Tire wear particles (TWPs) in the environment: occurrence, impacts and mitigation strategies

Tire wear particles (TWPs) are generated continuously from friction between vehicle tires and road surfaces, representing one of the largest sources of primary microplastics entering the global environment. First detected in roadway dust nearly six decades ago, TWPs are complex composites comprising 40–60% synthetic rubber (styrene-butadiene rubber), 20–45% fillers, and 5–15% chemical additives including vulcanization accelerators (e.g., DPG), antioxidants (e.g., 6-PPD), and metals such as zinc (approximately 8.7 mg Zn/g TWP). Global emissions are estimated at 6 million tons annually, equivalent to 0.23–1.9 kg per capita per year.TWPs enter aquatic environments primarily through stormwater-mediated transport, where high-intensity rainfall mobilises particles from road surfaces to receiving water bodies. Their intermediate density (~1.8 g/cm³) promotes suspension in turbulent flow, facilitating transport over considerable distances before deposition in sediments, estuaries, and wetlands. Environmental weathering of TWPs through UV radiation, temperature variation, and microbial biofilm formation, alters their physicochemical properties, increasing leaching of chemical additives and generating transformation products such as 6-PPD-quinone (6-PPDQ). These compounds have been detected globally in urban runoff, rivers, sediments, and road dust at concentrations approaching or exceeding ecotoxicological thresholds for aquatic organisms.Research has demonstrated multifaceted toxicological impacts across biological scales. In aquatic species, TWP exposure causes mortality in coho salmon (6-PPDQ LC50 0.8–0.95 μg/L), developmental abnormalities in fathead minnow embryos, hepatotoxicity in zebrafish via PPARγ disruption, and oxidative stress in invertebrates. Emerging evidence from in vitro studies indicates that TWP leachates induce cytotoxicity, inflammatory responses, and oxidative damage in mammalian cell lines, raising concerns for human health through multiple exposure pathways including contaminated water, airborne particles, and food chain transfer. Microbial communities colonising TWP surfaces show enrichment of potentially pathogenic strains, suggesting additional indirect health risks.Parallel to understanding impacts, research is advancing on mitigation strategies. Physicochemical approaches including sedimentation, filtration, and density separation show varying removal efficiencies, while biological methods such as constructed wetlands and biofiltration systems demonstrate promise for TWP capture from stormwater. The field is now moving towards integrated understanding of TWP distribution dynamics, transformation pathways, linked ecological and human health outcomes, and evidence-based remediation strategies.This Research Topic aims to advance understanding of the distribution dynamics, environmental fate, multi-domain impacts, and removal strategies for tire wear particles and their associated chemical additives. We seek to bring together cutting-edge research on occurrence patterns across environmental compartments, transformation processes under realistic conditions, mechanistic toxicity evidence spanning aquatic organisms to human health, and emerging approaches for TWP mitigation. The goal is to build a comprehensive picture that informs environmental monitoring, regulatory frameworks, and practical remediation globally.We welcome original research articles, reviews, methods papers, and perspective pieces addressing the following themes:• Analytical advances for quantification and characterisation of TWPs and chemical additives (e.g., 6-PPD, 6-PPDQ, DPG) in complex environmental matrices including water, sediment, soil, biota, and air.• Distribution dynamics and transport mechanisms across multiple environmental compartments, including the role of storm events, hydrological drivers, atmospheric transport, and factors controlling partitioning between water, sediment, and biota.• Weathering and transformation processes under natural and accelerated conditions, investigating changes to particle properties, additive leaching kinetics, formation of transformation products, and the influence of environmental factors (UV, temperature, pressure, microbial activity).• Physicochemical removal methods including sedimentation, filtration, membrane technologies, adsorption, density separation, and advanced oxidation processes for TWP and additive removal from water and wastewater.• Biological treatment approaches including constructed wetlands, biofiltration, microbial degradation, and the role of biofilms in TWP capture and transformation, with assessment of removal efficiencies and operational parameters.• Human health impacts including in vitro and in silico approaches assessing oxidative stress, inflammation, mitochondrial dysfunction, immune cell responses, and potential exposure pathways via inhalation, ingestion, and dermal contact.• Ecotoxicological effects across freshwater and marine organisms, from molecular mechanisms (e.g., PPARγ disruption, CYP induction, oxidative stress) to population-level outcomes, including species sensitivity comparisons.• Microbial interactions including biofilm formation, pathogen enrichment on TWP surfaces, antimicrobial resistance transfer, and implications for ecosystem function and public health.• Mitigation strategies at catchment and infrastructure scales, including stormwater treatment design, retrofitting of existing systems, and nature-based solutions, with attention to cost-effectiveness and co-benefits.• Comparative studies across climatic regions, traffic densities, and land-use types to identify vulnerability factors and inform global policy development.Submissions addressing linkages between environmental occurrence, biological impacts, and treatment efficacy are particularly encouraged, as are studies proposing integrated frameworks for risk assessment and management. Topic editors: Iain Robertson, MUHAMMAD JUNAID, Stuart Cairns Source: https://www.frontiersin.org/research-topics/79730/tire-wear-particles-twps-in-the-environment-occurrence-impacts-and-mitigation-strategies