This story was originally published by WIRED and is reproduced here as part of the Climate Desk collaboration.
A new study finds that technologies installed to remove “forever chemicals” from drinking water are also doing double-duty by removing harmful other materials—including some substances that have been linked to certain types of cancer.
The study, published Thursday in the journal ACS ES&T Water, comes as the Trump administration is overhauling a rule mandating that water systems take action to clean up forever chemicals in drinking water.
Per- and polyfluoroalkyl substances (PFAS), colloquially referred to as forever chemicals, are a class of thousands of chemicals that do not degrade in the environment and have been linked to a slew of worrying health outcomes, including various cancers, hormonal disorders, and developmental delays. Because they do not degrade, they are uniquely pervasive: a 2023 study from the US Geological Survey estimated that 45 percent of tap water in the US could contain at least one PFAS chemical.
Last year, the Biden administration finalized a rule establishing the first-ever legal limits of PFAS in drinking water, setting strict limits for six kinds of PFAS chemicals and mandating that water utilities needed to clean up drinking water under these limits by 2029. But in May, the Environmental Protection Agency said it would be reconsidering regulations on four of the six chemicals in the original rule and extend the deadline by two years. The changes come after widespread outcry from water utilities, who say that the costs of installing PFAS filtration systems would be far beyond what the agency originally estimated.
“There’s this gray area in between what is safe and what is legal where there’s still some risk, which is why we’re so concerned about all of these contaminants.”
“Building on the historic actions to address PFAS during the first Trump Administration, EPA is tackling PFAS from all of our program offices, advancing research and testing, stopping PFAS from getting into drinking water systems, holding polluters accountable, and more,” Brigit Hirsch, EPA press secretary, told WIRED in a statement. “This is just a fraction of the work the agency is doing on PFAS during President Trump’s second term to ensure Americans have the cleanest air, land, and water.”
Hirsch also emphasized that as EPA reconsiders standards for the four chemicals in question, “it is possible that the result could be more stringent requirements.”
Experts say the costs of cleaning up PFAS could have other benefits beyond just getting forever chemicals out of Americans’ water supply. The authors of the new study—all employees of the Environmental Working Group (EWG), a nonprofit that does research on chemical safety—say that technology that gets rid of PFAS can also filter out a number of other harmful substances, including some that are created as byproducts of the water treatment process itself.
The study looks at three types of water filtration technologies that have been proven to remove PFAS. These technologies “are really widespread, they’ve been in use for a really long time, and they’re well-documented to remove a large number of contaminants,” says Sydney Evans, a senior analyst at EWG and coauthor of the report.
Most routine water disinfection processes in the US entail adding a chemical—usually chlorine—to the water. While this process removes harmful pathogens, it can’t leach out PFAS or other types of contaminants, including heavy metals and elements like arsenic.
This method of disinfection can also, paradoxically, create some harmful byproducts as chlorine reacts to organic compounds present in water or in infrastructure like pipes. Long-term exposure to some of these byproducts has been linked to specific types of cancer. While there are some federal guidelines for water utilities to follow, experts say that a growing body of research illustrates that there’s a gap between what is legal and what is safe. (It’s also not uncommon for utilities to find water samples that exceed legal limits: Officials in Springfield, Massachusetts, and Akron, Ohio, have notified residents this year that their water was polluted with disinfection byproducts.)
“There’s this gray area in between what is safe and what is legal where there’s still some risk, which is why we’re so concerned about all of these contaminants,” says Evans, some of whose past work has focused on the links between disinfection byproducts and cancer.
“It’s really an interesting first effort to try to diagnose ancillary benefits—and perhaps unintended benefits—from installing advanced water treatment systems intended to remove PFAS,” says P. Lee Ferguson, a professor of civil and environmental engineering at Duke University. “This gets at a question many of us have asked, and that I’ve thought about quite a bit: [with] the very act of installing advanced treatment intended to remove really recalcitrant contaminants like PFAS, you really do have the potential to get a lot of other benefits.”
While putting together the study’s methodology, the researchers also demonstrated how large the gap in advanced technology is between smaller water systems and bigger ones. Just 7 percent of water systems serving fewer than 500 customers had some kind of advanced water filtration system, as opposed to nearly 30 percent of water systems serving more than 100,000 people. These smaller systems, the EWG researchers say, overwhelmingly serve rural and under-resourced populations. Cost explains a lot here: These types of technologies are much more expensive than treating water with chlorine. (In May, the EPA said it would launch an initiative called PFAS OUT, which will connect with water utilities that need to make upgrades and provide “tools, funding, and technical assistance.”)
The relatively small sample size of 19 water systems, and the lack of detail in the data, means there are some wide discrepancies in the results, says Bridger Ruyle, an assistant professor of environmental engineering at NYU who studies PFAS and water systems. Some of the systems in the study saw a nearly complete reduction in disinfection byproducts after they installed advanced filtration; at the other extreme, some water systems actually showed a gain in byproducts after they installed the filtration systems.
This, Ruyle says, doesn’t mean that the technology isn’t effective. Rather, it calls for more research into how variables like new exposure sources and seasonality might be affecting specific plants.
“In the lab, you can do all of these controlled studies, and you can say, ‘Oh yes, we eliminate all of the PFAS, and that also takes care of some other contaminant issues of concern,’” he says. “But when you’re talking about the real operation of a water facility, the environmental behavior of PFAS and these other chemicals are not the same. You could have different seasonal patterns, you could have different sources, you could have climate change impacting different components. And so, just because we’re treating a certain inflow of PFAS, a lot of other things could be happening to these other chemicals kind of independently.”
The question of cost comes back to who, exactly, needs to be on the hook to pay to clean up water. In communities across the country, water utilities are folding new PFAS testing and remediation measures into other needed upgrades, and some consumers are seeing their bills skyrocket. But understanding the full benefits of some of these fixes can help scientists and policymakers better grasp the path forward.
“This is an enormous financial challenge,” Ruyle says. “And at the same time, it’s a financial need. There’s a big focus now in the Trump administration from the MAHA movement [around] what are these causes of all of these health and well-being ills. If you’re not willing to put up the money to upgrade infrastructure, to actually address proven causes of environmental harm, then what are we going to do?”
This post has been syndicated from Mother Jones, where it was published under this address.