New method spots unreported forever chemicals

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous synthetic chemicals found in the air, water, and soil. They have contaminated drinking water, accumulated to levels of concern in some fish, and entered the bloodstreams of animals and humans, raising serious health concerns.

While some PFAS are being phased out, they’re often replaced with new ones that may also be toxic. Finding and keeping track of these emerging PFAS is challenging. New research has found a way to detect them.

Most commercial laboratories target about 40 PFAS, “but we know many, many more exist,” says Erin Baker, an analytical chemist at the University of North Carolina at Chapel Hill. The US Environmental Protection Agency, for example, maintains a list of more than 14,000 PFAS that may be used in making products resistant to oil, water, and heat. The problem is that “there’s only a few hundred chemical standards available to validate that you’re actually seeing these chemicals,” Baker says, “so we’re missing over 13,000.”

Along with her colleagues, Baker developed a new approach to detect PFAS that conventional methods may miss. It harnesses previously used techniques, such as liquid chromatography and high-resolution mass spectrometry, to identify different molecules in a mixture according to their mass, solubility, and polarity.

In a novel addition, the research team used ion mobility spectrometry to distinguish these molecules on the basis of their size and shape. “They’re putting together a bunch of techniques that not everybody does,” says EPA research scientist Mark Strynar, who was not involved in the research. “It is cutting edge; it is different and unique.”

This multidimensional approach helped Baker and her team detect 36 known and 11 previously unreported PFAS in North Carolina’s Cape Fear River. Eight of them weren’t on EPA’s list (Sci. Adv. 2023, DOI: 10.1126/sciadv.adj7048). “I was really shocked that we found these novel chemicals,” Baker says. “It shows that there’s a lot more out there that we’re missing and why such nontargeted analyses are so important.”

The work involved deploying passive samplers—embroidery hoops with two pieces of mesh and resin beads that bind PFAS—upstream and downstream of the Chemours chemical plant in 2016 for 2 weeks. Chemours, along with former company owner DuPont, has attracted lawsuits and millions of dollars in fines for decades of dumping PFAS into the Cape Fear River.

“Most PFAS we found are most likely coming from the company based on what we know they’re making and their patent literature,” says coauthor and environmental chemist Kaylie Kirkwood- Donelson, formerly a PhD student at North Carolina State University.

While researchers are yet to understand if the new PFAS pose health risks, known examples, such as GenX, a member of the PFAS family that they detected, have been linked to issues with the liver, the kidneys, the immune system, and potential cancer risks on the basis of animal studies. Baker and Kirkwood-Donelson hope their method can help pinpoint novel chemicals lurking in the environment whose toxicity can later be tested in the laboratory.

But their approach can’t quantify the amounts of such PFAS in the water. Also, ion mobility spectrometry is extremely expensive and not easily accessible. But “a decade ago, high-resolution mass spectrometry was not the norm,” Strynar says. “A decade from now, maybe ion mobility spectrometry is something more people will have access to,” he adds. That could help more PFAS be detected more frequently.