Take action: Urge Canada to regulate salmon-killing pollutant, 6PPD

Canada’s draft Priorities Plan is open for public comment until midnight tonight. Take action now.

For years it was a mystery – why were coho salmon dying in large numbers as they returned through urban areas on their way to spawn? The phenomenon, observed for decades, became known as “urban run-off mortality syndrome”. 

Painstaking research eventually found a major cause of this syndrome: 6PPD, a substance used in the manufacture of tires to prevent their degradation. The commercial chemical 6PPD breaks down with tire wear and reacts with ozone to turn into 6PPD-q, which is then washed into adjacent waterways when it rains. 

Researchers at the University of Washington published a seminal study in 2020,¹ identifying 6PPD-q as the main culprit in mass salmon deaths. Since then, a growing body of research is documenting evidence of 6PPD-q in waterways, its impacts on other aquatic species, and its effects when it interacts with other environmental contaminants.

Among the emerging findings:

• Ongoing sampling is detecting 6PPD-q at levels toxic to coho salmon in waterways in British Columbia, and at levels of concern in Toronto and Saskatoon.
• Globally, 6PPD-q has been detected in road runoff samples in countries including Japan, France, Germany, and Malaysia. In the United States alone, it has been estimated up to 1,900 tonnes of 6PPD-q is generated from tire tread wear. 6PPD-q is found not just in waterways, but in soil, dust, drinking water, and air.
• Apart from coho salmon, 6PPD-q is proving to have debilitating effects on additional freshwater species including lake trout and rainbow trout. 
• At least one study examined the effects of 6PPD-q on mice, finding effects in their lungs, suggesting risk of toxic injury in mammals, including humans. 6PPD-q has been detected in human urine samples and human digestive fluids.

Canada is taking notice. Earlier this year, Canada agreed to a request submitted by Ecojustice on behalf of Raincoast Conservation Foundation, Watershed Watch Salmon Society, and Pacific Salmon Foundation asking that 6PPD be assessed for toxicity under CEPA.

As a result, 6PPD and 6PPD-q are now listed as substances to be prioritized for assessment on Canada’s draft Proposed Plan of Priorities for Chemical Management (“Priorities Plan”).

Canada’s workplan says this assessment will start in “Fall 2024”, but it gives no timelines or details. 

In the meantime, more tires are being manufactured and imported, and coho salmon are continuing to die from 6PPD-q exposure near Canada’s roads and highways. As climate change alters weather patterns, extreme weather events with heavy rains will make things worse, as large pulses of road runoff with 6PPD-q are washed off into fish habitat. 

Other countries and regions are acting. In the United States, California and Washington have required tire manufacturers to evaluate alternatives to 6PPD. The US Environmental Protection Agency has published screening value concentrations for 6PPD-q so that states and authorized Tribes can consider it in their own water quality programs, and is funding stormwater management projects to stop 6PPD-q from entering waterways in the first place. In Europe, for the first time, the European Union is establishing emissions rules for tires and brakes. 

The time for action is now

Here’s what you can do: Canada’s draft Priorities Plan is open for public comment until 12 midnight, Pacific time, December 4.

Utilize our suggested email text and submit a comment by email to substances@ec.gc.ca, with “Comment on the Proposed Plan of Priorities” in the subject line.

Urge Canada to provide a firm timeline to complete its assessment and move to regulate 6PPD without delay. The evidence is clear. 

For more detailed information about the impacts of 6PPD, read more at Ecojustice. which includes a link to the request that Ecojustice made on behalf of Raincoast Conservation Foundation, Watershed Watch Salmon Society, and Pacific Salmon Foundation asking Canada to assess 6PPD and its transformation products to determine whether it is toxic or capable of becoming toxic, and its comment letter on the draft Priorities Plan.

Sample email

I would like to add my strong vocal and scientific support  for the aggressive, immediate and systematic inclusion of 6PPD and its related chemicals and breakdown products. 

This means the parent product, related chemicals, replacement candidates, and breakdown products.

Of note:  once implemented, it will take years before the ‘new and improved’ tires are on the market – meaning that even with strict and swift regulations, 6PPDq will continue to kill salmon until 2030 or thereabouts. This highlights the importance of urgent implementation, as well as leadership by Ottawa in getting the provinces to espouse green infrastructure initiatives at the highways and municipalities level.

6PPDq is diminishing access to food fish by indigenous Nations and communities. The episodic die off of pre-spawn coho salmon is reducing the availability of foods and contributing to a cascading decline in the species by precluding reproduction. The salmon die before they spawn.

Act now. Act wisely. Act with the future in mind.

Suggestions for your letter

It’s important that your letter comes from you and includes your particular thoughts. You could include all or some of these thoughts:

• The tire chemical breakdown product 6PPD-q is killing coho salmon in British Columbia streams. I urge the Government of Canada to eliminate 6PPD and related chemicals immediately and protect salmon now.
• 6PPD is used in tire manufacturing to prevent degradation. However, when this chemical breaks down from tire wear and is washed into our waterways, it has been determined to be toxic to coho salmon. 
• It has been four years since the important study identified 6PPD-q in Seattle runoff waters as a cause of the repeated mass mortality events in urban coho salmon populations (a phenomenon known as “urban runoff mortality syndrome”);
• Urban run-off mortality syndrome has been observed in waterways in British Columbia, and ongoing sampling there is finding 6PPD-q at levels toxic to coho salmon, an ecologically, economically and culturally significant species found across BC’s rivers, streams and coastal areas;
• Emerging research is identifying impacts of 6PPD-q on other aquatic species, with these effects compounded by co-occurring contaminants in runoff or wastewater;
• Tire wear contaminants are also a concern not only while they are in use, but at end-of life. Increasingly, tires are disposed of by recycling them into turf for sports fields and children’s playgrounds, where they may continue to shed 6PPD and its toxic breakdown product;
• Regulatory action is already being taken in other jurisdictions, including the states of Washington and California, and at the federal level in the United States.
• The evidence with respect to 6PPD’s harmful effect on the environment is clear. There is no legal impediment to listing 6PPD, its transformation products and related compounds under Schedule 1 of CEPA prior to the Plan of Priorities being finalized, so that immediate steps can be taken toward regulatory action.
• Here is a short summary (PDF) of the comment letter submitted by Ecojustice on behalf of Raincoast Conservation Foundation and Watershed Watch Salmon Society which provides additional information.

1. Tian et. al. (2021), A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon, Science  371(6525), 185–189. See also Alan Ohnsman, “Car Tire Dust Is Killing Salmon Every Time It Rains” (24 January  2023), Forbes, online.

You can help

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