PFAS (“Forever Chemicals”): Where They Actually Hide and How They Get Into You

Georden Jones, Founder, The Peer Review · Last updated: July 16, 2026

This post contains affiliate links. If you purchase through one, I earn a small commission at no extra cost to you. Read the full Affiliate Disclosure for details.

---

The Short Answer

PFAS forever chemicals — more formally, per- and polyfluoroalkyl substances — are a family of over 4,000 synthetic chemicals used since the 1940s to make things resist water, grease, and stains. They’re called “forever chemicals” because the carbon-fluorine bond that makes them useful is also one of the strongest in organic chemistry, so PFAS don’t break down naturally — they build up in soil, water, and human bodies over time. You’re exposed to them three main ways: through food and water (the dominant route, per the research), through household dust and air, and — to a smaller, more variable degree than recent headlines suggest — absorbed through skin. Health Canada and the EPA both regulate PFAS, though the two bodies don’t move at exactly the same pace or with the same priorities, which matters for what “regulated” means depending on where you live. This page breaks down what the evidence shows, where PFAS realistically show up in your home, and what to do about it — including options for readers who’d rather avoid PFAS-containing products altogether, no elevated risk finding required.

Evidence Rating: General Consensus. Strong, multi-body agreement that PFAS persist and accumulate in the body and environment, and are linked to several health effects — though the strength of evidence varies by specific outcome, and some claims, like the exact size of the cancer risk, are still actively debated in the research.

---

Table of Contents

• What PFAS (“Forever Chemicals”) Actually Are
• How PFAS Get Into Your Body
• What the Health Evidence Actually Shows
• Where PFAS Actually Hide
• What Regulators Are Doing About It
• How to Apply This as a Reader
• Prefer to Avoid PFAS Entirely? Here’s What to Look For
• What This Doesn’t Mean
• FAQ
• The Bottom Line
• References

---

What PFAS (“Forever Chemicals”) Actually Are

PFAS forever chemicals is an umbrella term for a family of more than 4,000 synthetic chemicals, not a single ingredient. They share one structural feature: a chain of carbon atoms bonded to fluorine, which is what makes them so good at repelling water, oil, and stains — and so resistant to breaking down. Industrial chemists started using PFAS in the 1940s, and by the 1950s they were showing up in consumer products because they solved a real problem: nothing else worked as well at making a pan nonstick or a jacket waterproof.

The “forever chemical” nickname isn’t marketing exaggeration — it’s a reasonably accurate description of the chemistry. The carbon-fluorine bond is one of the strongest known in organic chemistry, which is exactly why these substances resist heat, water, and microbial breakdown so well in a nonstick pan or a raincoat. That same stability means PFAS don’t degrade in the environment on any meaningful timescale, and some PFAS also bioaccumulate, meaning your body clears them slowly enough that ongoing exposure can build up faster than it’s eliminated.

---

How PFAS Get Into Your Body

There are three exposure routes, and the research doesn’t rank them equally — which matters, because it tells you where to focus.

Swallowed through food and water. A 2024 EPA-cited review of dermal exposure literature found that, across the exposure pathways studied, dietary intake was consistently the dominant route for PFAS exposure, ahead of dust ingestion, inhalation, and skin contact. PFAS get into food two ways: contaminated water used in growing or processing, and migration from food packaging (grease-resistant wrappers, microwave popcorn bags, take-out containers) directly into what you’re eating. A 2025 systematic review of 67 studies on chemical migration from food packaging found that cans, plastic wraps, and paperboard packaging all showed measurable migration, with fatty and acidic foods absorbing the most.

Inhaled through air and household dust. PFAS-treated carpets, upholstery, and textiles shed particles into household dust over time, and that dust gets inhaled or ingested — this matters more for children, who spend more time on floors and put their hands in their mouths more often.

Absorbed through skin. This is the pathway where the headlines and the broader research literature currently disagree the most, and it’s worth being precise about why. A single, widely-covered 2024 University of Birmingham lab study, using 3D human skin models, found that 15 of 17 tested PFAS were substantially absorbed through skin — including 13.5% of PFOA passing into the bloodstream. That’s a striking result from a well-designed lab study, and it’s worth taking seriously.

But zoom out to the broader dermal-exposure literature — including a 2024 review presented at an EPA PFAS workshop covering the existing body of dermal absorption research — and the picture is more mixed: dermal absorption is described as “not currently established as a major human exposure pathway” for most PFAS, particularly the ionic forms most PFAS take in the environment, due to limited data and limited absorption in that chemical form. The same review found dermal absorption potential was meaningfully higher for certain neutral-form PFAS specifically, meaning the real answer is “it depends heavily on the specific chemical, not PFAS as a category.” Both things are true: skin absorption is a real, confirmed pathway for some PFAS, and it is not (yet) established as the dominant one that some headlines implied.

---

What the Health Evidence Actually Shows

This is the part worth being precise about, because the strength of evidence differs a lot by specific health outcome — treating every PFAS health claim as equally certain is its own kind of inaccuracy. Where possible, this section leans on systematic reviews and consensus reports that pool many individual studies, rather than any single study, because that’s a more reliable basis for a real-world decision.

The most authoritative synthesis available is the National Academies of Sciences, Engineering, and Medicine’s 2022 consensus report, Guidance on PFAS Exposure, Testing, and Clinical Follow-Up, which reviewed the existing evidence base to guide clinicians. It identifies these outcomes as having a strong enough evidence base to warrant clinical attention: reduced antibody response to vaccines, elevated cholesterol in both adults and children, preeclampsia and gestational hypertension, and preliminary associations with kidney and testicular cancer (PFOA) and breast cancer (PFOS). The Agency for Toxic Substances and Disease Registry (ATSDR, part of the U.S. CDC) maintains a similar, more frequently updated summary:

Health outcome	PFAS implicated	Evidence type
Increased cholesterol levels	PFOA, PFOS, PFNA, PFDA	NASEM consensus report; 2025 updated systematic review and meta-analysis
Lower antibody response to some vaccines	PFOA, PFOS, PFHxS, PFDA	NASEM consensus report
Changes in liver enzymes	PFOA, PFOS, PFHxS	ATSDR summary
Pregnancy-induced hypertension and preeclampsia	PFOA, PFOS	NASEM consensus report
Small decreases in birth weight	PFOA, PFOS	ATSDR summary
Kidney and testicular cancer	PFOA	NASEM consensus report (preliminary)
Breast cancer	PFOS	NASEM consensus report; 2024 systematic review and meta-analysis
Thyroid cancer	Multiple PFAS	Mixed — see below
Childhood obesity	Multiple PFAS	2023 systematic review and meta-analysis

Both bodies frame this as an evolving picture rather than a closed case. NASEM notes that nearly 100% of people in the U.S. have measurable PFAS in their blood, which is part of why the guidance focuses on interpreting exposure rather than treating any detectable level as an emergency.

The cancer picture is the clearest example of why “linked to” and “proven to cause” aren’t the same sentence, and why it matters where a claim comes from. The original kidney and testicular cancer association traces back to a 2012 legal settlement panel (the C8 Science Panel), not a peer-reviewed causal study. Since then, the picture has gotten more, not less, complicated: a small 2023 Mount Sinai case-control study found a 56% increase in thyroid cancer risk per doubling of PFOS exposure, and the researchers themselves described it as a preliminary finding from a small sample that needs replication in larger studies before it should be treated as settled. Separately, a 2025 review published in Frontiers in Public Health argues that more recent, better-controlled epidemiological work hasn’t reproduced the original C8 panel’s kidney and thyroid findings as clearly, and that some of the original panel members have since published that the thyroid association “has gotten weaker” over time.

That’s not a contradiction — it’s what an active area of research looks like: one study finding a strong signal, a systematic review of the older evidence base finding a weaker one, and researchers on both sides calling for more data before drawing firm conclusions. Treating any single piece of that as the final word — in either direction — would be the same hazard-presented-as-certainty pattern Fear vs. Evidence covers in more depth.

---

Where PFAS Actually Hide

PFAS show up across an unusually wide range of product categories, because water/grease/stain resistance is useful in a lot of unrelated industries. Here’s where the evidence is strongest for everyday consumer exposure:

Product category	Where PFAS come in	What the evidence shows
Non-stick cookware	PTFE (Teflon) coating	Coatings made in the U.S. and Canada have been PFOA-free since 2013. The American Cancer Society states there’s no proven risk from normal use of modern PFOA-free nonstick cookware. Risk rises specifically when pans are overheated above 500°F (260°C) empty, which can release fumes and cause short-term “polymer fume fever.”
Air fryers	PTFE-coated baskets, crisper plates, and drip trays — the same coating chemistry as nonstick cookware, used by most major brands’ standard models	No independent lab testing has been done specifically on air fryers for PFAS release; assessments lean on the existing cookware science rather than air-fryer-specific data. That matters because the mechanism is the same (coating degradation above ~500°F/260°C) but the appliance design isn’t: enclosed, forced-convection heating reaches high temperatures faster and more evenly than a stovetop pan, especially if preheated empty. No study has directly measured whether typical home use crosses that threshold — worth flagging as an open question rather than a settled risk either way.
Dental floss	PTFE-coated floss, marketed as “glides easily”	A Harvard T.H. Chan School of Public Health cross-sectional study found women who used certain PTFE-coated floss (including Oral-B Glide) had measurably higher blood levels of PFHxS than non-users. Worth noting: this is currently based on a single well-designed study, not yet a systematic review — an emerging finding, not a long-established one.
Stain-resistant carpets & furniture	PFAS-based stain and soil repellent treatments	Contributes to household dust, a confirmed inhalation/ingestion exposure route, especially relevant for young children.
Waterproof clothing & outdoor gear	PFAS-based durable water repellent (DWR) coatings	Dermal exposure route with genuine but chemical-specific evidence (see above) — meaningfully absorbed for some neutral-form PFAS, less clear for others.
Food packaging (wrappers, popcorn bags, take-out containers)	PFAS-based grease-proofing agents	The FDA announced in February 2024 that manufacturers had voluntarily phased out PFAS grease-proofing substances in U.S. food packaging. A 2025 systematic review of 67 studies confirmed ongoing migration risk from cans, plastic wrap, and paperboard broadly (not PFAS-specific). Older stock and imported packaging may still contain PFAS-based grease-proofing.
Drinking water	Industrial runoff, firefighting foam contamination near airports/military sites	The most heavily regulated exposure route, and — per the dietary-exposure research above — a meaningful contributor to the dominant exposure pathway. Health Canada’s objective is 30 nanograms per litre for the combined total of 25 specific PFAS.

---

What Regulators Are Doing About It

Health Canada and the EPA are both actively regulating PFAS, but they’re not moving in lockstep — a good real-world example of the point made in Regulators 101: “different approach” doesn’t automatically mean “one of them is wrong.”

Health Canada set a drinking water objective of 30 ng/L for the combined total of 25 named PFAS in August 2024 — a precautionary, group-based approach rather than separate limits for each substance, adopted because the science on individual PFAS is still evolving and Canadians are realistically exposed to mixtures, not single compounds. In March 2025, Canada also proposed adding PFAS as a class to the toxic substances list under the Canadian Environmental Protection Act, with a proposed three-phase risk management plan: firefighting foam first (targeted for spring 2027), then non-essential uses in cosmetics, food packaging, textiles, paints, and cleaning products, with pharmaceuticals and medical devices addressed last, where there’s no current alternative.

The EPA finalized enforceable Maximum Contaminant Levels for PFOA and PFOS in April 2024 and confirmed in May 2025 that it will keep those specific limits in place. At the same time, the agency proposed rescinding the regulations covering three other PFAS (PFHxS, PFNA, and GenX) and extending water utilities’ compliance deadline from 2029 to 2031, pending a new rulemaking process expected to finalize in spring 2026.

Neither approach is more “correct” in an absolute sense — they reflect different regulatory philosophies (Canada’s broad precautionary class-based approach vs. the EPA’s substance-by-substance enforceable standard) and different political and legal processes. “PFAS are regulated” doesn’t mean the same specific thing in every country, and it isn’t a fixed target — it’s actively moving in both directions depending on the jurisdiction.

---

How to Apply This as a Reader

A few practical, evidence-backed adjustments, roughly in order of what the research supports as highest-impact:

1. Food, water, and packaging first. This is the dominant exposure route per the research — so filtering drinking water (if your municipal supply tests high, or you’re on a private well) and limiting regular use of PFAS-treated takeout packaging matter more than any single swap.
2. Check floss and cookware next. These have direct, well-documented exposure pathways for their specific routes (mucous membrane contact for floss; heat-driven fume release for overheated nonstick pans).
3. Don’t panic-replace your cookware. Modern PFOA-free nonstick cookware used normally (moderate heat, not preheated empty) doesn’t have proven risk according to the American Cancer Society. This is a hazard-vs-risk situation, not a “throw it all out” situation — see Our Method for how we weigh evidence like this in individual product reviews.
4. Read labels and ask. Health Canada recommends checking cosmetic and personal care labels for ingredient names containing “perfluoro,” and contacting manufacturers directly for products (like textiles) that aren’t required to disclose PFAS content.
5. Air out and dust regularly if you have PFAS-treated carpets or furniture, since household dust is a real, if smaller, exposure route — particularly for kids.

---

Prefer to Avoid PFAS Entirely? Here’s What to Look For

Some readers would rather avoid PFAS-containing products altogether, regardless of where the current risk assessment lands for normal use. That’s a completely reasonable personal choice on its own terms — you don’t need a scary headline or an elevated-risk finding to justify preferring a different material. Here’s what to look for by category, based on current, real product options:

Cookware. Uncoated cast iron and stainless steel contain no PTFE or PFAS coating by design. [AFFILIATE LINK: cast iron skillet] and [AFFILIATE LINK: stainless steel cookware set] are both widely available and, with basic care (seasoning for cast iron, avoiding scorching for stainless), last for decades. Enameled cast iron (like Dutch ovens) is another PFAS-free option for slow cooking: [AFFILIATE LINK: enameled cast iron dutch oven].

Air fryers. The same logic applies here as cookware, since most standard baskets use the same PTFE coating. Fully stainless steel baskets avoid the coating question entirely: [AFFILIATE LINK: stainless steel air fryer]. Ceramic-coated models (marketed as PTFE-free, sold under names like “Thermolon”) are another option, though — consistent with the honesty pattern in this article — that’s a manufacturer claim to verify per-brand rather than something independently lab-tested by us: [AFFILIATE LINK: ceramic-coated air fryer].

Dental floss. Look for silk or nylon floss explicitly marketed as PTFE-free rather than “glides easily” (a common marker of PTFE coating). [AFFILIATE LINK: PTFE-free silk floss] — always double-check current packaging, since formulations can change without notice and this isn’t something we’ve independently lab-tested.

Waterproof clothing. Several major outdoor brands have shifted to PFAS-free durable water repellent (DWR) treatments in recent years, driven partly by the same regulatory pressure covered above. Look for “PFAS-free DWR” or “fluorine-free” specifically on the product label, since “eco” or “sustainable” marketing language alone doesn’t guarantee it. [AFFILIATE LINK: PFAS-free rain jacket]

Carpets, rugs, and furniture. Untreated natural fiber options (wool, cotton, jute) avoid PFAS-based stain treatments entirely, though they’ll also stain more easily — a real trade-off worth knowing about upfront rather than discovering after a spill. [AFFILIATE LINK: natural fiber area rug]

Food storage. Glass and stainless steel containers avoid both PFAS-based grease-proofing and the coated-paper packaging issue entirely for anything you store or reheat at home. [AFFILIATE LINK: glass food storage set]

This post contains affiliate links. If you choose to purchase through one, I earn a small commission at no extra cost to you — full details in the Affiliate Disclosure. Product mentions above reflect publicly available manufacturer claims and current research, not independent lab testing by The Peer Review.

---

What This Doesn’t Mean

This isn’t a case for treating every PFAS-containing product as equally urgent, or for assuming every health claim attached to PFAS carries the same weight of evidence. Bioaccumulation and persistence in the environment are well-established facts, not up for debate. Some specific health associations — cholesterol changes, immune response, liver enzyme changes — have a reasonably solid evidence base across multiple systematic reviews and consensus reports. Others, like the exact size of the cancer risk, are still being actively debated by researchers using different methods and reaching different conclusions, and shouldn’t be treated as equally settled. The honest position is: PFAS exposure is worth reducing where it’s easy to — food packaging, water, floss — and the evidence for some specific harms is stronger than others. Both things are true at once, and preferring to avoid PFAS anyway, even where the risk evidence is still developing, is a legitimate personal choice rather than something that needs to wait for scientific certainty.

---

FAQ

---

The Bottom Line

PFAS are a large family of synthetic chemicals that persist in the environment and accumulate in the body, and the evidence for some health effects — cholesterol changes, immune response, liver enzyme shifts — is reasonably well established across multiple systematic reviews and a National Academies consensus report. Other claims, particularly around the exact size of cancer risk, are still being actively debated by researchers and shouldn’t be treated as equally settled. Food, water, and packaging are the dominant exposure route per the research — ahead of skin contact, which matters for some specific PFAS more than others. Health Canada and the EPA are both actively regulating PFAS, just on different tracks and timelines, and whether you choose to make targeted swaps or avoid PFAS-containing products altogether, both are reasonable responses to where the evidence currently stands.

Stay curious, stay critical.
Georden

---

References

1. National Academies of Sciences, Engineering, and Medicine. “Guidance on PFAS Exposure, Testing, and Clinical Follow-Up.” 2022.
2. Agency for Toxic Substances and Disease Registry (ATSDR/CDC). “How PFAS Impacts Your Health.” Updated July 22, 2025.
3. Health Canada. “Objective for Canadian Drinking Water Quality: Per- and Polyfluoroalkyl Substances.” August 27, 2024.
4. Health Canada. “Per- and polyfluoroalkyl substances (PFAS) and your health.”
5. Torys LLP. “Canada moves to add PFAS to list of toxic substances; proposes risk management strategy.” March 5, 2025.
6. U.S. Environmental Protection Agency. “EPA Announces It Will Keep Maximum Contaminant Levels for PFOA, PFOS.” May 14, 2025.
7. Sahmel, J. “Dermal Exposure Potential and PFAS: Recent Research.” EPA PFAS workshop review, 2024.
8. University of Birmingham / Environment International. “New study confirms forever chemicals are absorbed through human skin.” 2024.
9. Harvard T.H. Chan School of Public Health. “Some dental floss may expose people to harmful chemicals.”
10. U.S. Food and Drug Administration. “FDA Announces PFAS Used in Grease-Proofing Agents for Food Packaging No Longer Being Sold in the U.S.” February 28, 2024.
11. “Phthalates, bisphenols and per- and polyfluoroalkyl substances migration from food packaging into food: a systematic review.” Reviews on Environmental Health, July 17, 2025.
12. “Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer: Systematic review and meta-analysis.” Environmental Research, 2024.
13. van Gerwen, M., et al. “Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer risk.” eBioMedicine, 2023.
14. Kabir, E., et al. “The evolution of PFAS epidemiology: new scientific developments call into question alleged ‘probable links’ between PFOA and kidney cancer and thyroid disease.” Frontiers in Public Health, April 9, 2025.
15. “Exposure to perfluoroalkyl and polyfluoroalkyl substances and pediatric obesity: a systematic review and meta-analysis.” International Journal of Obesity, 2023.
16. “Exposure to per- and polyfluoroalkyl substances and breast cancer risk: a systematic review and meta-analysis of epidemiologic studies.” 2024.
17. “The relationship between PFAS exposure and dyslipidemia: an updated review, meta-analysis, and evaluation of bias.” European Journal of Epidemiology, 2025.
18. Healthline (citing American Cancer Society). “Is Nonstick Cookware Like Teflon Safe to Use?”
19. Mamavation. “Best Non-Toxic Air Fryers: PFAS-Free Picks.” Manufacturer-disclosure survey of ~80 air fryer products, 2023 (updated 2026) — no independent lab testing of air fryers specifically.

---

Author Bio

Georden Jones is the founder of The Peer Review. Read the full story.