EPA to Investigate Tire Chemical Linked to West Coast Salmon Deaths

The U.S. Environmental Protection Agency (EPA) announced plans to review the use of, and consider prohibiting, the rubber preservative found in tires known as 6PPD, in response to a petition from the Yurok Tribe, the Port Gamble S’Klallam Tribe and the Puyallup Tribe of Indians.

The chemical 6PPD is a rubber preservative used in tires as well as other applications, such as playground flooring, shoes and synthetic turf infill. It makes the rubber more durable, the EPA explained. 

However, tires and other objects can shed small particles containing this chemical. When the chemical reacts with ozone pollution, it forms 6PPD-quinone, or 6PPD-q, a chemical that is toxic to aquatic life. A 2021 study found that 6PPD-q in stormwater could be linked to coho salmon deaths over multiple decades.

According to Earthjustice, which submitted a petition in August to the EPA on behalf of the Yurok Tribe based in California, the Port Gamble S’Klallam Tribe and the Puyallup Tribe of Indians, both based in Washington state, 6PPD-q exposure can kill salmon quickly, within just hours.

“6PPD-q is the second most toxic chemical to aquatic species ever evaluated by EPA,” Earthjustice wrote in the petition. “The only chemical more toxic to aquatic species — the chemical war agent parathion — has been widely banned due to its toxicity and is no longer on the market in the United States.”

The coho salmon are important not just ecologically but culturally and economically. Additionally, 6PPD-q has been found to be acutely toxic to other aquatic life, including Chinook salmon, rainbow trout and steelhead trout.

“Many Tribes rely heavily on salmon and other aquatic resources for food and cultural practices. Healthy and accessible salmon populations are critical to the health and wellbeing of Tribes, including the practice and protection of Tribal Treaty Rights,” the EPA wrote on its webpage on 6PPD-q.

The EPA said it will publish an advanced notice of proposed rulemaking by next fall. The agency needs to collect additional information on 6PPD-q, including how it may impact other aquatic species and humans, as well as potential exposure of the chemical from other sources aside from tires. The agency also noted it will finalize a rule requiring companies that manufacture or import 6PPD to share lists and unpublished health and safety studies with the EPA by the end of next year. Further, the agency is providing grants for additional research and working toward stormwater pollution solutions.

“This is a victory for salmon and all species and people,” the Puyallup Tribal Council said in a statement. “6PPD is a major and uniquely lethal threat to the health of salmon in urban streams on our reservation. Banning this chemical from tires will be hugely important in protecting fish. We thank the EPA for taking our concerns seriously. We will always act to protect the fish, the water and our lands.”

The EPA noted it doesn’t have a specific timeframe or outcome for the rulemaking process — however, California has already required tiremakers to look for safer alternatives to 6PPD, Yale E360 reported. The U.S. Tire Manufacturers Association has also recently put out a statement that it is working with the EPA to study alternatives to the chemical.