Effects in descendant mice after generational low dose-rate 137Cs internal exposure

How does chronic low-dose internal exposure to Cesium-137 radiation over multiple generations affect offspring? In this study, we sought to infer the effects on humans from experiments on mice, whose spontaneous mutation rate in the next generation is very similar to that of humans. Cesium-137 water (100 Bq/mL) was provided as drinking water to A/J mouse strains for chronic, low-dose, and low-dose-rate internal exposure for more than 40 generations, following which, we examined individual effects in the exposed mice using a multi-pronged approach. Compared to the control group, DNA double-strand breaks and oxidative stress were significantly increased in the Cesium-137 group. However, no significant differences were observed between the two groups regarding chromosome aberration, micronuclei, and the whole genome sequence mutation analysis. Although no difference in carcinogenic rate was observed between the two groups, the rate of tumor growth was significantly suppressed in the Cesium-137 group. Cytokine levels in the Cesium-137 group showed a trend toward the activation of anti-tumor immunity, which likely contributed to the anti-tumor effect. For mice drinking water containing 100 Bq/mL (100,000 Bq/L) of cesium-137, no ill effects were observed on their offspring even after 25 generations of drinking.