報告書番号

V04

タイトル（和文）

中間周波磁界の生物影響評価

タイトル（英文）

Evaluation of biological effects of intermediate frequency magnetic field

概要 （図表や脚注は「報告書全文」に掲載しております）

中間周波磁界の影響を細胞レベルで評価するため、２kHz（0.91mT）、20kHz（1.1mT）あるいは60kHz（0.11mT）の磁界を微生物、酵母、動物細胞あるいはヒト由来細胞に曝露したが、いずれの試験においても遺伝子への影響はみられず、磁界に遺伝毒性やプロモーション作用はないことが明らかとなった。また、動物個体レベルで生殖・発生への影響を評価するため、様々な発生、成長段階の鶏胚に20kHz（1.1mT）あるいは60kHz（0.11mT）の磁界を曝露したが、発生への影響はないことが明らかとなった。さらに、ラットの胚・胎児の発生期間（妊娠７～17日）に20kHz（0.20mT）あるいは60kHz（0.10mT）の磁界を曝露したが、胚・胎児の発生過程に影響を与えないことが明らかとなった。また、雌雄親ラットを交配前２週間、交配中および妊娠７日目まで曝露した試験でも、磁界は親の受胎能および発生初期胚の発生過程に影響を与えないことが明らかとなった。

概要 （英文）

This report summarizes the results of the effects of intermediate frequency (IF) magnetic fields (MFs) on genotoxicity and promotion potential by in vitro studies and reproduction, embryo-fetal development by in vivo studies conducted in Environmental Science Research Laboratory in Central Research Institute of Electric Power Industry from 2004 to 2012. [A] (1) Genotoxicity studies: These studies consisted of mutagenisity, co-mutagenicity by bacterial mutation assay test, gene conversion test using by yeast, micronucleus formation test using by mammalian cell line, point mutation and chromosomal aberration by mouse lymphoma assay, and chromosomal aberration test by using human lymphoblast cell line. These cells were exposed to 0.91 mT(rms), 1.1 mT(rms) and 0.11 mT(rms) of IF MFs at 2 kHz, 20 kHz and 60 kHz, respectively, with or without known mutagens. All tests showed neither significant nor reproducible difference between MF exposed and unexposed control groups. (2) Promotion study: Bhas42 cell line was exposed to to 0.91 mT(rms), 1.1 mT(rms) and 0.11 mT(rms) of IF MFs at 2 kHz, 20 kHz and 60 kHz, respectively, without known promoter. The transformation tests for promotion or co-promotion potentials showed neither significant nor reproducible difference between MF exposed and unexposed control groups. These results showed the strong MFs did not have genotoxic, co-genotoxic, promotion or co-promotion potentials which can contribute to carcinogenesis. [B] Reproduction and developmental toxicity studies: (1) Chick embryo studies; White leghorn, fertile eggs were exposed to 1.1 mT(rms) at 20 kHz or 0.11 mT(rms) at 60 kHz MFs for 2, 7 or 11 days. In addition, fertile eggs given all-trans retinoic acid (RA), a known teratogen, were also exposed to 1.1 mT(rms) at 20 kHz or 0.11 mT(rms) at 60 kHz MFs for 2, 7 or 11 days. Under the experimental conditions tested, IF MFs did not produce any adverse effects on the development of chick embryos. Lack of modification by MFs on the teratogenicity of a known teratogen was also demonstrated. Furthermore, fertile eggs were exposed to 1.1 mT(rms) at 20 kHz or 0.11 mT(rms) at 60 kHz MFs for 19 days. This study did not produce any adverse effects on the development of chick embryos, either. (2) Rat studies; Pregnant rats were exposed to 0.20 mT(rms) at 20 kHz or 0.1 mT(rms) at 60 kHz MFs from gestation day 7 to day 17. Dams were sacrificed at gestation day 20, and their fetuses were examined. Under these experimental conditions, IF MFs exposed were neither embryo/fetotoxic nor teratogenic. In other studies, male and female rats were exposed to 0.20 mT(rms) at 20 kHz or 0.1 mT(rms) at 60 kHz MFs prior to and during mating, and copulated females were further exposed until gestation day 7. Dams were sacrificed at gestation day 13 and examined. IF MFs exposed during pre-implantation period were neither toxic to fertility, nor early embryonic development to implantation. All these results showed the lack of the effects of IF MFs on genotoxicity by in vitro studies and reproduction, embryo-fetal development by in vivo studies under the present experimental conditions.

報告者

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