PFAS In Watch Bands

Environmental Science and Technology Letters recently published an analysis of the per- and polyfluoroalkyl substances (PFAS) content of 22 different “smart” and “fitness” watch bands. These bands are often advertised as resistant to skin oils and sweat in part because they are comprised of fluoroelastomers, which are polymers (longer connected chains) of shorter-chain PFAS that provide chemical stability and resistance to degradation. However, PFAS compounds have been associated with a wide range of health concerns, including coronary heart disease in both men and women, as well as an increase in risk for diabetes; especially concerning given how ubiquitous these “forever chemicals” are.  

Of the bands tested, 15 of 22 were found to have fluorine concentrations greater than 1%, suggesting widespread use (only bands sold for < $15 did not contain fluorine). A targeted LC-MS/MS analysis for 20 PFAS compounds found perfluorohexanoic acid (PFHxA) to be the most common PFAS in these bands. The median concentration was 800 parts per billion (ppb) in these bands, roughly 4-fold higher than found in cosmetics.  

The U.S. Agency for Toxic Substances & Disease Registry does not consider dermal exposure to be a significant source of PFAS exposure (ingestion, placental transfer, and inhalation are listed as more likely), yet very little data exists for the PFAS content and skin absorption of these personal devices, many of which are worn throughout the day and night. We currently have an absence of evidence rather than evidence of safety. What data does exist suggests that PFAS absorption through the skin is quite likely to occur. A recent study using porcine skin as a model indicated that multiple PFAS (including PFHxA) do permeate skin within 8 hours of exposure. Until more evidence for safe use is available, less expensive silicone-only watch bands may be preferable.