Tire Wear Particles and 6PPD-Quinone in Freshwater Ecosystems: Ecotoxicological Effects, Food-Web Transfer, and One Health Implications

Introduction: The rapid growth of motor vehicle use has intensified non-exhaust emissions, particularly tire and road wear particles (TRWPs). Among these, the tire antioxidant 6PPD and its atmospheric transformation product, 6PPD-quinone (6PPD-Q), are emerging environmental contaminants. Recent studies link 6PPD-Q to Urban Runoff Mortality Syndrome (URMS) in coho salmon, raising concerns about cross-species vulnerability and One Health implications.
Methods: A systematic review was conducted following the PRISMA guidelines for abstracts. We systematically searched peer-reviewed literature and regulatory reports across major academic databases from January 2020 to mid-2026. Studies were screened based on predefined eligibility criteria, and risk of bias was formally assessed. Data were extracted regarding environmental occurrence, species-specific toxicity (LC50/EC50), molecular mechanisms, and exposure biomarkers.
Results: The systematic search yielded 200 initial records, of which 129 studies met the final inclusion criteria after rigorous screening. Of these, 14 studies evaluated environmental occurrence, demonstrating that 6PPD-Q is widely distributed in urban freshwater networks and sediments. Acute toxicity was analyzed in multiple studies, confirming extreme sensitivity in coho salmon (LC50 ~0.04 to 0.095 µg/L). Furthermore, numerous included studies reported sublethal effects in other aquatic species, highlighting blood-brain barrier disruption, oxidative stress, and lipid metabolism dysregulation. Human and veterinary biomonitoring studies (n=12) indicate systemic exposure, with 6PPD-Q detected in human matrices such as urine, blood, placental tissues, and cerebrospinal fluid.
Conclusions: Based on the systematic synthesis of the 129 included studies, 6PPD and 6PPD-Q constitute significant transboundary pollutants linking aquatic ecotoxicity to human systemic exposure. Current stormwater mitigation strategies may be insufficient, underscoring the urgent need for integrated One Health strategies, green chemistry alternatives, and coordinated cross-disciplinary biomonitoring to safeguard environmental and public health.