Expert Commentary

PFAS ‘forever chemicals’ in drinking water: An explainer and research roundup

We summarize studies on where PFAS are found, health impacts, the efficacy of consumer water filters, new methods of destroying PFAS, and racial disparities in PFAS exposure.

PFAS in drinking water
(Rudy and Peter Skitterians from Pixabay)

If it feels like news coverage of the compounds colloquially named “forever chemicals” is everywhere, there’s a reason: The pace of research and likely government regulation for PFAS, short for perfluoroalkyl and polyfluoroalkyl substances, is accelerating.

In March, the U.S. The Environmental Protection Agency proposed limits on six PFAS in drinking water under the national Safe Water Drinking Act. If enacted, the rule would cover the first new contaminant under the act since the 1990s. The EPA intends to issue the final rules by the end of the year. The move is part of the Biden administration’s plans to fight PFAS pollution.

PFAS contamination in air, soil and water is a worldwide problem that many governments and agencies have begun addressing, including the European UnionCanada and Japan.

Journalists would do well to educate themselves on PFAS because the issue now touches almost every beat: business, consumer, environment, health, infrastructure, legal and local municipalities that include water utilities. That’s why we created this explainer and research roundup. (For more on covering PFAS, see our related tip sheet, which includes a list of data resources.)

Let’s start with the basics. What are PFAS?

PFAS are a group of more than 12,000 man-made chemicals and compounds used in all kinds of products since the 1940s, according to the EPA’s master list. 3M, which created the first PFAS, began selling it to DuPont in the 1950s for use in nonstick cookware. PFAS compounds stave off heat, grease, oil and water. Manufacturers use or have used versions of them in products, including firefighting foam, construction materials, non-stick cookware, cosmetics, clothing, and food containers, to name a few. 

PFAS are made up of a chain of linked carbon and fluorine atoms. Because the man-made compounds don’t degrade easily in the environment — or the human body — they have earned the “forever chemicals” nickname.    

The most studied types of PFAS, are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Both were mostly phased out in the mid-2000s by the manufacturers, according to the EPA. Yet they remain in the environment and find their way into drinking water from contaminated sources including surface areas. The EPA is targeting four other chemicals that when used in combination are designed to replace PFOA and PFOS in some consumer and industrial products. These mixtures can pose a health risk ”greater than each chemical on its own,” according to the EPA.

Those chemicals, made up of fewer carbon atoms, “are more quickly eliminated from the human body than PFOA and PFOS,” according to an EPA fact sheet. “They are still persistent in the environment.”

In recent decades, certain PFAS  have been linked to numerous health issues, including potentially higher risk for some cancers, autoimmune diseases, thyroid issues, liver disease, fetal complications, vaccine resistance and high cholesterol, among other concerns. Even very small amounts of certain kinds of PFAS may pose health risks over a lifetime.

“We are all contaminated with PFAS, and nearly all of our drinking water is also contaminated,” said Linda Birnbaum, the former director of the National Institute of Environmental Health Sciences and the National Toxicology Program in an email to The Journalist’s Resource.

Researchers from the U.S. Geological Survey in August 2023 published a paper estimating that at least 45% of tap water in the U.S. contains at least one or more types of PFAS. Their study covers both tap water for municipal systems as well as private wells and rural drinking water systems. That’s important to note, as the EPA’s proposed rules do not include private wells.

“If the average American is worried about the quality of their drinking water, they can use this and other studies to get informed, evaluate their own personal risk and reach out to their local health officials about testing or treatment,” Kelly Smalling, lead author of the study and a research chemist at the U.S. Geological Survey, said in an email interview.

A 2020 study from the watchdog nonprofit Environmental Working Group (summarized below) estimates more than 200 million people — nearly two-thirds of Americans — have tap water contaminated with a mixture of the PFAS compounds at concentrations exceeding 1 parts per trillion, or ppt. That’s the equivalent of about one drop of PFAS in 20 Olympic sized swimming pools.

Research is “still ongoing to determine how different levels of exposure to certain PFAS may lead to adverse health outcomes,” according to the EPA.    

PFAS chemicals can last in the human body for a long time. Some have a half-life, or the time it takes the body to cut the presence of a substance to about half, of about eight years. They are mainly removed from the body by excretion, mostly through urine.      

What is the state of PFAS regulation in the United States?

There are currently no federal regulations for PFAS in drinking water.

But half of all U.S. states already either regulate or are moving to put limits on certain kinds of PFAS, according to Safer States, a public advocacy group that tracks state legislation and policy. The National Association of State Legislatures has state-by-state information on PFAS and drinking water.

And EWG tracks PFAS in drinking water across the country. It has data and an interactive map highlighting its findings. As of June 2022, EWG estimates some 2,858 locations in all 50 states, Puerto Rico and Guam have contaminated drinking water.

In 2016, the EPA issued an advisory to keep the combined levels of PFOA and PFOS in drinking water at 70 parts per trillion, or ppt, either separately or combined.

The March 2023 proposed national rule was released under  a 2019 formal PFAS action plan that also includes potentially establishing drinking water standards., and an update to that plan in 2020 that includes calls for establishing what’s called a maximum contaminant level (MCL) for PFOA and PFOS in drinking water. And as of July 1, 2023, 180 kinds of PFAS must be reported to the EPA’s Toxic Release Inventory program, which tracks the release of chemicals from industry and government.

The levels in the proposed drinking water rule announced in March call for levels far below that, at 4 ppt, for PFOA and PFOS, the lowest level most labs can detect for these two most studied kinds of PFAS. A “hazard index” is proposed to regulate the remaining four compounds commonly blended together and used as replacement chemicals for PFOA and PFOS.  They are: Perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX Chemicals),  Perfluorohexane sulfonic acid (PFHxS) and Perfluorobutane sulfonic acid (PFBS).

If finalized, the proposed regulation would mandate public water systems monitor, notify the public and bring down the level of the PFAS chemicals to the new standards. 

In June 2023, 3M announced a preliminary $10.3 billion settlement with thousands of public water suppliers that had sued over PFAS contamination and announced it planned to stop making PFAS chemicals by 2025. (It had already agreed to “phase out” some forms of PFAS in 2000.) The 3M settlement announcement followed a similar $1.2 billion announcement from DuPont, Chemours and Corteva.

But 22 attorneys general asked a judge in late July to block the 3M settlement saying it doesn’t do enough to resolve claims and is too restrictive on how cities and towns can use the funds, Politico reported.

In a regulatory filing with the U.S. Securities and Exchange Commission, 3M listed details of the proposed settlement including what systems are eligible. It’s worth a look at the public information for journalists searching for story ideas or information about specific communities and the settlement.   

How much does it cost to remove PFAS?

Many water utilities will have to improve filtration and systems to reduce the levels of PFAS in drinking water, especially in states that haven’t broached their own regulations already. The proposed EPA drinking water rule does not apply to private wells.

Because the chemicals are difficult to eradicate, upgrading water systems will be expensive.

The 2021 Infrastructure Investment and Jobs Act provides about $9 billion in funds over five years tied to PFAS, according to the White House. According to an EPA fact sheet, that breaks down to:
• $4 billion through the Drinking Water State Revolving Funds, including a requirement states earmark 25% for “disadvantaged communities or public water systems serving fewer than 25,000 people.”
 • $5 billion as grants via the Emerging Contaminants in Small or Disadvantaged Communities (EC-SDC) Grant Program, which promotes “access to safe and clean water in small, rural, and disadvantaged communities while supporting local economies” In February 2023, the EPA announced the first $2 billion of this funding was available.

Still, some communities worry that the federal funding is insufficient. The EPA estimates it will cost utilities $772 million to $1.2 billion to comply if the proposed rule is finalized. Utilities might have to increase water bills to pay for the costs, not a popular move for any municipal budget.

The American Water Works Association, whose members include public utilities, said in March it expects the cost to reach $3.8 billion annually for utilities to install recommended treatment systems for PFOA and PFOS removal, citing an analysis undertaken for the group by the firm Black & Veatch.

The EPA also estimated economic benefits of $908 million to be $1.2 billion, according to a report from Bloomberg Law.

“One of the important things that the EPA does when it puts out a draft rule like this, is to consider the economic costs and benefits,” says Jamie DeWitt, a professor of pharmacology and toxicology at East Carolina University who follows PFAS closely. “While the cost might translate to individual homeowners in terms of an increase in their water bill, it also means that there will be fewer economic costs imposed on individuals and societies due to the chronic diseases that have been linked to PFAS exposures.”

What have journalists been missing?

PFAS chemicals weren’t widely studied in the environment until the early 2000s, notes a fact sheet from the nonprofit Interstate Technology and Regulatory Council, a state-led coalition with public and private members from all 50 states, and Washington D.C. Since then, it’s been a “very active area of research,” according to the group. 

Yet many studies on PFAS don’t make it into media coverage unless researchers issue a press release, according to a study published in July 2023 in the journal Environmental Health, led by researchers from the nonprofit Green Science Policy Institute.

Of 273 peer-reviewed epidemiological studies on PFAS and human health  published between 2018 and 2020, fewer than 8% issued a press release, the researchers found. Those that issued a release were 20 times more likely to draw attention from journalists.

The number of important studies that appear to be overlooked was surprising, says lead author Rebecca Fuoco, whose full-time job is to publicize PFAS studies. 

“When studies are unpublicized, that is, not covered in the media, they’re also reaching fewer scientists,” Fuoco says. “We found a correlation between media coverage and scholarly citation. There were studies that my scientist colleagues had not seen or didn’t know about, which was even more shocking to see.”

It’s important to pay attention to the research when covering PFAS issues. To get you started, here are summaries of six recent studies along with suggestions of related studies for you to read. The studies cover where PFAS is found in drinking water geographically, health impacts, the efficacy of consumer water filters, new methods of destroying PFAS, and racial disparities in PFAS exposure.

Research Roundup

Population-Wide Exposure to Per- and Polyfluoroalkyl Substances from Drinking Water in the United States
David Q. Andrews and Olga V. Naidenko. Environmental Science & Technology Letters, October 2020.

The study: This research from the Environmental Working Group analyzes PFAS and PFOS found in drinking water in the United States using publicly available data from the EPA, the U.S. Geological Survey, Colorado, Kentucky, Michigan, New Hampshire, New Jersey, North Carolina and Rhode Island. The researchers estimate the number of people in the United States who may be exposed to combined PFAS in drinking water at concentrations above 1 part per trillion, or ppt (equivalent to 1 nanogram per liter) and above 10 ppt.

The findings:
The EWG scientists estimate more than 200 million people — nearly two-thirds of Americans — have tap water contaminated with a mixture of the PFAS compounds at concentrations exceeding 1 ppt, in part because PFAS chemicals are “nearly ubiquitous” in surface water, the predominant source of drinking water in the U.S. They based their estimates on a total U.S. population of approximately 330 million, with 297 million served by community water systems and 241 million people served by systems tested in 2013-2015 through the EPA’s Unregulated Contaminant Monitoring Program. The researchers also estimate between 18 million and 80 million people may be exposed to combined PFOA and PFOS concentration in drinking water at concentrations above 10 ppt.

The authors write:
“The overall prevalence of PFAS in drinking water, revealed by testing with sensitive analytical limits, suggests that the majority of large metropolitan surface water systems in the U.S. may contain detectable PFAS. Conventional drinking water treatment is typically ineffective for PFAS.”     

Why we’re highlighting this study: This study uses publicly available data from both federal and state sources. It details sample locations and the method used to extrapolate the figure showing broad contamination is likely. It also provides a preliminary estimate of contamination from private wells, often difficult to survey.

Related study:

Low-temperature mineralization of perfluorocarboxylic acids: Forever chemicals’ Achilles’ heel
Brittany Trang, et al. Science, August 2022. 

The study: All PFAS have at least one carbon atom that is fluorinated — a near indestructible structure. In this study, researchers use a new process to “deflourinate” a kind of PFAS, called PFCA      : they mix water and a solvent called dimethyl sulfoxide at relatively low temperatures (80 to 120 degrees centigrade) compared with other methods. That leaves carbon and inorganic fluoride, two far less harmful substances. Under laboratory conditions, the combination then breaks down within 24 hours after adding  sodium hydroxide, also known as caustic soda or lye.

The findings: Scientists found a weakness in the PFAS structure by targeting one end of the molecule in a process that heats PFAS in dimethyl sulfoxide with sodium hydroxide. Sodium hydroxide is what’s known as a reagent — a compound used to start a chemical reaction. The process broke down PFAS molecules quickly into relatively benign substances. The scientists successfully tested the method on 10 kinds of PFAS, including perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkyl ether carboxylic acid (PFECAs), PFOAs and GenX (the trade name of a compound developed by DuPont). 

In the authors’ words: “In contrast to other proposed PFAS degradation strategies, the conditions described here are specific to fluorocarbons, destroy concentrated PFCAs, give high fluoride ion recovery and low fluorinated by-product formation, and operate under relatively mild conditions with inexpensive reagents. The proposed mechanism is consistent with both computational and experimental results, provides insight into the complexity of PFAS mineralization processes, and may be operative but unrecognized in other PFAS degradation approaches.”

Why we’re highlighting this study: This study shows a simple process for breaking down one kind of  PFAS atomic structure. Scientists are now investigating how to use it for large amounts of PFAS chemicals outside the lab. While most methods use filters to remove PFAS, this method, if it can be used widely, breaks them down. The study drew widespread attention and hope that “forever” might not be forever after all.

Related studies: 

Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications
Kelly Smalling, et al. Environment International, August 2023.

The study: Scientists from the U.S. Geological survey set out to compare human PFAS exposure in tap water from publicly regulated supply and unregulated private well systems, the most comprehensive survey  to date. The researchers note that there’s limited information on PFAS in residential tap water , especially for consumers who get their water from private wells. Many studies look at water sources, like lakes and groundwater, rather than the residential tap. Roughly one in eight U.S. residents get water from private wells. Researchers aggregated sampled tap water results from 716 locations (269 private wells and 447 public supply systems) across the U.S. during 2016 to 2021. They tested for 32 types of PFAS. The samples were assessed by three labs and compared with possible contamination sources, like industrial sites that may contaminate sources of drinking water.

The findings: The researchers estimate at least 45% of tap water in the U.S. contains at least one or more types of PFAS, with figures ranging from one to nine types, with a median of two different PFAS types in. The research also confirms previous studies that found urban areas are more likely to have PFAS in tap water. The authors estimate the probability of not finding PFAS in tap water is about 75% in rural areas versus 25% in urban areas. Drinking water exposure, the scientists note, may be more common in the Great Plains, Great Lakes, Eastern Seaboard and central and southern California.

The authors say next steps may be to:

• Integrate more geospatial datasets and PFAS data to better identify vulnerable regions and populations.
• Expand monitoring to include rural small-and private-well dependent communities.
• Expand analysis methods used by drinking water monitoring programs in the U.S. and globally.

In the author’s words:  The findings support “the continued need for point-of-use tap water monitoring, with an emphasis on unmonitored private-wells and underserved communities on small community water supplies.”

Why we’re highlighting this study: There is limited information on PFAS in tap water on a national level, particularly from private well sources, from which about 45 million people get their water, many in rural areas. The authors note how prevalent PFAS chemicals are likely to be in urban water systems.

Related study:

Sociodemographic Factors Are Associated with the Abundance of PFAS Sources and Detection in U.S. Community Water Systems 
Jahred M. Liddie, Laurel A. Schaider and Elsie M. Sunderland.Environmental Science & Technology, May 15, 2023.

The study: In the first study of its kind, researchers from the Harvard T.H. Chan School of Public Health, the Harvard Paulson School of Engineering and Applied Science, and the Silent Spring Institute, a non-profit organization that investigates environmental chemicals, evaluate communities with a higher population of Black and Hispanic/Latino residents and their exposure to PFAS chemicals in their drinking water supplies versus other communities. They examine PFAS concentrations from more than 44,000 water samples from 7,873 community water systems across 18 states collected between January 2016 and August 2022.

The findings: People living in communities with higher proportions of Black and Hispanic/Latino residents are more likely to have tap water contaminated with certain PFAS chemicals than people living in other communities. Roughly one in four people in the states studied were served by water systems with at least one kind of PFAS chemical detected above 5 nanograms per liter..

The authors also find that each possible source of PFAS chemicals inside a watershed  — an airport or a fire training area — could be associated with much higher levels of PFAS in drinking water systems. Water from watersheds with a higher concentration of those sites were also more likely to ultimately wind up in water systems that served Hispanic and Black communities versus those without the potential PFAS sources, the researchers find.

In the author’s words: Community Water Systems’ (CWS) “watersheds with PFAS sources served higher proportions of Hispanic/Latino and non-Hispanic Black residents compared to those without PFAS sources. CWS serving higher proportions of Hispanic/Latino and non-Hispanic Black residents had significantly increased odds of detecting several PFAS. This likely reflects disparities in the siting of PFAS contamination sources. Results of this work suggest that addressing environmental justice concerns should be a component of risk mitigation planning for areas affected by drinking water PFAS contamination.”

Why we’re highlighting this study:  This is the first study directly examining socioeconomic factors, PFAS levels in drinking water and potential sources of the contamination. As a new federal-level rule is rolled out by the EPA, more data may become available to researchers to parse broader and more detailed findings around the social justice aspects of PFAS and drinking water.

Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFASs)
Nicholas J. Herkert, et al. Environmental Science & Technology Letters, March  2020.

The study: Researchers led by scientists at Duke University tested residential water filters used both inside home plumbing systems and in consumer products like water pitchers in two North Carolina regions. Because PFAS chemicals can be difficult to remove from full scale municipal and well water systems, the authors set out to look at how at-home filters performed. They collected 89 samples from 73 homes and screened for 16 different kinds of PFAS.

The findings:
Under-the-sink “dual stage” and reverse osmosis filters showed “near complete removal” for the PFAS chemicals the researchers evaluated. In all, researchers looked at 89 water samples; 76 of those samples went through “point of use” or POU filters, on in-home devices, while 13 filtered water via “point of entry” or POE filters, where water enters the home. Other (and less expensive) types of filters didn’t work as well for PFAS chemicals overall. Of the PFAS chemicals tested, those with “long chain” molecules were easier to remove than “short chain” molecules, with up to 70 percent removal and 40 percent removal respectively.

In the authors’ words: “We demonstrated that residential activated carbon POU/POE systems have variable performance. While under-sink reverse osmosis systems appear to be an ideal option for removing PFAS, they have a high capital cost. Ultimately, an activated carbon filter should provide some removal of PFAS from drinking water… and have a lower capital cost.”

Why we included this study: With an increasing number of PFAS related stories in the news, we wanted to provide research on what consumers can do to lessen their exposure, particularly from drinking water.

Related reading:

Per‐and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research
Suzanne E. Fenton, et al. Environmental Toxicology and Chemistry, March 2021. 

The study review: This overview published in 2021 surveys and assesses current research and what scientists know about PFAS chemicals and their toxicological effects, or what the chemicals and poisons do to a person’s body. The authors want to figure out a way to study more of the thousands of kinds of PFAS together rather than individually. The authors include and examine studies on PFAS chemical exposure that suggest a link to or higher risk of autoimmune disorders including thyroid disease, increased cholesterol levels, diminished vaccine response, low sperm count, liver damage, inflammatory bowel disease, increased risk of miscarriage, obesity and some cancers, among other impacts on human health.

The recommendations: The authors call for a way to better define relationships between a PFAS chemical’s structure and biomarkers, or indications that show a specific change or response in how the human body is supposed to operate. If a method can be found, scientists will learn more about a far larger number of PFAS chemicals than the limited number studied now, common effects and a way to respond to more versions of them in specific parts or areas of the body.

In the authors’ words: “There are only a handful of PFAS with enough health effects data for use in decision‐making, as evidenced by state‐led standard setting,” the authors write. “There are numerous health effects reported for those PFAS tested, which sets this family of chemicals apart from many others and elevates the need for precautionary action. With hundreds of PFAS lacking health effects data, translational research teams using innovative methodologies and carefully designed studies will be critical to our state of knowledge on human health toxicity of per‐and polyfluoroalkyl substances.”

Additional reading:  Scientific Basis for Managing PFAS as a Chemical Class,      
Carol F. Kwiatkowski, et al. Environmental Science & Technology Letters, August, 2020.


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