U.S. regulators say they will review the use of a chemical found in almost every tire after a petition from West Coast Native American tribes that want it banned because it kills salmon as they return from the ocean to their natal streams to spawn.

The Yurok tribe in California and the Port Gamble S’Klallam and Puyallup tribes in Washington asked the Environmental Protection Agency to prohibit the rubber preservative 6PPD earlier this year, saying it kills fish — especially coho salmon — when rains wash it from roadways into rivers. Washington, Oregon, Vermont, Rhode Island and Connecticut also wrote the EPA, citing the chemical’s “unreasonable threat” to their waters and fisheries.

The agency’s decision to grant the petition last week is the start of a long regulatory process that could see the chemical banned. Tire manufacturers are already looking for an alternative that still meets federal safety requirements.

“We could not sit idle while 6PPD kills the fish that sustain us,” Joseph L. James, chairperson of the Yurok Tribe, told The Associated Press. “This lethal toxin has no business in any salmon-bearing watershed.”