SEATTLE, July 7 — The man who first identified the chemical that kills adult coho salmon before they can spawn is now working on the harder part: what to do about it. Dr. Edward Kolodziej, a professor of civil and environmental engineering at the University of Washington Tacoma, was a co-author of the 2020 study that named 6PPD-quinone as the specific toxicant responsible for the mysterious die-offs.
The discovery was a landmark moment in urban watershed research — a rare instance of pinpointing a single molecule as the culprit in a complex environmental collapse. The detail that matters is that 6PPD-quinone is not something that enters the environment by accident or from a single factory pipe.
It forms when a common tire antioxidant, 6PPD, reacts with ozone on the road surface. The reaction product then washes off in rain, straight into the nearest stream. Kolodziej’s research has focused on the transport and transformation of organic pollutants in urban watersheds, and this particular transformation turned out to be lethal.
Under the hood, the technical reality is that the chemistry is both straightforward and stubborn. Kolodziej has characterised how tire wear particles move from roads to waterways, and how they react with ozone to form 6PPD-Q.
He has also studied the chemical’s persistence in the environment and its toxicity to aquatic organisms. The compound does not break down quickly, which means a single rain event can deliver a pulse of poison that kills fish outright. The work has not gone unnoticed by regulators.
Kolodziej’s findings have been cited in reviews by the Environmental Protection Agency and the California Department of Toxic Substances Control. That is the kind of attention that can shift policy, though the process is slow and the chemistry is complex. From discovery to mitigation The 2020 study was the breakthrough, but Kolodziej’s current focus is on solutions.
His ongoing research aims to develop strategies for mitigating tire pollution. That includes looking at green infrastructure — things like rain gardens and permeable pavements that can capture runoff before it reaches streams.
It also includes work on alternative tire materials that might not produce the same toxic byproduct when they hit the road. Kolodziej earned his Ph.D. in environmental engineering from the University of California, Berkeley. His research has been funded by the National Science Foundation and the EPA.
The funding reflects a growing recognition that tire pollution is not a niche problem. Every vehicle sheds rubber, and every city with roads has a runoff problem.
The irony, as ever, is that 6PPD is added to tires to prevent them from degrading. It is a safety chemical. The unintended consequence is that it creates a toxicant that kills fish at concentrations measured in parts per billion.
That is the kind of problem that requires both chemistry and engineering to solve. The road ahead Kolodziej’s work sits at the intersection of materials science, hydrology and toxicology. The question is whether the tire industry can reformulate its products fast enough to outpace the regulatory pressure building in states like California and Washington.
The technical reality is that replacing 6PPD is not trivial. It has been the standard antioxidant for decades, and any substitute must survive heat, friction and UV exposure without creating a different, unknown toxicant.
Kolodziej’s research into alternative tire materials is one of the few efforts that could provide a viable path forward. For now, the science is clear on what kills the fish. The engineering question — how to stop it — is the one that will occupy Kolodziej and his colleagues for the foreseeable future.
