Scientists warn that a tire preservative that breaks down into a lethal compound for coho salmon is spreading through waterways and want this week's United Nations plastics treaty talks to restrict it.
Timothy Rodgers, Rachel Scholes, and Simon Drew write for The Conversation.
In short:
- 6PPD, added to tires to prevent cracking, reacts with ozone to form 6PPD-quinone, a substance that kills coho salmon within hours at trace levels and harms other wildlife.
- Tires shed up to a fifth of their weight, releasing more than a million tons of particle-bound chemicals each year in the United States and European Union; researchers now detect tire additives in human samples.
- The authors urge the global plastics treaty this week to phase out hazardous tire additives, require transparent disclosure and create expert panels focused on safer substitutes.
Why this matters:
Tires are the stealthy plastic most drivers never consider. Every brake-squealing commute grinds their synthetic rubber into dust that washes from city gutters into streams, where 6PPD-quinone can wipe out an entire salmon run before spawning even begins. Early studies also link tire-borne chemicals to reproductive harm and neurotoxicity in mammals, hinting at risks for people living near busy roads. Because traffic is densest where populations cluster, urban residents and already stressed waterways receive the highest exposures. Adding tire additives to the plastics treaty would put the problem on the same global footing as ozone-eating CFCs, forcing manufacturers to find formulas that protect rubber without poisoning food chains and the communities that depend on them.
Related: Car tire chemicals are killing salmon and steelhead
