Tire chemical 6PPD linked to salmon deaths
Environmental chemists testified on April 1, 2026, in a federal trial in San Francisco, stating that a single car's tires could produce enough 6PPD-quinone to kill millions of salmon, and that 6PPD-q is the second-most toxic chemical to aquatic species ever evaluated. As of April 1, 2026: Commercial fishing groups and environmental organizations are suing 13 tire manufacturers, including Bridgestone and Michelin, over allegations that the chemical additive 6PPD from tires is polluting rivers and killing coho salmon, with estimates suggesting 40-90% of adult coho in urban watersheds may die annually from exposure. The EPA is reviewing 6PPD following a petition from Native American tribes and initiated a formal regulatory investigation into 6PPD and 6PPD-quinone under the Toxic Substances Control Act (TSCA) on December 11, 2024. "A 2025 study by Puget Soundkeeper's annual Pre-Spawn Mortality Survey found that 55.5% of coho salmon died before spawning." Juvenile coho salmon are also at risk, with approximately 80% dying within six hours of exposure to creek water containing 6PPDQ during spring storms." Tire manufacturers argue there is insufficient data to definitively link runoff chemicals to fish deaths, and that 6PPD-quinone degrades quickly.
Timeline
Want updates on this thread?
Track this story2026
7 updates
2026
7 updatesEnvironmental chemists testified in a federal trial that a single car's tires could produce enough 6PPD-quinone to kill millions of salmon, and that 6PPD-q is the second-most toxic chemical to aquatic species ever evaluated. The EPA is also reviewing the chemical 6PPD following a petition from Native American tribes.
Commercial fishing groups and environmental organizations have filed lawsuits against major tire manufacturers, alleging that the chemical 6PPD breaks down into 6PPD-quinone, causing significant coho salmon deaths. A federal trial concluded in late January 2026, with ongoing legal actions highlighting the chemical's impact on both adult and juvenile salmon, with estimates suggesting 40-90% of adult coho in urban watersheds may die annually from exposure.
via Green Network Asia·The Straits Times·Puget Sound Institute
The federal court trial, which lasted three days, involves 13 tire manufacturers, including Bridgestone and Michelin, with plaintiffs represented by Earthjustice. During the trial, defense argued that laboratory studies may not accurately reflect real-world conditions, and a witness stated that 6PPD-quinone degrades quickly.
During the ongoing federal court trial, tire manufacturers argued there is insufficient data to definitively link runoff chemicals from their products to the deaths of protected fish populations. Environmental groups countered that the chemical 6PPD transforms into 6PPD-quinone, harming salmon.
A '6PPD State of the Science Forum' was held, and a 2025 study by Puget Soundkeeper's annual Pre-Spawn Mortality Survey found that 55.5% of coho salmon died before spawning.
A federal court trial began in San Francisco on January 26, 2026, with West Coast fishers and conservationists suing tire companies over allegations that the chemical additive 6PPD from tires is polluting rivers and killing coho salmon. U.S. District Judge James Donato is presiding over the case.
via theguardian.com·courthousenews.substack.com·straitstimes.com
A new study indicates that juvenile coho salmon are also at risk from 6PPD-quinone, the toxic chemical derived from tire preservative 6PPD. Researchers found that approximately 80% of juvenile coho salmon exposed to creek water containing 6PPDQ during spring storms died within about six hours. This expands on earlier research that primarily focused on the impact of 6PPDQ on adult coho salmon.
2025
1 update
2025
1 updateReports highlight the critical situation in British Columbia, with confirmed salmon deaths linked to tire pollutants in areas like Cowichan, Vancouver Island, indicating a broader geographic impact.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
2024
5 updates
2024
5 updatesThe EPA initiates a formal regulatory investigation into 6PPD and 6PPD-quinone under the Toxic Substances Control Act (TSCA), seeking public input on alternatives and regulatory measures.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
The EPA intends to publish an advanced notice of proposed rulemaking in the fall of 2024 to gather more information for potential federal regulatory action on 6PPD.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
Washington State adopts an aquatic life criterion for 6PPD-quinone, setting a state-level water quality standard to protect sensitive aquatic species.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
The Canadian federal government decided in May 2024 to prioritize the assessment of 6PPD, a chemical linked to mass salmon deaths. Environmental groups have expressed encouragement regarding this decision.
via ecojustice.ca
The initial screening of potential alternatives to 6PPD by tire manufacturers is due, marking a key step in the industry's response to regulatory pressure.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
2023
7 updates
2023
7 updatesThe EPA publishes an analytical procedure to test for 6PPD-quinone, providing a standardized method for environmental monitoring.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
West Coast fishermen filed a lawsuit in November 2023 against 13 tire manufacturers, alleging that the chemical 6PPD-quinone from tires is killing coho salmon, Chinook salmon, steelhead trout, and other wildlife. This lawsuit claims toxic concentrations of the chemical have been discharged into waterways.
The U.S. Environmental Protection Agency (EPA) grants a petition submitted by multiple West Coast tribes to consider establishing regulations prohibiting the manufacturing of 6PPD in tires.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
California's Department of Toxic Substances Control officially begins regulating 6PPD in motor vehicles through its Safer Consumer Products Program.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
A study published in Environmental Science & Technology reveals that 6PPD-quinone disrupts the blood-brain barrier and other vascular systems in coho salmon, providing insight into its mechanism of toxicity.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
The White House Office of Science and Technology Policy identifies 6PPD-Q as an emerging contaminant, leading to the formation of a National Toxicology Program (NTP) work group to coordinate federal efforts, including human health effects.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
The California Department of Toxic Substances Control (DTSC) announces plans to list 6PPD as a Priority Product, initiating a process for manufacturers to notify the state and explore alternatives.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
2021
1 update
2021
1 updateFollowing the 2020 discovery, a widespread scientific investigation into 6PPD-quinone begins globally, with numerous reports appearing in scientific journals.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
2020
1 update
2020
1 updateResearchers from the University of Washington Tacoma, University of Washington, and Washington State University Puyallup publish a seminal study in Science, definitively identifying 6PPD-quinone (6PPD-Q) as the specific chemical responsible for coho salmon deaths.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
2017
1 update
2017
1 updateDr. Jenifer McIntyre's lab identifies tire wear particles as the toxic component in stormwater runoff that causes salmon mortality, narrowing down the source of the problem.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
1990
1 update
1990
1 updateCoho salmon deaths are first observed in urban streams of the Pacific Northwest, particularly after rainfall, leading to the recognition of 'urban runoff mortality syndrome' with an unknown cause.
via eopugetsound.org·theguardian.com·makingwaves.psp.wa.gov·nationalgeographic.com·washington.edu
2020
Story began · 5 years, 4 mo ago