One hundred and twenty-five tonnes of crumb rubber. That’s roughly 20,000 recycled tires packed into an average artificial turf field — and every time it rains, that rubber bleeds 6PPD-quinone into the storm drain.

A peer-reviewed study from the University of British Columbia, published in Environmental Science: Processes & Impacts, has found that synthetic turf fields across Metro Vancouver are leaching the tire-derived chemical into municipal stormwater systems at concentrations lethal to juvenile coho salmon. The contamination doesn’t fade with age: drainage samples from a field with six-year-old infill still exceeded the toxicity threshold.

Researchers analyzed infill from 12 fields — nine with standard crumb rubber, three with alternative materials — and collected stormwater during three rainstorms. The crumb rubber fields consistently released 6PPD-quinone alongside heavy metals including zinc and copper. Tests also identified numerous compounds not listed in regulatory inventories of tire ingredients.

“Every time it rains, these fields release a mix of chemicals into the drainage system,” said Katie Moloney, the PhD student who led the research. The investigation began after North Vancouver streamkeepers reported dead salmon in streams adjacent to a turf field in 2023.

The findings put municipalities in an uncomfortable position. Thousands of crumb rubber fields serve communities across North America, raising questions about how stormwater from these surfaces is managed. A previous UBC study showed that planted soil filters can cut 6PPD-quinone concentrations roughly tenfold, and non-rubber infills release fewer contaminants — but both options carry higher costs.

“This research can help guide decisions on field design and stormwater treatment to protect aquatic ecosystems,” said Dr. Rachel Scholes, the study’s supervising professor. The guidance comes with a price tag that most municipal budgets haven’t accounted for.

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