Indoor Climbing Gyms Might Be Chock Full of Toxic Rubber Additives, Study Finds

Indoor Climbing Gyms Might Be Chock Full of Toxic Rubber Additives, Study Finds

Climbing gyms might be teeming with toxic rubber particles, recent research suggests. The study found high levels of rubber additives in the air and dust of two climbing gyms, likely coming from the soles of specialized climbing shoes worn by gym goers. The authors say that customers and workers might be getting exposed to more of these particles at climbing gyms than they would be anywhere else in their daily lives.

The research was led by scientists from the University of Vienna, some of whom have previously studied how rubber and its property-enhancing additives can seep into the environment.

While much of this pollution is coming from tires and roads, the authors noticed that many pieces of sports equipment also contain plenty of rubber. Climbing shoes in particular are made with additives that make the rubber especially flexible and sticky, and the soles are designed to slowly wear away while climbing to produce the friction important for holding onto things. The net result is that lots of rubber particles are produced from these shoes that end up on climbing footholds. And the constant brushing away of these particles by climbers ensures that they regularly end up in the air waiting to be inhaled, the scientists hypothesized.

Previous research has already suggested that climbing gyms can contain lots of indoor dust and potential pollution, though some have argued that much of this originates from the chalk that climbers use. This time around, the researchers decided to look specifically for 15 known rubber-derived compounds in the air and dust of two climbing gyms, collecting samples at peak business hours.

A graphic of the team’s findings.
Graphic: Sherman et al/ChemRxiv

As other studies have, the researchers found high levels of total particulate matter in the gyms. They also detected nine out of the 15 rubber-derived compounds in the air, and 12 of these compounds in dust. Verifying their suspicions, they found high levels of these same compounds in climbing shoe samples, with one sample containing all 15. These compounds were also found in the powder collected from the top of climbing footholds, further supporting their hypothesis. And based on their estimates and other data, climbers and employees are likely getting more daily exposure to these additives at these gyms than they would anywhere else.

“These findings identify a previously unknown human exposure route to rubber additives and emphasize the global problem of the toxicity burden of plastic additives,” the authors wrote in their paper, released earlier this February as a preprint paper on ChemRxiv.

The team’s work hasn’t yet undergone the typical peer review process, so its conclusions should be taken with some added caution for now. The exact health impact of these compounds on humans is also still unclear, though certain ones such as 6PPD-quinone are known to be toxic to fish, while other studies have found that tire rubber particles in general can be harmful to our respiratory health.

At the very least, the researchers say that more should be done to mitigate the potential air pollution threat found inside these gyms. And much as tire manufacturers have started to do, the team argues that climbing shoe makers should be forced to remove and replace the rubber-derived compounds most likely to be harmful to human health in their products.

“Until rubber becomes safer, potential strategies to minimize exposure in climbing halls should also be considered, such as more frequent cleaning, mobile and stationary HEPA air filters, or banning of certain shoe models,” they added.

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