New study shows atmospheric compounds formed from tire wear may pose human health risk

Researchers from York U, Environment and Climate Change Canada found chemical compounds trigger inflammatory, toxic responses in human lung immune cells

TORONTO, May 27, 2026 – A new study published today in the journal Environment International reports that chemicals released from tires can transform into complex mixtures in the atmosphere that may pose previously unrecognized risks to human respiratory health.

Tire rubber contains antioxidant chemicals, most notably 6PPD and DPPD, that are released into the air as tiny particles during normal driving. A single compound formed from 6PPD, known as 6PPD-quinone was previously shown to be implicated in the death of coho salmon in urban waterways, but the broader atmospheric chemistry and potential human health impacts of these compounds have remained largely unexplored until now.

“The striking finding was that the mixtures were far more toxic than the original tire chemicals themselves and are far more toxic than the one compound previously implicated in environmental studies,” says York University Associate Professor Ali Abdul-Sater, who co-lead the study with researchers from Environment and Climate Change Canada. “This suggests that focusing on a single compound may substantially underestimate the real health risks associated with tire-derived air pollution.”

Abdul-Sater, with the School of Kinesiology and Health Science in the Faculty of Health at York and director of the Psoriatic Arthritis (PsA) CARE Hub, connected with research scientists John Liggio and Samar Moussa from Environment and Climate Change Canada. The federal government agency has a “library” of archived ambient samples on hand from across the country and the researchers used some of these samples from near Highway 401, and close to York University, for the study.

“When you oxidize one chemical from a tire, it probably makes hundreds of chemicals in the mixture, and you don't know which one of those, or all of them are causing the toxic effect that we're seeing,” explains Liggio. “Even though we can identify what they are chemically, you can't go out and buy that chemical and test only that chemical.”

In this study, they identified at least 150 chemicals and found 88 of them to be present in the roadside samples. They then recreated the mixture of tire derived chemicals in their laboratory and handed them off to Abdul-Sater.

At his lab at York, Abdul-Sater exposed human macrophage cells to this chemical mixture. Macrophages are immune cells that serve as the lungs’ first line of defense against inhaled particles. Surprisingly, while the fish-killing 6PPD-quinone was not found to be particularly toxic, the chemical mixture overall was.

“The results showed rapid cell death, substantial mitochondrial damage, and strong activation of inflammatory pathways,” says Abdul-Sater. “These effects were far more severe than those caused by the parent chemicals alone or by 6PPD-quinone, the single product that has received the most attention. Importantly, the concentrations that triggered these responses are comparable to estimated levels in human lung fluid based on real-world air quality measurements near busy roads.”

Moussa adds: “The original motivation for the project was to assess the toxicity of this one compound, but what we discovered was a potentially more complex issue that we aim to disentangle in future studies. When you breath in air, you take it all in, you are not selectively breathing this molecule or that molecule.”

The researchers say the results are preliminary and not cause for alarm, pointing out that these exposures have existed for half a century or more, but they may be one more environmental exposure that is contributing to the rise of chronic inflammation and related disease. Previous studies have shown negative health effects being correlated with living near major roadways.

“We have to think about this from a chronic exposure angle,” says Abdul-Sater. “These compounds may be increasing our proclivity to develop certain kinds of diseases.”

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Media Contact: Emina Gamulin, York University Media Relations, 437-217-6362, egamulin@yorku.ca