Release of polycyclic aromatic hydrocarbons from tire road wear particles in simulated digestive fluids: release rules and influencing factors

The behavior of polycyclic aromatic hydrocarbons (PAHs) released from tire road wear particles (TRWPs) in human digestive fluids may pose a significant risk to human health. However, the current understanding of the release pattern and influencing factors of PAHs from TRWPs is still insufficient. In this study, the release characteristics of PAHs from UV-aging TRWPs (ATRWPs) were systematically investigated by in vitro digestive simulation experiments, release kinetic model fitting and control variable experiments. The results showed that the total amount of PAHs released from ATRWPs in simulated intestinal and gastrointestinal fluids reached 32.7 and 60.5 mg/kg, respectively, with the highest amount of Phenanthrene (22.4 mg/kg), and the Elovich and double-constant release models demonstrated that PAHs release behaviors involved non-homogeneous diffusion by multiple mechanisms. In addition, UV aging significantly contributed to the release of PAHs from TRWPs, and digestive enzymes further exacerbated this process to some extent. In addition, the release behavior of PAHs from TRWPs was similar to that of PAHs from their main constituents (Road wear particles, Tire wear particles). These results suggest that aging effects, digestive enzymes, and composition of tire road wear micro are the main factors influencing the release behavior of PAHs from TRWPs.