Alarming news: A new study finds that several brands of fitness tracker and smartwatch bands contain “very high concentrations” of a man-made chemical that can harm our health.

University of Notre Dame researchers tested 22 wristbands at various price points — many were manufactured with fluoroelastomers, synthetic rubbers designed to repel sweat, skin oils and water.

Nine of the bands had elevated levels of perfluorohexanoic acid (PFHxA), a type of per- and polyfluoroalkyl substances (PFAS). These compounds are known as “forever chemicals” — and they’ve been linked to a host of health problems, including an increased risk of certain cancers.

“The most remarkable thing we found in this study was the very high concentrations of just one PFAS — there were some samples above 1,000 parts per billion of PFHxA, which is much higher than most PFAS we have seen in consumer products,” said Graham Peaslee, study co-author and professor emeritus in the Department of Physics and Astronomy.

PFAS have been detected in fast food containers, non-stick cookware, stain- and water-resistant fabrics, shampoo, cosmetics, paints and adhesives, among other products.

Smartwatches and fitness trackers are very popular wearable technology. In a 2019 survey, 21% of American adults reported wearing one often.

Peaslee said this is the first study to address PFAS in fitness trackers and smartwatch bands.

They’re called “forever chemicals” because they do not easily break down in the environment, persisting in soil and groundwater for long periods. A study out this week found they are pervasive in public water systems.

PFAS have been linked to health issues such as reduced immune function, elevated cholesterol, thyroid dysfunction, liver damage, developmental delays in children and an increased risk of certain cancers, particularly kidney and testicular cancers.

“Few studies so far have been published regarding the dermal absorption of PFAS,” said Alyssa Wicks, a graduate student in Peaslee’s lab and lead study author.

“One article published [in 2024] by a European research group found that a couple types of PFAS had significant transfer through the skin,” Wicks continued. “That initial study only examined around 20 of the 14,000 known types of PFAS, and more studies are needed to better understand how PFAS travel through the skin.”

In Wicks’s study, elevated levels of PFHxA were found in watchbands that cost over $15.

Exposure to high doses of PFHxA may harm the liver, thyroid, red blood cell count and the developing fetus.

Three of the bands included in the analysis were deemed expensive because they cost over $30 — all three contained considerably high amounts of fluorine.

Elevated fluorine levels are a strong indicator of PFAS contamination, the researchers said, because all PFAS molecules contain fluorine atoms.

“Fifteen of the 22 bands we tested had a high percentage of total fluorine concentrations, and nine contained PFHxA,” Wicks said. “The others used some other unidentified surfactant that wasn’t in our targeted analysis.”

The findings were published recently in the Environmental Science & Technology Letters journal.

Peaslee said the results warrant a more comprehensive study on PFAS in watchbands.