USask study finds rubber tire chemicals impacting river through urban runoff


Researchers at the University of Saskatchewan’s School of Environment and Sustainability say they’ve undertaken the first study of its kind in Canada to determine whether chemicals from rubber tires are entering waterways and endangering aquatic wildlife. 

The City of Saskatoon and USask collaborated on the study to examine chemicals that may leach from rubber tires, enter the stormwater system, then flow into the South Saskatchewan River. In particular, the study observed these issues within a cold-climate Canadian city. 

The study revealed high readings of tire rubber-related compounds in Saskatoon’s runoff, explains USask assistant professor Markus Brinkmann.

“Chemicals from rubber tire leachate have been associated with mortalities in Coho salmon in Washington State,” Brinkmann said in a statement. “However, we currently don’t know the effects on wildlife in our region,” he added. 

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Researchers in the Pacific Northwest have been studying why, for decades, as many as 90% of salmon would die when migrating through urban streams in an attempt to spawn in the Seattle, Washington, area. The scientists spent long hours isolating and testing molecules from some 2,000 chemicals in the tire-wear particles to identify whether a certain contaminant or combination of contaminants was particularly harmful. They narrowed it down to one named 6PPD-quinone, which, during testing, killed salmon within five hours of exposure to concentrations as low as 0.8 micrograms per litre.

In Canada, the new findings are from samples taken from snow facilities, snowmelt puddles, and about a dozen outfall sites along the South Saskatchewan River within the city in 2019 and 2020.

Beyond 6PPD-quinone, Saskatoon analysis found four bicyclic amines associated with tire rubber manufacturing and present in tire rubber leachate.

Russ Munro, director of Saskatoon Water, said further research is required to better understand the factors driving the findings.

“This is a great example of why continued research and partnerships with institutions like the University of Saskatchewan are so important,” said Munro. “Saskatoon Water operates within the guidelines set out by the Saskatchewan Water Security Agency and we’ll work with them to determine what next steps should be.”

The USask team has submitted a grant application to dig deeper into the toxicity of the compounds on fish and aquatic organisms in the South Saskatchewan River. Another joint application from USask and the city will focus on detection of the compounds.

Saskatoon participates in the Yellow Fish Road Program every year to educate residents about the impact communities can have on water runoff.


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