報告書番号

V10006

タイトル（和文）

中間周波磁界の生物影響評価 －60 kHz磁界のラット受胎能及び初期胚の発生に関する生殖発生毒性評価－

タイトル（英文）

- Effects of 60 kHz magnetic field exposure on the rat fertility and early embryonic development to implantation -

概要 （図表や脚注は「報告書全文」に掲載しております）

中間周波磁界の利用が急増しているが、健康リスクに関する科学的知見は不足しているため、1群24匹の9週齢Crl:CD(SD)雌雄ラットに交配前2週間、交配期間中、および交尾が成立した雌動物は妊娠7日（着床）まで、60 kHz、0.10 mT(rms) の正弦波、垂直磁界を1日22時間曝露し、受胎能及び初期胚の発生に対する影響を評価した。曝露試験は結果の信頼性を確保するため盲検法で行い、結果の再現性を確認するため2回繰り返して実施した。その結果、雌動物の体重増加、性周期、交尾率、受胎率、黄体数、着床数、生存・死亡胚数、妊娠動物の卵巣、子宮重量、および、雄動物の体重増加、精子数、精子運動性、異常精子率、精巣と精巣上体の重量は、曝露群と対照群間で2回の実験とも繰り返して統計学的有意差が生じた項目はなかったことから、磁界はラットの受胎能及び初期胚の正常な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）

Scientific evidence concerning health risk assessment of intermediate frequency magnetic field is insufficient. This study aims to determine whether or not a 20 kHz, magnetic field exposure has effects on fertility and/or early embryonic development to implantation. Male and female Crl:CD(SD) rats, 9 weeks old, were randomly assigned to magnetic field exposed or sham-exposed group, 24 for each group in each sex. They were exposed to 60 kHz, 0.10 mT(rms), vertically polarized sinusoidal MF, or sham-exposed for 22 h/d from 14 days prior to mating and during mating period of 14 days at the maximum. Copulated females were further exposed until gestation day 7. Background plus stray magnetic fields in a sham-exposed facility were less than 0.001 microT(rms) at 60 kHz. Dams were sacrificed at gestation day 13 and examined for developmental toxicity. Mated males were also sacrificed on the day of mating for male fertility evaluation. Obtained results were statistically evaluated. Identical experiments in a blind fashion were conducted twice to confirm the reproducibility of outcome. In the two experiments, no statistically significant changes related to magnetic field exposure were found in the estrous cycle, copulation index, fertility index, numbers of corpora lutea and implantation sites, numbers of dead and living conceptuses, and uterus weight. Although differences between the exposed and the sham-exposed groups in female body weight and ovary weight were found only in the first experiment, it was considered to be due to chance because of the lack of reproducibility. Abnormal findings in gross pathology and histopathology of uteri and ovaries were very low in both groups, and the incidence did not show statistically significant group differences in both experiments. There were also no significant differences between magnetic field exposed group and sham-exposed group in the male body weight, sperm counts and motility, sperm morphology, and weights of testes and epididymides. Abnormal findings in gross pathology and histopathology of testes and epididymides were very low in both groups, and the incidence did not show statistically significant group differences in both experiments. Under the present experimental conditions, a 60 kHz sinusoidal, 0.10 mT(rms) MF exposure during pre-implantation period was neither toxic to fertility nor early embryonic development to implantation in the rat.

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