WASHINGTON – New data released by the Environmental Protection Agency shows an additional 6.5 million Americans have drinking water contaminated by the toxic “forever chemicals” known as PFAS. It brings the total number of people at risk of drinking this contaminated tap water to about 165 million across the U.S.
“It is impossible to ignore the growing public health crisis of PFAS exposure. It’s detectable in nearly everyone and it’s found nearly everywhere, including the drinking water for a huge segment of the population,” saidDavid Andrews, Ph.D., acting chief science officer at the Environmental Working Group.
“The documented extent of PFAS contamination of the country’s water supply highlights the enormous scale of contamination,” he added.
The EPA’s new findings come from tests of the nation’s drinking water supply conducted as part of the Fifth Unregulated Contaminant Monitoring Rule, or UCMR 5, which requires U.S. water utilities to test drinking water for 29 individual PFAS compounds.
The EPA has said it will roll back limits on four PFAS in drinking water, leaving those chemicals unregulated. It plans to only retain standards for the two most notorious chemicals, PFOA and PFOS. These maximum contaminant levels or MCLs, set enforceable standards for the amount of contaminants allowed in drinking water.
Even with keeping the PFOA and PFOS MCLs in place, rolling back the four other limits will make it harder to hold polluters responsible and ensure clean drinking water.
In addition, the EPA’s plan to reverse the four science-based MCLs likely contradicts an anti-backsliding provision in the Safe Drinking Water Act. That law requires any revision to a federal drinking water standard “maintain, or provide for greater, protection of the health of persons.”
“It’s worrying to see the EPA renege on its commitments to making America cleaner and safer, especially as it ignores its own guidelines to do so,” said Melanie Benesh, EWG’s vice president for government affairs.
Widespread PFAS pollution
The Trump administration’s PFAS standards rollback could grant polluters unchecked freedom to release toxic forever chemicals into U.S. waterways, endangering millions of Americans.
EWG estimates nearly 30,000 industrial polluters could be discharging PFAS into the environment, including into sources of drinking water. Restrictions on industrial discharges would lower the amount of PFAS ending up in drinking water sources.
“Addressing the problem means going to the source. For PFAS, that’s industrial sites, chemical plants and the unnecessary use of these chemicals in consumer products,” said Andrews.
Health risks of PFAS exposure
PFAS are toxic at extremely low levels. They are known as forever chemicals because once released into the environment, they do not break down and can build up in the body. The Centers for Disease Control and Prevention has detected PFAS in the blood of 99 percent of Americans, including newborn babies.
For over 30 years, EWG has been dedicated to safeguarding families from harmful environmental exposures, holding polluters accountable and advocating for clean, safe water.
“Clean water should be the baseline,” Andrews said, “The burden shouldn’t fall on consumers to make their water PFAS-free. While there are water filters that can help, making water safer begins with ending the unnecessary use of PFAS and holding polluters accountable for cleanup.”
For people who know of or suspect the presence of PFAS in their tap water, a home filtration system is the most efficient way to reduce exposure. Reverse osmosis and activated carbon water filters can be extremely effective at removing PFAS.
EWG researchers tested the performance of 10 popular water filters to evaluate how well each reduced PFAS levels detected in home tap water.
###
The Environmental Working Group is a nonprofit, non-partisan organization that empowers people to live healthier lives in a healthier environment. Through research, advocacy and unique education tools, EWG drives consumer choice and civic action.
Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been extensively evaluated with regard to human exposures and health impacts [1, 2]. Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making linkages between exposure and disease difficult. The articles included in the Journal of Exposure Science and Environmental Epidemiology Special Topic “Assessing Exposure and Health Consequences of Chemicals in Drinking Water in the 21st Century” cover a range of topics, including: (i) new exposure and health research for regulated and emerging chemicals, (ii) new methods and tools for assessing exposure to drinking water contaminants, (iii) issues of equity and environmental justice, (iv) drinking water issues within the context of a changing climate. This Special Topic includes articles authored by experts across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, climate science, and others. Many of these papers emerged from an international symposium organized by ISGlobal and Yale scientists held in Barcelona in September 2022 [3].
Regulated chemicals
Chemicals that have been the focus of environmental health research include disinfection by-products (DBPs), nitrate, and metals. Although many of these chemicals are regulated, there is concern about low-dose exposures at concentrations below standards and guidelines, and risks of health endpoints not yet studied. Kaufman et al. explore new ways to assess DBP exposure, considering concentrations and specific toxicity potential in relation to birth defects risk [4]. Long-term exposure to DBPs and nitrate is addressed by Donat-Vargas et al. in relation to chronic lymphocytic leukaemia in Spain [5]. Friedman et al. examine temporal and spatial variability of manganese concentrations in a case study in the United States (US) [6]. Hefferon et al. evaluated sociodemographic inequalities in fluoride concentrations across the US [7]. Spaur et al. evaluate the contribution of water arsenic to biomarker levels in a prospective study in the US [8].
Chemicals of emerging concern
Many emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), microplastics, and 1,4-dioxane, have drinking water as the dominant exposure pathway for many populations. Yet, these remain largely unregulated or have standards and guidelines that vary widely across states and countries. Because only small percentages of the universe of contaminants are regulated in drinking water, routine monitoring data for many chemicals of emerging concern is frequently absent or very limited. To advance understanding of drinking water exposures to PFAS, Cserbik et al. [9]. and Kotlarz et al. [10]. evaluate and compare PFAS in drinking water and blood serum samples in two different settings: an urban setting not impacted by PFAS pollution in Spain [9] and among well water users living near a fluorochemical facility in the US [10], respectively.
New methods and tools for exposure assessment
There is a need for improved tools, methods, and data to evaluate drinking water related exposures. These tools and techniques remain somewhat limited and lag behind those of other stressors (e.g., air pollution). Also, despite water contaminants occurring in mixtures, most of the evaluations (and policies and regulations) are conducted chemical by chemical, ignoring potential interactions. Schullehner et al. present case studies of three approaches of exposure assessment of drinking water quality: use of country-wide routine monitoring databases, wide-scope chemical analysis, and effect-based bioassay methods [11]. Luben et al. elaborate and compare different exposure assessment metrics to trihalomethanes in epidemiological analyses of reproductive and developmental outcomes [12]. Escher et al. present in vitro assays to evaluate biological responses of including neurotoxicity, oxidative stress, and cytotoxicity in different types of drinking water samples (tap, bottled, filtered) [13] Isaacs et al. present newly developed automated workflows to screen contaminants of concern based on toxicity and exposure potential [14]. Dorevitch et al. develop a novel method to improve detection of particulate lead spikes [15].
Issues of equity, environmental justice, and vulnerable populations
A substantial portion of the population (e.g., 20% in the United States) have private water supplies (e.g., a household domestic drinking water well), which are not subject to any federal regulatory oversight or monitoring [16]. This presents an equity issue in access to data on drinking water quality, as discussed in Levin et al. [2]. and heterogeneity in state-based policies for drinking water prevention, as discussed by Schmitt et al. [17]. Spaur et al. [8], observed that water from unregulated private wells and regulated municipal water supplies contributes substantially to overall exposures (as measured by urinary arsenic and uranium concentrations) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide. Hefferon et al. evaluated environmental justice issues with respect to fluoride and found that 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit [7]. Friedman et al. show that manganese in drinking water frequently exceeds current guidelines in the US, and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible populations like children [6].
Chemical contamination may also pose a serious threat in the developing world. Today, around 2.2 billion people – or 1 in 4 – still lack safely managed drinking water at home [18]. In most of the world, microbial contamination is the biggest challenge. Because it has been understudied, the chemical risks remain obscure [19], and regulators often require local data to take action. Praveena et al. reviews the quality of different drinking water types in Malaysia (tap water, ground water, gravity feed system) and its implications on policy, human health, management, and future research [20].
Water quality in a changing climate
There is an urgent need to anticipate and prepare for current and future challenges in a rapidly changing world. We also need to foresee new challenges to address issues of water scarcity (e.g., increasing desalination, use of treated wastewater in densely populated urban areas to meet water use demands), and aging infrastructure for many middle- and high-income countries constructed in the nineteenth and twentieth centuries. The impacts of climate change on the water cycle are direct and observable, such as more frequent droughts and floods, sea level rise, and ice/snow melt. These events will challenge drinking water quality and availability through direct and indirect mechanisms [21]. There is still very limited knowledge on how climate events will affect the quality of finished drinking water. In our special issue, Oliveras et al. conducts a new analysis on the impacts of drought and heavy rain surrogates on the quality of drinking water in Barcelona, Spain [22].
Conclusion
Chemical contamination of drinking water is widespread. Although our knowledge on chemical risks in drinking water is increasing, there are knowledge gaps that make a slow translation to public health protection. We hope this issue highlights, elevates, and motivates research on chemical exposures via drinking water.
Drinking water contaminated with Pfas chemicals probably increases the risk of infant mortality and other harm to newborns, a new peer-reviewed study of 11,000 births in New Hampshire finds.
The first-of-its-kind University of Arizona research found drinking well water down gradient from a Pfas-contaminated site was tied to an increase in infant mortality of 191%, pre-term birth of 20%, and low-weight birth of 43%.
It was also tied to an increase in extremely premature birth and extremely low-weight birth by 168% and 180%, respectively.
The findings caught authors by surprise, said Derek Lemoine, a study co-author and economics professor at the University of Arizona who focuses on environmental policymaking and pricing climate risks.
“I don’t know if we expected to find effects this big and this detectable, especially given that there isn’t that much infant mortality, and there aren’t that many extremely low weight or pre-term births,” Lemoine said. “But it was there in the data.”
The study also weighed the cost of societal harms in drinking contaminated water against up-front cleanup costs, and found it to be much cheaper to address Pfas water pollution.
Extrapolating the findings to the entire US population, the authors estimate a nearly $8bn negative annual economic impact just in increased healthcare costs and lost productivity. The cost of complying with current regulations for removing Pfas in drinking water is estimated at about $3.8bn.
“We are trying to put numbers on this and that’s important because when you want to clean up and regulate Pfas, there’s a real cost to it,” Lemoine said.
Pfas are a class of at least 16,000 compounds often used to help products resist water, stains and heat. They are called “forever chemicals” because they do not naturally break down and accumulate in the environment, and they are linked to serious health problems such as cancer, kidney disease, liver problems, immune disorders and birth defects.
Pfas are widely used across the economy, and industrial sites that utilize them in high volume often pollute groundwater. Military bases and airports are among major sources of Pfas pollution because the chemicals are used in firefighting foam. The federal government estimated that about 95 million people across the country drink contaminated water from public or private wells.
Among those are toxicological studies in which researchers examine the chemicals’ impact on lab animals, but that leaves some question about whether humans experience the same harms, Lemoine said.
Other studies are correlative and look at the levels of Pfas in umbilical cord blood or in newborns in relation to levels of disease. Lemoine said those findings are not always conclusive, in part because many variables can contribute to reproductive harm.
The new natural study is unique because it gets close to “isolating the effect of the Pfas itself, and not anything around it”, Lemoine said.
Researchers achieved this by identifying 41 New Hampshire sites contaminated with Pfoa and Pfos, two common Pfas compounds, then using topography data to determine groundwater flow direction. The authors then examined reproductive outcomes among residents down gradient from the sites.
Researchers chose New Hampshire because it is the only state where Pfas and reproductive data is available, Lemoine said. Well locations are confidential, so mothers were unaware of whether their water source was down gradient from a Pfas-contaminated site. That created a randomization that allows for causal inference, the authors noted.
The study’s methodology is rigorous and unique, and underscores “that Pfas is no joke, and is toxic at very low concentrations”, said Sydney Evans, a senior science analyst with the Environmental Working Group non-profit. The group studies Pfas exposures and advocates for tighter regulations.
The study is in part effective because mothers did not know whether they were exposed, which created the randomization, Evans said, but she noted that the state has the information. The findings raise questions about whether the state should be doing a similar analysis and alerting mothers who are at risk, Evans said.
Lemoine said the study had some limitations, including that authors don’t know the mothers’ exact exposure levels to Pfas, nor does the research account for other contaminants that may be in the water. But he added that the findings still give a strong picture of the chemicals’ effects.
Granular activated carbon or reverse osmosis systems can be used by water treatment plants and consumers at home to remove many kinds of Pfas, and those systems also remove other contaminants.
The Biden administration last year put in place limits in drinking water for six types of Pfas, and gave water utilities several years to install systems.
The Trump administration is moving to undo the limits for some compounds. That would probably cost the public more in the long run. Utility customers pay the cost of removing Pfas, but the public “also pays the cost of drinking contaminated water, which is bigger”, Lemoine said.
Epidemiologic and animal studies both support relationships between exposures to per- and polyfluoroalkyl substances (PFAS) and harmful effects on the immune system. Accordingly, PFAS have been identified as potential environmental risk factors for adverse COVID-19 outcomes.
Objective
Here, we examine associations between PFAS contamination of U.S. community water systems (CWS) and county-level COVID-19 mortality records. Our analyses leverage two datasets: one at the subnational scale (5371 CWS serving 621 counties) and one at the national scale (4798 CWS serving 1677 counties). The subnational monitoring dataset was obtained from statewide drinking monitoring of PFAS (2016–2020) and the national monitoring dataset was obtained from a survey of unregulated contaminants (2013–2015).
Methods
We conducted parallel analyses using multilevel quasi-Poisson regressions to estimate cumulative incidence ratios for the association between county-level measures of PFAS drinking water contamination and COVID-19 mortality prior to vaccination onset (Jan-Dec 2020). In the primary analyses, these regressions were adjusted for several county-level sociodemographic factors, days after the first reported case in the county, and total hospital beds.
Results
In the subnational analysis, detection of at least one PFAS over 5 ng/L was associated with 12% higher [95% CI: 4%, 19%] COVID-19 mortality. In the national analysis, detection of at least one PFAS above the reporting limits (20–90 ng/L) was associated with 13% higher [95% CI: 8%, 19%] COVID-19 mortality.
Impact Statement
Our findings provide evidence for an association between area-level drinking water PFAS contamination and higher COVID-19 mortality in the United States. These findings reinforce the importance of ongoing state and federal monitoring efforts supporting the U.S. Environmental Protection Agency’s 2024 drinking water regulations for PFAS. More broadly, this example suggests that drinking water quality could play a role in infectious disease severity. Future research would benefit from study designs that combine area-level exposure measures with individual-level outcome data.
Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been extensively evaluated with regard to human exposures and health impacts [1, 2]. Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making linkages between exposure and disease difficult. The articles included in the Journal of Exposure Science and Environmental Epidemiology Special Topic “Assessing Exposure and Health Consequences of Chemicals in Drinking Water in the 21st Century” cover a range of topics, including: (i) new exposure and health research for regulated and emerging chemicals, (ii) new methods and tools for assessing exposure to drinking water contaminants, (iii) issues of equity and environmental justice, (iv) drinking water issues within the context of a changing climate. This Special Topic includes articles authored by experts across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, climate science, and others. Many of these papers emerged from an international symposium organized by ISGlobal and Yale scientists held in Barcelona in September 2022 [3].
Regulated chemicals
Chemicals that have been the focus of environmental health research include disinfection by-products (DBPs), nitrate, and metals. Although many of these chemicals are regulated, there is concern about low-dose exposures at concentrations below standards and guidelines, and risks of health endpoints not yet studied. Kaufman et al. explore new ways to assess DBP exposure, considering concentrations and specific toxicity potential in relation to birth defects risk [4]. Long-term exposure to DBPs and nitrate is addressed by Donat-Vargas et al. in relation to chronic lymphocytic leukaemia in Spain [5]. Friedman et al. examine temporal and spatial variability of manganese concentrations in a case study in the United States (US) [6]. Hefferon et al. evaluated sociodemographic inequalities in fluoride concentrations across the US [7]. Spaur et al. evaluate the contribution of water arsenic to biomarker levels in a prospective study in the US [8].
Chemicals of emerging concern
Many emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), microplastics, and 1,4-dioxane, have drinking water as the dominant exposure pathway for many populations. Yet, these remain largely unregulated or have standards and guidelines that vary widely across states and countries. Because only small percentages of the universe of contaminants are regulated in drinking water, routine monitoring data for many chemicals of emerging concern is frequently absent or very limited. To advance understanding of drinking water exposures to PFAS, Cserbik et al. [9]. and Kotlarz et al. [10]. evaluate and compare PFAS in drinking water and blood serum samples in two different settings: an urban setting not impacted by PFAS pollution in Spain [9] and among well water users living near a fluorochemical facility in the US [10], respectively.
New methods and tools for exposure assessment
There is a need for improved tools, methods, and data to evaluate drinking water related exposures. These tools and techniques remain somewhat limited and lag behind those of other stressors (e.g., air pollution). Also, despite water contaminants occurring in mixtures, most of the evaluations (and policies and regulations) are conducted chemical by chemical, ignoring potential interactions. Schullehner et al. present case studies of three approaches of exposure assessment of drinking water quality: use of country-wide routine monitoring databases, wide-scope chemical analysis, and effect-based bioassay methods [11]. Luben et al. elaborate and compare different exposure assessment metrics to trihalomethanes in epidemiological analyses of reproductive and developmental outcomes [12]. Escher et al. present in vitro assays to evaluate biological responses of including neurotoxicity, oxidative stress, and cytotoxicity in different types of drinking water samples (tap, bottled, filtered) [13] Isaacs et al. present newly developed automated workflows to screen contaminants of concern based on toxicity and exposure potential [14]. Dorevitch et al. develop a novel method to improve detection of particulate lead spikes [15].
Issues of equity, environmental justice, and vulnerable populations
A substantial portion of the population (e.g., 20% in the United States) have private water supplies (e.g., a household domestic drinking water well), which are not subject to any federal regulatory oversight or monitoring [16]. This presents an equity issue in access to data on drinking water quality, as discussed in Levin et al. [2]. and heterogeneity in state-based policies for drinking water prevention, as discussed by Schmitt et al. [17]. Spaur et al. [8], observed that water from unregulated private wells and regulated municipal water supplies contributes substantially to overall exposures (as measured by urinary arsenic and uranium concentrations) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide. Hefferon et al. evaluated environmental justice issues with respect to fluoride and found that 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit [7]. Friedman et al. show that manganese in drinking water frequently exceeds current guidelines in the US, and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible populations like children [6].
Chemical contamination may also pose a serious threat in the developing world. Today, around 2.2 billion people – or 1 in 4 – still lack safely managed drinking water at home [18]. In most of the world, microbial contamination is the biggest challenge. Because it has been understudied, the chemical risks remain obscure [19], and regulators often require local data to take action. Praveena et al. reviews the quality of different drinking water types in Malaysia (tap water, ground water, gravity feed system) and its implications on policy, human health, management, and future research [20].
Water quality in a changing climate
There is an urgent need to anticipate and prepare for current and future challenges in a rapidly changing world. We also need to foresee new challenges to address issues of water scarcity (e.g., increasing desalination, use of treated wastewater in densely populated urban areas to meet water use demands), and aging infrastructure for many middle- and high-income countries constructed in the nineteenth and twentieth centuries. The impacts of climate change on the water cycle are direct and observable, such as more frequent droughts and floods, sea level rise, and ice/snow melt. These events will challenge drinking water quality and availability through direct and indirect mechanisms [21]. There is still very limited knowledge on how climate events will affect the quality of finished drinking water. In our special issue, Oliveras et al. conducts a new analysis on the impacts of drought and heavy rain surrogates on the quality of drinking water in Barcelona, Spain [22].
Conclusion
Chemical contamination of drinking water is widespread. Although our knowledge on chemical risks in drinking water is increasing, there are knowledge gaps that make a slow translation to public health protection. We hope this issue highlights, elevates, and motivates research on chemical exposures via drinking water.
It was an ideal spot for families to swim and fish
Then Wisconsin officials tested the water
Snowden Lake in Stella, Wis., seen here on Oct. 20, 2025, has been contaminated with PFAS, known commonly as forever chemicals. (AP Photo/Michael Phillis)
STELLA, Wis. (AP) — Kristen Hanneman made a small decision in 2022 that would upend life for her entire town.
State scientists were checking private drinking water wells across Wisconsin for a widely used family of harmful chemicals called PFAS. They mailed an offer to test the well outside her tidy farmhouse surrounded by potato farms cut out of dense forest. Without much thought, she accepted.
Months later, Hanneman found herself on the phone with a state toxicologist who told her to stop drinking the water — now. The well her three kids grew up on had levels thousands of times higher than federal drinking water limits for what are commonly known as forever chemicals.
Hanneman’s well was hardly the only one with a problem. And the chemicals were everywhere. Pristine lakes and superb hunting made Stella a sportsman’s dream. Now officials say the fish and deer should be eaten sparingly or not at all.
Many residents here have known their neighbors for decades. If they want to move away from all this, it’s hard to sell their property – who, after all, would want to buy?
“Had I just thrown that survey in the garbage,” Hanneman said, “would any of this be where it is today?”
The town hall in Stella, Wis., on Friday, Dec. 5, 2025. (AP Photo/Morry Gash)
Stella is far from the only community near industrial sites and military bases nationwide where enormous amounts of PFAS have contaminated the landscape, posing a particular threat to nearby well owners.
Forever chemicals get their name because they resist breaking down, whether in well water or the environment. In the human body, they accumulate in the liver, kidneys and blood. Research has linked them to an increased risk of certain cancers and developmental delays in children.
Government estimates suggest as much as half of U.S. households have some level of PFAS in their water — whether it comes from a private well or a tap. But while federal officials have put strict limits on water provided by utilities, those rules don’t apply to the roughly 40 million people in the United States who rely on private drinking water wells.
Short of a random test, as in Stella, few may learn their water is tainted with the odorless, colorless chemicals.
At least 20 states do not test private wells for PFAS outside of areas where problems are already suspected, according to a survey of state agencies by The Associated Press. Even in states that do, residents often wait years for help and receive far fewer resources than people tied into municipal tap water.
PFAS are so common because they are so useful. Uniquely able to repel moisture and withstand extreme temperatures, the chemicals have been critical to making waterproof shoes, nonstick cookware and foam that could extinguish the hottest fires.
When the chemicals reach soil or water, as they have near factories and waste sites, they are extremely difficult to remove. North Carolina saw an early example, with well owners downstream from a PFAS manufacturing plant still dealing with tainted water years later. In rural northwest Georgia, communities are reckoning with widespread contamination from PFAS that major carpet manufacturers applied for stain resistance.
Robert Bilott, an environmental attorney who pursued one of the first major lawsuits against a PFAS manufacturer in the late 1990s, said many states don’t have the money to help.
“The well owners — the victims of the contamination — shouldn’t have to be paying,” he said. “But where’s this money going to come from?”
Attendees listen to presentations at the Chatsworth, Ga., town hall on Thursday, June 12, 2025. The group PFAS Georgia represents numerous residents and farmers in Dalton and Calhoun who allege their properties are contaminated with PFAS from the carpet industry. (Hyosub Shin/Atlanta Journal-Constitution via AP)Marie Jackson mows her lawn, Thursday, May 8, 2025, in Resaca, Ga. She spent her childhood playing and swimming in the Conasauga River, downstream from Dalton. Her idyllic memories are overshadowed by recollections of foam on the river and dead fish. (Hyosub Shin/Atlanta Journal-Constitution via AP)
Well owners often the last to know about contamination
The alarming results from Hanneman’s well triggered a rush of testing, beginning with the wells of nearby neighbors and later expanding miles away.
How the chemicals infiltrated water beneath Stella’s sandy soil was initially a mystery. State officials eventually suspected the paper mill in the small city of Rhinelander, a 10-mile (16-kilometer) drive from town. The mill had specialized in making paper for microwave popcorn bags — a product that was greaseproof thanks in part to PFAS.
The mill’s manufacturing process also produced a waste sludge which could be used as a fertilizer. By 1996, and for decades after with state approval, the mill spread millions of pounds on farm fields in and around Stella. Wisconsin officials now believe the PFAS it contained seeped into the subterranean reserves of groundwater that feed lakes, streams and many residential wells.
In September, the state sent initial letters assigning cleanup and investigation responsibilities to current and former owners of the mill. These companies point out that the state permitted their sludge spreading, starting long before the dangers of PFAS were widely understood.
The Ahlstrom paper mill in Rhinelander, Wis., on Friday, Dec. 5, 2025 (AP Photo/Morry Gash)
The problem in Stella remained hidden because well owners don’t have a utility testing their water.
Rhinelander’s water utility first tested for PFAS in 2013 to comply with federal rules. By 2019, the city shut down two utility-owned public wells to protect customers. In Stella, meanwhile, some well owners found out only last year that their water is unsafe.
The Hanneman family moved into their home when their oldest son was nearly two. He’s 19 now. His parents worry about all those years of exposure, and have joined an effort to sue the paper mill’s owners and PFAS manufacturers.
Several plaintiffs in the growing lawsuit allege property damage and that their cholesterol, thyroid and kidney diseases are linked to contaminated groundwater. The companies have denied responsibility.
Very tiny amounts of PFAS consumed regularly over years can be dangerous. As scientists better understood those risks, federal advice for water utilities slowly followed and tightened. The current limit is just 4 parts per trillion, or less than a drop diluted in an Olympic-size swimming pool.
The Environmental Protection Agency recommends private wells be tested for bacteria and a limited number of commonly found chemicals, but not PFAS unless it is a known local problem. Experts say testing mandates would be deeply unpopular. Many well owners value their freedom from government oversight and a monthly bill, and take pride in the taste of their water.
PFAS has turned some of those freedoms into liabilities. The chemicals can only be removed from water with costly filters that must be regularly monitored and replaced. Some well owners opt instead to drill deeper or even connect to city water pipes. Facing expensive and uncertain options, many resort to bottled water.
Tom LaDue baits a hook with his grandkids in 2022 before PFAS contamination was discovered in Snowden Lake in Stella, Wis. (Courtesy Tom LaDue via AP)
In Stella, residents are grappling with the chemicals’ unpredictable underground path. Though Tom LaDue’s backyard extends to the edge of a highly contaminated lake, testing found barely any PFAS in his family’s well.
Somehow, a neighbor farther back from the lake found 1,500 parts per trillion of PFAS in her shallower well — magnitudes above the federal limits for tap water. The mother of three in that house says she is regularly tired, which she blames on thyroid issues, wondering if the water is to blame.
In one picture from a few years ago, LaDue is baiting a hook as his grandson dangles a fishing pole over the side of their boat. The sun shines bright.
“It’s a nice lake and we fished in here,” he said. “Now they tell us we can’t eat the fish anymore.”
House by house
While utilities can rely on centralized treatment facilities, restoring safe water for well owners must be done household by household. Some well owners get left out as regulators, lawyers and companies strike deals over who gets help.
The treatment of residents in the lakeside town of Peshtigo, Wisconsin, depends on the street where they live.
The town faced a crisis nearly a decade ago when PFAS were detected in wells downstream from a fire technology plant owned by Tyco and parent company Johnson Controls, which manufactured firefighting foam. Wisconsin officials said the company was responsible for cleaning up the plant and must sample wells in a broad area to see where the pollution spread. Johnson Controls told state regulators it studied the area’s hydrology and geology and concluded it would pay for tests and drill new wells in a smaller section of town for which it maintains it is responsible.
Kayla Furton, a high school teacher who grew up in Peshtigo, lives in a home inside this area.
Had she lived two houses away, Furton would have had to pay out of pocket to treat the PFAS in her water.
Furton’s worries over what would happen to her neighbors beyond that line, including her sister, motivated her to run for the town’s board. During her time in office, Peshtigo leadership split over which fixes to pursue, and some well owners are still waiting on a long-term solution.
“Groundwater does not follow lines drawn on a map,” Furton said. “There’s nothing to say that, OK, the PFAS stops there.”
In a statement, Johnson Controls said it has taken full responsibility for the area it contaminated. The company said it has restored more than 300 million gallons of clean water to the environment and installed 139 new wells.
The state of Wisconsin says the company has not fully investigated the extent of the contamination, and filed a lawsuit in 2022. Johnson Controls said in December the parties were close to reaching an agreement; the Wisconsin Department of Justice said it does not comment on pending litigation.
The Cape Fear River flows over Lock and Dam No. 1 at Riegelwood, N.C., on Jan. 18, 2025. (AP Video/Carolyn Kaster)
Residents along the Cape Fear River in North Carolina have seen just how far forever chemicals can spread. In 2017, the Wilmington StarNews revealed that PFAS from a Chemours chemical plant in Fayetteville were washing into the river and contaminating the water supply. After being sued, the billion-dollar company agreed to test nearby wells and treat those with polluted water. It did not admit to any wrongdoing.
As in Stella, the company tested in a slowly expanding radius that grew by quarter-mile segments from its plant. Chemours agreed to keep testing wells until it reached the edge of the polluted area — a process it expected to take 18 months.
Seven years and some 23,000 wells later, testing is ongoing, with the contamination stretching far beyond what state regulators first imagined. Forever chemicals have been found in drinking water along nearly 100 miles (160 kilometers) of the river, from inland Fayetteville to the Atlantic coast.
According to an AP analysis of data submitted to the state’s Department of Environmental Quality, Chemours discovered high levels of PFAS in more than 150 new wells in 2025.
Many well owners “thought they were fine,” said Emily Donovan, an organizer and cofounder of the group Clean Cape Fear. “And now they’re finding out so late that they were also contaminated.”
The Chemours Company, Fayetteville Works in White Oak, N.C., on Tuesday, Dec. 9, 2025. (AP Photo/Carolyn Kaster)A sign at the entrance of Chemours’ Fayetteville Works in White Oak, N.C., on Tuesday, Dec. 9, 2025. (AP Photo/Carolyn Kaster)
In a statement, Chemours said its timeline for testing wells depends on factors outside its control, including whether residents allow it, and that of the roughly 1,250 wells it sampled last year, 12% had PFAS. Chemours said it continues to contact eligible homes, and that a sample is typically taken within a week of residents’ responding.
States leave well owners behind
In the absence of federal rules, responsibility falls to the states. But many states don’t look for contamination in private wells — and when those that do find it, many struggle to fund a fix.
One proactive state is Michigan, where millions rely on private wells. Officials there have tested groundwater and offered free tests to well owners near PFAS hot spots which, at hundreds of dollars per test, many owners are reluctant or unable to buy. The state provided more than $29 million in grants to clean up forever chemicals in its 2022 fiscal year, including hooking up nearly a thousand well owners to public water.
One of the biggest challenges is helping well owners understand why they should take the threat seriously.
“We are very lucky to get 50% of the people to say, ‘Yes, come test my well for free,’ let alone willing to put on a filter,” said Abigail Hendershott, executive director of Michigan’s multiagency team that responds to PFAS contamination.
New Hampshire, which dealt with an early PFAS crisis in Merrimack, has tested over 15,000 wells, more than half of which had levels exceeding federal standards. It provides generous rebates for homeowners to access clean water.
Elsewhere, millions of households are left on their own.
In northwest Georgia, some of the world’s largest carpet companies began applying PFAS for stain resistance in the 1970s. The companies continued using the chemicals, which entered the environment through manufacturing wastewater, for years, even after scientific studies and regulators warned of their accumulation in human blood and possible health effects, according to an investigation by The Atlanta Journal-Constitution, The Associated Press, The Post and Courier and AL.com. The companies say that they followed all required regulations and that they stopped using PFAS on carpets in 2019.
Faye Jackson gets her blood tested at a medical clinic in Calhoun, Ga., on Tuesday, Sept. 30, 2025, as her daughter Marie waits outside for her turn. Their blood tests revealed they have PFAS levels above the safety threshold outlined by national health experts. (Miguel Martinez/Atlanta Journal-Constitution via AP)
The chemicals have tainted much of the landscape, including the drinking water in cities and the waterways that crisscross the Conasauga River watershed, home to tens of thousands of people. But only well owners near the small city of Calhoun have been offered free tests, and then only under a court agreement. The contaminated river flows into Alabama, where state officials do not typically test private wells for PFAS.
Financial limitations are an oft-cited reason why states aren’t doing more.
Wisconsin, which relied on federal funds for its initial survey of wells, has scraped together resources to investigate PFAS in Stella. The state’s environmental agency has no budget for sampling or treatment and is pulling money and staff time from other programs, according to the head of the drinking and groundwater program. Supplying bottled water to impacted homes — once a rare expense — now requires the state to set aside $900,000 annually.
Meanwhile, enormous amounts of money that could help have been stuck in a bank account, collecting interest. Though state lawmakers voted in 2023 to provide $125 million for PFAS cleanup, the funding has been mired by a separate debate over whether to shield certain property owners from liability. In January, key legislators said they were getting closer to a deal that would release the money.
The EPA has allocated billions to states for PFAS treatment and testing, but much of that money goes to public utilities.
Construction is underway on a reverse osmosis treatment facility which is designed to filter out PFAS from local drinking water in Gadsden, Ala., on Wednesday, Nov. 19, 2025. (Will McLelland/AL.com/The Birmingham News via AP)
Federal officials are evaluating Stella for inclusion in the Superfund program, a large-scale decontamination process that would take years. They also partnered with Wisconsin officials to expand well sampling in July.
At an October public meeting in Stella, several residents asked if they should be worried about their well water.
There is a risk, state employees said, but they could not offer unlimited free tests to rule it out. Those who wanted one immediately would have to pay for it.
“We’re doing the best that we can with the funding that we have available,” said Mark Pauli, a drinking and groundwater supervisor.
In a statement, a spokesperson for the Wisconsin Department of Natural Resources said it had offered cost-free PFAS sampling for well owners within three miles of Stella and to many beyond that distance. The state said it provides owners of contaminated wells with guidance on treating their water and accessing financial help.
Nobody is accepting blame in Stella and finger pointing is circular. While the state is investigating, the current and former mill owners point to the state’s permit as exonerating and say they followed all state rules.
Ahlstrom, the Finnish company that has owned the mill since 2018, said in a statement it hasn’t used two of the most common types of PFAS found in Stella wells in its manufacturing process, and that it phased out all other types of PFAS in 2023. In late January, the company announced its own free bottled water program for residents.
Former owner Wausau Paper and its parent company Essity said they were cooperating with state officials and that the waste sludge they spread was tested for various contaminants, but not PFAS because it wasn’t required.
Wisconsin officials say the threat of PFAS in the sludge wasn’t well understood when they approved its use as fertilizer, and that the state will continue to require those who caused contamination to address its impacts.
That leaves residents, who did not contaminate their own wells, stuck hiring lawyers who argue these companies and PFAS manufacturers knew — or should have known — the risks.
A new normal in Stella
The crisis in Stella sparked by the test of her own well drove Kristen Hanneman to run for a town leadership role.
She spent months learning about the dangers of PFAS, then relaying that knowledge. It’s a town so small that she said talking to a few of the right people would spread word to just about everyone.
It’s been more than three years since Hanneman learned her well had PFAS levels near 11,500 parts per trillion. Federal limits are in the single digits. Her water supply is just as contaminated now as it was then. The family currently drinks and cooks with bottled water provided by the state.
Though some Stella residents have been able to access grant funding to drill deeper wells to reach clean water, the help was limited by household income, with some families disqualified if they made more than $65,000. Typically, the most a family could receive was $16,000 — about half of what it may cost for a replacement well.
Stories circulate in Stella about people who paid for a new well only for their water still to be contaminated. Wisconsin state officials confirmed that at least three households faced this dilemma.
“Do we spend $20,000 to $40,000 on a new well for it to still be a problem?” Hanneman said.
One couple said replacing their well cleaned out much of their savings. Many are concerned about how much their home values have dropped.
A grant did help Cindy Deere, who worries about how 25 years of drinking the water in Stella may affect her health. She replaced her well and a test confirmed the new one was PFAS-free. Still, she has a hard time trusting the water.
“It’s a constant worry,” she said. “Is it going to turn bad?”
The paper mill is still permitted to spread sludge in the county that includes Stella. Its PFAS levels have recently tested well within new state guidelines.
Experts said sludge from industry and manufacturers is most likely to contain PFAS. Wisconsin developed testing guidelines for those sources for that reason, officials said.
But the state doesn’t require another type of sludge — treated waste from septic systems, which capture household sewage — to be tested for PFAS. A local septic company has been spreading it in Stella — in 2024 alone, it applied hundreds of thousands of gallons to farms and elsewhere, state records show. The company did not respond to multiple requests for comment.
Dianne Kopec, who has researched PFAS in wastewater at the University of Maine, said that without testing, officials can’t know if the practice recycles the chemicals back onto the soil in Stella.
“Given what we know today, continuing to spread sludge on agricultural fields is ludicrous,” Kopec said. “When you find yourself in a hole, it is best to stop digging.”
Snowden Lake in Stella, Wis., seen on Friday, Dec. 5, 2025, is contaminated by PFAS and officials say the fish is no longer safe to eat. (AP Photo/Morry Gash)
___
Associated Press writers Todd Richmond in Madison, Wis., Jason Dearen in Los Angeles and M.K. Wildeman in Hartford, Conn., contributed. Dylan Jackson and Justin Price of The Atlanta Journal-Constitution contributed from Atlanta.
___
This story is part of an investigative collaboration with The Atlanta Journal-Constitution, The Post and Courier and AL.com. It is supported through AP’s Local Investigative Reporting Program.
___
The Associated Press receives support from the Walton Family Foundation for coverage of water and environmental policy. The AP is solely responsible for all content. For all of the AP’s environmental coverage, visit https://apnews.com/hub/climate-and-environment.
Search by postal code for water quality reports and filter recommendations
WASHINGTON – This year’s update to the Environmental Working Group’s Tap Water Database shows millions of Americans are drinking water tainted with harmful chemicals, heavy metals and radioactive substances. Many of these contaminants are at levels far above what scientists consider safe.
EWG’s latest analysis includes water quality data collected between 2021 and 2023 from nearly 50,000 water systems. It identified 324 contaminants in drinking water across the country, with detectable levels in almost all community water systems.
“This is a wake-up call,” said Tasha Stoiber, Ph.D., a senior scientist at EWG. “For over 30 years, EWG has been at the forefront of advocating for stronger drinking water protections. Outdated federal regulations continue to leave millions of people at risk of exposure to harmful substances.
“Our Tap Water Database is the only resource providing consumers in every state access to accurate information about water contaminants, health risks and steps to reduce exposure through filtration – information they need so they can take action,” she said.
The levels of contamination in many locations fall largely below the Environmental Protection Agency’s outdated legal limits. But they often far exceed EWG’s health-based standards, the sweeping analysis of nationwide water utility tests found.
The Tap Water Database empowers virtually everyone in all 50 states and the District of Columbia to check local water quality and take action to improve it, if necessary. By entering their ZIP code, users can easily find detailed information about the contaminants in their local water supply, including tips on choosing the right water filter to reduce exposure.
“Consumers shouldn’t need to worry if their water is safe to drink,” said Sydney Evans, a senior science analyst at EWG. “The burden also shouldn’t fall to individuals to filter out hazardous substances that shouldn’t be in water taps to begin with.”
The update highlights contaminants in U.S. drinking water, including the toxic “forever chemicals” known as PFAS, that are in the drinking water of over143 million people. Tap water throughout the U.S. can also contain volatile organic compounds, nitrate and arsenic, among many other contaminants. These pollutants, often linked to cancer, developmental issues and other health risks, are found in nearly all community water systems.
Harmful disinfection byproducts and radiological contaminants also persist in water supplies in many communities.
Hexavalent chromium, or chromium-6, is a carcinogen made infamous by the Erin Brockovich case in Hinkley, Calif., and it’s in the drinking water of over 250 million Americans. There is no federal limit for chromium-6, despite its widespread presence and link to cancer and organ damage.
EPA efforts to safeguard drinking water continue to lag
Despite mounting scientific evidence and public concern about U.S. drinking water quality, federal action remains slow. In 2024, the Biden EPA introduced its first drinking water standards in more than 20 years, setting health-protective maximum contaminant limits for six PFAS.
“For too long, outdated federal standards have failed to reflect the latest science on drinking water, leaving millions exposed to harmful chemicals,” said Melanie Benesh, vice president of government affairs at EWG. “While the new PFAS standards represent a historic step forward, they are only a fraction of what is needed to protect public health.”
The EPA standards are critical in reducing PFAS contamination in the nation’s water supply. But these vital new protections could be at risk if the Trump administration tries to roll them back, along with weakening other steps the Biden EPA took to tackle PFAS pollution.
“Safe drinking water shouldn’t be a political debate – it’s a fundamental right. A rollback of these hard-won protections would be a devastating setback. We must push for stronger, science-based regulations to ensure safe water for every American,” said Benesh.
###
The Environmental Working Group is a nonprofit, non-partisan organization that empowers people to live healthier lives in a healthier environment. Through research, advocacy and unique education tools, EWG drives consumer choice and civic action.
An interdisciplinary team of researchers has developed a machine learning framework that uses limited water quality samples to predict which inorganic pollutants are likely to be present in a groundwater supply. The new tool allows regulators and public health authorities to prioritize specific aquifers for water quality testing.
This proof-of-concept work focused on Arizona and North Carolina but could be applied to fill critical gaps in groundwater quality in any region.
Groundwater is a source of drinking water for millions and often contains pollutants that pose health risks. However, many regions lack complete groundwater quality datasets.
“Monitoring water quality is time-consuming and expensive, and the more pollutants you test for, the more time-consuming and expensive it is,” says Yaroslava Yingling, co-corresponding author of a paper describing the work and Kobe Steel Distinguished Professor of Materials Science and Engineering at North Carolina State University.
“As a result, there is interest in identifying which groundwater supplies should be prioritized for testing, maximizing limited monitoring resources,” Yingling says. “We know that naturally occurring pollutants, such as arsenic or lead, tend to occur in conjunction with other specific elements due to geological and environmental factors. This posed an important data question: with limited water quality data for a groundwater supply, could we predict the presence and concentrations of other pollutants?”
“Along with identifying elements that pose a risk to human health, we also wanted to see if we could predict the presence of other elements – such as phosphorus – which can be beneficial in agricultural contexts but may pose environmental risks in other settings,” says Alexey Gulyuk, a co-first author of the paper and a teaching professor of materials science and engineering at NC State.
To address this challenge, the researchers drew on a huge data set, encompassing more than 140 years of water quality monitoring data for groundwater in the states of North Carolina and Arizona. Altogether, the data set included more than 20 million data points, covering more than 50 water quality parameters.
“We used this data set to ‘train’ a machine learning model to predict which elements would be present based on the available water quality data,” says Akhlak Ul Mahmood, co-first author of this work and a former Ph.D. student at NC State. “In other words, if we only have data on a handful of parameters, the program could still predict which inorganic pollutants were likely to be in the water, as well as how abundant those pollutants are likely to be.”
One key finding of the study is that the model suggests pollutants are exceeding drinking water standards in more groundwater sources than previously documented. While actual data from the field indicated that 75-80% of sampled locations were within safe limits, the machine learning framework predicts that only 15% to 55% of the sites may truly be risk-free.
“As a result, we’ve identified quite a few groundwater sites that should be prioritized for additional testing,” says Minhazul Islam, co-first author of the paper and a Ph.D. student at Arizona State University. “By identifying potential ‘hot spots,’ state agencies and municipalities can strategically allocate resources to high-risk areas, ensuring more targeted sampling and effective water treatment solutions”
“It’s extremely promising and we think it works well,” Gulyuk says. “However, the real test will be when we begin using the model in the real world and seeing if the prediction accuracy holds up.”
Moving forward, researchers plan to enhance the model by expanding its training data across diverse U.S. regions; integrating new data sources, such as environmental data layers, to address emerging contaminants; and conducting real-world testing to ensure robust, targeted groundwater safety measures worldwide.
“We see tremendous potential in this approach,” says Paul Westerhoff, co-corresponding author and Regents’ Professor in the School of Sustainable Engineering and the Built Environment at ASU. “By continuously improving its accuracy and expanding its reach, we’re laying the groundwork for proactive water safety measures across the globe.”
“This model also offers a promising tool for tracking phosphorus levels in groundwater, helping us identify and address potential contamination risks more efficiently,” says Jacob Jones, director of the National Science Foundation-funded Science and Technologies for Phosphorus Sustainability (STEPS) Center at NC State, which helped fund this work. “Looking ahead, extending this model to support broader phosphorus sustainability could have a significant impact, enabling us to manage this critical nutrient across various ecosystems and agricultural systems, ultimately fostering more sustainable practices.”
The paper, “Multiple Data Imputation Methods Advance Risk Analysis and Treatability of Co-occurring Inorganic Chemicals in Groundwater,” is published open access in the journal Environmental Science & Technology. The paper was co-authored by Emily Briese and Mohit Malu, both Ph.D. students at Arizona State; Carmen Velasco, a former postdoctoral researcher at Arizona State; Naushita Sharma, a postdoctoral researcher at Oak Ridge National Laboratory; and Andreas Spanias, a professor of digital signal processing at Arizona State.
This work was supported by the NSF STEPS Center; and by the Metals and Metal Mixtures: Cognitive Aging, Remediation and Exposure Sources (MEMCARE) Superfund Research Center based at Harvard University, which is supported by the National Institute of Environmental Health Science under grant P42ES030990.
-shipman-
Note to Editors: The study abstract follows.
“Multiple Data Imputation Methods Advance Risk Analysis and Treatability of Co-occurring Inorganic Chemicals in Groundwater”
Authors: Akhlak U. Mahmood, Alexey V. Gulyuk and Yaroslava G. Yingling, North Carolina State University; Minhazul Islam, Emily Briese, Carmen A. Velasco, Mohit Malu, Naushita Sharma, Andreas Spanias and Paul Westerhoff, Arizona State University
Abstract: Accurately assessing and managing risks associated with inorganic pollutants in groundwater is imperative. Historic water quality databases are often sparse due to rationale or financial budgets for sample collection and analysis, posing challenges in evaluating exposure or water treatment effectiveness. We utilized and compared two advanced multiple data imputation techniques, AMELIA and MICE algorithms, to fill gaps in sparse groundwater quality data sets. AMELIA outperformed MICE in handling missing values, as MICE tended to overestimate certain values, resulting in more outliers. Field data sets revealed that 75% to 80% of samples exhibited no co-occurring regulated pollutants surpassing MCL values, whereas imputed values showed only 15% to 55% of the samples posed no health risks. Imputed data unveiled a significant increase, ranging from 2 to 5 times, in the number of sampling locations predicted to potentially exceed health-based limits and identified samples where 2 to 6 co-occurring chemicals may occur and surpass health-based levels. Linking imputed data to sampling locations can pinpoint potential hotspots of elevated chemical levels and guide optimal resource allocation for additional field sampling and chemical analysis. With this approach, further analysis of complete data sets allows state agencies authorized to conduct groundwater monitoring, often with limited financial resources, to prioritize sampling locations and chemicals to be tested. Given existing data and time constraints, it is crucial to identify the most strategic use of the available resources to address data gaps effectively. This work establishes a framework to enhance the beneficial impact of funding groundwater data collection by reducing uncertainty in prioritizing future sampling locations and chemical analyses.
In real-world testing, researchers found that a carbon-based material placed underground sharply lowered PFAS in groundwater and required minimal maintenance.
How to Make Spanakopita-Inspired Potato Crust QuicheClose
Credit: Viktoriya Skorikova / Getty Images
Scientists from Brown University, the University of Minnesota, and the U.S. Navy found that injecting colloidal carbon into contaminated soil can trap PFAS chemicals underground, dramatically reducing contamination.
In field tests, PFAS concentrations fell from over 50,000 nanograms per liter to undetectable levels within 10 months, capturing both long- and short-chain PFAS compounds.
The approach could cost less than half as much as current cleanup methods and require minimal maintenance, offering a sustainable solution for communities dealing with PFAS pollution.
Over decades, per- and polyfluoroalkyl substances (PFAS) have slowly woven their way into our daily lives, without most of us ever noticing. They’re the stuff that prevents your eggs from sticking to the frying pan, waterproofs your jackets, allows makeup to last an entire day, and keeps those fast-food wrappers grease-resistant.
They’re also the stuff that earned the unsettling nickname “forever chemicals” thanks to carbon-fluorine bonds so strong that once these chemicals enter the environment, they tend to stay there. Forever. And that durability has become a serious problem. Scientists are increasingly recognizing that PFAS may cause a range of health issues, even as these chemicals have been detected in groundwater near military bases, airports, industrial sites, and municipal water systems across the United States. Cleaning them up has proven frustratingly difficult, expensive, and often temporary. Public-facing advice has often focused on avoiding products that contain PFAS or relying on above-ground water filtration, which requires almost constant upkeep. But now a few savvy researchers say they may soon have a solution for that, too.
Researchers from Brown University and the University of Minnesota, alongside industry partners and the U.S. Navy, tested whether an ultrafine carbon material could be injected directly into contaminated soil to trap PFAS in place. Their findings, published inThe Journal of Hazardous Materials, show that it may be a wild enough idea to work.
The team tested an activated carbon material known as “colloidal carbon,” which acts like a microscopic sponge that can trap PFAS chemicals underground. They began by trialing it in lab conditions, collecting soil from a contaminated site, before testing it on the real thing, taking it to a field at a Navy training area known to have extremely high PFAS levels.
The researchers ran a “push-pull” test, injecting the carbon into the ground, creating an underground treatment zone where PFAS bind as groundwater flows through the net, then pumping the water back out to measure how much of the PFAS made it through. In their tests, the PFAS concentrations dropped from more than 50,000 nanograms per liter to tktk, below detection limits, within 10 months. Importantly, the carbon net captures both long-chain and short-chain PFAS. This is a big deal for the potential cleanup of these forever chemicals because short-chain PFAS are harder to remove, yet are becoming increasingly common as manufacturers move away from older compounds.
Just as important from an economic standpoint is that, according to the team’s analysis, the long-term operating costs of this carbon-based approach would be less than half those of the existing PFAS remedies. And because the system would exist underground, it would require little maintenance.
“This study shows that we can create an effective treatment zone underground that dramatically reduces PFAS levels with far lower long-term costs,” Matt Simcik, a professor in the School of Public Health and co-author of the study, shared in a statement. “The effectiveness of this method, combined with the fact that the system requires very little ongoing maintenance, makes this a promising option for real-world cleanup efforts. For communities facing PFAS contamination, this represents a major step forward toward practical, sustainable technologies that can protect drinking water and reduce long-term exposure risks.”
It’s critical to note that this isn’t a silver bullet — at least not yet. The researchers are clear that more work is needed to understand how long underground carbon remains effective and how it could perform under different soil conditions. But the study does offer some good news and a potentially practical path forward in the fight against forever chemicals. And, on a similarly impactful note, it shows just how important it is that we work on this issue together.
”The project shows the importance of partnerships between practitioners, government, and academia,” William Arnold, a professor in the College of Science and Engineering, said. “The expertise, experience, and insight of the individuals who made up the team were needed for this lab-to-field project to succeed.”
Throughout the fall, Harvard Chan faculty will share evidence-based recommendations on urgent public health issues facing the next U.S. administration. Ronnie Levin, instructor in the Department of Environmental Health, offered her thoughts on policies that could address contamination in the country’s drinking water supply.
Q: Why is drinking water quality a pressing public health issue?
A: The U.S. has arguably the best and most reliable drinking water in the world, and that’s because we’ve spent a lot of money and time getting it in that shape. On the other hand, our drinking water is not risk-free. It’s not perfectly safe—it can contain lead, nitrate, PFAS, arsenic, and uranium, as examples. In addition, there are racial and ethnic disparities in contaminant exposures, so not everybody gets the same quality of drinking water.
Q: What are the biggest challenges facing the next administration around improving drinking water quality?
A: A hundred years ago, we sunk a lot of money into water treatment and infrastructure, but then we stopped putting in that kind of investment. Now our water systems are severely aging and deteriorated, and we haven’t continued to maintain the older ones. And when we build new ones, they’re not always as well designed as the old ones.
In addition, science has moved on—we’ve found things in our drinking water that we thought weren’t bad, like PFAS, that turn out to be biologically active at very low levels. Lead, arsenic, and nitrate cause health effects at lower levels than we knew when we set the standards decades ago. We now need to catch up.
Ronnie Levin. Photo: Kent Dayton Q: What are your top policy recommendations to address drinking water quality?
A: There’s been recent progress toward reducing lead in drinking water. On Oct. 8, the Environmental Protection Agency (EPA) announced a rule that requires all lead pipes in U.S. water systems to be replaced within the next decade, lowers the current level for taking action to reduce lead exposure from 15 to 10 parts per billion, and also implements several other policies to reduce exposure to lead from drinking water. If the rule is implemented and enforced, millions of people will have cleaner, safer water. Importantly, it will particularly enhance environmental protection among disadvantaged and low-income populations, which have been disproportionately impacted by lead-contaminated water.
There are several other contaminants I’d like to see the government address. PFAS are a class of thousands of chemicals that are in all kinds of consumer products. We don’t even know all of them, because industry keeps tweaking them to be different and cheaper, and industry doesn’t have to report how they get used. There are PFAS everywhere, contaminating water, soil, air, and food, and they build up in people and the environment over time.
We don’t know a lot about the thousands of different PFAS because it takes years to do studies, and we haven’t known about them for that many years. But research so far has suggested that PFAS are associated with a host of biological changes, even at very low levels. PFAS exposure has been linked with many adverse health outcomes, such as decreased immune system function, thyroid disease, and kidney and testicular cancers.
The EPA recently set regulations for six PFAS chemicals, ones that we know are the easiest to measure and are associated with numerous health effects. Many people are researching PFAS, but industry is constantly altering the formulations for new and different applications, and so there’s no way to stop this train. But the EPA’s efforts are really good news.
Another issue that the EPA needs to address is revising the standard for arsenic in drinking water. We’ve known that arsenic is a poison for a really long time, and that’s actually what makes it so useful—we use it in chemotherapies, pesticides, and herbicides. It has a lot of other useful applications, like in paints and glassmaking. But arsenic has negative health effects across the board, including cardiovascular harms, liver damage, neurotoxicity, and reproductive toxicity.
The arsenic limit for drinking water—which was set in 2001 at 10 parts per billion—is probably an order of magnitude too high. It was looking like the EPA might propose lowering the arsenic standard in the next few years, but with the change in administration, that likelihood is looking dim. There’s a lot of resistance from industry and water utilities, but I think taking action on arsenic will be easier than regulating so many different types of PFAS, which is going to take a lot longer.
As for the EPA’s nitrate standard, it is dangerously high, and violations of the nitrate standard are the most common health-based violations of drinking water standards.
In general, the EPA is behind in keeping the drinking water standards up to date with the current scientific literature. Setting standards is a laborious process and, in addition, there is tremendous pushback from the “drinking water industry”—public water systems, which are often cities themselves, or semi-governmental agencies like the Massachusetts Water Resources Authority, which oversees water systems in the Boston metropolitan area. There are 50,000 active public water systems in the U.S., and there is a lot of complaining from those systems about the difficulty and expense of meeting stricter standards.
Q: What’s the evidence supporting those recommendations?
A: My colleagues and I wrote a 2023 review article about the exposure risks of a wide range of drinking water contaminants, including PFAS, arsenic, and more. In that article, we cited a number of studies linking these chemicals to health harms:
A 2023 meta-analysis of over a dozen different studies found that several types of PFAS may lower the body’s ability to produce antibodies after receiving vaccines, particularly for diphtheria, rubella, and tetanus. A 2022 meta-analysis of over 100 rodent and human epidemiological studies identified a link between PFAS exposure and liver injury. A 2013 study followed almost 4,000 individuals for around two decades, and found that higher arsenic levels in urine were associated with increased mortality from lung, prostate, and pancreatic cancers. A 2015 meta-analysis of over a dozen studies identified a link between arsenic exposure and adverse pregnancy outcomes and infant mortality. A 2021 study analyzed nationwide data collected by the Centers for Disease Control and Prevention, finding that an increased level of arsenic in urine was associated with heart disease mortality. Q: What do you hope can be accomplished to improve drinking water quality in the next four years?
A: Addressing both PFAS and arsenic will be difficult and expensive, and also take a lot of political will. The Supreme Court has tied the EPA’s hands through decisions such as eliminating the Chevron deference, which called for deferring to federal agencies for their judgments where federal law is silent or unclear, and the 2023 Sackett v. EPA case, which limited the agency’s power to regulate wetlands and waterways. The EPA can’t just issue regulations, it has to get laws passed through Congress, which is much harder to do. It used to be that the courts would defer to the EPA, but now the agency is going to have to make a much stronger case for regulations.
Regarding lead, now that the Biden administration has finalized the new lead pipe rule the government needs to make sure that the rule is implemented and enforced.
We have to regain a commitment to protecting human health and the environment, and clean drinking water should be a top priority. We have a lot of hard work to do.
:max_bytes(150000):strip_icc():format(webp)/Scientists-Underground-Fix-PFAS-Drinking-Water-FT-DGTL0126-8a7f79e48b49459390a775a27583088e.jpg)
GET WET! 