What Are Forever Chemicals? The Nickname, and What It Gets Right

This page is about the nickname: where it came from, what forever is actually claiming, and the two places where it quietly overstates and understates the case. If you want the chemistry — the carbon-fluorine bond, the 14,000-substance family tree, the drinking-water limits, the litigation that produced the human evidence — the PFAS article is the one to read, and it goes deeper than this one will. The endocrine disruptors guide covers why persistent synthetic chemicals in the body are worth caring about in the first place.

The phrase has an author and a date. Joseph Allen, an environmental health researcher at the Harvard T.H. Chan School of Public Health, used it in a Washington Post op-ed published on 22 January 2018 Allen 2018. His reasoning was a mnemonic rather than a chemical argument: the family's acronyms — PFASPer- and polyfluoroalkyl substances — the technical family name , PFOAPerfluorooctanoic acid — the eight-carbon PFAS at the centre of the DuPont litigation, PFOSPerfluorooctanesulfonic acid — the eight-carbon PFAS in the original Scotchgard and in firefighting foam — all open with the letters P and F. Persistent. Forever.

It is worth being clear about the status of the term. No regulator writes it into a rule. It appears in no chemical registry, on no safety data sheet, in no CASChemical Abstracts Service — the registry that assigns unique identifiers to chemical substances entry. It is a piece of vocabulary, and it spread the way vocabulary spreads: into headlines, then class-action filings, then a Mark Ruffalo film, then ordinary conversation. Within five years it had done what four decades of technical papers had not managed, which was to make a category of industrial chemistry legible to people who do not read technical papers.

A nickname that travels that fast usually travels because it is vivid, not because it is exact. This one happens to be both — but only for one of the several things people assume it means. That distinction is most of what this article is about.

Almost everything in your kitchen falls apart eventually. Bread goes mouldy, wood rots, a cotton shirt in the compost heap is gone in a season. The reason is not that those materials are fragile. It is that something eats them — a bacterium or a fungus carrying an enzyme shaped for the job, because there has been an evolutionary reason to build one. Persistence, in that framing, is not an exotic property. It is the absence of a consumer.

Fully fluorinated carbon chains barely occur in nature, so nothing has ever had a reason to evolve the enzyme. Microbiologists have looked hard. What they find is instructive: bacteria can and do attack polyfluorinatedPartly fluorinated — some carbon atoms in the chain still carry hydrogen, which is where microbial enzymes get a grip compounds, stripping away the hydrogen-bearing sections. Then the process stops, and what is usually left is a shorter, fully fluorinated fragment nothing can touch Wackett 2022. The review that reports this is titled Nothing Lasts Forever, and its conclusion is the honest version of the nickname: partial breakdown happens, complete breakdown of a perfluorinated chain essentially does not — and the partial kind often manufactures the persistent kind out of the less persistent kind.

So forever is shorthand for a stack of specific failures. Nothing eats them. Sunlight does not break them. The coagulation, sedimentation and chlorination steps a municipal water plant runs do not remove them. Incineration can destroy them, but only at temperatures and with emissions controls most waste facilities do not have. What the word does not tell you is which clock it is talking about — and there are at least three, running at wildly different speeds.

Read that table twice, because it contains the two corrections this article exists to make. For the planet, forever is an understatement — there is no known end to the soil and ocean clocks, and the rain falling on Antarctica now carries the stuff. For you, it is an overstatement. Your body clears these compounds. Slowly, over years, but it clears them. The replacement chemistries such as GenX clear in days, which was the whole basis for calling them safer, and which turned out to answer a narrower question than it appeared to.

A 2020 inventory catalogued more than 200 use categories and subcategories across 64 industrial sectors, covering more than 1,400 individual PFAS across 64 industrial sectors Glüge et al. 2020. Non-stick pans get almost all the attention. Pans are not the main event.

There is a single pattern underneath every one of those 200 categories: somebody wanted a surface to shed water, grease or dirt. Once you have the pattern you can predict the products without a list, which is useful, because there is no list on any label.

Walk through a normal morning. The bathroom first: waterproof mascara, long-wear foundation, liquid lipstick. A 2021 survey tested 231 North American cosmetics for total fluorine and found high levels in 52% of 231 North American cosmetic products tested — 82% of waterproof mascaras of them, with waterproof mascara the worst category at 82% and long-wear foundation at 63% Whitehead et al. 2021. Most of those products listed no fluorinated ingredient on the pack. Then the floss — the slippery kind slides because it is coated in PTFEPolytetrafluoroethylene — the same fluoropolymer used in non-stick pan coatings.

Lunch. A separate survey collected 407 food-packaging samples from 27 fast-food chains and detected fluorine in 46% of food-contact papers and 20% of paperboard sampled across 27 US fast-food chains of food-contact papers and 20% of paperboard Schaider et al. 2017. A grease-proof wrapper is grease-proof for a reason, and hot greasy food sitting on treated paper is about the most efficient transfer arrangement anyone could design. The coat on the way home is a durable water-repellent finish. The tap you fill a glass from is the constant, low-dose one; the tap water guide covers what removes them and what does not.

Now the unflattering part, stated plainly: no label reliably tells you. PFAS-free is a voluntary marketing claim with no standardised definition in most markets and no required testing behind it, and independent total-fluorine testing has repeatedly found fluorine in products carrying it. Sometimes that is contamination from shared manufacturing lines rather than a deliberate ingredient. From where you stand in the shop, the distinction is academic.

No — and this is the place where the nickname does the most damage to people's understanding of their own situation. When the contaminated water supply serving Ronneby, Sweden was cut off, researchers had a rare natural experiment: a population with a known high exposure that abruptly ended. They measured mean serum half-lives of 2.7 years for PFOA, 3.4 years for PFOS and 5.3 years for PFHxS Li et al. 2018. Long, but finite.

The catch is arithmetic. A half-life only draws the level down if the input stops, and for almost everyone the input has not stopped — the wrapper, the jacket, the tap and the dust are all still there. What you get instead is a steady state, where clearance and exposure roughly cancel out. That is why national blood surveys keep finding detectable levels in almost everyone despite two decades of phase-outs.

One study makes the finite-ness concrete. Australian researchers randomised 285 firefighters with elevated levels to plasma donation every six weeks, blood donation every twelve weeks, or nothing at all, and followed them for a year. Mean serum PFOS fell by 2.9 ng/mL in the plasma-donation arm over twelve months, versus 1.1 ng/mL for whole-blood donation and no change in the observation arm in the plasma group and 1.1 ng/mL in the blood group, against no change in the group that did nothing Gasiorowski et al. 2022. Take the right lesson from that. It shows the body burden is not permanent and can be shifted by ordinary attrition. It does not show that shifting the number changes anyone's health, because nobody has run that study — the relationship between serum level and outcome is the dose-response question, and it is not settled.

The strongest argument against the phrase is that it flattens a family of roughly 14,000 substances into one word. A solid fluoropolymer gasket in a chemical plant and PFOS in a barrel of firefighting foam behave nothing alike in a body: the first is a large, insoluble, biologically inert sheet, the second a small mobile molecule that binds to blood proteins and travels. Industry makes this argument regularly, and it is not purely self-serving — it is chemically true.

The counter-argument was set out carefully in 2020. A group of researchers examined the polymers of low concernAn industry framework arguing that large, stable, insoluble polymers should be assessed separately from small mobile chemicals, because the finished material itself is biologically inert case for treating fluoropolymers separately, and argued it fails on lifecycle grounds rather than on the toxicity of the finished sheet Lohmann et al. 2020. Making a fluoropolymer requires small mobile PFAS as processing aids; disposing of one releases them again. The inert object in the middle of its life is not the whole of its life.

And the reason the nickname survives every objection is that persistence is the one property every member of the family genuinely shares — and it is the property that makes every other decision irreversible. Rainwater sampled across locations including Antarctica and the Tibetan Plateau exceeds current US drinking-water advisory levels for PFOA Cousins et al. 2022. Whatever the toxicology eventually concludes about any individual member, nobody gets to take that back.

The fair verdict: the name is imprecise about harm and accurate about permanence. Being precise about harm would require 14,000 separate answers, most of which have never been researched, and waiting for them is how the last fifty years went. It is also worth noting that these compounds rarely arrive alone — the combination effects problem applies here as much as anywhere. A nickname that gets people to act on the one property everything shares is doing more work than a technical term that gets them to act on nothing.

Less than the headlines suggest, and more than nothing. Water is the highest-leverage lever most people have, because it is continuous and because filtration genuinely works — activated carbon and reverse osmosis both reduce these compounds substantially, and a standard jug filter is not the same thing as a certified one. After that it is a short list of swaps: stainless or cast iron instead of non-stick, unwrapped food where you can, uncoated floss, and declining the optional stain treatment on new upholstery.

What is not worth doing is paying a premium for a PFAS-free claim with no test number behind it. And the honest framing on all of it, which the individual-action articles tend to skip: exposure at this scale is a regulatory problem wearing a shopping-list costume. The EU's proposed universal restriction and the US drinking-water limits are the interventions that move the numbers. Everything on your own list is a reasonable hedge in the meantime — which is roughly what Eso-Friendly means as a standard.

The short version is that forever chemicals is a nickname doing two jobs at once, and doing one of them badly. As a description of what happens in soil, groundwater and the ocean it is not exaggerated — it may be too mild, because there is no known endpoint at all. As a description of what happens in you it is wrong in a way that matters, because the half-life is years and the level falls once the exposure does.

What the nickname got right is the thing that made everything else inevitable. Seventy years of a genuinely useful chemical property were exploited before anyone asked seriously what happens to the molecules afterwards, and the answer turned out to be: nothing happens to them. They are still here. They will be here after the regulation lands, after the substitutes replace the substitutes, and after everyone who argued about the name has stopped arguing. For the chemistry behind that, the PFAS article is next — and if you want the specific molecules, PFOS and GenX go one level down again.