Tiny rubber particles emitted by car tires, long known to harm wildlife, may also pose a danger to humans, according to a new study.
The chemical 6PPD, added to tires to prevent cracking, is transformed when exposed to ozone pollution from vehicle emissions. One of the compounds formed in this process, 6PPD-quinone, has been linked to the mortality of spawning coho salmon in the Pacific Northwest. For decades, heavy rainfall has led to a sharp increase in salmon mortality as contaminated stormwater entered urban waterways.
A new study has found that many other chemicals produced by tire wear can pose a threat to humans when inhaled. "When you oxidize one chemical from a tire, you likely create hundreds of other chemicals in the mixture," said study co-author John Liggio of Environment and Climate Change Canada.
To understand the potential health risks associated with air pollution from car tires, researchers exposed human immune cells to a mixture of tire-related pollutants, as well as pure 6PPD quinone. According to a study published in the journal Environment International, the mixture caused rapid cell death, along with other negative effects. The findings, while far from conclusive, suggest that the risks associated with tire air pollution may be higher than previously thought.
Remarkably, as lead study author Ali Abdul-Sater of York University in Toronto noted, 6PPD quinone itself was not particularly harmful to human cells. "This suggests," he said, "that focusing on one compound may significantly underestimate the true health risks associated with air pollution from tires.".
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