報告書番号

U00037

タイトル（和文）

商用周波磁界と免疫系（その８） --350 μTrms回転円磁界の30週間曝露がマウス白血病進行度の経時的変化に与える影響--

タイトル（英文）

Power frequency magnetic field and immunologic system (part8)-Effects of 350 μTrms circularly polarized, magnetic field exposure up to 30 weeks on the time course of leukemia development in mice-

概要 （図表や脚注は「報告書全文」に掲載しております）

磁界影響として一部の疫学調査で白血病増加が示唆されているため、白血病を高率に自然発症するAKRマウス312匹を用い、50 Hz、350 μTrms回転円磁界を6、12、18、24、30週間曝露した。血液学的、解剖学的、病理組織学的検査を盲検法で実施し、血清、脾臓、肺、肝臓で7種類のサイトカインとタンパク質量を測定した。また、検査結果からスコア化した個体ごとの白血病進行度に対照群と曝露群で差が生じるかどうかも調べた。臓器重量の増加や腫大、リンパ腫細胞の浸潤などが18週目前後から観察され、30週目まで漸増した。対照群と曝露群を比較すると、血液学的検査における白血球数・白血球組成、解剖学的検査における臓器重量・腫大の有無、病理組織学的検査におけるリンパ腫細胞の浸潤・増殖程度の大部分の項目、ならびに白血病進行度に統計学的な有意差は認められず、磁界曝露は白血病の進行を促進しないことが明らかとなった。

概要 （英文）

Based on a suggestive association between magnetic field (MF) exposure and increased risk of leukemia in epidemiology, we exposed 312 of AKR/J female mice, which spontaneously develop lymphatic leukemia, to 50 Hz, 350 μTrms, circularly polarized MF for 6, 12, 18, 24 or 30 weeks from 5 weeks of age. Exposures were performed over 22 hours a day, 7 days a week. Background 50 Hz MF was less than 0.02 μTrms. Experiment was conducted in a blind fashion. At each time-point mice were sacrificed and organ weight measurements, hematological examination, gloss pathological examination, and histopathological examination were conducted. Amounts of seven cytokines (IL-1β, IL-2, IL-4, IL-6, IL-10, GM-CSF and TNF-α) and protein in sera, spleens and lungs were also measured. Group difference of each endpoint was statistically evaluated. Increases of organ weights, swelling rate, frequency and rate of lymphoma cell proliferation/infiltration became evident from 18 weeks of exposure; these values continously increased untill the termination of 30-week exposure. However, most of these changes between exposed and control groups were not statistically significant. Slight acceleration of leukemia development in exposed group was suggestive, however the tendency was again not statistically significant. These results indicated that MF exposure did not affect the leukemia development and amounts of cytokines in exposed AKR mice under conditions examined.

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