Tires and toxics (6PPDQ)

A tire-related chemical found to kill coho salmon and other fish has come under intense worldwide investigation ever since Puget Sound researchers isolated the singular compound from among thousands of pollutants residing in stormwater. The chemical, 6PPD-quinone (6PPDQ), was virtually unknown until its isolation in 2020. Now, it is recognized as one of the most toxic chemicals ever seen in the aquatic environment. Scientists from at least 10 countries have been measuring its effects on a variety of fish and other organisms. Meanwhile, other researchers have been probing the chemical’s influence and damage at the cellular level. In rapid succession, dozens of reports in scientific journals have described some remarkable findings — and yet much about 6PPD-Q remains unexplained.

Source: Encyclopedia of Puget Sound

Overview

Environmental engineers and chemists at the University of Washington Tacoma have identified a mysterious compound implicated in the deaths of large numbers of coho salmon in Puget Sound. The chemical is linked with a rubber additive commonly used in tires and is thought to kill more than half of the spawning coho that enter the region's urban streams every year. 

A returning Coho Salmon at the Suquamish Tribe's Grovers Creek Hatchery. Photos: K. King/USFWS (CC BY-NC 2.0)

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Untold numbers of hatchery fish may be dying from exposure to tire-contaminated runoff, according to a new study.

Finding a replacement for 6PPD in tires is one major challenge; another is to prevent the highly toxic derivative 6PPD-Q from reaching salmon streams and killing fish.

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The search for why large numbers of spawning coho salmon have been dying in Puget Sound's urban streams goes as far back as the 1980s and culminated this year with the discovery of a previously unidentified chemical related to automobile tires. We offer a detailed timeline for the discovery. 

Environmental engineers and chemists at the University of Washington Tacoma have identified a mysterious compound implicated in the deaths of large numbers of coho salmon in Puget Sound. The chemical is linked with a rubber additive commonly used in tires and is thought to kill more than half of the spawning coho that enter the region's urban streams every year.