What Is PFAS? Forever Chemicals Explained in Plain English

What is PFAS, in plain English?

PFAS stands for per- and polyfluoroalkyl substances. It is not one chemical but a family of thousands of man-made chemicals that all contain chains of carbon bonded to fluorine. That carbon-fluorine bond is one of the strongest in chemistry, which is exactly why PFAS are useful: they repel water, grease and stains and survive high heat (ECHA).

The same strength is the problem. PFAS break down extremely slowly, so they build up in water, soil, wildlife and people. That is why they are nicknamed "forever chemicals". The US EPA notes PFAS are now found in water, air, fish, soil and the blood of people and animals around the world (US EPA).

You will often see a few names:

• PFOA (perfluorooctanoic acid), once used to make non-stick coatings.
• PFOS (perfluorooctane sulfonate), once used in stain-proofing and firefighting foam.
• PFHxS and PFNA, two more that EFSA groups with PFOA and PFOS.
• PTFE (the polymer behind many non-stick coatings, sometimes sold as Teflon), which is itself a fluoropolymer and falls within broad PFAS definitions.
• TFA (trifluoroacetic acid), a very small PFAS increasingly found in water.

Where are PFAS found?

ECHA lists major uses across textiles, construction, electronics, firefighting foams, food contact materials, cars, aerospace and medical products (ECHA). In everyday life that means:

• Cookware: non-stick pans with PTFE coatings. See our guides to non-stick alternatives.
• Food packaging: grease-resistant paper and card, such as some takeaway wrappers, pizza boxes and microwave popcorn bags. The UK government is testing items like these (GOV.UK).
• Textiles and outdoor gear: water- and stain-repellent finishes on jackets, carpets and upholstery. HSE has flagged textiles, carpets and upholstery as consumer articles that may release PFAS (National Law Review).
• Cosmetics: a 2021 study screened 231 products and found foundations, mascaras and lip products most often high in fluorine, usually without it appearing on the label (Whitehead et al. 2021).
• Water: PFAS reach drinking water sources from industry, firefighting foam and waste.
• Food: EFSA identifies drinking water, fish, fruit, eggs and egg products as the main dietary sources in Europe (EFSA).

Are PFAS harmful? What the evidence says

The evidence is strongest for a handful of well-studied PFAS. Most of the thousands of others have little data.

• Immune system. In 2020 EFSA set a group tolerable weekly intake (TWI) of 4.4 nanograms per kilogram of body weight for PFOA, PFOS, PFNA and PFHxS combined. The critical effect was a reduced immune response to vaccination in children. EFSA said toddlers and other children are the most exposed, and that exposure in pregnancy and breastfeeding is the main source for infants (EFSA).
• Cancer. In November 2023 the WHO's cancer agency IARC classified PFOA as Group 1, "carcinogenic to humans", based mainly on animal and mechanistic evidence, with limited human evidence for kidney and testicular cancer. PFOS was classified as Group 2B, "possibly carcinogenic to humans" (IARC).
• Pregnancy and birthweight. A September 2026 UKHSA rapid review found an association between PFOS (and PFAS mixtures containing PFOS) and lower birthweight. It found the evidence too limited to judge links with heart disease, diabetes, some cancers and other outcomes from local industrial exposure (UKHSA).
• Other effects. ECHA notes some PFAS are linked to reproductive and developmental effects and possible hormone disruption (ECHA).

Important context: "linked to" and "associated with" are not the same as proven to cause harm at everyday levels. Risk depends on which PFAS, how much and for how long. That uncertainty, plus the fact that PFAS do not go away, is why regulators are acting on the whole group.

Are all PFAS the same?

No. Scientists often split them into long-chain PFAS (such as PFOA and PFOS, with longer carbon chains) and short-chain PFAS (such as PFBA, PFHxA and the very small TFA). Long-chain PFAS were the first to be studied and restricted. Industry has since switched many uses to short-chain versions, which leave the body faster but are more mobile in water and harder to remove.

That matters for filters. In the Duke and NC State home study, ordinary carbon filters removed roughly 60 to 70% of long-chain PFAS but only about 40% of short-chain PFAS, while reverse osmosis and good two-stage under-sink filters removed nearly all of those tested (Herkert et al. 2020). In a Belgian consumer test, a gravity filter that removed all long-chain PFAS cut TFA by only about 15% (Test-Achats). It is also why regulators increasingly treat PFAS as one group rather than chemical by chemical (ECHA).

How are PFAS regulated in the UK and EU?

Drinking water

There is no statutory PFAS standard for drinking water in England and Wales yet. The DWI's guidance, updated in March 2025, sets a guideline of 0.1 micrograms per litre for the sum of 48 PFAS and requires water companies to monitor and act (DWI). In 2025, none of 30,000 PFAS tests in Wales reached that level (DWI annual report). The EU is adopting a 0.1 micrograms per litre standard for 20 individual PFAS, an approach the DWI considers valid.

The UK PFAS Plan

Published by Defra on 3 February 2026, the plan commits to consulting on a statutory PFAS limit for drinking water, testing food packaging, considering restrictions on PFAS in firefighting foams, and launching a public PFAS information site (GOV.UK).

UK REACH

PFOA and PFOS are already restricted. HSE's 2023 analysis recommended considering further UK REACH restrictions, starting with firefighting foams, and looking at consumer articles such as textiles, carpets, cleaning products and waxes (HSE, National Law Review).

EU universal restriction

Five countries proposed restricting around 10,000 PFAS as a group in 2023. ECHA's risk committee adopted its opinion in March 2026, backing a broad ban with few exceptions. The socio-economic committee's final opinion is expected at the end of 2026 and adoption in 2027 (White & Case). Separately, EU packaging rules restrict PFAS in food-contact packaging from 12 August 2026 (Packaging Gateway). These EU rules do not automatically apply in Great Britain, but many products sold here are made for both markets.

How can you lower your PFAS exposure?

You cannot avoid PFAS completely, but you can cut some of the easy routes. In rough order of impact and cost:

1. Check your water. Your water company publishes quality data. If you want an extra layer, choose a filter certified to NSF/ANSI 53 or 58 for PFOA and PFOS. See our PFAS water filter guide and best water filter guide. Boiling does not remove PFAS (NSF).
2. Swap worn non-stick pans for stainless steel, cast iron, carbon steel or ceramic-coated pans, especially if you replace them anyway.
3. Cut grease-proof takeaway packaging where you can: decant food, and pop popcorn on the hob.
4. Choose untreated textiles. Skip "stain-resistant" finishes on sofas and carpets and look for PFAS-free claims on outdoor clothing.
5. Check cosmetic labels for ingredients containing "fluoro" or "PTFE", especially in long-wear foundations, mascaras and lip products.
6. Keep perspective. Diet matters too: EFSA lists fish, eggs and fruit as major sources, but those foods also have real nutritional benefits, so do not cut them out over PFAS.

Bottom line

PFAS are a large family of very persistent man-made chemicals used for water, grease and heat resistance. A few, especially PFOA and PFOS, are well studied and linked to effects on immunity, birthweight and, for PFOA, cancer. UK and EU regulators are moving towards group restrictions. For households, the practical steps are simple: check your water and use a certified filter if you want one, replace worn non-stick pans, cut grease-proof packaging and treated textiles, and read cosmetic labels.