What are PFAS and where you're actually exposed
Almost everyone has PFAS in their blood, but nobody is exposed to them evenly. A few sources do most of the work and the rest barely register. Here is roughly how much PFAS a typical adult takes in from each source in a day, sorted from worst to trivial, along with who actually needs to pay attention.
| Source | PFAS per day (regular use) | Where it comes from | Who it actually matters for |
|---|---|---|---|
| Freshwater fish you catch yourself | ~280 ng, if eaten weekly1 | Lakes and rivers downstream of contamination | People who regularly eat fish they catch in lakes or rivers |
| Drinking water | ~8 ng at the legal limit; 10-100× that near a contamination source2 | Groundwater near military bases, factories, and airports; some public systems | Anyone on a private well, or a utility flagged for PFAS |
| Gear, textiles, cosmetics | ~1-10 ng, mostly from house dust3 | Waterproof and stain treatments that shed into dust | No one in particular; a small dose spread across everyone |
| Store-bought or ocean fish | ~1 ng, if eaten weekly1 | Diluted ocean water and controlled aquaculture | No one in particular |
| Food packaging | ~0 today; a real source before 20244 | Grease-proof wrappers, popcorn bags, molded-fiber takeout | No one now; watch imports and old stock |
| Cookware (nonstick) | ~0 from an intact pan5 | PTFE coatings, only when scratched to bare metal or overheated | No one, unless a pan is damaged or left to smoke |
Order-of-magnitude estimates for a 70 kg adult drinking 2 liters of water a day and eating one 8 oz serving of fish a week. They mix PFOS-specific and total-PFAS measurements, so read them as rough magnitudes, not lab results. For comparison, the European food-safety limit works out to about 44 ng a day for four PFAS combined6. One weekly serving of local freshwater fish clears that on its own.
What PFAS actually are
PFAS stands for per- and polyfluoroalkyl substances: carbon chains studded with fluorine. There are more than 12,000 of them on the EPA's list. Industry has made them since the 1940s because the carbon-fluorine bond repels both water and oil and shrugs off heat and acid, which is handy in nonstick pans, waterproof jackets, grease-proof wrappers, firefighting foam, and cosmetics. The two you have heard of, PFOA (Teflon) and PFOS (Scotchgard), were phased out in the US years ago but are still in the environment and still in people.
Why they don't leave
That same carbon-fluorine bond is the problem. It is one of the strongest single bonds in organic chemistry, so nothing in nature takes it apart: not sunlight, not soil bacteria, not your liver. PFAS build up in water, soil, fish, and us, and in your body they are measured in years. PFOA takes two to eight years to drop by half, PFOS three to seven.
That persistence is why more than 98% of Americans carry PFAS in their blood, and why the drinking-water limits sit at 4 parts per trillion, a few drops across dozens of Olympic pools: PFAS appear to cause harm even at trace doses. The one bit of good news is that levels are falling. Average PFOS is down more than 80% and PFOA more than 70% since the early-2000s phase-outs.
What actually matters
The table is sorted by dose per day, but dose is not the whole story. What matters is how large the source is, how many people it reaches, and whether you can do anything about it.
Drinking water comes first on that test. It is not the biggest single serving (a plate of local bass beats it), but nearly everyone drinks tap water every day, contamination is common near bases, factories, and airports, and it is the one source you can fix outright. The EPA set its first enforceable limit in 2024 and expects the rule to cut exposure for about 100 million people, though utilities have until 2031 to comply. If you do one thing, test your water and put in a reverse-osmosis filter.
Fish is next. Freshwater fish you catch yourself carry far more PFAS than anything from a store. The median fillet ran about 278 times higher than commercial fish in one national analysis. If you fish and eat your catch, that is probably your largest single exposure. Ocean and farmed fish are much lower.
Food packaging used to matter and mostly doesn't now. As of February 2024 the grease-proofing PFAS in fast-food wrappers, popcorn bags, and takeout containers are no longer sold for food use in the US. Old stock and imports are the only holdouts.
Cookware barely registers. An intact nonstick pan is stable at normal cooking temperatures; the FDA's own review found only paper grease-proofing, not nonstick coatings, worth acting on. Replace a pan scratched down to metal, don't leave one heating empty until it smokes, and you are done.
Gear, textiles, and cosmetics are a slow background source that turns up mostly in house dust. No single item is worth losing sleep over. I wouldn't pay extra to make everything in the house stain-proof, but I also wouldn't throw out a jacket over it.
Full disclosure: I build a product in this space, so weigh the part below accordingly.
Be first in line
Cutting what comes in only handles half the problem. PFAS keep recirculating between your gut and bloodstream for years, so whatever is already stored in you stays there. That loop is what I'm working on with NeutraOat, a modified oat fiber designed to bind PFAS in the gut so they leave the body instead of cycling back. A human pilot in highly exposed people is running now, with first results in October 2026.
Reserve one now for a fully refundable $20 deposit, credited in full toward your first bottle. You get launch priority and the October pilot results before anyone else.
Sources
- Environmental Working Group, analysis of PFAS in US freshwater fish (2023): ewg.org. One 8 oz serving ≈ 1,934 ng of PFOS; freshwater fish ran ~278× commercial fish.
- US EPA, PFAS in drinking water, 4 ppt limit for PFOA and PFOS: epa.gov. 8 ng/day assumes 2 L at the limit.
- Estimated daily intake of PFAS from house dust: Science of the Total Environment (2022).
- US FDA, grease-proofing PFAS no longer sold for food packaging (Feb 2024): fda.gov.
- US FDA, authorized uses of PFAS in food-contact applications: fda.gov.
- EFSA, tolerable weekly intake for four PFAS, 4.4 ng/kg body weight per week (2020): efsa.europa.eu. Works out to ~44 ng/day for a 70 kg adult.