Deciphering the aging-driven transformation of tire wear particles: Reshaping adsorption, leaching dynamics, and biointerfacial impacts

Tire wear particles (TWPs) are a major source of microplastic pollution, yet their environmental behavior and risks remain insufficiently understood, particularly under environmental aging. This review synthesizes current knowledge on aging-induced transformations of TWPs and their implications for contaminant dynamics and ecological effects. Aging processes, including photooxidation, mechanical abrasion, and biodegradation, significantly alter the physicochemical properties of TWPs, leading to increased surface area, enhanced polarity, and progressive fragmentation. These changes regulate key environmental processes, including contaminant adsorption/desorption and the diffusion-controlled release of embedded additives. In addition, aging can induce the formation of environmentally persistent free radicals (EPFRs), which generate reactive oxygen species and mediate redox transformations of co-existing contaminants. Collectively, these coupled processes govern the environmental behavior of TWPs by enhancing chemical exposure, reactivity, and biological interactions, ultimately amplifying ecological risks. This review highlights that TWP-associated toxicity emerges from the interplay among physicochemical transformation, contaminant interactions, and chemical release during aging. Future research should prioritize integrated experimental designs and environmentally realistic conditions to improve predictive assessments of TWP-associated risks.