How your smartwatch may be raising your risk of cancer

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 commonly used in the production of everything from fabrics to nonstick cookware and cosmetics.

They do not break down in the body or the environment, hence the nickname ‘forever chemicals’, and are found around the world in air, water, fish and soil.

Some studies have linked them to birth defects, an increased risk of prostate, kidney and testicular cancer and fertility problems.

The new paper tested 22 different brands of smart watches and found that 15 of them contained PFAS chemicals, although they did not reveal which brands.

They found that more expensive brands were more likely to contain high levels of toxins than cheaper brands.

These devices are all the rage in a wellness revolution increasingly focused on individuals interested in tracking their sleep, exercise and heart rate data.

It is believed that around 21 percent of American adults and 35 percent of British adults use a smartwatch, wearing them for an average of eleven hours at a time.

This means that around 54 million people in the US and 13 million in Britain 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 retails online for $89 (£70) and the AppleWatch, which retails online for between $249 (£195) and $799 (£625).

Many of these brands automatically come with a flexible, silicon-like band, although customers can swap this out for other options.

Traditionally, researchers have concluded that the most common way PFAS takes up residence in the body is by swallowing or inhaling.

However, some research has suggested that prolonged skin contact with a PFAS chemical can cause it to be absorbed through your skin, but it is unclear whether 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 determine what health effects they can have on the body.

This study, that was published in the magazine Environmental Science and Technology Letterstargeting a PFAS called Fluoroelastomers.

These are sometimes added to watch straps to help them retain color even after frequent contact with oil from the skin, but it is not always clear which brands use the chemical.

To determine how widespread the chemical was, Notre Dame researchers performed chemical analyzes on each of the watch straps.

They checked whether the tires contained fluorine, a sign that the PFAS in question was present.

In 15 of the products, which is about 68 percent of the products tested, researchers found evidence of PFAS.

Most of those tires were advertised as containing fluorine, but two tires tested did not disclose that the chemical was used in the manufacturing process.

The bands costing more than $30 (£23) had higher fluorine content than those under $15 (£11).

The researchers also conducted chemical analyzes for other types of PFAS chemicals, aside from fluoroelastomers, and found that all 22 contained at least some signs of one of the chemicals.

The researchers said these forever chemicals likely entered the product as a cleaning agent during the manufacturing process.

The researchers noted that it is unclear whether people readily absorb fluoroelastomers through the skin, and if so, how much they absorb.

A 2022 study in Germany where participants wore sunscreen containing a chemical called PFAS for 115 days found that 1.6 percent of the total amount of chemical applied was absorbed through the skin.

On the more extreme side, another 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 into the skin.

The authors said: ‘These limited studies suggest that dermal absorption of PFAS may represent a significant route of exposure for short-chain PFAS when used in consumer products that contact the skin.’

While the science is still evolving, says study author Alyssa Wicks, consumers may still want to pay attention to what’s in their tire, out of an abundance of caution.

Dr. Wicks said, “If the consumer is looking to purchase a more expensive tire, we recommend that they read the product descriptions and avoid those that list them as containing fluoroelastomers.”