Scientists pinpoint chemical that’s been killing coho salmon. It comes from car tires

Coho salmon returning to freshwater each fall often die, gasping for breath and swimming aimlessly, before they are able to spawn. Scientists now know why.

After years of chemical sleuthing, scientists have pinpointed the toxic substance that’s been killing large numbers of coho salmon in Northwest creeks.

It’s 2-anilino-5-([4-methylpentan-2-yl]amino)cyclohexa-2,5-diene-1,4-dione, or 6PPD-quinone for short.

Never heard of it? You’re not alone.

You can’t buy it anywhere. No one manufactures it. And it’s not put into car tires, plastic or any other products that might wind up polluting creeks.

The mysterious substance—purplish-pink when concentrated but invisible when dissolved—was absent from chemical databases that researchers consulted to try to identify the poison lurking in creeks near busy roadways.