The toxic tyre chemical no one is measuring

Every time a vehicle moves, its tyres shed tiny particles. Some of these particles carry a chemical that, in the U.S., was found killing salmon in urban streams after rain. India is selling more vehicles than ever before, yet experts say there is no data on how much of this chemical reaches the country’s rivers. The chemical is 6PPD (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine), an additive used worldwide to increase tyre durability. It became a concern after researchers from the U.S. published a study in the journal Science in December 2020, linking a compound formed from 6PPD to mass deaths of coho salmon in urban streams after rain. “6PPD is used to neutralise ozone, prevent cracks in the rubber, and extend the lifespan of the tyre,” according to a January review article in RSC Advances by the Royal Society of Chemistry. The review opens by noting that India’s tyre market is expanding with its automotive industry, then examines the toxic effects of 6PPD-quinone (6PPD-Q), a byproduct formed when 6PPD reacts with ozone. Echoing the same, Paul Sharp, a chemist and Professor Emeritus, University of Missouri, Columbia, USA, says, “6PPD-Q is the ozonisation byproduct of 6PPD and formed as a tyre wear particle. It has no boundaries and is ubiquitous all over the motorised world. These can make their way into water bodies during rainstorms, leading to rapid/mass death of aquatic species.” Responding to Mongabay-India’s email interview, Sharp explains that as tyres wear down, 6PPD reacts with ground-level ozone to form 6PPD-Q. Edward Kolodziej, a…This article was originally published on Mongabay