The U.S. EPA has called 6ppd-quinone, the toxic offshoot of the tire antidegradant 6ppd, the second-most toxic chemical the agency has ever encountered, at least toward aquatic species.
The first is parathion, a chemical war agent developed in the 1940s that does not discriminate in its attacks on the nervous system. 6ppd-quinone is showing increasing evidence that it, also, is toxic to humans.
Achieving the top toxic spots in the chemical industry is not sought-after recognition—just ask the manufacturers of FKMs and other chemicals contained within the PFAS ban proposals.
While the debate is ongoing over long- and short-chained chemicals in the PFAS realm, the danger of 6ppd-quinone seems clear.
Coho and Chinook (king) salmon, along with certain fisheries of steelhead trout, are at a fraction of the levels they were only one and two decades ago, and their decline has been traced directly to 6ppd-quinone.
As the tire manufacturing industry scrambles to find an alternative for 6ppd, considered critical to consumer safety in preventing tire cracking and splitting, affected Native American tribes in the Pacific Northwest and fishing groups that depend on the fish for their livelihoods are speaking up.
The opposition to 6ppd is getting stronger, and it is getting litigious.
Stopping the chemical additive from its presence in the stream of commerce is not likely to occur any time soon—there simply are too many cars on the road with too many tires containing 6ppd and no viable way of tracing them retroactively.
What can be done in the interim is mitigation—infrastructure efforts that can absorb or otherwise disperse tire road wear particles, such that the environmental effects from 6ppd-quinone are benign.
A University of Nevada study recently showed that rubber-modified asphalt—which contains ground rubber, typically from end-of-life tires—absorbs 6ppd-quinone, preventing it from entering the streams and waterways of the Pacific Northwest.
And infrastructure efforts like tire and road wear-specific gutters along the berms of byways could be a stop-gap solution.
Perhaps there is an argument that tire manufacturers could have joined the critical search for an alternative to 6ppd sooner. Perhaps more could have been done at an earlier time.
As it stands today, an alternative does not exist.
What does exist—what must continue to exist—is the symbiotic relationship between all groups involved, from the tire manufacturers to the companies searching for an alternative; to the Puyallup, Yurok and Port Gamble S'Klallam tribes and the fish species themselves; and to the fishing groups seeking action and the other animals depending on the fish as a food source.
And certainly, to consumers who demand safety.
As each of the affected groups maintains their own priorities in the matter, this interim period of research and discovery puts mitigation front and center.
The interconnectivity of all species—that essential and delicate ecological balance, hard to achieve and easy to lose—depends on it.
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