What independent studies exist measuring PFAS transfer from smartwatch bands to human skin?
Executive summary
Independent research directly measuring PFAS transfer from smartwatch bands to living human skin is extremely limited: the University of Notre Dame team measured high, extractable PFAS in bands but did not perform human exposure tests [1] [2], while separate laboratory studies using in vitro human skin models have shown PFAS can penetrate skin under controlled conditions [3] [4]. Taken together, the evidence indicates a plausible dermal exposure pathway but stops short of quantified transfer rates from bands to real people over real-world wear conditions [5] [6].
1. The band study that started the debate
A University of Notre Dame analysis of 22 commercially available smartwatch and fitness-tracker bands reported elevated fluorine and detectable PFAS—most commonly perfluorohexanoic acid (PFHxA)—with median concentrations near 800 ppb and at least one sample exceeding 16,000 ppb [2] [1]; the team called this the first study to address PFAS specifically in watch bands and flagged fluoroelastomer materials as a primary source [1] [6]. That study used solvent extraction and targeted analysis of 20 PFAS species to demonstrate “readily extractable” PFHxA on band surfaces, a finding the authors said creates an opportunity for skin exposure even though the band work did not itself measure transfer into human tissue [2] [6].
2. What those band data actually measure — and what they do not
The Notre Dame work quantified PFAS that can be chemically extracted from band materials, not PFAS found in wearer blood or skin following use; the authors and journalists repeatedly note the distinction that extractable concentrations were high but that direct human testing was not performed [1] [5]. Peaslee and colleagues emphasized both the novelty of detecting part‑per‑million–range extractables in wrist-worn consumer items and the need for follow-up exposure studies because solvent-extractable PFAS only implies potential transfer rather than documented dermal uptake in situ [7] [2].
3. Independent dermal-absorption studies that inform the plausibility of transfer
Separate, independent laboratory studies using human skin models and in vitro systems have shown PFAS can pass through human skin analogues and be absorbed into underlying tissue, with at least one report noting absorption of “as much as 60%” for some PFAS when applied in a cream to a human skin model [4] [3]. Peer-reviewed work cited by multiple outlets—such as a 2024 Environment International study using 3D human skin equivalents—supports the conclusion that dermal bioavailability of certain PFAS is measurable in controlled experiments [3]. These studies are independent of the watch‑band testing but are the primary scientific evidence that PFAS detected on surfaces could, under some formulations and conditions, move across skin barriers [3] [4].
4. The evidence gap: no published human wear‑study measuring band-to-skin transfer
Despite suggestive in vitro data and extractable PFAS on bands, there is no published, independent human in vivo study yet that quantifies how much PFAS transfers from a fluoroelastomer watch band to live human skin during typical wear [5] [6]. Media coverage and the Notre Dame team repeatedly call for comprehensive exposure studies because current work either measures surface residues (bands) or models skin absorption in lab systems—none combine both in human subjects under realistic conditions [6] [5] [1].
5. Where scientists and public-health observers converge — and what remains contested
Researchers and advocates agree the combination of high extractable PFHxA on some bands and laboratory demonstrations of dermal uptake establishes a credible exposure pathway worthy of further study and regulatory attention [2] [3]. Critics and cautious experts underscore the missing link: quantifying transfer rates from bands to human skin, the influence of sweat or lotions, and realistic dose‑response implications remain unresolved; multiple outlets and the study authors themselves explicitly call for those human-focused exposure trials [8] [5] [6]. Until such targeted exposure studies are published, assertions about the magnitude of risk from wearing a smartwatch band rest on plausible but indirect evidence drawn from the Notre Dame extractable‑PFAS work and independent in vitro dermal absorption studies [1] [3].