Evaluation of influences of air-borne particulates by molecular and cellular biological methods

空气中的微粒是近几十年来主要的空气污染物。特别是直径小于2.5 μm的颗粒物（PM2.5）来自柴油尾气，被认为是对人体有害的物质。空气中PM2.5的浓度与肺癌的诱发呈正相关。我们获得了大阪、东大阪和酒井市的空气微粒，并分析了它们的颗粒大小和化学成分的分布。采用生物测定和分子生物学方法测定了其致突变性和内分泌干扰能力。在大阪市和东大阪市（市区），颗粒粒径分布呈2个峰，分布在直径约2μm处。致突变性和内分泌干扰活性符合小尺寸峰（直径小于2 μm）的分布。在酒井市（居民区），冬季颗粒物样本的内分泌干扰活性强于夏季。空气中微粒的浓度逐年逐渐下降。分子实验结果表明，颗粒中含有的强诱变剂3-硝基苯并蒽酮（NBA）在人和大肠杆菌细胞中引起G:C到T: a碱基变化突变。DNA中的NBA加合物被易出错的DNA聚合酶V （umuDC）错误编码，导致突变。这些结果对预防肺癌和估计空气中悬浮微粒对人群的危害有价值。

Air-borne particulates are major air pollutants in these decades. Especially, the particulate smaller than 2.5 μm diameter (PM2.5) is originated from diesel exhaust gas and considered to be a harmful substance to human health. Concentration of the PM2.5 in air has been shown positive correlation to induction of lung cancer. We obtained the air-borne particulates in Osaka, Higashi-osaka and Sakai Cities and analyzed their distribution of the particulate sizes and chemical composition. We also measured mutagenicity and endocrine disturbing ability of the particulates by bioassays and molecular biological methods.In Osaka and Higashi-osaka Cities (urban area), the distribution of the particulate size showed two peaks that were divided at approximately 2μm diameter. The mutagenicity and endocrine-disturbing activity were agree to the distribution of the small size peak (smaller than 2 μm diameter). In Sakai City (residential area), the endocrine-disturbing activity is stronger in the winter particulate sample than the summer one. The concentration of the particulate in air has gradually decreased year by year.As a result of molecular experiment, 3-nitrobenzanthrone(NBA), a strong mutagen contained in the particulate, caused G:C to T:A base change mutations in human and Escherichia coli cells. The NBA adducts in DNA was miscoded by the error-prone DNA polymerase V (umuDC), and they induced mutations.These results are valuable for prevention of lung cancer and for risk estimation of human population of the air-borne particulates.