Hyderabad: Smartwatches and fitness trackers could expose the skin to "forever chemicals", suggests a study published in ACS' Environmental Science & Technology Letters. It found that wristbands made from fluorinated synthetic rubber contain high levels of perfluorohexanoic acid (PFHxA), which is a type of forever chemical. Instead of being present in low-cost products, the chemical is found more prominently in expensive wristbands, the study said.
Graham Peaslee, the corresponding author of the study says that the discovery stands out because of the "very high concentrations" of one type of forever chemical in the items that are in prolonged contact with our skin.
Researchers believe the high levels of PFHxA in wristbands are due to its use as a surfactant during the production of fluoroelastomers. Currently, scientists don't fully understand how easily PFHxA penetrates the skin or its potential health effects. However, recent studies suggest a significant amount may pass through the skin under normal conditions.
The forever chemical
Per- and polyfluoroalkyl substances (PFAS) are chemicals known for their durability and ability to repel water, sweat, and oil. These properties make them useful in many consumer products, such as stain-resistant bedding, menstrual products, and fitness wear, including smartwatch and fitness tracker wristbands.
These bands are made from fluoroelastomers, synthetic rubbers composed of PFAS chains, which help prevent discolouration and repel dirt. While this makes the bands ideal for sweaty workouts, it also means they could introduce these chemicals to the skin.
To explore this issue, Peaslee and co-authors Alyssa Wicks and Heather Whitehead examined several commercially available wristbands for the presence of fluorine and 20 individual PFAS.
Expensive wristbands contained more fluorine
The team tested 22 wristbands from various brands and price points, including both new and used ones. They found that all 13 bands advertised as being made from fluoroelastomers contained fluorine. Interestingly, two of the nine bands not advertised as fluoroelastomers also contained fluorine, suggesting the presence of PFAS.
Wristbands priced over $30 had more fluorine than those under $15. After chemical extraction, the wristbands were tested for 20 PFAS. PFHxA was the most common, found in nine out of 22 wristbands. The median concentration of PFHxA was nearly 800 parts per billion (ppb), with one sample exceeding 16,000 ppb.
In comparison, the team's 2023 study on cosmetics found a median PFAS concentration of about 200 ppb.
Currently, only six PFAS have federally defined exposure limits for drinking water in the US, and limits for other PFAS and exposure routes are still being studied. "We have never seen extractable concentrations in the part-per-million range (>1000 ppb) for any wearable consumer product applied to the skin," says Peaslee.
Lead author Wicks recommends opting for cheaper wristbands made from silicone. For those considering higher-priced bands, it's advised to read product descriptions carefully and avoid those containing fluoroelastomers.
