EWG study: PFAS water treatment has double benefits, cutting toxic PFAS and carcinogens
Advanced filtration systems can also reduce DBPs, nitrates and heavy metals at the same time
WASHINGTON – Advanced systems for removing the toxic “forever chemicals” known as PFAS from drinking water can deliver far greater health benefits than previously thought. They also slash levels of other harmful contaminants, a new peer-reviewed Environmental Working Group study finds.
The research underscores the fact that PFAS water filtration systems can also help reduce levels of cancer-causing disinfection byproducts, or DBPs, agricultural nitrates and heavy metals like arsenic and uranium – all chemicals linked to health harms.
The study, published today in ACS ES&T Water, analyzed data from 19 U.S. utilities and the Environmental Protection Agency’s national water monitoring program. The findings show that PFAS removal technologies such as granular activated carbon, ion exchange and reverse osmosis can also lower levels of multiple harmful substances found in drinking water.
“PFAS treatment isn’t just about ‘forever chemicals,’” said Sydney Evans, EWG senior science analyst and lead author of the study. “It’s also opening the door to improving water treatment across the board.
“Advanced PFAS water treatment is a turning point that can help us clean up a broader mixture of contaminants and bring drinking water quality in line with today’s public health science,” added Evans.
A potential game-changer
In the 19 systems EWG studied, installation of advanced PFAS treatment technologies led to an average 42% drop in the level of trihalomethanes in drinking water, while haloacetic acid levels dropped 50%. Trihalomethanes and haloacetic acid are cancer-causing byproducts of water disinfection.
“DBPs and other harmful contaminants in drinking water are not emerging or unknown threats – we’ve known about them for a while. They’re regulated and they’re widespread,” said Varun Subramaniam, EWG science analyst and co-author.
“These kinds of reductions caused by PFAS filters are a game changer for public health, especially since where there are PFAS, there are always other chemicals, too,” he added.
EWG’s Tap Water Database, updated earlier this year, shows the extent of widespread drinking water contamination throughout the U.S. The study highlights the levels of several other contaminants in the countless communities relying on PFAS-polluted tap water.
Environmental injustice
EWG’s study also identified systemic inequities: Only 7% of very small water systems, defined as those serving fewer than 500 people, use advanced filtration. As a result, millions of Americans in rural and underresourced communities remain exposed to PFAS, hazardous disinfection byproducts and heavy metals.
By contrast, 28% of the largest utilities use the technology.
“This is a textbook case of environmental injustice,” Subramaniam said. “The communities least able to afford advanced filtration often face the highest health risks. Without targeted investment, these gaps will only widen.”
The research underscores an urgent need to rethink U.S. water policy. Most pressing is a shift away from one-chemical-at-a-time regulation toward holistic strategies that protect the full spectrum of pollutants. This work should start in the communities that need it most.
“This study exposes a dangerous blind spot in federal water policy,” said Melanie Benesh, EWG vice president of government affairs. “Communities wouldn’t just filter out PFAS, they’d be eliminating multiple toxic chemicals at the same time.”
“By ignoring these co-benefits, the EPA is leaving Americans exposed and missing a huge economic and public health opportunity,” Benesh said.
Regulatory setbacks threaten progress
The findings come amid backlash over the EPA’s recent rollbacks, including a plan to weaken long-sought protections against forever chemicals in drinking water.
In May, less than a full year after new standards were finalized, the EPA announced it would weaken key limits on four PFAS in drinking water and delay compliance deadlines. Critics say the pending rollback could prolong harmful exposures, particularly in communities unable to implement PFAS treatment technology independently.
EWG’s study also flags major gaps in national water monitoring. Inconsistent reporting to the EPA’s monitoring program hinders tracking co-occurring contaminants and evaluating treatment effectiveness. Standardized, nationwide monitoring and treatment-focused regulations would better reflect real-world water contamination patterns.
Despite the costs of installing advanced PFAS treatment, EWG’s research underscores the outsize public health returns of removing multiple hazardous contaminants at once. Today only 8% of U.S. water systems are equipped with filters capable of getting PFAS out, leaving millions of Americans – especially in small and rural communities – vulnerable to health risks.
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 they 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.
Very low doses of PFAS have been linked to suppression of the immune system. Studies show exposure to PFAS can also increase the risk of cancer, harm fetal development and reduce vaccine effectiveness.
For over 30 years, EWG has been dedicated to safeguarding families from harmful environmental exposures, holding polluters accountable, and advocating for clean, safe water.
EWG’s study urges federal and state leaders to:
- Boost federal and state funding for advanced filtration in under-resourced systems.
- Strengthen national water monitoring to guide smarter policies.
- Adopt regulations that account for co-occurring contaminants and expand public health protection.
“This isn’t just about PFAS,” said Evans. “When we fix one problem, we can solve several others. The opportunity to protect public health at scale is too big to ignore – if we’re smart about it.”
###
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.
Journal
ACS ES&T Water
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
PFAS treatment as an opportunity for broader drinking water improvements: Evidence from U.S. water systems
Article Publication Date
4-Sep-2025
Forever chemicals are more acidic than we thought, study finds
New, more accurate acidity measurements could make PFAS easier to track
University at Buffalo
image:
An illustration of a PFAS breakdown product in its negatively charged and neutral forms, depicted in a dynamic back-and-forth between these states. The accompanying chart illustrates a plot that allowed a University at Buffalo-led team to determine its acid dissociation constant or pKa.
view moreCredit: University at Buffalo
BUFFALO, N.Y. — One of the ways that per- and polyfluoroalkyl substances (PFAS) earn their “forever chemical” nickname and persist in the environment is their acidity.
Many of these toxic chemicals are highly acidic, meaning they easily give up their protons and become negatively charged. This allows them to dissolve and spread in water more easily.
Now, new research has found that some PFAS are even more acidic than previously thought — an insight critical for predicting their mobility in the environment and potential impacts on human health.
It comes from a University at Buffalo-led team that introduced a new and rigorous experimental method to determine the acidity of 10 types of PFAS and three of their common breakdown products.
Published last month in Environmental Science & Technology Letters, their measurements of these chemicals’ acid dissociation constant, or pKa, were mostly lower, in some cases dramatically, than those reported in experimental studies and predicted by computational chemistry models. In one case, the pKa of GenX, a replacement for perfluorooctanoic acid (PFOA) in the manufacturing of Teflon, was found to be about one thousand times lower than the measurement listed in a previous study.
The lower the pKa, the more likely a chemical is to give up a proton and exist in its charged form.
“These findings suggest that previous measurements have underestimated PFAS’ acidity. This means their ability to persist and spread in the environment has been mischaracterized, too,” says the study’s corresponding author, Alexander Hoepker, PhD, a senior research scientist with the UB RENEW Institute.
More accurate pKa measurements help efforts to understand the behavior of PFAS in the environment. A chemical’s pKa could mean the difference as to whether it remains dissolved in water, sticks to soil or a biological membrane or perhaps volatilizes into the air.
“If we’re going to understand how these concerning chemicals spread, it’s very important we have a reliable method for the accurate determination of their pKa values,” says Diana Aga, PhD, director of RENEW and SUNY Distinguished Professor and Henry M. Woodburn Chair in the UB Department of Chemistry.
The work was supported by the National Science Foundation and done in collaboration with Scott Simpson, PhD, professor and chair of the St. Bonaventure Department of Chemistry, and researchers from Spain’s Institute of Environmental Assessment and Water Research.
Combining experiments with computations
PFAS are made of a highly fluorinated, water-repelling tail and a more water-loving headgroup. Many of the most scrutinized PFAS have a highly acidic headgroup, making them more likely to give up a proton and exist in its charged form.
Whether a PFAS exists in its neutral or charged form depends on the pH level of their surrounding environment. That’s where pKa comes in. It tells scientists the pH level at which a given PFAS is equal to flip from neutral to charged, or vice versa.
But there has been much disagreement about the pKa measurements of some PFAS, like PFOA, with different teams coming up with widely different values. One of the reasons for this may be the glass used during their experiments.
“PFAS likes to stick to glass. When that happens, it throws off traditional, so-called bulk measurements that quantify how much PFAS is in a solution,” Hoepker says. “In other cases, too much organic solvent is used to get PFAS into solution, which similarly biases the pKa measurement.”
To address this challenge, the UB team used fluorine and proton (hydrogen) nuclear magnetic resonance (NMR) spectroscopy — think MRI for molecules. NMR places a sample in a strong magnetic field and probes its atomic nuclei with radio waves.
When a PFAS headgroup is negatively charged, nearby fluorine atoms respond at a different (radio) frequency.
Reading these atom-level signatures lets the researchers tell whether a PFAS molecule is charged or neutral — capabilities that other methods that have been used previously cannot provide.
“This unique measurement allows NMR to inherently account for PFAS losses to glass or other adsorption behaviors, so your pKa measurements don't end up way off the mark,” Hoepker says.
Some PFAS are so acidic (pKa of less than zero) that generating them in their neutral form would require super-acidic conditions (a pH level of less than zero) that are impractical in standard labs. In those cases, the research team paired NMR experiments with electronic-structure calculations using density functional theory to predict the NMR shifts of the neutral and ionized forms.
“We augmented partial NMR datasets with computational predictions to arrive at more accurate pKa values,” Hoepker says. “This NMR-centered hybrid approach — integrating experimental measurements with computational analyses — enhanced our confidence in the results and, to our knowledge, has not previously been applied to PFAS acidity.”
Problem PFAS measured more accurately
The PFAS that has been the most difficult to measure is PFOA, once commonly used in nonstick pans and deemed hazardous by the Environmental Protection Agency last year.
The team found its pKa to be –0.27, meaning it will be negatively charged at practically any realistic pH level. Previous experimental studies had measured its pKa as high as 3.8 and more commonly around 1, while the computational methods COSMO-RS and OPERA had determined its pKa at 0.24 and 0.34, respectively.
Trifluoroacetic acid (TFA) — an emerging PFAS increasingly detected in waters worldwide and likely transported through the atmosphere and deposited by rain — was found to be far more acidic than previously reported, with a pKa of around 0.03. Earlier estimates had anywhere from 0.30 to 1.1.
Notably, the team determined the pKa values for several prominent emerging PFAS that had never been measured, such as 5:3 fluorotelomer carboxylic acid (5:3 FTCA), and PFAS ethers like NFDHA and PFMPA that are newer PFAS but are also likely to pose challenges for regulators due to their health effects.
“This new experimental approach of determining pKa values for PFAS will have wide-ranging applications, from being able to validate computationally derived values, to facilitating the development of machine learning models that can better predict pKa values of newly discovered PFAS contaminants when reference standards are not available,” Aga says. “In turn, knowledge of the pKa values of emerging PFAS will allow researchers to develop appropriate analytical methods, remediation technologies, and risk assessment strategies more efficiently.”
Aside from Simpson, other co-authors include Silvia Lacorte, a senior scientist with the Spanish Institute of Environmental Assessment and Water Research; Aina Queral Beltran, a University of Barcelona PhD student and former visiting student at UB; and UB Chemistry graduate students Damalka Balasuriya and Tristan Vick.
Journal
Environmental Science & Technology Letters
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Experimental Determination of pKa for 10 PFAS, Mono-, Di-, and Trifluoroacetic Acid by 19F-NMRArticle link copied!
No comments:
Post a Comment