Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Wuerzburg, Wuerzburg, Germany.
Toxicol Lett. 2011 Nov 10;207(1):89-95. doi: 10.1016/j.toxlet.2011.08.004. Epub 2011 Aug 12.
Current pollution limits indicating potential harm to human health caused by nitrogen dioxide have prompted a variety of studies on the cytotoxicity and genotoxicity of nitrogen dioxide (NO₂) in vitro. The present study focuses on toxic effects of NO₂ at the WHO defined 1-h limit value of 200 μg NO₂/m(3) air, equivalent to 0.1 ppm NO₂. Nasal epithelial mucosa cells of 10 patients were cultured as an air-liquid interface and exposed to 0.1 ppm NO₂ for 0.5 h, 1 h, 2 h and 3 h and synthetic air as negative control. After exposure, analysis of genotoxicity was performed by the alkaline single cell microgel electrophoresis (comet) assay and by the micronucleus test. Depression of proliferation and cytotoxic effects were checked by the micronucleus assay and the trypan blue exclusion assay. The experiments demonstrated significant DNA fragmentation even at the shortest exposure duration of half an hour in the comet assay. The amount of DNA fragmentation significantly increased with extended NO₂ exposure durations. The amount of DNA fragmentation increased with extended exposure durations to synthetic air at a significantly lower level as compared to NO₂ exposure. Micronucleus inductions were seen only at the longest exposure duration of 3h. There were no changes in proliferation seen in the micronucleus assay under any experimental setup. Moreover, no signs of necrosis, apoptosis or changes in viability were detected. Data demonstrate genotoxicity of NO₂ at concentrations found in the urban atmosphere during short exposure durations. DNA alterations in the micronucleus assay at an exposure time of 3h indicate a significant DNA alteration possibly being hazardous to humans.
目前的污染限值表明，二氧化氮对人类健康造成的潜在危害促使人们开展了各种关于二氧化氮（NO₂）在体外的细胞毒性和遗传毒性的研究。本研究重点关注的是在世界卫生组织（WHO）定义的 1 小时 200μg NO₂/m³ 空气浓度限值（相当于 0.1ppm 的 NO₂）下，NO₂的毒性效应。我们将 10 名患者的鼻腔上皮黏膜细胞进行气液界面培养，并以 0.1ppm 的 NO₂浓度暴露 0.5 小时、1 小时、2 小时和 3 小时，同时以合成空气作为阴性对照。暴露后，通过碱性单细胞凝胶电泳（彗星）试验和微核试验进行遗传毒性分析。通过微核试验和台盼蓝排斥试验检测细胞增殖抑制和细胞毒性效应。实验表明，即使在彗星试验中最短的暴露时间（半小时），也会出现明显的 DNA 片段化。随着 NO₂暴露时间的延长，DNA 片段化的数量显著增加。与 NO₂暴露相比，在合成空气暴露时间延长时，DNA 片段化的数量增加幅度较低。仅在最长的 3 小时暴露时间观察到微核诱导。在任何实验设置下，微核试验中均未观察到细胞增殖的变化。此外，未检测到细胞坏死、凋亡或活力变化。这些数据表明，在短时间暴露于城市大气中发现的浓度下，NO₂具有遗传毒性。在 3 小时的暴露时间下，微核试验中的 DNA 改变表明存在明显的 DNA 改变，可能对人类健康造成危害。
