These results of our study demonstrated that age impacts the short term mutagenic effects of
IR exposure on spermatogenic cells resulting in an increased mutant frequency in
derivatives of irradiated differentiating spermatogenic cells. Disasters, such as the nuclear
accidents at Chernobyl, and Fukushima and natural sources of IR induce DNA damage in
living organisms. At Fukushima, older workers were selected as volunteers that stayed to
contain the disaster. Young workers were not selected as volunteers because the long-term
effects of IR exposure had a greater chance of being realized in them. However, short term
effects on male reproductive biology should also be considered.