The short answer
PFAS are long-lasting man-made chemicals used for nonstick and stain-resistant products. IARC classifies PFOA as a known and PFOS as a possible carcinogen; the strongest cancer links are kidney and testicular cancer. Filtering water and reducing certain products lower exposure.
IARC classifies PFOA, one specific PFAS chemical, as a known human carcinogen (Group 1), and PFOS as possibly carcinogenic (Group 2B).
People are mainly exposed by drinking contaminated water and using certain treated products.
It is most strongly linked to kidney and testicular cancer.
A carcinogen classification describes hazard — whether something can cause cancer — not your personal risk at a given exposure.
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The full explanation.
The simple version
PFAS are a large family of man-made chemicals. They are used to make things nonstick, waterproof, and stain-resistant. They break down very slowly, which earned them the nickname "forever chemicals." Scientists are still learning about their health effects. Two of the best-studied ones are linked to cancer.
What PFAS are
PFAS stands for per- and polyfluoroalkyl substances. Thousands of related chemicals have been used since the 1950s in nonstick cookware, food packaging, water-repellent fabrics, and firefighting foam. In 2023, IARC classified PFOA as carcinogenic to humans (Group 1). It classified PFOS as possibly carcinogenic to humans (Group 2B). Most PFAS have never been evaluated.
How people are exposed
Common ways people come into contact with them:
- Drinking water contaminated near some industrial sites, airports, or military bases.
- Certain food packaging, nonstick cookware, and stain- or water-resistant products.
- Household dust and some consumer products.
- Working in PFAS manufacturing or firefighting.
The cancer connection
The strongest cancer evidence is for kidney (renal cell) cancer and testicular cancer. Research into other cancers is ongoing.
In 2023 the International Agency for Research on Cancer (IARC), a World Health Organization agency, evaluated two PFAS chemicals. It put PFOA in Group 1, carcinogenic to humans. That is its strongest evidence category. PFOS went into Group 2B, possibly carcinogenic to humans. No classification covers the PFAS family as a whole.
Hazard is not the same as risk
Hazard and risk sound alike, and they are not the same thing. Calling PFOA a carcinogen is a statement about hazard. It says the chemical can cause cancer under some conditions. It does not describe your personal risk. That depends on how much you take in, for how long, and on other factors. A neighbor of a contaminated well is not in the same position as someone who owns a nonstick pan. The Group 1 label answers "can it cause cancer?" It does not answer "how likely is that for me?"
How to lower your exposure
- Check whether your water system reports PFAS. Use a certified filter, such as reverse osmosis or activated carbon, if levels are high.
- Reduce use of products marketed as stain- or water-resistant when practical.
- Follow EPA drinking-water limits set for several PFAS.
- Support monitoring near known contamination sources.
Drinking water is the easiest PFAS exposure to reduce, but it is one part of a bigger picture. To see where PFAS sits among all the things that affect cancer risk, read our overview of cancer prevention and what raises cancer risk.
The bottom line
PFOA is a known human carcinogen (IARC Group 1). PFOS is possibly carcinogenic (Group 2B). The useful step is knowing which water sources and products bring PFAS into your life, then cutting those you can. A classification is not worth losing sleep over. Spend your attention on the risks you can change.
Sources
Words to know
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Common questions
Does pfas cause cancer?
Two of them are classified. IARC calls PFOA a known human carcinogen and PFOS a possible one. The wider PFAS family has not been classified as a whole. How much any one person's risk rises depends on how much they are exposed to and for how long.
How are people exposed to pfas?
Most exposure happens by drinking contaminated water and using certain treated products.
Which cancers are linked to pfas?
It is most strongly linked to kidney and testicular cancer. IARC evaluated two specific PFAS in 2023; most of the thousands of PFAS have not been individually classified.
How can I reduce my exposure to pfas?
The main steps are filtering drinking water and reducing certain treated products.
Does a carcinogen label mean I will get cancer?
No. A classification is about hazard — whether pfas can cause cancer under some conditions — not a prediction that any one exposed person will develop cancer. Your actual risk depends on the amount and length of exposure and other factors.
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Last updated: 2026-08-18Next planned review: 2028-07-05
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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