Persistence of Radiation-Induced Chromosome Aberrations in Marmoset and Man

The yield of chromosome aberrations was followed for a period of 2 yr following whole-body irradiation of marmosets, and for 3 yr following an accidental whole-body exposure of a human. The yield of dicentrics plus rings decreased significantly 1 wk after irradiation of marmosets, but did not change in man until 5 wk after exposure. The yield of dicentrics and rings in the human has remained relatively constant for 3 yr, at one-half that immediately after irradiation. In the marmosets, a further decrease in yield was observed at 30 wk following 300 R and at 45 wk following 100 R, so that the yield was around 2%, compared with 40% immediately after 200 R and 15% immediately following 100 R. The yield remained at this low level through 90 wk after exposure. These differences in the persistence of aberrations in marmoset and man are considered both in terms of the different patterns of lymphocyte recovery in the two species following irradiation, and in terms of differences in lymphocyte turnover rate and life-span, once the lymphocyte count had returned to preirradiation levels.