Can your smartwatch band expose you to harmful chemicals?

While your fitness tracker helps you monitor steps and heart rate, new research suggests it could also expose you to harmful chemicals. Scientists have found that several popular smartwatch bands contain significant levels of PFHxA (perfluorohexanoic acid), a concerning chemical that can be absorbed through the skin.

In a detailed study of 22 watch bands from different brands and price ranges, researchers discovered that many bands marketed as containing “fluoroelastomers” – a synthetic rubber designed to resist sweat and oils – contained significant levels of PFHxA. This chemical could easily transfer to the wearer’s skin, raising concerns, especially since approximately 21% of Americans wear smartwatches or fitness trackers for more than 11 hours a day.

Smartwatch bands expose users to harmful PFAS chemicals

Graham Peaslee, the study’s corresponding author, highlighted the significance of the findings, noting, “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.” This is particularly concerning considering millions of people wear these devices for extended periods. In a 2020 study cited by the researchers, participants wore their devices for an average of 11.2 hours daily. The bands tested came from various manufacturers and price ranges, although specific brands were not disclosed in the study.

PFHxA is part of the larger family of synthetic chemicals known as PFAS (per- and polyfluoroalkyl substances), often called “forever chemicals” due to their ability to remain in the environment and human body for long periods. While PFAS are found in items like non-stick cookware, food packaging, and cosmetics, their presence in watch bands worn directly on the skin creates a distinct exposure risk.

Led by scientists from the University of Notre Dame, the research team tested watch bands for fluorine content. They found that all 13 bands labelled as fluoroelastomers contained significant fluorine, along with two unmarked bands, indicating fluoroelastomers may be more common in these products than advertised.

Health risk associated with smartwatches

The study found that watch bands priced above $30 contained high levels of fluorine, with concentrations of PFHxA exceeding 1,000 parts per billion (ppb), much higher than in most consumer products. In contrast, cheaper bands under $15 were free of these chemicals. Some bands even exceeded 16,000 ppb, far surpassing the 200 ppb found in cosmetics.

The timing of this study is crucial as regulatory bodies in both the U.S. and Europe have started addressing PFHxA concerns. In 2023, the U.S. EPA identified potential health risks linked to PFHxA, such as liver, blood, and endocrine system effects. Meanwhile, the EU has moved to restrict its use.

Of particular concern is that these watch bands, often marketed for sports and fitness, are worn during activities that cause sweating. Studies show that PFHxA can be extracted from materials with synthetic sweat, and shorter-chain PFAS like PFHxA are more easily absorbed by the skin. The researchers stress that more studies are needed to understand the health risks of this exposure.

Lead author Alyssa Wicks advises consumers to carefully read product descriptions and avoid bands listed as containing fluoroelastomers if they prefer a higher-priced option. For those concerned, the researchers recommend choosing lower-cost silicone wristbands instead.