As cities and towns plan to remove several harmful “forever chemicals” from drinking water, scientists are starting to focus on a less-studied version of the chemicals that is showing up virtually everywhere they look.
Trifluoroacetic acid, or TFA, could be one of the most widespread forever chemicals in the environment, according to a growing body of research. While there’s no consensus on its effects on human health, TFA does not break down naturally, and its similarity to per- and polyfluoroalkyl substances (PFAS) tied to cancer and other diseases is enough to warrant further study, researchers said.
“It’s absolutely everywhere,” said Sarah Hale, an environmental researcher who manages ZeroPM, a project funded by the European Union. “TFA will be the next discussion in America, I can guarantee it. It will be about how should we treat it and what should we do.”
The attention on TFA underscores the game of whack-a-mole that scientists and communities face with forever chemicals. With thousands of identified versions of the substances, the chemicals are practically ubiquitous in the global economy, and researchers are still determining the exact health risks associated with many of them.
But TFA could pose a particularly difficult problem down the line, due to how much it would cost to take it out of drinking water, experts say.
The substance is extremely small, mobile and water soluble. As a result, it cannot be removed from water using the filtration systems that many communities are installing now for large, widely studied forever chemicals, said Rainer Lohmann, a professor of oceanography at the University of Rhode Island.
“All the filters we have right now don’t work on TFA,” said Lohmann, whose research includes water pollutants. “If we ever reach the conclusion that it might be of concern, then of course removing it from drinking water is going to be extremely painful and expensive.”
Forever chemicals got their nickname because they do not degrade on their own and are extremely resistant to heat, oil and water. They have been used in fire suppressants, nonstick pans, semiconductors and a host of other products and are now widespread in the environment.
Some forever chemicals in the PFAS family are linked to serious health problems, including fertility issues, liver damage and cancer. But most of the substances — TFA included — are not regulated in water, indoor air or soil.
TFA’s likely sources include pesticides and pharmaceuticals. Many PFAS also degrade into TFA when they go through an incinerator or a sewage treatment plant, said Heidi Pickard, a postdoctoral fellow at Harvard University.
Another leading source of TFA is refrigerants introduced to replace gases that deplete the ozone layer. According to research from Pickard, TFA concentrations in the environment likely increased after the Montreal Protocol, the landmark global environmental treaty that spurred the phase-out of ozone-depleting substances and a search for alternatives.
There’s currently no requirement that TFA be removed from water. Also, unlike the types of PFAS that are widely considered to be toxic, TFA moves quickly through the human body, meaning that it might not do as much damage to people, some researchers have said.
“There’s the question of, how sure we are that it will accumulate in your body to cause a toxicological effect,” Hale said. “But the other side is saying, ‘If you ingest high enough concentrations of it, it could elicit [an] effect.’”
A few studies have indicated a link between TFA and cancer, as well as reproductive health problems, said Stephanie Eick, an assistant professor of environmental health at Emory University. A recent study out of China suggested that TFA exposure could increase one’s risk of diabetes, but more research is needed, she said.
“I don’t feel like we have a good sense of what the scope of the problem could be,” Eick said. “It would not surprise me if in a few years, we learn that exposure to TFA is linked to a lot of these same health outcomes, such as cancer and hypertension, that at this time we know are strongly linked to some older PFAS that are well-studied.”
Pushback and ‘mistakes of the past’
Amid the scrutiny on TFA, the chemical and refrigeration industries are pushing back on concerns about the threat it might pose.
Currently, EPA does not define TFA as a PFAS, but some scientists and environmental groups say that it should be classified as such. Industry groups, however, oppose that idea.
“It’s not a PFAS,” said Kevin Fay, executive director of the Sustainable PFAS Action Network. “TFA is naturally occurring, and EPA has consistently staked out that position.”
Fay noted that TFA is a simpler, structurally different compound from large PFAS, such as PFOA and PFOS. EPA this year classified both of those substances as hazardous pollutants, as well as included them in the first-ever national limits on PFAS in drinking water. Chemical companies are now suing to overturn the pair of regulations.
The chemical giant Chemours, which makes a refrigerant that degrades entirely into TFA, describes the chemical in a fact sheet as “95% naturally occurring” and says that “TFA from manmade sources DOES NOT pose a risk to the environment or human health.”
“We are committed to the responsible manufacturing and use of our products,” Chemours spokesperson Cassie Olszewski said in an email.
Chemours and Fay both cited a 2022 United Nations report, which says that TFA is not likely to cause adverse effects in terrestrial and aquatic organisms.
The focus on TFA could be coming from the “natural refrigerant industries” trying to gain an edge over competitors, said Fay. His organization represents a variety of manufacturing companies, including Honeywell, which makes some products that degrade into TFA.
“It’s important to monitor [TFA] … but we don’t think it’s a risk,” Fay added.
Others are skeptical of that perspective.
Robert Bilott, a partner at the law firm Taft Stettinius & Hollister who helped uncover the health risks of PFOA and PFOS, said he sees parallels between the conversation now about TFA and those that occurred with PFAS in the 2000s.
“We heard the argument that there wasn’t any risk of harm [back then], and it was only through decades of litigation and digging into internal company files that we were able to learn there was a risk of the chemicals,” Bilott said. “We’ve got to make sure we don’t repeat the mistakes of the past.”
As for TFA’s classification, David Andrews, a senior scientist at the Environmental Working Group, said the substance meets the definition of PFAS established by the Organization for Economic Cooperation and Development, an intergovernmental organization.
“What we know about PFAS should run additional scrutiny onto TFA and all the chemicals that break down into TFA,” Andrews said.
Pickard, the Harvard University postdoc, said there are reasons not to compare TFA to many other PFAS based on current information about health risks. But she disputed the notion that most TFA in the environment is naturally occurring.
While she was a master’s student at Memorial University in Canada, Pickard studied PFAS concentrations in ice cores in the Canadian Arctic. She first planned to measure for the “typical suite of PFAS” but decided to also look for very small forever chemicals like TFA, she said.
In an ensuing 2020 research paper, she and other researchers found that TFA concentrations increased in the ice cores “with the exact timing” of when new refrigeration gases were introduced after the Montreal Protocol, she said. Signed in 1987, the treaty spurred nations to phase out ozone-depleting chlorofluorocarbons (CFCs), leading to the rise of new substances for refrigeration and cooling.
“In these remote regions, I was basically able to say that TFA was coming from these CFC replacements,” Pickard said.
The ‘unaccounted-for’ PFAS?
The big question facing researchers is whether TFA levels will reach a point that could be dangerous to people — and if so, what is that level?
Another unknown: How much are Americans exposed to TFA already?
Although EPA has approved methods for measuring many types of PFAS in water, TFA is not included in them, said Katie Pelch, an environmental health scientist at the Natural Resources Defense Council.
As a result, water utilities are not monitoring for TFA in their water and wastewater, said Steve Via, manager of federal relations at the American Water Works Association.
Still, the limited testing that has been done has identified TFA as a very common forever chemical, often present in high concentrations, Pelch said.
“A lot of PFAS data that we have right now is kind of limited to what’s in those standard, validated EPA methods. We’ve always known that there’s a large faction of unaccounted-for PFAS,” Pelch said.
“As we’re learning more, we’re learning that a lot of the unaccounted-for PFAS in the water is probably TFA,” she continued.
For example, a 2023 study published in Environmental Science & Technology found TFA in 95 percent of drinking water samples that researchers tested in Indiana. Its scope was limited, however, to just 81 participants.
But a 2017 study from researchers in Germany found TFA occurring “ubiquitously” in surface waters there. In addition, several environmental groups this year found high levels of TFA in rainwater around southeast Michigan.
Lohmann, of the University of Rhode Island, said the substance appears to be accumulating in plants, especially those that grow in water.
EPA spokesperson Remmington Belford said the agency is working to manage the risks of emerging contaminants like TFA. So far, EPA has identified the substance as a likely byproduct of incinerating aqueous film-forming foam, a firefighting foam used by the military and others that is thought to be a major contributor to PFAS pollution.
“EPA remains committed to protecting public health and the environment by addressing various contaminants and pollutants, including substances like trifluoroacetic acid (TFA),” Belford said.
For now, water providers in the U.S. are preparing to comply with EPA’s new limits on PFAS in drinking water. Cost concerns are already on the horizon. To comply, many utilities will turn to a filtration method known as granular activated carbon treatment, Via said.
By comparison, the main filtration method for smaller forever chemicals like TFA is known as reverse osmosis. That system is more expensive and more energy-intensive, and it creates PFAS-laden wastewater that is not easy to dispose of, Via said.
“As systems install or consider treatment alternatives, what happens if in a few years, after having made that investment, another PFAS that is a short chain comes up?” he asked. “Certainly, everyone is keeping an eye toward short-chain PFAS.”
In light of the health risks posed by some PFAS, it’s worth thinking about ways to reduce emissions of TFA now, Lohmann said. When it comes to refrigerants, for example, there are alternatives that do not break down into TFA and that also contribute less to global warming, he said.
“The lesson we should’ve learned [from PFAS] is that you want to be proactive, rather than reactive,” he said. “But my colleagues might say it’s already too late to be proactive about this.”
Correction: An earlier version of this report previously misstated when Heidi Pickard conducted research on PFAS in the Canadian Arctic.
