New US research has found that smart watches and fitness trackers may contain high levels of toxic PFAS "forever chemicals" that can be absorbed through the skin, potentially leading to "severe" exposure to the dangerous substance.

The University of Notre Dame study examined PFAS (labeled chemical substances) in 22 common brands. It detected 15 substances at levels much higher than those commonly found in consumer products and clothing.

Graham Peaslee, a researcher at the University of Notre Dame, said that while the speed at which PFAS crosses the skin is unknown, studies have found that it can be absorbed, and that the finding is "concerning" because these The strap will put pressure on your wrist for a long time. -Author of the study.

The levels of PFAS detected in the strips were "much higher than most PFAS we see in consumer products," Peaslee added.

PFAS are a class of about 15,000 compounds commonly used to make products that resist water, stains and heat. They're called "forever chemicals" because they don't break down and accumulate naturally, and have been linked to cancer, kidney disease, liver problems, immune disorders, birth defects and other serious health problems.

These chemicals are often added to consumer products, such as rain gear or hiking gear, as water repellents, although researchers at the University of Notre Dame were surprised to find that levels of the chemicals were as high in watches as in firefighting gear. While natural rubber may not contain PFAS, synthetic rubber may contain these chemicals to prevent sweat and dirt from building up over time, Peasley said.

While the study did not identify which brands tested positive for PFAS, it noted that it tested watches from Nike, Apple, Fitbit and Google.

Some brands advertise their use of PFAS in watch straps—the term “Viton watch strap” indicates their use. However, not all ads promote the use of chemicals. Products containing PFAS are $50 more expensive than products without PFAS, Peaslee said.

"Obviously they're charging a premium for all these beautiful PFAS," he said.

Research earlier this year found that up to 60% of PFAS in creams applied to human skin models was absorbed, a rate that surprised some researchers. This finding is particularly concerning because many watches are marketed as "sporty" and designed for exercise. Previous research has found that sweat may increase the rate of PFAS absorption.

The study examined individual PFAS compounds and found the highest levels of PFHxA, a synthetic chemical that belongs to the PFAS group, in 40 percent of the bands. The chemical is commonly used in clothing, carpets, paper and pesticides and has been linked to liver disease. Peaslee said it's an understudied compound, in part because it's harder to detect in human blood than other types of PFAS, making his findings all the more concerning. The European Union has proposed banning the use of PFHxA in consumer products such as watch straps.

Researchers also discovered perfluorooctanoic acid (PFOA), a compound the EPA found to be safe at almost no exposure level in drinking water.

Peasley said watches with silicone straps are a safer option.

"I don't need anyone to rush to throw away their Christmas gifts, but next time you buy a gift, stay away from the ones that contain PFAS," Peasley said.