Tire wear particles (TWP) are a prevalent form of microplastics (MPs) extensively distributed in the environment, raising concerns about their environmental behaviors and risks. However, knowledge regarding the properties and toxicity of these particles at environmentally relevant concentrations, specifically regarding the role of environmentally persistent free radicals (EPFRs) generated during TWP photoaging, remains limited. In this study, the evolution of EPFRs on TWP under different photoaging times and their adverse effects on were systematically investigated. The photoaging process primarily resulted in the formation of EPFRs and reactive oxygen species (O, ⋅OH, and O), altering the physicochemical properties of TWP. The exposure of nematodes to 100 μg/L of TWP-50 (TWP with a photoaging time of 50 d) led to a significant decrease in locomotory behaviors (e.g., head thrashes, body bends, and wavelength) and neurotransmitter contents (e.g., dopamine, glutamate, and serotonin). Similarly, the expression of neurotransmission-related genes was reduced in nematodes exposed to TWP-50. Furthermore, the addition of free-radical inhibitors significantly suppressed TWP-induced neurotoxicity. Notably, correlation analysis revealed a significantly negative correlation between EPFRs levels and the locomotory behaviors and neurotransmitter contents of nematodes. Thus, it was concluded that EPFRs on photoaged TWP induce neurotoxicity by affecting neurotransmission. These findings elucidate the toxicity effects and mechanisms of EPFRs, emphasizing the importance of considering their contributions when evaluating the environmental risks associated with TWP.

中文翻译：

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光老化轮胎磨损颗粒上环境持久性自由基的产生及其对秀丽隐杆线虫神经传递的神经毒性作用

轮胎磨损颗粒（TWP）是微塑料（MP）的一种普遍形式，广泛分布在环境中，引起了人们对其环境行为和风险的担忧。然而，关于这些颗粒在环境相关浓度下的性质和毒性的知识，特别是关于 TWP 光老化过程中产生的环境持久性自由基 (EPFR) 的作用的知识仍然有限。本研究系统地研究了不同光老化时间下TWP上EPFR的演变及其不利影响。光老化过程主要导致 EPFR 和活性氧（O、·OH 和 O）的形成，从而改变 TWP 的物理化学性质。线虫暴露于 100 μg/L 的 TWP-50（光老化时间为 50 d 的 TWP）会导致运动行为（例如头部摆动、身体弯曲和波长）和神经递质含量（例如多巴胺）显着下降。 、谷氨酸和血清素）。同样，暴露于 TWP-50 的线虫中神经传递相关基因的表达也有所降低。此外，添加自由基抑制剂可显着抑制 TWP 诱导的神经毒性。值得注意的是，相关分析显示EPFRs水平与线虫的运动行为和神经递质含量之间存在显着负相关。因此，得出的结论是，光老化 TWP 上的 EPFR 通过影响神经传递来诱导神经毒性。这些发现阐明了 EPFR 的毒性作用和机制，强调了在评估与 TWP 相关的环境风险时考虑其贡献的重要性。