The short answer
PFAS are long-lasting man-made chemicals used for nonstick and stain-resistant products. IARC classifies PFOA as carcinogenic to humans and PFOS as possibly carcinogenic; IARC found limited human evidence linking PFOA to kidney and testicular cancer. Checking your water system's PFAS results against EPA's drinking-water limits is one practical step.
IARC classifies PFOA, one specific PFAS chemical, as a known human carcinogen (Group 1), and PFOS as possibly carcinogenic (Group 2B).
ATSDR (CDC) lists contaminated drinking water, food packaged in material that contains PFAS, contaminated soil or dust, and some workplaces as ways people are exposed.
IARC found limited evidence in humans linking PFOA 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 simple version
This page is a short guide for anyone worried about PFAS in their water or household products.
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. IARC has classified two of them for cancer risk.
What PFAS are
PFAS stands for per- and polyfluoroalkyl substances. Thousands of related chemicals exist. IARC says the general population is exposed mainly through food and drinking water, and potentially through consumer products such as food packaging, cookware and waterproof clothing. 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:
- Contaminated drinking water.
- Food packaged in material that contains PFAS, and some consumer products such as stain-resistant or water-repellent items.
- Contaminated soil or dust.
- Some workplaces. IARC says exposures are highest for PFAS manufacturing workers and firefighters using firefighting foam.
The cancer connection
IARC found limited evidence in humans linking PFOA to kidney (renal cell) cancer and testicular cancer.
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. PFOS went into Group 2B, possibly carcinogenic to humans, based on strong mechanistic evidence but inadequate human data. 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. 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, and compare the report with the EPA drinking-water limits, which cover six PFAS (for example 4.0 parts per trillion each for PFOA and PFOS).
- EPA has a fact sheet on treatment options for removing PFAS in drinking water.
- For other ways to reduce exposure, see ATSDR's guidance or call 800-232-4636.
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). Ask your water utility for its PFAS results, and ask your care team if you have questions about your own risk.
Sources
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?
ATSDR (CDC) lists contaminated drinking water, food packaged in material that contains PFAS, contaminated soil or dust, and some workplaces. ATSDR notes that exposure to PFOA and PFOS from today's consumer products is generally lower than exposure from PFAS-contaminated drinking water.
Which cancers are linked to pfas?
IARC found limited evidence in humans linking PFOA 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?
Check your water system's PFAS results against EPA's drinking-water limits. EPA publishes a fact sheet on treatment options for removing PFAS from drinking water. For other steps, call ATSDR at 800-232-4636 or ask your care team.
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: 2026-10-16Next planned review: 2028-07-05
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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, and this 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 then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. 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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