報告書番号

V05002

タイトル（和文）

中間周波磁界の生物影響評価 --微生物変異原性試験による助変異原性の評価--

タイトル（英文）

Biological effect of intermediate frequency magnetic field-evaluation of co-mutagenicity for chemical mutagens by bacterial mutation test-

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、微生物復帰変異試験を用い、中間周波磁界に化学物質の変異原性を増強する作用（助変異原性）があるか評価した。化学物質に対し感受性の高い４種類の試験菌株に対し、ラジカル発生剤、DNA結合性薬剤および代謝活性化により変異原性をもつ４種類の化学物質をそれぞれ添加し、さらに、2kHzで910μT（国際ガイドラインの146倍）、20kHzでは、1.1mT（同176倍）、60Hzでは110μT（同18倍）の磁界を、それぞれ48時間、同時に曝露した。その結果、いずれの菌株でも、また、いずれの化学物質に対しても、磁界曝露による再現性のある有意な復帰変異コロニー数の増加は見られなかった。このことから、本研究で検討した中間周波磁界の曝露条件では、助変異原性がないことが明らかとなった。

概要 （英文）

In contrast to extremely low frequency and radio frequency electromagnetic fields (EMF), the biological effects of the intermediate frequency (IF; 300Hz to 10MHz) EMF have not been studied very well. In this research, we have investigated the co-mutagenic potential of the IF magnetic fields (MFs) by using bacterial mutation test. Two strains of Salmonella typhimurium (TA98, TA100) and two strains of Escherichia coli (WP2 uvrA, WP2 uvrA/pKM101) were chosen to cover a wide point mutation spectrum, including AT base substitution, GC base substitution, suppressor mutation, and frame shift. We also chose five chemical mutagens, t-butyl hydroperoxide (BH, hydroxyl radical precursor), 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (AF2, DNA reactive reagents), N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG, DNA reactive reagents), 2-amino anthracene (2AA, DNA reactive promutagen which is activated metabolically by rat S9mix)) and benzo[a]pyrene (BaP, DNA reactive promutagen which is activated metabolically by rat S9mix). For the co-mutagenicity tests, each MF exposure condition, such as 910ｵTrms (146 time greater than ICNIRP guideline) at 2kHz, 1.1mT rms (176 times) at 20kHz and 110ｵT rms (18 times) at 60kHz, was exposed simultaneously with each chemical mutagen. The mutation rate was estimated by counting revertant colonies. The ratio of the colony number of MF exposed to unexposed groups was mostly in the range of 0.9 - 1.1. In statistical analysis, neither significant nor reproducible difference was found between the mutation rates for all MF exposure condition and for all chemical mutagens in all test strains. The strong IF MFs did not have co-mutagenic potentials for the chemical mutagens in the experimental conditions.

報告者

キーワード