Cancer incidence and mortality rate in children of A-bomb survivors

The purpose of this paper is to summarize the previous findings of carcinogenesis and mortality rate in children born to A-bomb survivors. The Radiation Effects Research Foundation has collected 72,228 children born to A-bomb survivors from May 1946 through 1984. Of their parents, 31,159 parents had been exposed to significant doses (≥0.01 Sv), with a mean genital dose of 0.435 Sv. Among a hypothetic population of 100,000 children of A-bomb survivors exposed to an mean genital dose of 0.4 SV, radiation-induced diseases were considered to occur in only 250 children or less. An earlier large-scale survey during the period 1948-1956 has revealed an evidence of significant increase in stillborn, congenital malformation, and infantile death. In the 1946-1982 survey concerning carcinogenesis in 72,216 children of A-bomb survivors, cancer was found to be detected in 92 children, with no statistically significant increase in cancer risk with increasing radiation doses in their parents. The survey on mortality rate in 67,586 children of A-bomb survivors has revealed no evidence of significant increase in mortality rate from diseases, other than cancer, and in the incidence of lethal cancer. For A-bomb survivors, genetic doubling doses were considered to be 1 Sv or more. Further, when genetic doubling doses are calculated, the contribution rate of genital cell disturbance should be considered in the incidence of spontaneously induced disease. There is no supportive evidence of genetic effects of A-bomb radiation in children of A-bomb survivors; however, genetic effects of A-bomb radiation cannot be denied completely. Continuing survey is expected to be done for children of A-bomb survivors. (N.K.)