By Stephen Beech
Elevated levels of potentially toxic “forever chemicals” have been found in several smartwatch wristbands.
The chemicals were more common in more expensive wristbands, say scientists.
PFAS (Per- and polyfluorinated alkyl substances), also known as Forever Chemicals, are a large family of more than 10,000 highly persistent chemicals that don’t occur in nature.
Smartwatches and fitness trackers have become popular forms of wearable tech, accompanying many people throughout their days and nights.
But new research by American scientists warns that they may expose the skin to forever chemicals in the process.
More expensive wristbands made from fluorinated synthetic rubber revealed “particularly high” amounts of one forever chemical, perfluorohexanoic acid (PFHxA), according to the study published in the journal Environmental Science & Technology Letters.
Corresponding author Professor Graham Peaslee, of the University of Notre Dame in Indiana, said: “This discovery stands out because of the very high concentrations of one type of forever chemical found in items that are in prolonged contact with our skin.”
He says PFAS chemicals last seemingly forever in the environment and repel water, sweat and oil.
Because of the latter properties, manufacturers include the chemicals in many consumer products, such as stain-resistant bedding, menstrual products and fitness wear, including smartwatch and fitness tracker wristbands.
The bands contain fluoroelastomers – synthetic rubbers made from chains of PFAS – to create a material that avoids discoloration and repels dirt.
Though the durability makes the bands great for sweaty workouts, the researchers say it might also present a source of these compounds to get under the wearer’s skin — literally.
Peaslee plus co-authors Alyssa Wicks and Heather Whitehead investigated several commercially available watchbands for the presence of fluorine as well as 20 individual PFAS.
They screened 22 wristbands from a range of brands and price points, most of them newly purchased but a few previously worn.
All of the 13 bands advertised as being made from fluoroelastomers contained the element fluorine.
But two of the nine bands that did not advertise being made from fluoroelastomers also contained fluorine, indicating the potential presence of PFAS.
Of those tested, wristbands that cost more than $30 contained more fluorine than those under $15.
Next, following a chemical extraction, all the wristbands were checked for 20 different PFAS.
PFHxA was found to be the most common, appearing in nine of 22 tested wristbands.
The median PFHxA concentration was found to be nearly 800 parts per billion (ppb), and one sample exceeded 16,000 ppb.
Comparatively, previous research by the team in 2023 on cosmetics found a median concentration of around 200 ppb of PFAS.
Currently, only six PFAS have federally defined exposure limits for drinking water in the United States; exposure limits for other PFAS and other exposure routes are still being studied.
Peaslee said: “We have never seen extractable concentrations in the part-per-million range for any wearable consumer product applied to the skin.”
The team suggests that the large amounts of PFHxA found in the wristbands may be a result of the compound being used as a surfactant during the fluoroelastomer manufacturing process.
Scientists do not currently understand how readily PFHxA transfers into the skin, nor the potential health effects it poses once it gets there, although Peaslee says recent studies suggest that a significant percentage could pass through human skin under normal conditions.
Study lead author Wicks says the team recommends buying lower-cost wristbands made from silicone.
She added: “If the consumer wishes to purchase a higher-priced band, we suggest that they read the product descriptions and avoid any that are listed as containing fluoroelastomers.”
