Tired of Pollution: The Hidden Costs of Tire Particles, 6PPD-quinone, and the Grass Beneath Our Tires

Abstract

Tire wear particles are an increasingly recognized source of microplastic pollution, releasing chemical additives into terrestrial and aquatic ecosystems. One compound of growing concern is 6PPD-quinone (6PPD-q), a transformation product of a tire additive that has been linked to fish mortality and is now being detected in soils and surface waters. While the harmful effects of 6PPD-q on aquatic organisms are well documented, far less is known about how it affects terrestrial plants, which may play an important role in slowing or preventing contaminant movement into aquatic environments. To address this gap, we investigated how tire-derived particles and pure 6PPD-q affect bluebunch wheatgrass (Pseudoroegneria spicata), a native grass important for soil stabilization and ecosystem health in western North America. In controlled greenhouse experiments, plants were exposed to different concentrations and forms of tire particles and pure 6PPD-q across two soil types. Plant responses were measured using germination, height, survival, and total biomass. Plant responses were analyzed Results showed that exposure to 6PPD-q significantly reduced plant height and biomass in most conditions.. Although plants survived exposure, reduced growth, especially in natural soil, indicates that 6PPD-q negatively affects plant performance. These findings highlight potential ecological risks and suggest that contamination may weaken plant health, with implications for ecosystem stability, contaminant transport through the environment, and limitations for using vegetation for remediation.