報告書番号

V08003

タイトル（和文）

中間周波磁界の生物影響評価 －ラットを用いた20 kHzおよび60 kHz磁界の急性毒性評価－

タイトル（英文）

Acute toxicity of intermediate frequency magnetic fields in the rat - Exposures to 20 kHz, 0.20 mT or 60 kHz, 0.10 mT, sinusoidal magnetic field -

概要 （図表や脚注は「報告書全文」に掲載しております）

雌雄各1群12匹の7週齢Crl:CD(SD)ラットに20 kHz、0.20 mT(rms) （ICNIRP公衆ガイドラインの32倍）または60 kHz、0.10 mT(rms) の正弦波、垂直磁界を1日22時間、14日間曝露した。曝露実験は盲検法にて実施し、2回繰り返して再現性を確認した。また、ふたつの曝露棟の違いを検証する無曝露実験も実施した。無曝露実験および磁界曝露実験において、ラットの体重増加と一般状態に異常はなかった。曝露終了後の剖検での内臓異常所見、臓器重量とその体重比、血液学的検査8項目、血液生化学的検査17項目において、無曝露実験におけるふたつの曝露棟間、および、磁界曝露群と対照群間で再現性のある統計学的有意差はなかった。磁界曝露に関連する再現性のある変化が認められなかったことから、本実験条件下では、中間周波磁界の14日間曝露はラットに急性毒性を示さないことが明らかになった。

概要 （英文）

Because of the present lack of biological research data on intermediate frequency (IF) magnetic field (MF) exposure, scientific evidence concerning possible health effects is necessary for health risk assessment. This study aims to determine whether or not IF MF exposures have acute toxicity in the rat. Male and female Crl:CD(SD) rats, 7 weeks old, were randomly assigned to MF-exposed or sham-exposed group, 12 for each group in each sex. They were exposed to 20 kHz, 0.20 mT(rms) or 60 kHz, 0.10 mT(rms), vertically polarized sinusoidal MF, or sham-exposed for 14 days. The emitted MFs at animal exposure space varied less than 2 %. At the maximum MF intensity of 0.20 mT(rms) at 20 kHz or 0.10 mT(rms) at 60 kHz, background plus stray MFs in the sham-exposed facility were less than 0.001 microT(rms) at the IF MFs and 0.03 microT(rms) at 50 Hz, respectively. Experiments were conducted in a blind fashion and duplicated. Prior to the MF exposure experiments, sham-sham experiments were performed to verify that animal exposure facilities provide identical housing conditions when the MFs were not emitted from exposure coils. During the 14 days of exposure, animals were weighed and their health status was observed. No indications of morbidity were found, and there were no significant differences in body weight between exposed and sham-exposed rats at any time during the exposure. After the exposure, animals were sacrificed and organs were weighed, and they were evaluated for gloss pathology, blood hematology and clinical chemistry. Sporadic pathological changes were observed in some rats that did not show significant group differences. Differences in some organ weights and hematology and clinical chemistry parameters were seen between exposed and sham-exposed groups. However, since the differences were not reproducible in duplicated experiments and were not correspondent between 20 kHz and 60 kHz exposures, they were due to chance. These results together suggest that the present study failed to demonstrate any acute toxicity in the rats exposed to the sinusoidal 20 kHz, 0.20 mT(rms) or 60 kHz, 0.10 mT(rms) MF.

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