Phenol-formaldehyde resin microplastic (PF-MP) is one of the major inhalable microplastics in environments released from the manufacture, processing and usage of PF materials. The associated toxicities of PF-MP might be affected by photoaging. In this study, the dynamic evolutions of the oxidative potential (OP) and redox-active species, including environmentally persistent free radicals (EPFRs), reactive oxygen species (ROS), peroxides and conjugated carbonyls, as well as the associated cytotoxicity of PF-MP were systematically investigated as a result of the simulated sunlight irradiation. As the photoaging time extended, the OP of PF-MP increased. The contents of the produced conjugated carbonyls, ROS and PF-bound EPFRs due to light irradiation increased as well, and displayed significant correlations with the OP (Spearman r > 0.6, p < 0.05). The photoaged PF-MP distinctly increased the cellular ROS and reduced the cell viability of human lung epithelial adenocarcinoma cells (A549). The cytotoxicity of PF-MP showed a similar trend with the OP level in PF-MP, suggesting that the produced active species induced the in vitro toxicities. The results not only highlight the adverse health effects of photoaged PF-MP, but also provide new perspectives for the environmental risks of airborne MPs.

酚醛树脂微塑料（PF-MP）是从PF材料的制造，加工和使用所释放的环境中的主要可吸入微塑料之一。PF-MP的相关毒性可能会受到光老化的影响。在这项研究中，氧化电位（OP）和氧化还原活性物质的动态演变，包括环境持久性自由基（EPFR），活性氧物质（ROS），过氧化物和共轭羰基，以及相关的PF-的细胞毒性作为模拟阳光照射的结果，系统地研究了MP。随着光老化时间的延长，PF-MP的OP增加。由于光辐照而产生的共轭羰基，ROS和PF结合的EPFR的含量也增加，并显示出与OP的显着相关性（Spearman r> 0.6，p  ＜0.05）。光老化的PF-MP明显增加人肺上皮腺癌细胞（A549）的细胞ROS并降低其细胞活力。PF-MP的细胞毒性与PF-MP中的OP水平显示出相似的趋势，这表明所产生的活性物质诱导了体外毒性。结果不仅突出了光老化PF-MP对健康的不利影响，而且为机载MP的环境风险提供了新的观点。