PFAS

Summary

PFAS are per- and polyfluoroalkyl substances, a family of thousands of toxic synthetic chemicals. They have been used in hundreds of categories of products, including nonstick pans, stain repellent carpets, waterproof clothing, fast food wrappers and firefighting foam. Many uses are ongoing while some uses, such as use in fast food wrappers are ending. 

PFAS are widely known as “forever chemicals” because they do not break down in the environment and accumulate in people’s bodies over time, especially in blood and the liver.

Numerous studies have found that, even at low levels, exposure to PFAS may result in serious health harms, including suppression of the immune system, cancer, endocrine disruption, thyroid changes, accelerated puberty and liver damage.

Analyzing state and federal data, EWG scientists estimate that more than 200 million Americans could have PFAS-contaminated drinking water at levels over 1 part per trillion, or ppt. EWG scientists have also identified more than 40,000 industrial or municipal sites that are potential sources of PFAS contamination in all 50 states and Puerto Rico.

In 2024, the Environmental Protection Agency finalized unprecedented first-time drinking water limits for several PFAS: PFOA, PFOS, GenX, PFNA and PFHxS and a limit for mixtures of GenX, PFBS, PFNA and PFHxS. But the rule doesn’t address thousands of other PFAS.

The EPA’s maximum contaminant levels, or MCLs, set the highest level of a contaminant allowed in drinking water. The MCLs for PFAS contaminants are 4 ppt  for PFOA and PFOS and 10 ppt for GenX, PFNA and PFHxS.  The agency also set a hazard index, a tool it uses to address cumulative risks from mixtures of chemicals, for GenX, PFBS, PFNA and PFHxS.

These are among the most protective legal limits in the world for PFAS in drinking water. 

Ending upstream discharges of PFAS and advanced water filtration will help water utilities with levels higher than the limits meet the new regulations and systems will have five years to comply. 

The PFAS MCLs were set based on how much it will cost systems to treat water to meet them, as well as how PFAS harm health.

The new limits are also the first new regulations for unregulated contaminants in drinking water to be finalized by the EPA in over 20 years. The agency last set an MCL in 2000, for uranium.

And the EPA is collecting data about 29 other PFAS for its fifth Unregulated Contaminant Monitoring Rule program, or UCMR 5, between 2023 and 2025 from all utilities in the U.S. that serve over 3,000 people, as well as some smaller systems.

How do PFAS get into drinking water?

PFAS are synthetic, meaning they are made by humans and don’t occur naturally in the environment. Yet tests have found them nearly everywhere, including streams, rivers and lakes and even rainwater – threatening not only people but also wildlife.

They’re also frequently found in aquifers. Once in groundwater, PFAS can travel long distances and contaminate private wells. 

Thousands of different PFAS compounds have been produced since the 1930s. They’re used in many different manufacturing processes and common consumer products like non-stick cookware, food packaging, and stain-resistant carpet and furniture. 

Major sources of PFAS contamination in water are firefighting training sites, where PFAS-containing firefighting foam runs off or is washed off pavement and other surfaces into nearby waterways; industrial sites, where PFAS may be discharged into waterways; landfills; and wastewater treatment plants and the biosolids (human waste) they produce, which are frequently used as fertilizer on farms.

Some types of PFAS are volatile and can travel long distances in the air, meaning they can contaminate soil and water far from where they were discharged. 

And some types of PFAS are no longer manufactured or imported in the U.S., but may be found in some imported products and as legacy contamination in the environment. 

What are the toxic effects of PFAS in drinking water?

PFOA, the most infamous PFAS, is a carcinogen that severely polluted the drinking water near a DuPont manufacturing plant in Parkersburg, W.Va.

A decade of studies documented links between exposure to PFOA and testicular and kidney cancer, thyroid disease, ulcerative colitis, high cholesterol and pregnancy-induced hypertension and preeclampsia. Later studies linked exposure to endocrine disruption and developmental health impacts, and reduced effectiveness of vaccines.

PFOS, another well-studied fluorinated chemical, was for many years a key ingredient in 3M’s Scotchgard fabric protector and other stain and water-resistant coatings.

PFOS was also widely used in firefighting foams, especially aqueous film-forming foam used for putting out fuel-based fires at military bases, airports, and industrial sites.

Studies show PFOS exposure is linked to a range of serious health problems, including decreased birth weight, high cholesterol levels and cardiovascular disease. Research has also shown links between PFOS and liver damage, thyroid disease, increased risk of cancer and immune system suppression, reducing the body’s ability to respond to vaccines. 

Hundreds of other studies have found similar health harms linked to the numerous types of PFAS that have been introduced to replace PFOS and PFOA. 

Is there a safe level of PFAS in water?

The short answer is no – there is no safe level for PFAS in your water. There is growing agreement among scientists that the entire class of PFAS may be harmful to human health, even if exposure is a small amount. 

Although the EPA’s 2024 landmark drinking water standards, including limits on PFOA and PFOS, are welcome, health harms can still occur when PFAS are present at lower levels.

Based on the agency’s review of toxicity studies, EWG is using even stricter health guidelines of 0.09 ppt for PFOA (to protect against immune system harm, lower birth weight, and high cholesterol) and 0.3 ppt for PFOS (to protect against birth weight and heart issues).

For other PFAS, based on health assessments published by the EPA and its recommendations for use for similar compounds, EWG urges the following health-based guidelines:

• GenX: 9 ppt (to protect against liver damage)
• PFBS: 2000 ppt (thyroid harm)
• PFDA: 0.006 ppt (developmental and immune harm) 
• Chemicals similar to PFDA (PFDoA, PFNA, PFTeDa, PFTrDA and PFUndA): 0.006 ppt
• PFHxS: 0.001 ppt (developmental effects)
• Chemicals similar to PFHxS (PFDS and PFHpS): 0.001 ppt
• PFHxA: 1000 ppt (postnatal body weight effects)
• Chemicals similar to PFHxA (PFBA, PFHpA and PFPeA): 1000 ppt
• Total PFAS: 1 ppt (increased risk of cancer, reduced effectiveness of vaccines and developmental harm) 

What should be done to reduce exposure to PFAS in drinking water?

For home water filtration options, reverse osmosis and activated carbon filters can reduce or eliminate PFOA and other PFAS contaminants. Active carbon filters are less effective at removing the shorter-chain replacement PFAS, such as GenX, but we don’t know the extent of their water contamination.

EWG maintains an interactive map of known detections of PFAS in the U.S. and a map of suspected industrial discharges of PFAS – locations of sites known to produce or use PFAS, or suspected of using. 

Exposure to PFAS is not limited to water. It may also occur through food and food packaging. While the food packaging industry is transitioning away from the use of PFAS EWG still recommends that people lower their exposure to  fast food wrappers, often coated in PFAS, by preparing meals at home and avoiding paper tableware and microwave popcorn. 

We also recommend not using nonstick cookware, often coated with PFAS, especially if its coating is scratched. Consider switching to alternatives such as stainless steel, glass and cast iron.

PFAS can also be found in personal care products, another source of exposure.

Read EWG’s tips for avoiding PFAS. 

References

A. Blum et al., The Madrid Statement on Poly- and Perfluoroalkyl Substances (PFAS). Green Science Policy Institute. 2014. Republished in Environmental Health Perspectives, May 2015. Available at greensciencepolicy.org/madrid-statement./ 

Danish Ministry of the Environment Perfluoroalkylated Substances: PFOA, PFOS and PFOS: A Evaluation of Health Hazards and Proposal of a Health Based Quality Criterion for Drinking Water, Soil and Ground Water. Environmental Project No. 1665, 2015. Available at www2.mst.dk/Udgiv/publications/2015/04/978-87-93283-01-5.pdf 

Danish Veterinary and Food Administration, Ministry of Environment and Food of Denmark. Fluorinated Substances in Paper and Board Food Contact Materials (FCM). 2015.

DuPont GenX, 8(e) Filings with EPA, 2010–2013. Available at assets.documentcloud.org/documents/2746960/GenX8eFilings.pdf 

See also: Sharon Lerner, New Teflon Toxin Causes Cancer in Lab Animals The Intercept, 2016. Available at theintercept.com/2016/03/03/new-teflon-toxin-causes-cancer-in-lab-animals./ 

Environmental Working Group, Teflon Chemical Harmful at Smallest Doses. 2016. Available at www.ewg.org/research/teflon-chemical-harmful-at-smallest-doses  

EWG, Scientists in N.J., Germany Support ‘No Safe Level’ of Teflon Chemical in Drinking Water. 2016. Available at www.ewg.org/enviroblog/2016/10/scientists-nj-germany-support-no-safe-level-teflon-chemical-drinking-water 

New Hampshire Department of Environmental Services, In-Home Water Filtration Options for PFCs in Household Drinking Water. 2016. Available at www.des.nh.gov/organization/commissioner/documents/pfoa-inhome-treatment-20160518.pdf 

New Jersey Drinking Water Quality Institute, Health-Based Maximum Contaminant Level Support Document: Perfluorooctanoic Acid (PFOA). 2016. Available at www.nj.gov/dep/watersupply/pdf/pfoa-hb--mcl-public-review-draftwithappendices.pdf

New Jersey Department of Environmental Protection, Draft Technical Support Document: Interim Specific Ground Water Criterion for Perfluorononanoic Acid (PFNA, C9). 2017. Available at www.dep.nj.gov/wp-content/uploads/dsr/375-95-1-tsd.pdf 

L. Schaider et al., Fluorinated Compounds in U.S. Fast Food Packaging. Environmental Science & Technology Letters, 2017, 4(3). Available at pubs.acs.org/doi/abs/10.1021/acs.estlett.6b00435

See also: EWG, Many Fast Food Wrappers Still Coated in PFCs, Kin to Carcinogenic Teflon Chemical. 2017. Available at www.ewg.org/research/many-fast-food-wrappers-still-coated-pfcs-kin-carcinogenic-teflon-chemical

X. Hu et al., Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants. Environmental Science & Technology Letters, 2016, 3(10). Available at pubs.acs.org/doi/abs/10.1021/acs.estlett.6b00260

Z. Wang et al., A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)? Environmental Science and Technology, 2017, 51(5). Available at pubs.acs.org/doi/abs/10.1021/acs.est.6b04806