of fatty acid], so they’re mimicking some other bodily function. Typically, when a chemical is harmful it’s because your body thinks it’s something else and it triggers some kind of response.

When you create synthetic organic chemicals that look like something else that the body uses naturally, you often run into problems. Some PFAS can also cross the blood-brain barrier, and some of them cross the placental barrier.

Benji Jones

Are all PFAS created equal?

Elsie M. Sunderland

Chemically, different PFAS molecules look quite different from each other. If you’re talking about something like lead, you’re talking about one compound; it looks one way and has a series of effects in the body. The problem with PFAS, in part, is that there are thousands of chemical structures. If you prove one is bad, we have all of these other ones.

Everybody calls PFAS the chemical wack-a-mole. You get rid of one of them and the industry just uses another one. Then, it takes a decade to figure out that this other PFAS chemical is just as bad, and then the industry uses yet another one.

The best ways to limit your exposure to PFAS

Benji Jones

So how do we avoid ingesting PFAS?

Elsie M. Sunderland

Cosmetics and personal care products tend to have active ingredient lists, and if any ingredient has a “fluoro” something in it, beware. You can go to websites like Environmental Working Group, which say what to look for and score different products according to their health implications.

One of the main ways for PFAS to go from a product to the human body is through dust. So an easy way to reduce exposure is to wipe down your surfaces. Be clean. Takeout food is harder, because there’s no product list [for the to-go containers].

Just be careful when you see “PFOA free” on something like a nonstick pan, because then it probably means that they just use a different kind of PFAS. Look for “PFAS-free” or “certified nontoxic.”

Benji Jones

What about in water? Do Brita filters or reverse osmosis systems get rid of them, or is bottled water better?

Elsie M. Sunderland

Those filters all remove some PFAS, but reverse osmosis is the most effective for taking all of them out. A paper [published in 2020] is quite encouraging because it shows that all of these different water filtration systems did remove some of them.

Bottled water is known to have high concentrations of PFAS. There was a case in Massachusetts a couple of years ago where bottled water had very high concentrations of PFAS in it because it was sourced from PFAS-contaminated water. So I think you’re better off drinking filtered water from a known source.

Paul Bersebach/MediaNews Group/Orange County Register via Getty Images

Benji Jones

How do you know whether your water source has PFAS in it?

Elsie M. Sunderland

You should be able to see it on your water utility bill. Utilities are all monitoring them now.

Benji Jones

What about air? Do air filters, like HEPA filters, help remove PFAS from the indoor environment?

Elsie M. Sunderland

HEPA filters capture fine particles, which reduce the amount of dust you inhale. So, yes, [they could help reduce PFAS exposure].

The chemical and fossil fuel industries are at fault

Benji Jones

Who’s to blame for spreading PFAS in the US?

Elsie M. Sunderland

Companies like 3M and Dupont. The industry has known for decades that these chemicals are really bad, but they’re incredibly profitable.

And the fossil fuel industry. These synthetic organic chemicals are typically fossil fuel derivatives. We talk about climate change and chemical exposure as two separate issues, but we should start thinking about them together. As we move away from fossil fuel combustion and towards renewable energy, the industry is going to turn their products into plastics and synthetic chemicals.

Benji Jones

Is the US government doing anything about this?

Elsie M. Sunderland

They’ve actually done a lot. It’s one of the only bipartisan issues related to environmental health, largely because there are vocal communities that have been affected in regions with different political affiliations.

But it’s difficult. The EPA typically assesses individual chemicals, instead of regulating chemicals as a class, which is what we need for PFAS because there are thousands of different chemicals that make up the class. For example, EPA is still doing work to map the Adverse Outcome Pathway for some legacy PFAS including PFOS and PFOA and this takes many years, while these compounds are no longer the ones being produced and have been replaced by new chemicals.

If we want to [limit our exposure to PFAS] we should act quickly. We should ban the non-essential uses, get rid of new production, and regulate them as a class. Most of the ways we use PFAS, we don’t need to, so why are we doing it?