GENETICS CONFERENCE 



likely that any individual and specific 

 pathology in a post-irradiation gen- 

 eration can ever be attributed with 

 certainty to the effects of the bomb, 

 but if there is a definite increase in 

 the occurrence of abortions, miscar- 

 riages, stillbirths, and abnormal prod- 

 ucts of conception, one may surmise 

 that this is related to the bombing— 

 although some of the effects need not 

 necessarily be genetic. Appropriate 

 control studies in other Japanese cities 

 are therefore of the utmost impor- 

 tance. 



The survivors of the bombing re- 

 ceived amounts of irradiation ranging 

 from negligible to just short of lethal. 

 It is impossible to say on a priori 

 grounds whether an adequate number 

 of people absorbed sufficient radiation 

 to produce enough dominant muta- 

 tions to result in detectable effects. 

 However, comparison of this situation 

 with the experimental data on infra- 

 human material suggests that these 

 effects, if detectable, will be small. 

 The median lethal dose for whole 

 body irradiation in man is probably 

 in the neighborhood of 500 Roentgen 

 units (Shields Warren. Physiol. Rev., 

 1944, 24:225-238). It is likely that 

 many individuals in Hiroshima and 

 Nagasaki who received high but sub- 

 lethal doses of irradiation sustained 

 other injuries which, in combination 

 with the radiation damage, resulted in 

 death. Thus, the mean radiation dose 

 received by the surviving population 

 will be lower than expected from a 

 consideration of the median lethal dose 

 alone. In terms of radiation genetics 

 this is a small exposure, expected from 

 data on animals to produce a fre- 

 quency of dominant mutations which 

 would increase the normal frequency 

 of abnormal offspring by so small a 

 proportion as to be difficult to demon- 

 strate. Large-scale studies, utilizing all 

 available material, plus accurate vital 



197 



statistics, are thus necessary if data of 

 value are to be obtained. In this con- 

 nection it is important to bear in mind 

 that the available children born to 

 parents who received significant 

 amounts of irradiation will probably 

 not exceed 12,000 or 13,000 within the 

 next 10 years. 



The Japanese had recognized the 

 importance of genetic studies and, 

 under great difficulties, were organiz- 

 ing a program in Hiroshima when the 

 Atomic Bomb Casualty Commission 

 arrived. They had planned to com- 

 pare the present and future frequency 

 of abnormal births in Hiroshima with 

 the frequencies reported in their med- 

 ical literature and vital statistics dur- 

 ing the prew^ar years. But it is by no 

 means sure either that the prewar 

 figures were sufficiently accurate or 

 that the present reporting of vital 

 statistics would be wholly effective in 

 detecting rare effects of the atomic 

 bomb radiations. It cannot be too 

 strongly emphasized that there is at 

 present absolutely no reliable evidence 

 on which to base any opinion concern- 

 ing the absolute or relative frequency 

 of congenital abnormalities among 

 children being born in Hiroshima and 

 Nagasaki. Unfortunately, a good deal 

 of misinformation is currently in cir- 

 culation. 



Two independent programs, one 

 Japanese and one American, would 

 involve needless duplication of effort. 

 A joint undertaking is therefore indi- 

 cated. In view of the fact that the 

 Japanese are actively attempting to 

 initiate genetic studies, it seems that 

 any American efforts which may ma- 

 terialize should contemplate coopera- 

 tion with the Japanese in an attempt 

 to ensure an efficient and satisfactory 

 program. The Neel report contains the 

 following seven specific recommenda- 

 tions as to the organization of a pro- 

 gram: 



