When it rains in Campbell River, a time many people prefer to stay inside, Barb Round puts on her raincoat and sets off to Simms Creek with a bag full of gear to test for a toxin proven to be deadly to migrating coho salmon.

Testing in the rain is the second step of a three-part process volunteers like Round undertake to determine the levels of  6PPD-quinone (6PPD-q) in the creek. The chemical 6PPD is used in the manufacturing of vehicle tires to minimize cracking and extend the service life of tires. 

Scientists have learned that when 6PPD interacts with ozone in the atmosphere, it produces 6PPD-q. This compound is released onto roadways in the form of tire dust. When it rains, it washes into urban streams and has been found to be responsible for killing migrating coho in large numbers before they can lay their eggs. The phenomenon, observed for many years, is known as "urban run-off mortality syndrome." It has similar impacts on other fish, including rainbow trout and lake trout.

Round and her husband, Doug, take the first sample from Simms Creek before the rain. It is followed by a second during the rain when runoff from roads flows into the creek. The final sample is taken after rainfall to see how long the toxin persists in the water and whether concentrations are increasing or decreasing.

Since testing began, toxic levels of 6PPD-q, which only have to be in small amounts, have been detected in Campbell River's watershed.

The volunteers are part of a network of 31 local groups, citizen scientists, and First Nations, who are sampling 53 waterways across 99 locations from Victoria to Campbell River.

Since 6PPD-q was first discovered in 2020 by scientists in Washington state as the culprit in mass coho deaths, the aim on Vancouver Island is to pinpoint areas of significant road runoff where it is washing into creeks from stormwater. Researchers want to understand how the concentration of this toxin changes over time and in different locations. Once the sources are identified, they will collaborate with local and regional governments to advise on remediation efforts.

Change is already in motion south of the border to eliminate 6PPD from production.

In 2023, California's Department of Toxic Substances Control mandated that vehicle tire producers investigate safer alternatives to the chemical. Adopted to protect public and environmental health, this ruling follows years of testing that found traces of 6PPD in California鈥檚 streams. 

And the research efforts on Vancouver Island may also soon pay off.

Peter Ross, senior scientist at Raincoast Conservation Foundation, said the federal government has concluded a public consultation on 6PPD and 6PPD-q and plans to conduct a study. He believes within the next year or so, a ban will likely be announced.

"There's probably no chemical that I can think of over the last 20 years on the Canadian market that has so clearly and unequivocally led to the demise of fish than 6PPD-quinone," he said. 

"I would guess that by this time next year, the Government of Canada will announce it has deemed that this chemical is harmful to the Canadian environment, and it will face regulatory phase out or elimination."

While good news, even if a ban is announced next year, the regulatory process could take years, Ross added. This means coho will continue to face die offs like the one discovered at the mouth of Brothers Creek in West Vancouver last year, which was found to be caused by 6PPD-q, coupled with B.C.鈥檚 drought.

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Meanwhile, in Campbell River, volunteers like Barb and Doug said they are eager to support efforts to conserve salmon, which are so vital to the region's ecosystem and the communities they feed.