![Return of salmon to Elwha River](https://assets1.cbsnewsstatic.com/hub/i/r/2024/04/22/4c1e3f6e-2abe-4536-b9d6-14fcdc12768a/thumbnail/640x360/dad66d4d42b7a5527472e4618d7583d0/gettyimages-181277307.jpg?v=a23cb4bdf4fa7f3cb72e5118085577f9#)
Tire toxicity faces fresh scrutiny after salmon die-offs
Tires emit huge volumes of particles and chemicals as they roll along the highway, and researchers are only beginning to understand the threat. One byproduct of tire use, 6PPD-q, is in regulators' crosshairs after it was found to be killing fish.