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Per- and Polyfluoroalkyl Substances (PFAS) in Drinking Water


Download the factsheet, What We Know: Per- and Polyfluoroalkyl Substances (PFAS) (PDF) to learn more.

Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of synthetic chemicals used to make products resistant to water, heat, and stains. PFAS, often referred to as “forever chemicals,” do not easily break down in the environment and are difficult to destroy. Detected in drinking water and drinking water sources throughout the United States, their chemical properties make PFAS difficult to treat and remove using conventional water treatment processes.

There is not yet enough research to suggest safe exposure levels for each PFAS. Trace doses of several of the most-researched compounds have been linked to harmful health effects and an increasing number of communities across the country are detecting these chemicals and working to address contamination.

How are people exposed to PFAS?

PFAS are used in industrial applications and found in consumer goods such as clothing, food packaging, cookware, cosmetics, and carpet as well as a fire-fighting foam known as aqueous film-forming foam (AFFF). People are exposed to PFAS by consuming contaminated water and food, breathing in dust with PFAS, and contact with consumer products that contain PFAS.

Sources of contamination include not only industrial and manufacturing facilities, but landfills where PFAS have leached into groundwater, and places where PFAS-based firefighting foam AFFF has been used such as airports, military sites, chemical plants, and aboveground petroleum storage facilities.

Designed for long-term stability, PFAS do not easily break down and are difficult to destroy. PFAS cycle through the environment: incineration facilities can release PFAS into the air; contaminated biosolids produced by wastewater treatment facilities have been linked to PFAS in vegetables grown on farm fields where it was applied.1,2

What is the evidence of health effects?

Trace doses of several of the most-researched compounds have been linked to health issues from cancers and increased cholesterol levels to preeclampsia during pregnancy.3 Scientific research shows that PFAS affect the immune, endocrine and metabolic systems. 4, 5, 6, 7 But very little is known about a majority of PFAS, including how long they linger in our bodies (referred to as half-life), their toxicity and how different PFAs may interact in our bodies.

Research into the potential health implications of PFAS indicates reason for concern. Perfluorooctanoic acid (PFOA), one of the most well-studied PFAS, has been linked to kidney and testicular cancer, 8, 9, 10 decreased antibody responses to vaccines, 11 liver damage, increased cholesterol levels,10 increased risk of thyroid disease, 10 increased risk of decreased fertility, decreases in birth weight, 12 and increased risk of pregnancy-induced hypertension and preeclampsia.10, 13 This evidence of harmful health effects led to the phasing out PFOA and perfluorooctanesulfonic acid (PFOS) in the United States.14

Most people in the United States have one or more specific PFAS in their blood, particularly PFOA and PFOS. But there is no treatment for PFAS exposure, and blood testing does not provide a clinical diagnosis or definitively say if a person’s health has been or will be affected.15

Evidence is now emerging that shorter chain PFAS such as GenX, used as replacements for the phased-out chemicals, also persist in the environment and bioaccumulate in people with possible health effects.16, 17, 18, 19 Federal agencies are funding and conducting research to better understand exposure to additional PFAS.

How are PFAS regulated?

There are not yet any federally enforceable standards for PFAS in drinking water in the United States but the U.S. Environmental Protection Agency (EPA) has begun developing a national primary drinking water standard for PFOA and PFOS and is considering ways to evaluate additional PFAS. The EPA established a health advisory level in 2016 for two PFAS -- PFOA and PFOS -- at a combined total of 70 parts per trillion in drinking water. As of June 2022, the EPA has lowered the health advisories for PFOA, PFOS and set final health advisories for GenX and PFBS. The health advisories are now 0.004 ppt for PFOA, 0.02 ppt for PFOS, 10 ppt for GenX, and 2,000 ppt for PFBS.20

In the absence of a federal drinking water standard, numerous U.S. states have enacted limits for PFAS in drinking water, surface water and groundwater based on different health effects such as fetal and infant growth delays, thyroid dysfunction, infertility, alterations in liver function, and/or impaired immune function.21, 22, 23

Beginning in 2023, the EPA will require some of the largest public drinking water systems to monitor for 29 different PFAS.24

Under the Toxic Substances Control Act, manufacturers are now required to submit detailed information on some PFAS to the EPA to guide potential regulatory action and are prohibited from using certain long-chain PFAS without prior review and approval. No PFAS have been designated hazardous substances yet.25

In recent years, states have regulated the presence of PFAS in drinking water, food packaging and consumer products; restricted use of PFAS firefighting foam; allocated funds for cleanup and remediation and sued manufacturers of PFAS chemicals.23

Some experts and environmental advocates suggest regulating PFAS as a class rather than trying to regulate each chemical individually, establishing a single drinking water standard for the entire PFAS class, for example.26 Other potential strategies include regulating groups of PFAS, or subclasses, that have similar chemical properties or regulating by common adverse health effects, co-occurrence with other PFAS or a combination of these characteristics.

Some suggest that PFAS should be restricted to essential uses and only permitted when there are no safer alternatives.27 There are already many functional alternatives to PFAS that provide adequate technical performance and continued innovation will deliver many more. The Department of Defense is researching effective alternative fire-fighting foams to AFFF.28

For more information

The AAAS EPI Center helps local and state leaders understand the current scientific evidence as they seek to address potential PFAS contamination. Additional information can be found in our Addressing Per- and Polyfluoroalkyl Substances (PFAS) in Drinking Water: Guides for Local and State Leaders. Please contact for additional resources, information, or to participate in a PFAS event.


Additional Resources

U.S. Agency for Toxic Substances and Disease Registry, Toxicological Profile for Perfluoroalkyls

U.S. Environmental Protection Agency, PFAS Strategic Roadmap

C8 Science Panel

Interstate Technology Regulatory Council (ITRC), PFAS Fact Sheets


Last updated May 25, 2023

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2. Schilling Costello CM, Lee LS. Sources, Fate, and Plant Uptake in Agricultural Systems of Per- and Polyfluoroalkyl Substances. Curr Population Rep. 2020.

3. PFAS-Tox Database. Published April 16, 2021. Accessed May 21, 2021.

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8. Barry, V. et al, "Perfluorooctanoic Acid (PFOA) Exposures and Incident Cancers among Adults," Environmental Health perspectives, vol. 121, pp. 1313-1318, 2013.

9. W. Nicole, "PFOA and Cancer in a Highly Exposed Community: New Findings from the C8 Science Panel," Environmental health perspectives, 2013.

10. C. S. Panel, "Probably Link Reports,", Parkersburg, West Virginia, 2012.

11. DeWitt, J. C. et al, "Exposure to per-fluoroalkyl and polyfluoroalkyl substances leads to immunotoxicity: epidemiological and toxicological evidence.," Jounral of Exposure Science & Environmental Epidemiology, vol. 29, pp. 148-156, 2019.

12. Negri, E. et al, "Exposure to PFOA and PFOS and fetal growth: a critical merging of toxicological and epidemiological data.," Critical reviews in Toxicology, vol. 47, no. 6, pp. 489-515, 2017.

13. Wikstrom, S. et al, "Early pregnancy serum levels of perfluoroalkyl substances and risk of preeclampsia in Swedish women.," Scientific Reports, vol. 9, no. 1, 2019.

14. "Risk Management for Per- and Polyfluoroalkyl Substances (PFASs) under TSCA," Environmental Protection Agency, 2016. [Online]. Available:

15. ECOS, ERIS, ASTHO. Clinicians FAQ. Accessed May 21, 2021.

16. Kabadi, S. V. et al, "Internal exposure-based pharmacokinetic evaluation of potential for biopersistence of 6:2 fluorotelomer alcohol (FTOH) and its metabolites," Food and Chemical Toxicology, vol. 112, pp. 375-382, 2018.

17. S. C. Gordon, "Toxicological evaluation of ammonium 4,8-dioxa-3H-perfluorononanoate, a new emulsifier to replace ammonium perfluorooctanoate in fluoropolymer manufacturing," Regulatory Toxicology and Pharmacology, vol. 59, no. 1, pp. 64-80, 2011.

18. R. C. Buck, "Toxicology Data for Alternative “Short-Chain” Fluorinated Substances," Molecular and Integrative Toxicology , pp. 451-477, 2015.

19. Wang, Z. et al, "Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors," Environmental International, vol. 60, pp. 242-248, 2013.

20. EPA. Drinking Water Health Advisories for PFOA and PFOS. Accessed July 19, 2022

21. ITRC. PFAS - Per- and Polyfluoroalkyl Substances. Basis of Regulations. Published September 3, 2019. Accessed May 21, 2021.

22. ECOS. Processes & Considerations for Setting State PFAS Standards. Published April 29, 2021. Accessed May 21, 2021.

23. NCSL. Per- and Polyfluoroalkyl Substances (PFAS) | State Legislation and Federal Action. Published January 25, 2021. Accessed May 21, 2021.

24. EPA. Monitoring Unregulated Drinking Water Contaminants. Fifth Unregulated Contaminant Monitoring Rule. Published March 11, 2021. Accessed May 21, 2021.

25. EPA. PFOA, PFOS, and Other PFAS. PFAS Laws and Regulations. Published November 17, 2020. Accessed May 21, 2021.

26. Cousins IT, DeWitt JC, Glüge J, Goldenman G, Herzke D, Lohmann R, et al.2020a. Strategies for grouping per- and polyfluoroalkyl substances (PFAS) to protect human and environmental health. Environ Sci Process Impacts. 22(7):1444–1460, PMID: 32495786, 10.1039/d0em00147c.!divAbstract

27. Cousins IT, Goldenman G, Herzke D, Lohmann R, Miller M, Ng CA, Patton S, Scheringer M, Trier X, Vierke L, Wang Z, DeWitt JC. The concept of essential use for determining when uses of PFASs can be phased out. Environ. Sci.: Processes Impacts. 2019, 21, 1803-1815

28. SERDP, ESTCP. Per- and Polyfluoroalkyl Substances (PFAS). Accessed May 21, 2021.

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