Genotoxicity of airborne particles from the urban area in Sapporo : Evaluation of the particulate samples collected over 22 year by bioassays

为研究空气中颗粒物的遗传毒性，对1974年以来24年间采集的日本北海道最北部大城市札幌的空气中颗粒物样本进行了分析。实验结果如下：1.实验结果表明：艾姆斯试验测定致癌物质浓度及致突变性。在24年的观测期内，多环芳烃（PAHs）的浓度明显下降，而硝基芳烃的浓度没有明显下降。TA98和TA100菌株的诱变活性仅略有下降。这些结果表明，多环芳烃的浓度并不是大气中肺癌风险的适当指标，并且在观察期间，空气中颗粒物的致突变性对人体健康的风险没有显著降低。小鼠淋巴瘤细胞诱变性测定。利用小鼠淋巴瘤细胞系L5178Y细胞进行诱变实验，有效检测了空气中悬浮颗粒物引起的突变和染色体畸变。间接诱变活性（+S9）明显降低，而直接诱变活性（-S9）无明显变化。体外微核试验检测致突变性。结果表明，利用中国仓鼠肺成纤维细胞进行体外微核试验，可以检测空气中颗粒物的致突变性。在观察期内，+S9试验体系的诱导微核发生率相当稳定。对于-S9测试系统，发病率在20世纪80年代初升高，其他年份波动较小。代谢缺陷新试验菌株的开发。通过基因破坏，建立了硝基还原酶活性完全抑制和部分抑制的新菌株YG7128和YG7132。同时也建立了o -乙酰转移酶缺陷菌株YG7126和YG7130。这些菌株能有效地检测到硝基芳烃，表明硝基芳烃在空气悬浮颗粒样品的总致突变活性中所起的作用相当大。少

To investigate genotoxicity of airborne particles, the airborne particulate samples collected in Sapporo, the most northern large city in Hokkaido, Japan, during the period of 24 years from 1974 were analyzed. The results obtained are followings :1. Concentrations of carcinogenic substances and mutagenicity assayed by Ames test.Concentrations of polycyclic aromatic hydrocarbons (PAHs) markedly decreased during the observation period of 24 years, while concentrations of nitroarenes did not. Mutagenic activities assayed by TA98 and TA100 strains did only slightly decrease. These results indicates that concentrations of PAHs is not an appropriate indicator for the atmospheric risk of lung cancer and further the risk to human health did not significantly decrease over the observation period in terms of mutagenicity in airborne particles.2. Mutanenicity assayed by mouse lymphoma cells.Mutagenicity assay using the L5178Y cell, a cell line of mouse lymphoma cells, efficiently detected mutatio … More ns and chromosomal aberration induced by the airborne particulate samples. The indirect mutagenic activities (+S9) clearly decreased over the period, while direct mutagenic activities (-S9) did not.3. Mutagenicity assayed by in vitro micronucleus test.It was shown that mutagenicity of airborne particles is possibly assayed by in vitro micronucleus test using Chinese hamster lung fibroblast cells. The incidences of induced micronucleus were rather stable for +S9 test system over the observation period. For the -S9 test system, the incidences were elevated in early 1980s with small fluctuations for other years.4. Development of new test strains with metabolic deficits.By gene disruption, new test strains for Ames assay, YG7128 and YG7132 with completely and partially inhibited nitroreductase activities, were established. YG7126 and YG7130, O-acetyltransferase deficient strains, were also established. These strains effectively detect nitroarenes and it was shown that contribution by nitroarenes was considerable among the total mutagenic activities in the airborne particulate samples. Less