Strain differences in life shortening and early onset of malignant lymphomas of mice continuously exposed to low-dose-rate gamma-rays

Abstract

We previously reported that life shortening induced by continuous gamma-ray irradiation at a low-dose rate in B6C3F1 mice appeared to be caused by death due to the early onset of malignant lymphomas. Life shortening and tumor development in C3H/He Nrs mice irradiated with ¹³⁷Cs-gamma-ray at a dose rate of 20 mGy/22 hr/day for about 400 days (total dose: 8 Gy) were examined to verify the strain differences and tumor types. Lifespan was significantly shortened for 141 and 39 days in irradiated male and female C3H/He Nrs mice, respectively, than that of non-irradiated mice. Significant life shortening was observed in mice died of malignant lymphomas, mammary tumors, ovarian tumors, liver tumors, acute myeloid leukemias (in female), and soft tissue tumors (in female). These results suggest that life shortening due to early onset of malignant lymphomas and the other various tumors occurs in irradiated C3H mice as well as B6C3F1 mice. This work was supported by a grant from Aomori prefecture, Japan.