PFAS Identified in Smartwatch and Fitness Bands Using LC–MS/MS

A study recently published in Environmental Science & Technology Letters has found significant concentrations of perfluorohexanoic acid (PFHxA) in fluoroelastomer watch bands, raising concerns about potential health risks associated with wearable devices (1). Led by a team of researchers from the University of Notre Dame, the study examined 22 watch bands using particle-induced gamma-ray emission (PIGE) spectroscopy and liquid chromatography tandem mass spectrometry (LC–MS/MS) to detect the presence of per- and polyfluoroalkyl substances (PFAS).

Runner on forest trail wearing smartwatch for fitness tracking and outdoor exercise. | Image Credit: © S u n n y B u n n y - stock.adobe.com

PFAS are a group of human-made chemicals that are ubiquitous in nature. They do not easily break down in the environment, which means they accumulate in soil, water, and living organisms. It is estimated that the cost to clean up PFAS pollution could reach £1.6 trillion in the UK and Europe (2). This bioaccumulation in bodies, both animals and humans, is a cause for concern. The health risks include hormone disruption, decreased fertility, changes in liver function, and an increased risk of cancer.

This study is the first of its kind to investigate PFAS in smartwatch and fitness bands. The team began their investigation with PIGE spectroscopy to screen for total fluorine on the surface of the watch bands. Of the 22 bands analyzed, 15 presented fluorine concentrations greater than 1%, suggesting a widespread use of fluoroelastomers. LC–MS/MS was then employed to identify specific PFAS compounds present in the watch bands. The results revealed that PFHxA was the most frequently detected compound, with concentrations ranging from below the limit of detection to 16,662 ng/g. The team had anticipated finding various smaller chain PFAS during their study but were surprised by the dominance of PFHxA and its high concentrations.

To further validate the presence of PFAS precursors, six watch bands underwent direct total oxidative precursor (dTOP) assay, to quantify PFASs that may otherwise be missed by conventional targeted analysis. This approach confirmed that PFHxA was directly extractable from the watch bands’ surfaces, indicating significant potential for dermal exposure.

The study's findings are particularly concerning given the popularity and widespread use of wearable devices and the direct skin contact involved. These devices can be worn for long periods of time by the user, including overnight, during rest periods, and during periods of high exertion. The cumulative effects of low-dose, long-term exposure to PFHxA via dermal exposure require more detailed and comprehensive research. There is a need for industries to work towards the development and implementation of safer, PFAS-free alternatives. This approach would mitigate the long-term environmental and health impacts associated with these persistent chemicals. Until that time, the analytical science community will continue to use all the tools at their disposal to monitor and mitigate PFAS contamination worldwide (3).

References

(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) Cost to Clean Up Toxic PFAS Pollution Could Top £1.6tn in UK and Europe, The Guardian,https://www.theguardian.com/environment/2025/jan/14/cost-clean-up-toxic-pfas-pollution-forever-chemicals(accessed 2025-01-20).

(3) Workman, J. A Review of the Latest Separation Science Research in PFAS Analysis. Supplement to LCGC International: Hot Topics in PFAS 2024, 12–18.