Your smartwatch might be making you sick, new research says
The hidden risks in your trusted daily tracker

Many of us rely on our running watches daily, using them as an essential training tool to track pace, distance and heart rate. You may also use it to keep an eye on your health, studying your HRV, looking at your training load to see if you need more rest and potentially even monitoring your menstrual cycle. However, new research, as reported in The Guardian, suggests that some of these handy devices come with an unexpected downside—high levels of toxic PFAs, also known as “forever chemicals.” Here’s what you should know about your trusted tracker.
The study
PFAs are substances used to make products resistant to water, stains and heat, and have been linked to serious health risks, including cancer, liver disease and immune disorders. They are known as “forever” chemicals because they do not naturally break down. A recent study from the University of Notre Dame found that 15 out of 22 common smartwatch and fitness tracker bands tested contained PFAs at levels significantly higher than those typically found in consumer products.
Why this matters for runners
Runners are particularly at risk, because sweat may increase the rate at which PFAs are absorbed through the skin. Previous research found that up to 60 per cent of certain PFAs in skin-applied products can be absorbed. Since fitness watch bands are worn tightly against the skin for prolonged periods, this could mean a continuous exposure to harmful chemicals. “The levels detected in the bands were much higher than most PFAs we have seen in consumer products,” said Graham Peaslee, a Notre Dame researcher and co-author of the study. While the exact rate at which these chemicals are absorbed remains unclear, their persistent nature means they accumulate in the body over time, raising long-term health concerns.
Choosing a safer alternative
The study did not name specific brands that tested positive for PFAs, but it did examine models from well-known companies such as Apple, Fitbit, Google and Nike. Some brands openly advertise their use of fluoroelastomer bands—a material that contains PFAs—while others do not disclose their presence. Interestingly, Peaslee noted that bands containing PFAs were often priced higher than those without. If you’re concerned about exposure, switching to a silicone band may be a safer choice. “I don’t need someone to rush to throw away their Christmas gifts, but next time you buy one, move away from those with PFAs,” Peaslee advised. As more research emerges, runners should consider researching their gear choices—not just for performance, but for long-term health as well.