報告書番号

V11065

タイトル（和文）

中間周波磁界の生物影響評価-ヒト培養細胞を用いた染色体異常試験による遺伝毒性評価-

タイトル（英文）

Effect of Intermediate Frequency Magnetic Fields on Chromosome Aberrations or co-Genotoxic Potentials by in vitro Chromosome Aberration Tests using Human Lymphoblast Cell Line, TK6

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究では、ヒト培養細胞TK6を用いた染色体異常試験により、中間周波磁界の遺伝毒性および化学物質の遺伝毒性の修飾作用の有無について評価した。2kHzで0.91mTrms（ICNIRP改定ガイドラインの34倍）、20kHzで1.1mTrms（同41倍）、60Hzで0.11mTrms（同4.1倍）の磁界を、それぞれ24時間曝露した。また、既知の遺伝毒性物資であるMMCを磁界と同時曝露し、染色体異常の誘発過程に影響するか検討した。顕微鏡下にて、染色体の数および構造を観察し、染色体異常率をt検定により評価した。実験は5回繰り返し再現性を確認した。その結果、いずれの周波数帯の磁界曝露に対しても、またMMC添加した場合でも、統計学的に有意な染色体異常率の差は見られなかった。これらのことから、本研究で検討した高い磁束密度の中間周波磁界は、ヒト細胞に対する染色体異常および化学物質の遺伝毒性の修飾作用を持たないことが示された。

概要 （英文）

In contrast to extremely low frequency and radio frequency electromagnetic fields (EMF), the biological effects of intermediate frequency (IF; 300Hz to 10MHz) EMF have not been studied very well. In our previous studies, we have reported the novel exposure system which can generate strong IF magnetic fields (MFs) of 0.91mTrms (23 times greater than revised ICNIRP guidelines for public) at 2kHz, 1.1mTrms (41 times) at 20kHz and 0.11mTrms (4.1 times) at 60kHz of IF MFs for in vitro research. We have also reported that the exposure of the IF MFs did not have genotoxic potentials which are mutagenic, co-mutagenic and/or gene conversion potentials in microbial genotoxicity tests, or micronucleus formation or chromosomal aberration (ca: deletion) in rodent cell lines, and did not have promotion or co-promotion potentials in a Bhas42 cell line. In this study, we have investigated the effects of the IF MFs on chromosomal aberration or co-genotoxic potential in human lymphoblast cell line, TK6. The assay can detect chromosomal aberration such as structural aberration and numerical aberration, which can relate with genotoxic carcinogenesis, in human cells with normal p53 function. The TK6 cells were exposed to MFs of 0.91mTrms at 2kHz, 1.1mTrms at 20kHz or 0.11mTrms at 60kHz, for 24 hrs at 37 degree Celsius in 5% carbon dioxide. After the exposure, the cells were treated with colcemid to obtain metaphase cells. The chromosomal aberrations were estimated under microscopic observation. In statistical analysis, neither significant nor reproducible difference in the rate of chromosomal aberration was found between exposure and control groups under the all MF exposure conditions. To examine the effects on co-genotoxic potential, the cells were simultaneously exposed to each MF with MMC (mitomycin C) that potentiates chromosomal aberrations. In statistical analysis, neither significant nor reproducible difference in the rate of chromosomal aberration was found between exposure and control groups under the all MF exposure conditions. These results indicated that the strong IF MFs, used in this study, did not have genotoxic or co-genotoxic potentials in human lymphoblast cell line.

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