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Certain more expensive styles of smartwatches may not only be helping Americans stay fit, but may be exposing unsuspecting users to a high dose of “chemicals forever”, a new study has found.
More expensive bracelets made from fluorinated synthetic rubber usually contain large amounts of one of these compounds, called perfluorohexanoic acid (PFHxA), according to the research, published on Wednesday at Letters of Environmental Science and Technology.
“This discovery stands out because of the very high concentrations of a type of chemical that is forever found in items that come into prolonged contact with our skin,” corresponding author Graham Peaslee, a PFAS expert at the University of Notre Dame and nuclear physicist. .
PFHxA is one of thousands of types of per- and polyfluoroalkyl substances (PFAS), a group of man-made compounds known for their ability to persist in the human body and in nature. It is found in many types of household products, certain firefighting foams and industrial waste, some types of PFAS to have been linked to cancer and other serious diseases.
Because of PFAS’s ability to repel water, sweat and oil, manufacturers have long included these compounds in items such as stain-resistant textiles, menstrual products and fitness wear, they noted the authors
The wristbands in question contain what are known as “fluoroelastomers”, synthetic rubbers made from PFAS chains, which are very durable during sweaty workouts and help prevent discoloration.
But the researchers warned that because the bands are so durable, they could provide easy access for chemicals to get into the wearer’s skin forever.
Meanwhile, previous research has shown that more than a fifth of Americans use a smartwatch or fitness tracker, and do so for extended periods of time, the authors noted.
The scientists ended up examining 22 bracelets of a variety of brands and prices, looking for both fluoride, which indicates the possible presence of PFAS, and 20 individual types of PFAS. They found that not only did the 13 bands advertised as being made of fluoroelastomers contain the element fluorine, so did two of the nine bands that were not marketed as such.
Of all the bracelets sampled, the researchers observed that those that cost more than $30 contained more fluoride than those that cost less than $15.
When they checked all the bracelets for 20 different types of PFAS, they found that PFHxA was the most common, showing up in nine of the 22 bracelets tested.
The average concentration of PFHxA was nearly 800 parts per billion (ppb), with one sample exceeding 16,000 ppb, the study found. For comparison, a 2023 cosmetics study by the team found an average concentration of about 200 ppb of PFAS.
To date, there are no federal regulatory limits that dictate safe levels for PFAS exposure through the skin. Currently, only the Environmental Protection Agency has been put exposure thresholds for drinking water and only for six types of PFAS.
That said, Peaslee emphasized that he and his colleagues “have never seen extractable concentrations in the part per million range (>1000 ppb) for any portable consumer product applied to the skin.”
The scientists acknowledged that they currently do not understand how easily PFHxA can be transferred to the skin or whether the compound poses a health risk upon entry.
However, the study’s lead author, Notre Dame graduate student Alyssa Wicks, recommended opting for less expensive wristbands made from silicone.
“If the consumer wants to buy a higher-priced band, we suggest they read the product descriptions and avoid any that contain fluoroelastomers,” Wicks said.
