Nearly half of all Coho salmon returning to Puget Sound streams each year die before they can spawn. Long attributed to toxic stormwater runoff washing into streams, the specific chemicals responsible for this pre-spawn mortality went unidentified until a team of researchers from UW Tacoma, UW, and WSU Puyallup, began studying particles from new and used tire wear.
Coho salmon. Credit: NOAA Fisheries
Through several years of detailed laboratory testing of more than 2,000 tire-born chemicals, many of them unknown, and observing their effects on juvenile hatchery Coho salmon, in 2021 the team discovered a molecule known as 6PPD-Quinone (6PPD-q) to be the “smoking gun.” Just one millionth of a gram of 6PPD-q per liter of water produces a lethal concentration. That’s equivalent to one drop of compound in an Olympic-size swimming pool.
To learn about the latest research and concerns about this toxic chemical, here is a link to a detailed article titled Scientists Worldwide Immersed in Studies of Deadly Tire Chemical.