Tanaka S, Tanaka I B, Sasagawa S, Ichinohe K, Takabatake T, Matsushita S, Matsumoto T, Otsu H, Sato F
Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan.
Radiat Res. 2003 Sep;160(3):376-9. doi: 10.1667/rr3042.
Late effects of continuous exposure to ionizing radiation are potential hazards to workers in radiation facilities as well as to the general public. Recently, low-dose-rate and low-dose effects have become a serious concern. Using a total of 4000 mice, we studied the late biological effects of chronic exposure to low-dose-rate radiation as assayed by life span. Two thousand male and 2000 female 8-week-old specific-pathogen-free (SPF) B6C3F1 mice were randomly divided into four groups (one nonirradiated control and three irradiated). Irradiation was carried out for approximately 400 days using (137)Cs gamma rays at dose rates of 21 mGy day(-1), 1.1 mGy day(-1) and 0.05 mGy day(-1) with total doses equivalent to 8000 mGy, 400 mGy and 20 mGy, respectively. All mice were kept under SPF conditions until they died spontaneously. Statistical analyses showed that the life spans of mice of both sexes irradiated with 21 mGy day(-1) (P < 0.0001) and of females irradiated with 1.1 mGy day(-1) (P < 0.05) were significantly shorter than those of the control group. Our results show no evidence of lengthened life span in mice continuously exposed to very low dose rates of gamma rays.
持续暴露于电离辐射的晚期效应，对辐射设施中的工作人员以及普通公众都是潜在危害。近来，低剂量率和低剂量效应已成为严重关切的问题。我们使用总共4000只小鼠，通过寿命测定研究了慢性暴露于低剂量率辐射的晚期生物学效应。将2000只8周龄雄性和2000只8周龄雌性无特定病原体（SPF）B6C3F1小鼠随机分为四组（一组未受辐照作为对照，三组受辐照）。使用（137）Csγ射线以21 mGy天-1、1.1 mGy天-1和0.05 mGy天-1的剂量率进行约400天的辐照，总剂量分别相当于8000 mGy、400 mGy和20 mGy。所有小鼠均饲养在SPF条件下直至自然死亡。统计分析表明，接受21 mGy天-1辐照的雌雄小鼠（P < 0.0001）以及接受1.1 mGy天-1辐照的雌性小鼠（P < 0.05）的寿命均显著短于对照组。我们的结果表明，没有证据显示持续暴露于极低剂量率γ射线的小鼠寿命会延长。
