Cumulative genetic damage in children exposed to preconception and intrauterine radiation

Using a mathematical model and newly developed computer software, the data from the Tri-State Leukemia Survey involving different combinations of radiation exposures to the father and mother prior to conception and to the mother during pregnancy were analyzed. The hypothesis that radiation exposure produces genetic damage which may be expressed in the child both as indicator disease and as leukemia was tested. The genetic damage was estimated in terms of the proportion affected by a given exposure. The relative risk of leukemia and certain other indicator diseases among those "affected" could then be estimated. The results were obtained by direct minimization of the total chi-square. The results show that there are at least two distinguishable risk groups, one group with lower (one or two exposures), and the other group with higher (two or three) radiation exposures. The estimates for the proportion affected are 0.13 and .04 for the lower and higher exposure groups, respectively. The relative risks of leukemia and indicator diseases are 25.0 and 5.0, respectively. The 95% confidence intervals for the proportion affected in the lower and higher exposure categories are (.0075, .02) and (.028, .055), respectively, and for the relative risk of leukemia are (16.0, 35.0). These results have confirmed and extended the findings of our preliminary report published in the Journal of the American Medical Association in May 1977.