In the early 2000s, National Oceanic and Atmospheric Administration scientists in the USA discovered that at least 60 percent of coho salmon in Seattle’s urban waters died before they had a chance to spawn, taking the next generation with them.
Samples from waterways near the busiest roads had the highest levels of contaminants and the highest pre-spawn mortality rates.
A research team from the University of Washington and Washington State University then honed in on automobile chemicals as the likely culprit.
It took nearly a decade to identify that the dust shed from tyres contains 6PPD-quinone, an oxidised version of a chemical used to make tyres more durable.
One chemical.
From tyre wear.
Killing 60 percent of an entire salmon population.
That’s not background pollution.
Ecosystem Collapse
That’s ecosystem collapse triggered by commuter traffic.
For coho, a keystone species in the Pacific Northwest food chain and a cultural pillar for Native American tribes in the region, the prognosis is dire.
Many stormwater drains feed into rivers and streams where adult coho return each fall to spawn, especially in urban areas like Seattle. Since the 1990s, Seattle’s active citizen science groups have recorded masses of dead coho washing up after storms. The fish die within hours of a 6PPD-quinone surge, first swimming deliriously in circles, mouths agape as if gasping for air.
Every year, scientists reckon every person sheds almost six pounds of 6PPD-carrying tire dust onto America’s highways and roads, where it’s swept by rain or wind off into the environment. The chemical is everywhere, they say. It has already been found in waterways around the world, in the air, and in human blood and urine.
In Urine
New research has shown the chemical to be lethal in varying degrees to rainbow trout, brook trout, and white-spotted char.
It is now known to be floating in human urine, blood, and cerebrospinal fluid, especially of pregnant women.
A 2024 peer-reviewed study found that the chemical likely enters the human body through ingestion, inhalation, or skin contact, and posits that 6PPD-quinone can quickly reach tissues and major organs, especially the liver and lungs. It’s not known to be toxic to humans at the levels observed right now, but that research could have other implications.
A cocktail of chemicals. They everywhere thanks to Mankind.
Who would’ve believed that rubber from tyre wear, is a major pollutant causing mass deaths in coho salmon and other fish in the Pacific Northwest? Google says it disrupts brain function and leads to erratic swimming before spawning. Rain washes tyre particles and this toxic chemical from roads into streams, where it kills salmon within hours. It’s prompted urgent calls for safer tyre alternatives and regulations. Will action save the salmon and other aquatic life? Do politicians hooked on growth and more growth, understand?
“Chinook” raises an interesting point on “growth and more growth.”
Politicians are addictively focused on GDP and worship growth. But growth means more and more cars on our roads and more pollution not only in air but now proven in river water and to fish life.
This leads to another level of argument. NZ has the highest car ownership per capita with 869 cars per 1000 people.
Yet public transport lags. Rail journeys are now expensive catering for the affluent tourist, e.g Coastal Rail trip Picton-Kaikoura, ($280 one way) Tranz Alpine ($330 one way). So Kiwis have drive cars. Dumb governments who don’t give a toss about pollution of air and now proven rivers.
Thanks to Tony Orman for calling attention to a little known but near universal pollutant contributing to the decline of wild salmon stocks. Has any freshwater scientist actually asked tyre companies to modify their manufacturing process?
A good reason why we need independent citizen scientists on all bodies managing waterways.
This is the strongest argument I know for national environmental standards and enforcement of water pollution.