Bone marrow cytology in Hiroshima atomic bomb survivors 5 years following exposure

Bone marrow aspiration smears obtained from 35 individuals, 5 years following expsoure to the Hiroshima atomic bomb, were intensively evaluated for radiation related cytologic abnormalities. No definite radiaton related changes were observed, but some findings were very suggestive. The most interesting of these was the occurrence of internuclear bridges joining erythroid precursors in the marrow smears of seven (20%) of the heavily exposed survivors. Although not specific it is likely that this lesion is indicative of residual stem cell damage and some degree of ineffectual erythropoiesis. The bone marrow morphologic lesions may be good markers of residual radiation damage but they are too infrequent in their occurrence to be of value as a biologic dosimeter. The findings in this study also suggest that a gradual disappearance of radiation induced late bone marrow changes continues for periods of 3 to 5 years or more following high dose acute radiation exposure.