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Juvenile coho salmon swimming in shallow water.

Photo Credit: Roger Tabor

press release

Groups urge federal government to investigate tire chemical implicated in mass salmon deaths

February 6, 2024

VANCOUVER/UNCEDED xʷməθkʷəy̓əm (MUSQUEAM), Sḵwx̱wú7mesh (SQUAMISH) AND səlilwətaɬ (TSLEIL-WAUTUTH) TERRITORIES — Ecojustice, on behalf of Raincoast Conservation Foundation, Watershed Watch Salmon Society, and Pacific Salmon Foundation, has formally requested the federal Minister of Environment and Climate Change, Steven Guilbeault, prioritize 6PPD for investigation, in light of emerging research linking the chemical commonly used in tires to mass die-offs of coho salmon.

6PPD is used in tires to help make them last longer. When the chemical comes into contact with ozone in the air it turns into 6PPD-quinone (6PPD-q), highly toxic to coho salmon. While the source of mass coho deaths in urban areas was unknown for decades, a seminal 2020 study confirmed 6PPD-q as the cause.

As vehicle tires wear down on roadways, 6PPD makes its way into urban rivers and streams through rain run-off, and has been measured at concentrations which are toxic to coho salmon. Climate change exacerbates these effects — when there are droughts followed by heavy rains, the build-up of 6PPD on roadways is swept into streams with low water levels, resulting in higher concentrations of the contaminant.

6PPD has been documented in road runoff and wastewater at levels of concern in Toronto and Saskatoon, and now in B.C. waterways.

Chemicals that cause harm to people and the environment should be regulated. The first step to making that happen is to have the toxicity of chemicals of concern assessed under the Canadian Environmental Protection Act (CEPA). 

Coho salmon are considered a keystone species that supports entire ecosystems. When there are mass die-offs of keystone species like coho salmon, it can have a ripple effect that is felt by other species and sometimes even entire ecosystems.

More research is needed to understand 6PPD’s effects on other vulnerable fish species, such as chinook, rainbow trout and brook trout, as well as on the wider environment.

Daniel Cheater, Ecojustice lawyer, said:

“The science is clear: 6PPD-q is responsible for mass deaths of coho salmon as they pass through urban areas. More research is still needed to determine whether 6PPD-q is toxic to other salmonids, aquatic species, and our ecosystems at large. It’s time for Canada to take steps towards regulating 6PPD in Canada and protect wild salmon.

“The U.S. and the European Union recognize the dangers posed by 6PPD and are taking action towards regulating it. Under CEPA, when other jurisdictions take action on toxics, Canada must review the decision for themselves to determine whether the substance is toxic — or can become toxic.”

Dr. Peter S. Ross, Senior Scientist and Director of Healthy Waters at Raincoast Conservation Foundation, said: 

“I can think of no more important chemical requiring review than the tire chemical 6PPD. It kills salmon, plain and simple.

“This is another example of a chemical that escaped Ottawa’s risk assessment process, and underscores the need for greater scrutiny of new chemicals.

“There is a clear and urgent need for Ottawa to accelerate its risk-based evaluation of the tire chemical 6PPD. Adult salmon are being killed outright by tire chemicals before they get the chance to reproduce — this is bad for fish, bad for people and bad for the environment.”

Lina Azeez, Habitat Programs Director at Watershed Watch Salmon Society, said:

“Our dependence on cars is well established. We must ensure the choices, we, as a society, make are supported by the best possible science. With emerging research showing us the direct impacts of tire wear and tear on salmon and other fish species, it is our responsibility to hold regulators to a higher standard and demand the source of the problem be tackled. Everything is connected. Urban runoff and pollution impact salmon, which in turn impacts the very building blocks of our ecosystem.” 

Michael Meneer, President & CEO, Pacific Salmon Foundation, said: 

“Many salmon populations are in serious condition, particularly those who spend more time in fresh water habitat, and researchers in Canada and the United States have identified that 6PPD in tires can kill coho salmon when it breaks down in the environment. This harmful toxin is something we can take action on now, and we hope that the federal government will prioritize this investigation and work with us to find a solution that will protect wild Pacific salmon.”


Ecojustice uses the power of the law to defend nature, combat climate change, and fight for a healthy environment. Its strategic, public interest lawsuits and advocacy lead to precedent-setting court decisions and law and policy that deliver lasting solutions to Canada’s most urgent environmental problems. As Canada’s largest environmental law charity, Ecojustice operates offices in Vancouver, Calgary, Toronto, Ottawa, and Halifax.

Raincoast Conservation Foundation is comprised of scientists and conservationists whose work focuses on the land, waters and wildlife of coastal British Columbia. Their area of research includes a program addressing threats facing the survival of wild salmon, a group of species that play a foundational role in marine and terrestrial ecosystems. Raincoast’s work also includes the Healthy Waters program, carried out in partnership with Indigenous communities and other partners to build pollution monitoring capacity in salmon watersheds. 

Watershed Watch Salmon Society is a federally registered charity established in 1998 to advocate for the conservation and restoration of B.C.’s wild salmon and their habitats. Diverse and abundant wild salmon runs are essential for the healthy function of coastal and riparian ecosystems across B.C., vital to the culture and food sovereignty of First Nations, and highly valued by people across our province for food, culture, commerce and recreation. Watershed Watch is working to raise awareness and push for systemic change for the many populations of wild salmon that are in steep decline, driven by the cumulative effects of climate change, habitat loss and degradation, overfishing, pollution, and harmful aquaculture practices. 

The Pacific Salmon Foundation, founded in 1987, is a non-profit environmental organization dedicated to the conservation and restoration of wild Pacific salmon and their habitats in B.C. and the Yukon. For us, it’s salmon first, salmon always and we never go it alone. We work with First Nations, Government, ENGO partners, industry and all people for salmon who share the desire to save and restore these iconic species.