この研究は、マウスのイン・ビボ実験で、胎児期および乳児期の磁界（ELF-MF：50 Hz、65 μT）ばく露による遺伝毒性とそれに関連した電離放射線作用の変化を調べた。ELF-MFばく露群は、ELF-MFの24時間ばく露を妊娠12日目から30日間行った。X線＋ELF-MFばく露群は、同様のELF-MFばく露の開始直前に1 GyのX線照射を受けた。その他にELF-MF擬似ばく露、X線単独ばく露の実験群も用意した。出生後1日目から140日目まで複数回の赤血球小核試験、および42日目での雄生殖細胞への遺伝毒性、細胞毒性作用を調べた。その結果、ELF-MFの催奇形性作用は見られず、生存率および成長、発達への影響もなかった；小核試験では、ELF-MFの最長ばく露期間後にのみ、若干の遺伝毒性損傷が起きたが、ばく露終了後数ヶ月のうちにこの影響は徐々に消失した；ELF-MFは、赤血球での電離放射線誘発性の遺伝毒性に何も影響しなかった；一方、雄生殖細胞のX線への応答をELF-MFが変化させるように見えた､と報告している。
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The genotoxic effects of prenatal and postnatal exposure of mice to a 50 Hz-magnetic field and prior X-radiation on erythrocytes and sperms should be investigated.
Pregnant mice were divided into 4 groups (n=2 dams per group): 1) only exposure to the magnetic field (n=20 pups), 2) only X-radiation (1 Gy) on day 11.5 post conception (n=25 pups), 3) X-radiation and subsequent exposure to the magnetic field (n=31 pups), 4) sham exposure (n=27 pups).
On day 42 after birth, 43 young animals were sacrificed for sperm and testes examinations and the rest was killed after 140 days (remark EMF-Portal: it is not stated how many animals from each group were sacrificed and possibly more animals were killed in total. Specifications on this are contradictory and the numbers of animals used in each test are not fully comprehensible).
ばく露時間: continuous form day 11.5 post conception to day 21 after birth (weaning) (30 days in total)
|ばく露時間||continuous form day 11.5 post conception to day 21 after birth (weaning) (30 days in total)|
|ばく露装置の詳細||polycarbonate cages were placed in solenoid (0.8 m in length and 0.13 m in radius, with 552 turns of 2.5 mm2 copper wire, wound in two layers in continuous forward-backward fashion around a cylinder made of PVC; applied voltage was 6.5 V (rms)); the field was uniform between ± 5% in the volume where the mice were exposed; the solenoid was not shielded against the electric field, as the induced electric field was negligible due to the low voltage used; temperature and the relative humidity were 22°C and 40%, respectively|
|Sham exposure||A sham exposure was conducted.|
|Additional information||control and X-radiation groups were placed in a switched off solenoid|
|磁束密度||65 µT||effective value||-||-||-|
Significanly increased numbers of micronuclei in comparison to the sham exposure group (group 4) were found in groups 2 (X-radiation alone) and 3 ( X-radiation and MF exposure) at several points in time. Only after 42 days, a significantly higher amount of micronuclei compared to the sham exposure group was also observed in group 1 (magnetic field alone).
The mean testes weight was significantly smaller in all exposure groups (groups 1-3) compared to the sham exposure group. Exposure to the magnetic field alone or to X-radiation alone resulted in a significantly reduced amount of post-meiotic haploid spermatids compared to the sham exposure group and to a combination of X-radiation and MF exposure. The mean sperm numbers were significantly reduced in X-radiated mice in comparison to the sham exposure group and to a combination of X-radiation and MF exposure.
In the comet assays, the combination of X-radiation and MF exposure resulted in significantly reduced DNA damage compared to X-radiation alone.
No teratogenic effects were found in any group.
The authors conclude that prenatal and postnatal exposure of mice to a 50 Hz-magnetic field has only a slight genotoxic potential, but it might modulate the effects of prior X-radiation on sperms.