Science

PFAS / Forever Chemicals

Synthetic compounds engineered to be chemically indestructible are now in the blood of virtually every person on Earth — and the companies that made them knew.

The short version

PFAS (per- and polyfluoroalkyl substances) are a class of approximately 15,000 synthetic chemicals used in nonstick cookware, food packaging, firefighting foam, stain-resistant fabric, and hundreds of industrial applications — valued precisely because they resist heat, water, and chemical breakdown.
That same indestructibility means PFAS accumulate in the environment and human body indefinitely; they are now detectable in virtually all human blood samples tested globally, in breast milk, in cord blood, and in drinking water sources serving hundreds of millions of Americans.
Health effects associated with PFAS exposure include kidney and testicular cancer, thyroid disease, immune suppression, elevated cholesterol, reduced vaccine effectiveness in children, and reproductive harm — with no known safe level of exposure for the most studied compounds.
3M and DuPont knew of PFAS toxicity for decades before regulatory action was taken, suppressed internal research, and fought cleanup liability — a pattern documented through internal corporate documents obtained in litigation.

What it is

PFAS — per- and polyfluoroalkyl substances — are a class of approximately 15,000 synthetic chemicals characterized by chains of carbon-fluorine bonds, among the strongest bonds in organic chemistry. This bond strength is what makes them useful: PFAS repel water, oil, heat, and chemical degradation with unmatched stability, which is why they were incorporated into nonstick cookware (Teflon), water-repellent clothing (Gore-Tex), grease-resistant food packaging (microwave popcorn bags, fast food wrappers), firefighting foam (AFFF, used extensively at military bases and airports), carpet and upholstery stain treatments (Scotchgard), and hundreds of industrial processes from semiconductor manufacturing to aerospace. 3M began producing PFAS compounds in the 1940s; DuPont used PFOA (a specific PFAS) in the manufacture of Teflon from the 1950s onward. By the late 20th century, PFAS were embedded in manufacturing supply chains globally.

The same chemical stability that makes PFAS industrially valuable makes them environmentally catastrophic. Carbon-fluorine bonds are so strong that biological processes and conventional environmental degradation do not break them down on any human-relevant timescale. They persist in soil, water, and living tissue indefinitely — which is why they are called 'forever chemicals.' PFAS released into the environment from manufacturing facilities, military bases, airports, and landfills migrate into groundwater and surface water; PFAS applied to consumer products enter wastewater systems and eventually drinking water supplies. A 2023 study in Environmental Science & Technology Letters estimated that PFAS contamination has made rainwater unsafe to drink virtually everywhere on Earth by EPA reference levels — including in Antarctica and the Tibetan Plateau, remote from any PFAS source.

Human PFAS exposure has become near-universal. The CDC's National Health and Nutrition Examination Survey found detectable PFAS in the blood of approximately 97% of Americans tested — a finding replicated in populations worldwide. PFAS have been detected in breast milk at levels that, in some studies, exceed the concentrations found in maternal blood. Cord blood studies confirm PFAS exposure begins before birth. The specific compounds most studied — PFOA and PFOS, both now largely phased out but replaced by newer PFAS compounds whose long-term effects are less well characterized — have been found at elevated levels in communities near military installations that used AFFF firefighting foam, near PFAS manufacturing facilities, and in areas where PFAS-containing sewage sludge was applied as agricultural fertilizer for decades.

The regulatory timeline on PFAS is a case study in regulatory delay despite clear corporate knowledge of harm. Internal 3M documents, obtained through litigation and made public over several decades, show that 3M scientists identified PFAS as persistent environmental contaminants and documented health effects in animal studies as early as the 1970s. DuPont internal documents — revealed through litigation by attorney Rob Bilott and later documented in the 2019 film Dark Waters — show the company was aware of PFOA's health effects, its presence in local water supplies near its Washington, West Virginia plant, and its transfer to the fetus through the placenta, while publicly denying any risk. The EPA's first drinking water health advisory for PFOA and PFOS was issued in 2016 — decades after the companies had the relevant information. The EPA set legally enforceable Maximum Contaminant Levels for six PFAS compounds in drinking water in 2024, the first binding federal PFAS drinking water standards.

Why it matters

The health effects associated with PFAS exposure are extensive and increasingly well-documented, though the full picture remains incomplete because human populations have been exposed to PFAS for decades and epidemiological studies take time. The International Agency for Research on Cancer classified PFOA as a Group 1 human carcinogen (the highest certainty category) in 2023, based on evidence for kidney and testicular cancer. Other well-documented health associations include thyroid disease and disruption of thyroid hormone levels, elevated cholesterol, liver damage, ulcerative colitis, and preeclampsia. Particularly alarming is evidence that PFAS suppress immune function: several studies have found that PFAS exposure in children is associated with reduced vaccine response — meaning children with higher PFAS exposure show lower antibody responses to childhood vaccines, potentially undermining vaccination effectiveness at a population level.

The cleanup liability from PFAS contamination is enormous and the legal battles are still being waged. The Department of Defense estimated in 2019 that cleanup of PFAS contamination at military installations would cost at least $2 billion; subsequent analyses have revised that estimate upward dramatically, with some projections exceeding $30 billion. 3M agreed in 2023 to pay up to $10.3 billion to settle claims from public water utilities for PFAS contamination — the largest environmental settlement in U.S. history at the time. DuPont, which spun off its PFAS liabilities into a separate company (Chemours) before acknowledging the scope of the problem, has faced separate legal actions. The pattern — companies generate billions in profits from PFAS-containing products, externalize the contamination costs onto communities and governments, and then contest liability for decades — is textbook regulatory and legal arbitrage.

The 'regrettable substitution' problem has haunted PFAS regulation from the beginning. When PFOA and PFOS were phased out under regulatory pressure in the 2000s, chemical companies replaced them with shorter-chain PFAS compounds marketed as safer alternatives — GenX, PFBS, and others. Subsequent research found many of these alternatives also persist in the environment, accumulate in the body, and show similar toxicity profiles. The regulatory system evaluates chemicals one at a time, while the industry can generate new compounds faster than toxicology can characterize them. The EPA's 2024 drinking water standards covered six specific compounds; approximately 14,994 remain unregulated at the federal level. This whack-a-mole dynamic is why environmental and public health advocates have pushed for a class-based regulatory approach that addresses all PFAS compounds together rather than evaluating each one separately.

The PFAS crisis illustrates a systemic failure in how the United States regulates industrial chemicals. Unlike the European Union's REACH framework — which requires chemical manufacturers to demonstrate safety before market introduction — the U.S. Toxic Substances Control Act (TSCA) as originally enacted in 1976 presumed new chemicals safe until proven otherwise, placed the burden of proof on the EPA rather than manufacturers, and required the EPA to demonstrate not just risk but that the risk was 'unreasonable' using a cost-benefit standard that routinely favored economic activity over precaution. The 2016 Frank R. Lautenberg Chemical Safety for the 21st Century Act reformed TSCA modestly, giving the EPA more authority to evaluate existing chemicals. The PFAS contamination that accumulated under the prior framework will be paid for by communities, water utilities, and taxpayers for generations.

PFAS / Forever Chemicals

The short version

What it is

Why it matters

Sources & Further Reading