PFAS: The “Forever Chemicals” in Your Water, Food, and Blood
Per- and polyfluoroalkyl substances (PFAS) are a family of more than 14,000 synthetic chemicals defined by extraordinarily stable carbon-fluorine bonds — the strongest single covalent bond in organic chemistry. That stability is what gives non-stick cookware its non-stick, waterproof jackets their repellency, food packaging its grease resistance, and firefighting foams their effectiveness. It also means these chemicals essentially do not break down in the environment or the body, earning them the nickname forever chemicals. PFAS have now been detected in drinking water serving roughly 200 million Americans, in virtually every rainfall sampled worldwide, and in the blood of more than 98 percent of people tested in the United States.
Substantial epidemiological evidence links PFAS exposure to cancer, thyroid disease, liver injury, cholesterol elevation, reduced vaccine response, pregnancy complications, and developmental effects in children. Regulatory response has accelerated sharply since 2023. This article lays out what PFAS are, where they come from, what we know about their health effects, how testing works, and what lowers ongoing exposure.
Table of Contents
What PFAS Are
PFAS share a structural backbone of carbon atoms fully substituted with fluorine atoms. The best-studied members are PFOA (perfluorooctanoic acid, formerly used in making nonstick coatings (polytetrafluoroethylene, PTFE)) and PFOS (perfluorooctanesulfonic acid, formerly used in stain-repellent treatments and firefighting foam). Both have been phased out of U.S. production but remain in the environment indefinitely. Newer replacement chemicals like GenX (hexafluoropropylene oxide dimer acid, HFPO-DA), ADONA (ammonium 4,8-dioxa-3H-perfluorononanoate), and F-53B (6:2 chlorinated polyfluoroalkyl ether sulfonate) were developed as substitutes but many have shown similar or even greater toxicity and persistence.
Major Exposure Sources
- Drinking water — public-water supplies near military bases, airports (firefighting foam), and manufacturing facilities often have the highest levels. Private wells in affected regions can have dramatically higher levels.
- Non-stick cookware (older or degraded).
- Greaseproof food packaging — microwave popcorn bags, fast-food wrappers, pizza boxes, compostable tableware.
- Waterproof and stain-resistant fabrics — treated outdoor gear, carpets, upholstery.
- Cosmetics — particularly long-wear foundation, mascara, and lipstick.
- Dental floss — some PTFE-coated varieties.
- Fish from contaminated waters — PFAS bioaccumulate up the food chain.
- Dairy and meat from exposed livestock.
Documented Health Effects
A 2022 consensus report from the National Academies of Sciences, Engineering, and Medicine (NASEM) found sufficient evidence of an association between PFAS exposure and:
- Kidney cancer (in adults). PFOA is classified as a Group 1 human carcinogen by the International Agency for Research on Cancer (IARC).
- Elevated cholesterol (dyslipidemia, in adults and children). PFOA/PFOS raise total and low-density lipoprotein (LDL) cholesterol.
- Decreased antibody response, including to vaccines, in adults and children.
- Decreased infant and fetal growth (lower birth weight).
The same report found limited or suggestive evidence of an association with:
- Breast cancer (in adults).
- Testicular cancer (in adults).
- Thyroid disease and dysfunction (in adults).
- Pregnancy-induced hypertension — gestational hypertension and preeclampsia.
- Liver enzyme changes (in adults and children), such as elevated alanine aminotransferase (ALT).
- Ulcerative colitis (in adults).
Thyroid disease: both hyperthyroidism and hypothyroidism, and altered thyroid-stimulating hormone (TSH) across populations. Liver injury: elevated alanine aminotransferase (ALT) and enhanced fatty liver.
Additional associations with diabetes, cardiovascular disease, immune dysregulation, and neurodevelopmental effects are actively being investigated.
Regulatory Developments
On April 10, 2024 the U.S. Environmental Protection Agency (EPA) finalized drinking-water limits for six PFAS: 4.0 parts per trillion (ppt) each for PFOA and PFOS, among the lowest allowable limits for any regulated contaminant; 10 ppt each for PFHxS (perfluorohexane sulfonic acid), PFNA (perfluorononanoic acid) and HFPO-DA (GenX); and a Hazard Index of 1 for mixtures of two or more of PFHxS, PFNA, HFPO-DA and PFBS (perfluorobutane sulfonic acid). On May 14, 2025 the EPA announced that it would keep the PFOA and PFOS limits, give water systems the option of two more years — to 2031 — to comply, and rescind the limits for PFHxS, PFNA, GenX and the Hazard Index mixture; it proposed rules to do this on May 18, 2026. European regulatory bodies and individual U.S. states (Maine, Vermont, Michigan) have moved to ban or restrict PFAS in food packaging, cosmetics, firefighting foam, and consumer products. Class-action litigation against manufacturers has produced multi-billion-dollar settlements.
Blood Testing
A clinical-grade blood PFAS panel typically measures 10–40 PFAS species and costs $200–500 out of pocket. The National Academies’ 2022 guidance reads the result as the sum of seven specific PFAS in serum or plasma: MeFOSAA (methylperfluorooctane sulfonamidoacetic acid), PFHxS, PFOA, PFDA (perfluorodecanoic acid), PFUnDA (perfluoroundecanoic acid), PFOS and PFNA. Below 2 ng/mL, adverse effects are not expected and the usual standard of care applies. From 2 to under 20 ng/mL there is a potential for adverse effects, and the guidance calls for exposure reduction where a source is found, a lipid panel, screening for high-blood-pressure disorders at every prenatal visit, and breast cancer screening by the usual guidelines. At 20 ng/mL or higher it adds thyroid function testing (thyroid-stimulating hormone, TSH, over age 18), checks for kidney cancer including a urinalysis (over age 45), and checks for testicular cancer and ulcerative colitis (over age 15). The guidance is written for clinicians, and not every clinician is familiar with it.
Where Exposure Comes From and What Lowers It
- Drinking-water treatment. Reverse-osmosis and certain activated-carbon-block filters remove most PFAS. Carbon pitchers alone are variable; NSF/ANSI 53 or 58 certification (standards of NSF International and the American National Standards Institute) specifically for PFOA/PFOS marks the filters tested against these chemicals.
- Non-stick cookware. Older or worn non-stick pans are a source; cast iron, stainless steel, ceramic, and glass are the uncoated alternatives.
- Greaseproof food packaging — compostable tableware, microwave popcorn bags, and fast-food wrappers are common sources.
- Dental floss. Some PTFE-coated dental floss is a source; PTFE-free floss is sold as well.
- Personal-care products. A nonprofit cosmetics-ingredient database lists product ingredients. “PFAS-free” claims can be checked against the ingredient list, where PFAS ingredients carry “fluoro-” prefixes.
- Freshwater fish from known contaminated waters. States publish PFAS fish advisories.
- Public water supplies fall under the EPA limits described above, and some states set their own standards.
Accelerating Elimination from the Body
PFAS half-lives in humans are measured in years. Biological elimination is slow. Strategies with some evidence of accelerating clearance:
- Bile-binding fiber. Daily cholestyramine (a bile-acid sequestrant) has been studied and shown to accelerate PFAS elimination. Soluble fibers such as psyllium, beta-glucan, and pectin may provide a weaker but safer natural analog.
- Plasma and blood donation. A 2022 randomized trial in 285 Australian firefighters (Gasiorowski et al.) found that over 12 months, plasma donation every 6 weeks lowered blood PFOS by 2.9 ng/mL and blood donation every 12 weeks by 1.1 ng/mL; only plasma donation lowered PFHxS, and plasma donation had the larger effect.
- Weight change. Rapid weight loss is described as mobilizing PFAS from fat stores.
- Breastfeeding does transfer PFAS to infants but is still net-beneficial in most assessments.
Key Research Papers
- National Academies of Sciences, Engineering, and Medicine (2022). Guidance on PFAS Exposure, Testing, and Clinical Follow-Up. The National Academies Press, Washington, DC. — doi:10.17226/26156
- Gasiorowski R, Forbes MK, Silver G, et al. (2022). Effect of plasma and blood donations on levels of perfluoroalkyl and polyfluoroalkyl substances in firefighters in Australia: a randomized clinical trial. JAMA Network Open 5(4):e226257. — PubMed PMID: 35394514
- U.S. Environmental Protection Agency. Per- and Polyfluoroalkyl Substances (PFAS): PFAS National Primary Drinking Water Regulation (final rule April 10, 2024; proposed changes announced May 14, 2025). — epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas
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