Take toxins out of tires to protect salmon, other wildlife

Many people understand that dams kill salmon — but what about tires? Most would be surprised to learn that our tires produce the second-most toxic chemical to aquatic species ever evaluated. Yet despite the lethal threat to aquatic species like Endangered Species Act-protected salmon and steelhead, tire manufacturers continue to rely on a dangerous chemical called 6PPD.  Earlier this month, our two groups representing Pacific coastal fishing-dependent communities filed suit against 13 of the largest U.S. tire manufacturers to help change that.  

When 6PPD reacts with ground-level ozone, it transforms into 6PPD-q — second only to the chemical war agent parathion in its toxicity to aquatic species. While parathion has been banned around the globe, somehow the tire industry continues to get away with using 6PPD despite its known devastating impacts to salmon and steelhead, especially in Puget Sound’s urban waterways. Tire manufacturers have known for years that they need to invest in less toxic alternatives to 6PPD, yet they continue to kill fish that are protected under the ESA.  

In recent years, studies found 6PPD-q mainly responsible for “urban runoff mortality syndrome,” which kills up to 100% of coho salmon returning to spawn in urban streams. Even very small exposures kill coho within hours.  The substance is imperiling the recovery of 24 populations of coho and Chinook salmon — as well as steelhead trout — that are listed as endangered or threatened under the ESA.  Salmon and steelhead face a number of threats, including from climate change and drought, which is precisely why these fragile populations cannot withstand further toxic assault from 6PPD-q in their habitat.

Not only is the tire industry’s continued use of 6PPD harming keystone species like salmon and steelhead, but it is also harming fishing communities that have long relied upon the availability of these fish for their livelihoods. Coho salmon were once abundant for our region’s fishing operations, but that is no longer the case, thanks in part to the toxicity of 6PPD-q.  

Chinook salmon once supported tens of thousands of commercial salmon fishing jobs on the West Coast. California’s entire salmon fleet was thrown out of work in 2023 because too few salmon now survive as juveniles in the state’s rivers.  Many of these rivers are contaminated with 6PPD-q.  Very low coho numbers also legally restrict commercial salmon harvesters from access to more abundant Chinook fisheries, and thus severely limit their catch. 

Tire manufacturers have used 6PPD in tires since the 1950s to keep them from degrading too quickly. However, there are a number of potential alternatives to 6PPD in tires. Research is under way in California and Washington, and preliminary alternatives have been identified. It is time for industry to invest in options that better protect both our most vulnerable aquatic species and West Coast fishing jobs.  

While the majority of research has looked at the impacts of 6PPD-q on salmon and steelhead, emerging science has also pointed to toxicity in mammals — including a potential risk to human health. The chemical is also present in sediments and soils, household dust and even human urine. Tire companies should take a much more precautionary approach with a chemical that has already proven so dangerous to aquatic species.  

For years, urban runoff mortality syndrome has decimated salmon returning to freshwater streams in the Pacific Northwest. We now know that 6PPD-q is largely to blame for these die-offs, yet tire companies continue to get away with blatant ESA violations that continue to harm both salmon and the livelihoods of fishing-dependent communities. The ESA exists to prevent exactly this type of devastation. It is time for these tire manufacturers to be held accountable.