It began some 20 years ago. Something was decimating salmon that had been restored to creeks around Puget Sound. After a rain but before the fish spawned, they displayed odd behaviors, then died within hours. In some streams up to 90% of coho salmon was lost. Now a team of scientists has solved the mystery. They took samples and saw chemicals related to tire particles. So the team brewed up a test by soaking shredded tire tread in water. The salmon died. 6PPD-quinone, a ubiquitous tire rubber–derived chemical is the culprit. It induces acute mortality in coho salmon. As tire treads break down through use, 6PPD reacts with ozone to form 6PPD-quinone. This chemical ends up in urban rivers and streams through stormwater runoff and is deadly to the salmon that are migrating to reproduce.
Team member Jenifer McIntyre, a toxicologist and professor at Washington State University, says the team hopes manufacturers will be willing to look for a replacement. The scientists are concerned about broader health impacts from the chemicals in tires, including on humans, especially because tires are often recycled to make artificial turf for sports fields. “It seems to me that there could be inhalation of those finer particles,” Dr. McIntyre said. “Now you’ve got that leaching happening on the lung tissue.”
It’s a complicated story but you can read the team’s findings in the journal Science.
Catrin Einhorn, New York Times
Bob Conroy