An investigation into fluoroelastomer watch bands has revealed high levels of perfluorohexanoic acid (PFHxA), a short-chain per- and polyfluoroalkyl substance (PFAS). LCGC International spoke to Professor Graham Peaslee from the University of Notre Dame about his team’s study using liquid chromatography tandem mass spectrometry (LC–MS/MS) and PFHxA's potential for dermal absorption, and the subsequent environmental and health impacts.
LCGC International spoke to Graham Peaslee, professor emeritus at the University of Notre Dame, about his team’s investigation into the levels of per- and polyfluoroalkyl substance (PFAS) in common fluoroelastomer watch bands using liquid chromatography tandem mass spectrometry (LC–MS/MS). His research focus lies at the interface between any nuclear or atomic physics measurement method and materials that impact society, such as PFAS in consumer products.
In your paper you investigate the presence of perfluorohexanoic acid (PFHxA) in fluoroelastomer watch bands (1). Why did you decide to undertake this investigation?
This project was driven by observing a full-page ad in a magazine that was advertising fluoroelastomer watch bands. We were surprised anybody was advertising it as a per- and polyfluoroalkyl substance (PFAS) until we realized that the public wouldn’t recognize that as a PFAS. So, my students started collecting as many volunteers as they could to test watchbands.
What advantages did liquid chromatography tandem mass spectrometry (LC–MS/MS) offer in detecting PFHxA?
Our quick scanning technique for fluorine (called particle-induced gamma-ray emission [PIGE]) only tells you there is fluorine present, not which kind of PFAS. The LC–MS/MS allowed us to identify which PFAS was there—and we tested for 20 or so—but only one (PFHxA) stood out with very high concentrations, which was unusual. Typically, we get a half dozen or more different types and at much lower concentrations.
Did your findings correspond with what you had hypothesized prior to your investigation?
We knew from our prior work that any fluoropolymer we measure has smaller chain PFAS in them as well, so that part was confirmed in our hypothesis of what was expected. What we didn’t expect was that it was just one PFAS (PFHxA) and in quantities 100–1000 times higher than most other products.
What challenges remain in evaluating the dermal absorption of short-chain PFAS such as PFHxA from wearable devices?
There was a dermal absorption study conducted by Stuart Harrad and his team at the University of Birmingham, UK, that measured for the first time comparative absorption numbers for a whole group of PFAS in realistic conditions on a human skin mimic (2). This study showed that a significant fraction of PFHxA would get into the skin, and similarly a significant fraction of that would end up in the bloodstream. That isn’t good news.
How do the concentrations of PFHxA detected in fluoroelastomer watch bands compare to those found in other consumer goods?
The PFHxA concentrations are much higher in watch bands; the only other product with similar levels is firefighter turnout gear made with PFAS layers.
Why were PIGE spectroscopy and direct total oxidative precursor (dTOP) used during this investigation, and how did they complement the LC–MS/MS analysis?
The PIGE measurement tells us within minutes which samples have fluorine, and which do not. That allowed us to pick sub-sets of samples to measure for PFAS, with no need to waste much time and effort on samples that don’t have fluorine. We include some as a comparison, but the PIGE work allows us to find the approximate answer within days, and then it takes months to do the specific measurements. The dTOP measurements were performed to show that PFHxA was coming directly out of the surface of the watchband, and that there weren’t other PFAS in there that we couldn’t see.
Is there anything else you would like to add?
We think it is important that consumers know about their options with watch and fitness bands; this will drive manufacturers in the direction of PFAS-free products, which helps clean up what eventually ends up in the landfill and contaminates our drinking and irrigation water. That’s the side nobody ever remembers; you don’t have to be exposed directly to fluorinated consumer products, your children will be drinking the remains of them for a generation or more to come.
(1) Wicks, A.; Whitehead, H. D.; Peaslee G. F. Presence of Perfluorohexanoic Acid in Fluoroelastomer Watch Bands. Environ. Sci. Technol. Lett. 2024, 12 (1), 25–30. DOI: 10.1021/acs.estlett.4c00907
(2) Namazkar, S.; Ragnarsdottir, O.; Josefsson, A.; et al. Characterization and Dermal Bioaccessibility of Residual- and Listed PFAS Ingredients in Cosmetic Products. Environ. Sci. Technol. Lett. 2024, 26 (2), 259–268. DOI: 10.1039/D3EM00461A
Image courtesy of Peaslee
Graham Peaslee is a professor of physics emeritus at the University of Notre Dame. He still leads an active research group there in applied nuclear science where he brings established nuclear measurement techniques to pressing environmental issues. Most notably, this includes the rapid detection of total fluorine as a surrogate for PFAS, and screening environmental samples and consumer products to understand their fate and transport. He has over 245 publications, most with student co-authors. He earned a bachelor’s degree in chemistry from Princeton University, and a PhD in chemical physics from the State University of New York in Stony Brook, NY. He is currently the chief scientific officer of Forever Analytical Solutions, a spin-off company formed in 2024 to help address the need for a rapid screening method for PFAS.