THE GENETIC-EFFECTS OF HUMAN EXPOSURES TO IONIZING-RADIATION

The data on the potential genetic effects of atonic bombs collected over the course of the past 46 years are reviewed. No statistically significant effect of parental exposure to the ionizing radiation of the bombs on the frequency of congenital malformations, stillbirths, survival, physical growth and development, malignant tumors with onset prior to age 20, certain chromosome abnormalities, or mutations involving the structure and function of a battery of proteins teas found. The effect of exposure averaged over all indicators, however, is slightly positive. This finding appears to be the current best estimate of the genetic effect of the exposure of humans to ionizing radiation. From the data on the control children in this study, the contribution of spontaneous mutation each generation to each of these indicators was estimated, and we calculated the amount of acute ionizing radiation necessary to increase this spontaneous rate by 100% (the so-called doubling dose). This is estimated to be between 1.7 and 2.2 Sv equivalents, with an. error term difficult to estimate. It is argued that, for exposures to chronic ionizing radiation, the doubling dose is approximately 3.4-4.4 Sv equivalents, again with an error term extending well beyond this interval. Our review of the experimental data from mice with respect to eight specific locus and phenotype systems suggests good agreement with the estimate for humans. This estimate is about four times higher than the estimate employed in most past treatments of the genetic risks of exposure to ionizing radiation.