The State of California has adopted a rule that will require tiremakers to find a new alternative to a chemical that is currently in use that has been found to kill an endangered salmon species.

6PPD, a chemical that helps reduce tire cracking and extends the life of tires, has been added to California’s list of Priority Products, which identifies consumer products that contain chemicals that are potentially dangerous to people or the environment.

Its inclusion means tire manufacturers will have until Nov. 30 to notify state regulators if they currently make tires that contain the chemical.

According to the California Department of Toxic Substances Control, 6PPD reacts with ozone in the air to form another chemical called 6PPD-quinone.

That new chemical was found to kill coho salmon as they migrate upstream for their yearly spawn and has been detected in streams at a level that has been shown to kill the salmon in laboratory studies.

Coho salmon can live in both freshwater and saltwater and are protected under the Endangered Species Act. A subspecies, the Central California Coast coho salmon, is an endangered species.

Coho salmon turn red and return to the exact place of their birth, in this case the White River, to spawn. (iStock via Getty Images)
Coho salmon turn red and return to the exact place of their birth, in this case the White River, to spawn. (iStock via Getty Images)

A link between coho deaths and 6PPD was first discovered by scientists in the Pacific Northwest. California Native American tribes who rely on the fish have been among the most negatively impacted by the mass die-offs.

California regulators say 6PPD and 6PPD-quinone have shown to possibly have negative effects on other aquatic organisms.

Tire manufactures are required to now look into new alternatives to replace 6PPD. The state says it’s working with the U.S. Tire Manufacturers Association to navigate the process.

“We are working with the U.S. EPA, other states, researchers and the Tire Manufacturers Association to find a path to make tires safer for our environment without compromising on-road safety,” said DTSC Director Dr. Meredith Williams.

DTSC Deputy Director Karl Palmer said 6PPD has played a crucial role in the safety of tires on California’s roads and there is currently no widely available safer alternative.

Because of this, regulators and manufactures are working together to find alternatives that ensure the “continued safety of the tires on California’s roads while protecting California’s fish populations and the communities that rely on them.”

For more on the California Department of Toxic Substances Control, click here.

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