NATIONAL INSTITUTE OF RADIOLOGICAL SCIENCES 9-1, 4~chome, Anagawa, Chiba-shi, Japan Furthermore, considering that the rescue operation was done 18 years ago, I don't think that the treatment without giving them inorganic iodine was inadequate. Additional comments on: 1. The body burden of the Rongelapese and Utirikese is considered to have been increased by the fallout due to the following test explosion after their return to Rongelap and Utirik. fallout was not so much to injure them, However, the amount of At that time, namely in 1954 and 1957, if they found some benefit in returning to their home islands and wished to live there, I feel that it was not necessarily wrong to have made them return. 2. On the exposed Japanese fishermen the cytogenetical studies have been continued since 1964 by the staffs of our Division. The chromosome analyses are done by 2 day culture of peripheral lymphocytes. Some of the results are summarized in the attached paper. We found intimate correlation between the frequency of stable chromosomeaberrations and estimated external dose or minimum value of neutrophils which indicates the severity of early radiation syndrome. According to the report by Lisco and Conard (BNL 50029, p. 137), correlation of chromosomal aberrations and severity of early radiation P16