Your smartwatch band may contain chemicals that scientists have linked to fertility problems and cancer, according to a new study.
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are chemicals that are widely used in the manufacturing of everything from fabrics to nonstick pans and cosmetics.
They do not break down in the body or the environment, hence the nickname “forever chemicals”, and have been found in air, water, fish and soil around the world.
Some studies have linked them to birth defects, increased risk of prostate, kidney and testicular cancer, and fertility problems.
The new paper tested 22 different brands of smartwatches and found that 15 of them contained PFAS chemicals, although it did not reveal which brands.
They found that more expensive brands were more likely to have high levels of toxins than less expensive brands.
These devices are all the rage in a wellness revolution increasingly focused on people interested in tracking their sleep, exercise, and heart rate data.
About 21 percent of American adults and 35 percent of British adults are believed to wear a smartwatch, wearing it for an average of 11 hours at a time.
Smartwatches offer programs to track sleep habits, heart rate, exercise, and more. The average user carries their device 11 hours a day, according to the study
Some studies have suggested that long-term use of products containing PFAS can cause these chemicals to be absorbed through the skin and stored in the body.
This means that around 54 million people in the US and 13 million in the UK could be exposed to these chemicals for long periods every day.
The researchers did not share which brands they tested.
Some popular options include the ASWEE Smart Watch, which sells online for $89 (£70) and the AppleWatch, which sells online for between $249 (£195) and $799 (£625).
Many of these brands automatically come with a flexible silicon-like band, although customers can upgrade to other options.
Traditionally, researchers have concluded that the most common way PFAS take up residence in the body is by swallowing or inhaling them.
However, some studies have suggested that prolonged skin contact with a PFAS chemical can cause the skin to absorb it, but it is unclear if this is common or if it has an effect on the body.
There are thousands of different types of these chemicals, and organizations like the Environmental Protection Agency are actively working to track what health effects each one might have on the body.
This study, which was published in the magazine Environmental science and technology lettersfocused on a PFAS called Fluoroelastomers.
The ASWEE smartwatch that sells on Amazon for $89. The Apple Watch sells online for between $249 and $799
They are sometimes added to watch straps to help them retain color even after frequent contact with skin oils, but it’s not always clear which brands use the chemical.
So, to determine how widespread the chemical was, Notre Dame researchers performed chemical analyzes on each of the watch straps.
They were looking to see if the bands contained fluorine, a sign that the PFAS in question was present.
In 15 of the products, which is about 68 percent of those tested, researchers found evidence of PFAS.
Most of those bands had advertised that they contained fluorine, but two of those analyzed did not disclose that the chemical was used in the manufacturing process.
Bracelets that cost more than $30 had higher levels of fluoride than those that cost less than $15.
The researchers also performed chemical analyzes for other types of PFAS chemicals besides fluoroelastomers, and found that all 22 contained at least some signs of one of the chemicals.
Researchers said these permanent chemicals likely entered the product as a cleaning agent during the manufacturing process.
A 2024 study mapped out the different potential sources of several different types of PFAS chemicals from manufacturing facilities. Each dot of a different color corresponds to a different potential type of industry.
The researchers noted that it is unclear whether people easily absorb fluoroelastomers through the skin and, if they do, how much they absorb.
A 2022 study in Germany in which participants used sunscreen with a PFAS chemical for 115 days found that 1.6 percent of the total amount of chemical applied was absorbed into the skin.
At the most extreme end, a different study conducted in 2024 by British researchers found that applying PFAS to lab-grown skin cells caused about 58 percent of the total amount of chemical applied to be absorbed by the skin. .
The authors said: “These limited studies suggest that dermal absorption of PFAS may represent an important exposure route for short-chain PFAS when used in consumer products that come into contact with the skin.”
Although the science is ongoing, said study author Alyssa Wicks, consumers may still want to pay attention to what’s in their band out of an abundance of caution.
Dr Wicks said: “If the consumer wishes to purchase a higher priced bracelet, we suggest they read the product descriptions and avoid those that state they contain fluoroelastomers.”