PFAS are a large family of synthetic “forever chemicals” used since the 1940s to make products water-, grease-, and stain-resistant. They earn the nickname because their carbon-fluorine bonds barely break down, so they build up in the environment and in our bodies. Nearly everyone now has some PFAS in their blood, which is why they are one of the defining contamination stories of our time.
Key takeaways
– PFAS stands for per- and polyfluoroalkyl substances, a group of thousands of human-made chemicals.
– They are called “forever chemicals” because they resist breaking down and persist for years in bodies and the environment.
– The main exposures are drinking water, food and food packaging, and consumer products; the EPA set the first national drinking-water limits in 2024.
What PFAS actually are
PFAS (per- and polyfluoroalkyl substances) are a class of manufactured chemicals built around extremely stable carbon-fluorine bonds, the strongest in organic chemistry. The EPA counts thousands of distinct PFAS compounds. The two most studied, PFOA and PFOS, have been largely phased out of US production, but they persist in the environment and newer PFAS have taken their place. That chemical stability is exactly what makes them useful and what makes them a problem.
Why they are called forever chemicals
Because those carbon-fluorine bonds barely degrade, PFAS do not break down in nature the way most substances do. The first PFAS made in the 1940s are still around. They accumulate in soil and water, move up the food chain, and build up in the human body over time, leaving slowly over years. That persistence is the whole reason a trace exposure today still matters decades later.
Where PFAS are used
Their water, grease, and stain resistance put them in a huge range of products: nonstick cookware, waterproof and stain-resistant clothing, grease-proof food packaging like fast-food wrappers and microwave popcorn bags, carpets and furniture, some cosmetics and dental floss, and firefighting foams. See our guides on PFAS in cookware and PFAS in clothes.
How you are exposed
Drinking water is a major route: a 2023 US Geological Survey study estimated at least 45 percent of US tap water contains one or more PFAS. Food, food packaging, household dust, and consumer products add to it. Contamination is often worst near industrial sites, military bases, and airports that used PFAS firefighting foam. See PFAS in drinking water.
Why people are concerned
Studies link higher PFAS exposure to raised cholesterol, thyroid and liver effects, immune effects, lower birth weights, and increased risk of certain cancers including kidney and testicular cancer. The science is still developing for many of the thousands of PFAS, but the concern for the well-studied ones is strong enough that the EPA set the first national drinking-water limits in 2024, capping PFOA and PFOS at 4 parts per trillion.
What you can do
You cannot avoid PFAS entirely, but you can cut the big exposures: filter your drinking water, retire nonstick cookware, and skip waterproof, stain-resistant, and grease-proof products. There is no proven way to remove PFAS already in your body, so prevention is the main lever. See how to avoid PFAS.
Explore specific PFAS topics: the chemistry behind forever chemicals, PFAS in cosmetics, PFAS in pesticides, PFAS in well water, and how to test your water for PFAS.
More PFAS guides: how PFAS gets into water, PFAS in fish, PFAS in biosolids, and the PFAS-free products list.
FAQ
What does PFAS stand for?
PFAS stands for per- and polyfluoroalkyl substances, a family of thousands of synthetic chemicals built on stable carbon-fluorine bonds. They are widely called “forever chemicals” because they resist breaking down in the body and the environment.
Why are PFAS called forever chemicals?
Because their carbon-fluorine bonds are so stable that they barely degrade in nature. PFAS made in the 1940s still persist today, and they accumulate in soil, water, and the human body, leaving the body only slowly over years.
Where do PFAS come from?
They are manufactured for water, grease, and stain resistance and used in nonstick cookware, waterproof clothing, food packaging, carpets, some cosmetics, and firefighting foam. From these uses they enter water, soil, food, and dust, which is how people are exposed.
Are PFAS dangerous?
Higher exposure to the well-studied PFAS is linked to raised cholesterol, thyroid and liver effects, immune effects, lower birth weights, and certain cancers. The risk depends on the specific PFAS and dose, and many of the thousands of compounds are still being studied.
Does everyone have PFAS in their body?
Effectively yes. Because PFAS are so widespread in water, food, and products, nearly everyone tested has measurable PFAS in their blood. That is why reducing new exposure, rather than chasing a detox, is the practical focus.
The bottom line
PFAS are durable, useful, and unfortunately near-permanent chemicals that have spread through our water, food, and products and into nearly everyone’s body. You cannot escape them completely, but understanding where they come from lets you cut the biggest exposures, starting with your drinking water.
