On 6 April 1938, a DuPont chemist called Roy Plunkett went to use a cylinder of gas and found that nothing came out. The cylinder still weighed as much as a full one. When he and his assistant looked inside, the gas had turned into a white powder.
That powder was so slippery, and so resistant to heat and to almost every chemical, that it became Teflon. Not bad for a cylinder that had stopped working.
Sixty-five years later, a national health survey tested the blood of 2,094 Americans. Four chemicals from the same family as that powder turned up in more than 98% of them.
They are PFAS, the "forever chemicals", and they hide in pans, pizza boxes, floss, mascara, school uniforms and rain. Your body takes years to get rid of half of what it holds. And the companies that made them knew far more, far earlier, than they told anyone.
The strongest bond
PFAS stands for per- and polyfluoroalkyl substances. It is not one chemical but thousands, all made by people, all built around chains of carbon and fluorine.
The bond between carbon and fluorine is among the strongest in chemistry. That is the whole point of them. It lets them shrug off water, grease, stains and heat, which is why industry has used them since the 1940s. It is also why they are "forever": nature has almost nothing that can break them apart.
Two of them made the family famous. PTFE is the coating on non-stick pans, sold as Teflon. It has one of the lowest frictions of any solid, and it is said to be the only known surface a gecko cannot stick to. Your body, unfortunately, is not a gecko. PFOS, made by 3M, was the key ingredient in Scotchgard, the fabric protector. A third, PFOA, was used to make the Teflon.
Years, not days
Much of what you eat or drink is out of you within hours or days. PFAS are not.
When the blood of 26 retired fluorochemical workers was tracked after they stopped work, the average time for their bodies to clear half of each chemical was 3.8 years for PFOA, 5.4 years for PFOS and 8.5 years for PFHxS. So if every exposure stopped today, half your PFOS would still be with you in five years, and a quarter of it in ten. No detox tea beats a half-life of five years.
The slowness cuts both ways. 3M announced in 2000 that it would stop making PFOS and PFOA. Within a few years, PFOS levels in Americans had fallen by 32% and PFOA by 25%. Cut the source, and the body does the rest, slowly.
There is also a reason men carry more PFOS than women. When a team modelled thirteen years of US blood data, menstruation explained about 30% of the gap. Blood that leaves the body takes PFAS with it. Remember that, because it comes back later.
What they are linked to
With thousands of chemicals in the family, the best evidence comes from one river valley.
Around DuPont's Washington Works plant, near Parkersburg in West Virginia, PFOA had been getting into the drinking water for decades. In 2005 and 2006, 69,030 people from the area gave blood and health records to the C8 Health Project, named after PFOA's nickname. Their average PFOA was 500% higher than in the rest of the country.
An independent science panel, paid for by DuPont under a court settlement, spent years on the results. It found probable links between PFOA and six conditions: kidney cancer, testicular cancer, thyroid disease, high cholesterol, ulcerative colitis, and pre-eclampsia, the high blood pressure of pregnancy.
The follow-up is still running. A 2026 update tracked 32,050 people from the valley, community members and plant workers, up to 2020. The kidney and testicular cancer links held, and new ones appeared with thyroid and pancreatic cancer. The World Health Organization's cancer agency now classes PFOA as carcinogenic to humans.
Children show it too. In Japan, among 1,558 children, those whose mothers had the highest PFOS late in pregnancy had 61% higher odds of common infections by age four: ear infections, pneumonia, RSV, chickenpox. In Denmark, among 1,503 children, each doubling of the mother's PFOS went with 23% more hospital admissions for infection by the same age. These are links, not proof, but they point the same way.
The mother's levels matter because what she carries reaches her child. What Your Mother Passed On That Was Never in Your Genes, linked below, has how chemicals stored in a mother's body come out in her milk, and how their levels fell where they were banned. With half-lives in years, cutting your own intake counts most in the years before a pregnancy.
The thyroid has a plausible route. In the lab, PFHxS, PFOS and PFOA bind to transthyretin, one of the proteins that carries thyroid hormone in the blood. They bind 12.5 to 50 times more weakly than the hormone itself. That is a possible mechanism. The claim that PFAS cause a hidden underactive thyroid behind normal blood tests goes further than the evidence.
What the companies knew
The case started with cows.
Wilbur Tennant farmed near Parkersburg, downstream from a landfill where DuPont had been dumping PFOA. His cattle were dying. The lawyer he found, Robert Bilott, had spent eight years defending chemical companies. He took the case anyway, and filed suit in 1999.
A report on the farm, by three vets chosen by DuPont and three by the Environmental Protection Agency, blamed the farmer: "poor nutrition, inadequate veterinary care and lack of fly control". The cows, apparently, had only themselves to blame. Then a court ordered DuPont to hand over its files. There were 110,000 of them.
They showed that DuPont knew by 1961 that PFOA enlarged the livers of mice, and understood by 1993 that it caused tumours of the testes, pancreas and liver in lab animals. The chemical was worth about a billion dollars a year in profit. Production went on.
A class action for about 70,000 people with contaminated water settled in 2004, which is how the blood tests and the science panel came about. Then came more than 3,500 personal-injury cases. DuPont lost the first three, and in 2017 settled the rest for $671.7 million.
3M's story runs in parallel. Organic fluorine compounds had been found in ordinary people's blood in 1968. In 1997, 3M found PFOS in blood from blood banks around the world, though its own documents point to knowledge from the 1970s. In 2018 it paid $850 million to end Minnesota's water-pollution case, and in 2023 it agreed to pay $10.3 billion to US public water systems. In December 2022, it announced that it would stop making and using PFAS altogether.
Bilott told the whole story in his book, . The film Dark Waters tells it too.
The replacements
When PFOA had to go, something else had to make the Teflon. One answer was GenX, made by Chemours, the company DuPont spun off. Its plant in Fayetteville, North Carolina, released GenX into the Cape Fear River, a source of drinking water for the Wilmington area. In rats, GenX caused many of the same problems as PFOA, though only at much higher concentrations, and it leaves the body far faster. Less persistent is not the same as harmless.
The old ones have been restricted worldwide, one at a time. Under the Stockholm Convention on persistent pollutants, PFOS was listed in 2009, PFOA in 2019 and PFHxS in 2022. Most PFOS is now made in China. Each listing took years, and each time something new took the old chemical's place. Whack-a-mole, with a chemistry degree.
So read pan labels carefully. "PFOA-free" means the pan was made without one particular processing chemical. The coating is still PTFE, which is itself a PFAS. If you want no fluorine coating at all, look for "PTFE-free" and "fluoropolymer-free", or skip coatings altogether.
Heat matters too. PTFE begins to break down at about 260 °C. Above that, its fumes can kill pet birds, and in people they cause polymer fume fever, flu-like symptoms that pass within a day or two in fresh air. Ordinary frying, at about 204 to 232 °C, stays below that. The margin is not large.
Cast iron and stainless steel avoid the question. A cast-iron pan seasoned with fat becomes non-stick through use, and it will outlive any coating. A in three sizes, already seasoned, covers what the non-stick pan did.
Water
Contamination is often worst near airports, military bases and fire-training grounds, where firefighting foam made with PFAS has been used for decades. Private wells near them, or near fields spread with sewage sludge, carry the most risk, and they escape the routine testing that public supplies get.
What to Drink Instead of Plain Water, linked below, has the scale: a worldwide analysis of 45,000 groundwater samples found harmful PFAS levels in 31% of them, including in places with no obvious source nearby.
So find out before you buy anything. In the US, the Environmental Working Group's tap water database shows what your supply has reported. Elsewhere, ask your water supplier for its PFAS results. A well needs its own test.
If you do need a filter, the type matters. In 73 homes in North Carolina, every under-sink reverse osmosis and two-stage under-sink filter removed nearly all PFAS. The other carbon filters removed about 60 to 70% of the long-chain kinds and about 40% of the short-chain ones: pitchers, fridge filters, tap-mounted filters and single under-sink ones. Of eight whole-house systems, four made the water worse.
Reverse osmosis takes the minerals out too. Why "Drink More Water" Is Incomplete Advice has why that makes good salt on your plate matter more.
Food
Grease has to be stopped from soaking through paper somehow, and PFAS do it well.
When about 400 samples of packaging from US fast-food chains were tested, 46% of the wrappers and bags that touch food contained fluorine, and 20% of the boxes. Across a decade of US national health data, the more of their food people ate at home, the lower their levels of all five PFAS measured. Fast food, pizza and restaurant meals went the other way. Microwave popcorn did too: eating it daily for a year went with up to 63% more of one of them, PFDA. Your own kitchen turns out to be a filter.
The wrappers are changing, in the US at least. In February 2024, the Food and Drug Administration announced that PFAS grease-proofers for paper and paperboard were no longer being sold into the US market, and in January 2025 it withdrew the 35 authorisations for them. Other countries set their own rules. Of the four ways the agency allows PFAS to touch food, those paper coatings were the only one it judged a possible concern for your diet. Non-stick coatings were on the list and not among the worries, which fits the heat figures above.
There is a kitchen test. Put a drop of oil on a paper container. If it beads instead of soaking in, the paper has been grease-proofed. That could be PFAS or another coating, and either way it is not where hot, fatty food should sit.
Even the eco swap has it. When 39 brands of drinking straws sold in Belgium were tested, PFAS turned up in almost every material, paper and bamboo most often. Only the stainless steel straws were clean.
The simplest fix is food you cook yourself. Meat, fish and eggs, cooked at home in an iron or steel pan, carried in glass or steel rather than paper, cut out most of what packaging adds.
One honest caveat is that food is only as clean as where it came from. Near a 3M plant in Belgium, residents were advised not to eat eggs from their own hens within 5 kilometres. A backyard hen eats what is in the soil.
Fish has the same caveat, and it depends on the water. When over 500 samples of fish fillets from US rivers, streams and the Great Lakes were tested, their median PFAS level was 278 times higher than in the commercial fish tested by the Food and Drug Administration, and PFOS made up about three-quarters of it. Sea fish from the shop stays on the menu. If you eat what you catch in a river or lake, check the local fish advice first.
The home and the body
Some of the routes are things you would never think to check.
When the blood of 178 middle-aged women was tested, three things went with higher PFAS: flossing with Oral-B Glide, having stain-resistant carpet or furniture, and living in a city with a contaminated water supply. Glide and its competitors tested positive for fluorine; floss like that is made with PTFE. Uncoated floss does the same job, and a sold as PTFE- and PFAS-free is easy to find.
Make-up is another. Of 231 cosmetics bought in the US and Canada, foundations, mascaras and lip products were most often high in fluorine, which is added for water resistance and wear. Most of the labels did not say so, so a clean ingredient list proves little. When one does name an ingredient starting with "fluoro" or "perfluoro", or PTFE, that is the giveaway. Waterproof and long-wear are the words to question.
Then there are school uniforms. All 72 stain-resistant children's items bought in the US and Canada contained PFAS, and the uniforms had the highest levels, on a par with outdoor wear. The 100% cotton uniforms had more than the blends. "Cotton" is no guarantee. "Stain-resistant" is the label to skip, and when a rain jacket needs replacing, look for one sold as PFAS-free.
Ski wax is the extreme case. Racing wax made with PFAS is heated onto the base of skis, and the heat sends fumes and particles into the room. Professional wax technicians have some of the highest PFAS levels of any job ever measured, in their blood and in the air they work in, the fluorochemical industry included. Then fluorinated ski waxes were banned. In waxing rooms tested in 2020 and again in 2023, PFAS in the dust had fallen about a hundredfold. Take the source away, and even a room recovers.
At home, a damp mop and a vacuum keep down the dust from treated carpets and sofas, and when they need replacing, you can choose ones without the stain treatment.
Getting them out
Sauna and sweat are often sold as the way to flush PFAS out. When blood, urine and sweat from 20 people were tested, some old PCBs came out in sweat. None of the PFAS found in their blood did, in any useful amount. Enjoy the sauna. It is not a PFAS exit. You sweat. They stay.
Blood is an exit. In Australia, 285 firefighters, exposed through foam and carrying more PFOS than the general population, were randomly assigned to give plasma regularly for a year, give blood, or simply be watched. Plasma donation cut their PFOS by 2.9 ng/mL and blood donation by 1.1, while the watched group's stayed where it was. It is the same logic as menstruation: what leaves in the blood takes PFAS with it.
Breastfeeding is another exit, with a catch. Among 633 women from the West Virginia project, each month of breastfeeding went with 3% less PFOA and PFOS in the mother, and 6% more PFOA and 4% more PFOS in the baby. The chemicals leave the mother by going to the child. The same authors still call breast milk the optimal food for infants. The catch is why lowering your own load before a pregnancy matters so much.
That is not a plan to drain yourself. It is a side benefit if you donate anyway. For everyone else, the exit is time: cut what is coming in, and the half-lives start working for you.
Should you test your blood? In 2022, the US National Academies advised testing for people with a history of high exposure, and gave a scale for the total of seven PFAS in the blood. Below 2 ng/mL, no harm is expected. Between 2 and 20, there may be a risk, especially in pregnancy. Above 20, the risk is higher. The firefighters in the plasma test all started at 5 ng/mL or more of PFOS alone. If you live or work near a known source, a test tells you where you stand. If you do not, your water results tell you more, for less.
In the rain
There is a limit to all of this, and it is the sky.
In 2022, a team compared PFAS levels in rain, soil and surface water around the world with safety guidelines. Rainwater often carried PFOA and PFOS far above the US Environmental Protection Agency's lifetime advisory levels for drinking water. Soils everywhere carried them too. Their conclusion was that the planet had passed a safe limit for these chemicals.
The bears say the same. At Svalbard, far up in the Arctic and nowhere near a factory, PFAS turned up in most polar bear mothers and in their cubs, four months old and still suckling, in both 1998 and 2008. PFOS, the main one, was lower in 2008, a sign that the phase-out reached even there. Most of the acids in PFOA's branch of the family were higher.
So zero is not on offer, to you or anyone. That is a reason to go after the big routes and not worry about the small ones: your water if your supply is affected, hot food in grease-proof paper, the coated pan, the coated floss, the stain-resistant label.
Nothing sticks
Roy Plunkett's powder was valuable because nothing would stick to it. The trouble is that its chemical relatives stick to us, for years.
What you can do is stop adding to the pile, and the place to start is what you drink every day.
This week, look up your water supply's PFAS results, and only buy a filter if they say you need one.
Wondering what else is in your glass? What to Drink Instead of Plain Water — and What the Popular Alternatives Do to Your Body — the 13-drink test that found only three drinks better than water, why broth beats a branded sports drink, and what heat and time put into a plastic bottle.
Planning a family? What Your Mother Passed On That Was Never in Your Genes — what crosses the placenta, the poison the placenta gathered instead of blocking, what breast milk carries, and why none of this is anyone's fault.
Know someone still frying on a scratched non-stick pan? Send them this, and the story of the cylinder that stopped working.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional, especially if you live or work near a known source of PFAS contamination, if you are pregnant or planning a pregnancy, or if you have a test result that worries you.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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