Published April 2026 — Updated Regularly

PFAS Forever Chemicals Explained: What They Are, Where They Come From, and Why They Matter

Last updated: May 2026

You've probably heard the term "forever chemicals" — in news stories about contaminated water, cancer lawsuits, or environmental disasters. But what exactly are they? Why is everyone suddenly paying attention? And if you've been exposed, what does that actually mean?

Here's what you need to know about PFAS forever chemicals — starting from the basics.

What Are PFAS?

PFAS stands for per- and polyfluoroalkyl substances. It is a group of more than 12,000 synthetic (man-made) chemicals that share one key feature: they all contain chains of carbon atoms bonded to fluorine atoms.

The carbon-fluorine bond is one of the strongest chemical bonds in nature. This is why PFAS are so extraordinarily durable — they do not break down when exposed to heat, water, oil, acid, or sunlight. In chemistry terms, they are extremely persistent. In everyday terms, they are essentially indestructible.

This durability is why scientists call them "forever chemicals." Once created, they persist in the environment — and in the human body — indefinitely. A molecule of PFOA (one type of PFAS) released 50 years ago is still in the environment today. It will be there 50 years from now.

What Are PFAS Used For?

PFAS were first developed in the 1940s. The chemical and manufacturing industries valued them because their resistance to heat, water, and grease made them useful for a huge range of applications. Over the following decades, PFAS were incorporated into:

• Nonstick cookware — Teflon's nonstick coating is made with PFAS
• Waterproof and stain-resistant clothing — GORE-TEX and similar fabrics use PFAS coatings
• Food packaging — Grease-resistant paper, microwave popcorn bags, pizza boxes, fast food wrappers
• Firefighting foam (AFFF) — Aqueous film-forming foam used at military bases and airports to fight jet fuel fires
• Semiconductor and electronics manufacturing
• Carpets and upholstery — Scotchgard-type stain resistance
• Cosmetics — Certain mascaras, foundations, and lip products
• Dental floss — Some brands used PFAS coatings
• Medical devices
• Paper and cardboard products

By the 1990s and 2000s, PFAS were found in the blood of virtually every American ever tested. A 2007 CDC study found PFAS in the blood of 98% of Americans sampled. We were all exposed, largely without our knowledge or consent.

How Did PFAS Get Into Our Water?

The main routes of water contamination are:

Military and Airport Firefighting Foam

This is the leading cause of localized, severe PFAS contamination. AFFF — the foam used to fight jet fuel fires at military bases and airports — contains massive concentrations of PFAS. For decades, this foam was used in training exercises, accidental fires, and emergency responses. The foam soaked into the ground, leached into groundwater, and ended up in the drinking water of surrounding communities.

The Department of Defense has now identified contamination at hundreds of military installations. Communities near these bases have some of the highest PFAS levels measured anywhere in the country — levels hundreds or thousands of times above the new EPA limits.

Industrial Manufacturing

Companies like 3M and DuPont manufactured PFAS chemicals in large quantities, releasing them into air, water, and soil for decades. The communities near these plants — Cottage Grove, Minnesota (3M); Parkersburg, West Virginia (DuPont); Fayetteville, North Carolina (Chemours) — experienced severe contamination.

Landfills and Biosolids

PFAS-containing products that ended up in landfills gradually leached chemicals into groundwater. Similarly, "biosolids" — processed sewage used as agricultural fertilizer — sometimes contain PFAS from personal care products and industrial wastewater, contaminating soil and wells on farms where they were applied.

Why Are They Called "Forever Chemicals"?

The "forever" in forever chemicals refers to both environmental persistence and bioaccumulation in the human body.

Environmental persistence: PFAS do not degrade in the environment. They move through soil into groundwater, travel through rivers, and eventually reach drinking water sources. Once contaminated, a groundwater aquifer can remain contaminated for generations. Standard water treatment — chlorination, filtration — does not remove PFAS. You need specialized treatment (activated carbon, reverse osmosis, or ion exchange) to remove them.

Bioaccumulation: PFAS build up in living organisms over time. When you drink PFAS-contaminated water, the chemicals absorb into your bloodstream and bind to proteins in your blood, liver, kidneys, and other organs. Because they do not break down and are only slowly eliminated, they accumulate over years of exposure. This is why someone who drank contaminated water for 20 years faces much higher health risks than someone who drank it for 1 year.

What Do PFAS Do to the Body?

PFAS cause harm through several biological mechanisms:

Endocrine Disruption

PFAS interfere with the body's hormone systems — particularly thyroid hormones and sex hormones. Thyroid hormones control metabolism, growth, and brain development. PFAS bind to the proteins that carry thyroid hormones in the blood, disrupting this system. This is why thyroid disease — both hypothyroidism and hyperthyroidism — is elevated in PFAS-exposed populations.

Immune System Suppression

PFAS are documented immunosuppressants. Studies of children exposed to PFAS through breast milk or drinking water show reduced antibody production after vaccination — meaning their immune systems respond less effectively to vaccines. This immune suppression likely contributes to increased cancer risk as well, since a healthy immune system plays a role in identifying and destroying early cancer cells.

Liver Toxicity

The liver is a primary site of PFAS accumulation and processing. High PFAS exposure is associated with elevated liver enzymes and non-alcoholic fatty liver disease.

Carcinogenicity

Multiple PFAS compounds are classified as possible, probable, or known carcinogens. The evidence is strongest for kidney cancer and testicular cancer, which are now classified as having "sufficient" scientific evidence of a causal link to PFAS exposure by the National Academy of Sciences.

Which PFAS Are the Most Dangerous?

There are thousands of PFAS compounds, but the most studied and most dangerous include:

• PFOA (perfluorooctanoic acid): Used in making Teflon; linked to kidney cancer, testicular cancer, thyroid disease, and pregnancy complications. Now largely phased out in the U.S. but still found in the environment at high levels from past contamination.
• PFOS (perfluorooctane sulfonic acid): The main ingredient in AFFF firefighting foam; linked to the same cancers as PFOA. 3M was the primary manufacturer and phased out production in 2002, but PFOS from past use remains widespread.
• GenX (HFPO-DA): A newer PFAS compound used by Chemours as a "replacement" for PFOA — but now linked to similar health concerns. Heavily contaminated the Cape Fear River in North Carolina.
• PFNA, PFHxS, PFBS: Other PFAS compounds with documented health effects, now subject to EPA regulatory limits.

What Did Industry Know — and When?

This is at the heart of PFAS litigation. Internal documents from 3M and DuPont — obtained through litigation and investigative journalism — show that these companies were aware of PFAS health risks as far back as the 1950s and 1960s.

A 2019 New York Times investigation revealed that 3M knew PFAS was toxic and accumulating in human blood as early as the 1950s. Internal DuPont documents showed the company's scientists knew PFOA caused cancer in animals by the 1980s — and the company kept producing and contaminating for decades after that.

That's the part that doesn't get talked about enough. The science wasn't hidden from everyone. It was hidden from you.

Plaintiffs in PFAS litigation argue that these companies had a duty to disclose what they knew and to stop contaminating water supplies. The companies dispute many of these allegations, but multiple settlements suggest they assessed significant litigation risk.

What Is Being Done About PFAS?

The regulatory and legal response to PFAS has accelerated dramatically:

• EPA drinking water limits: The first-ever federal MCLs for PFAS took effect in 2024, requiring water utilities to test and reduce PFAS to near-zero levels
• EPA Superfund designations: The EPA designated PFOA and PFOS as Superfund hazardous substances, allowing use of Superfund cleanup authority for contaminated sites
• DOD cleanup: The Department of Defense has begun remediation at contaminated military bases, though progress is slow and incomplete
• Industry phase-outs: Long-chain PFAS (like PFOA and PFOS) have been phased out by major U.S. manufacturers, replaced by shorter-chain compounds — some of which also raise health concerns
• Litigation: Billions of dollars in settlements have been reached, and personal injury litigation continues for individuals who developed cancer from PFAS exposure

If You Have Been Exposed

If you have lived near a military base, industrial PFAS site, or contaminated water supply — and you have developed kidney cancer, testicular cancer, thyroid cancer, or another PFAS-linked condition — you may have legal rights.

The AFFF MDL in South Carolina is actively accepting personal injury claims. Filing costs nothing upfront; attorneys work on contingency and are paid only if you receive compensation.

Find out if you qualify for PFAS compensation →

Sources

• National Academies of Sciences. "Guidance on PFAS Exposure, Testing, and Clinical Follow-Up." 2022.
• U.S. EPA. "PFAS Explained." epa.gov/pfas/pfas-explained
• Lerner S. "3M Knew About the Dangers of PFOA and PFOS Decades Ago, Internal Documents Show." The Intercept, 2018.
• Rich N. "The Lawyer Who Became DuPont's Worst Nightmare." The New York Times Magazine, 2016.
• ATSDR. "Toxicological Profile for Perfluoroalkyls." 2021.