Fishermen Sue Tire Manufacturers Over Chemical Linked to West Coast Salmon Deaths

A federal courtroom in San Francisco is becoming the latest battleground over the future of West Coast salmon.

On Jan. 26, a case brought by commercial fishing groups went before a judge, accusing major tire manufacturers of using a chemical additive that can be lethal to endangered fish once it washes into rivers and streams. The lawsuit targets companies including Bridgestone, Michelin, and Pirelli, along with several other U.S. tire makers.

At the center of the dispute is 6PPD, a compound used to prevent tires from breaking down when exposed to air and ozone. According to the plaintiffs, that same chemical transforms into a toxic byproduct known as 6PPD-quinone once tire particles are washed off roads during storms. They argue this runoff can devastate salmon populations along the California and Alaska coasts.

The suit, backed by the Institute for Fisheries Resources and the Pacific Coast Federation of Fishermen’s Associations and represented by Earthjustice, claims the chemical’s use violates the Endangered Species Act by harming threatened populations of coho and Chinook salmon, as well as steelhead trout.

During testimony, University of Washington researcher Edward Kolodziej said 6PPD-quinone can kill coho salmon within hours and is a major driver of so-called “urban runoff mortality,” where salmon die before they can spawn.

Tire companies countered that the science relies heavily on lab studies and that real-world concentrations are far lower. They also argue there is currently no safer alternative to 6PPD.

Hearings continue through Jan. 29, with a ruling expected later.