Department of Ecology
January 25, 2023
We are taking action to reduce 6PPD-quinone, a chemical that is deadly to coho salmon
For over 20 years, scientists faced a toxic mystery: coho salmon returning to urban streams and rivers in the Puget Sound region were dying before they could lay their eggs. The culprit was unknown, but it seemed linked to toxic chemicals running off our roads and highways.
The fate of the salmon carries weight far beyond that single species. The endangered Southern Resident orca whales rely on salmon for food. Salmon are intertwined with the health and culture of Indigenous communities and are a key part of tribal treaty rights. Washington’s economy and food supply depend on healthy salmon runs. Salmon are important to our well-being.
In 2020, a group of researchers finally made a breakthrough — they pinpointed a specific chemical as the killer: 6PPD-quinone, the last part pronounced “qui-KNOWN,” a toxic chemical released from automotive tires that ends up in roadway dust and can run into streams. The chemical is created when 6PPD, a preservative that helps tires last longer, reacts with ozone in the atmosphere.
With a culprit identified, the hard work of reducing contamination from something as widespread as tire dust is now underway. Alongside tribal governments, interest groups, and federal, state, and local organizations, we have begun planning the most effective ways to reduce the amount of 6PPD-quinone going into the water.