358 high incidence of diabetes. Serum assayfor vitamin B,, showed generally high levels; the explanation was not apparent. Radionuclide body burden evaluation in the Marshallese people has been complicated byseveralthings. The people were evacuated from their island soon after the accident and did not return until 3 years later. During the 5 years since the original contaminating event, additional weaponstests held in the area have contributedto the fission products in the environment. Finally, since the diet includes a variety of imported foods, the people are not living in a ‘‘closed”’ environment, and therefore may not be rapidly approaching equilibrium with the environmentalfission products, as might be expected under other circumstances. Bodyburdens of gamma-emitting fission products (such as Cs’*’ and Zn**) were measuredin a whole-body counter and checked byradiochemical analysis of urine specimens. Body burdens of Sr°* were estimated from urinary excretion as determined by radiochemical analyses. Both the external dose measurements on RongelapIsland and the levels of radioactive isotopes in the food on the island indicated that some increase in Cs'37, Zn**, and Sr®° body burdens was to be ex- pected when the people returned there in 1957. The Cs'*’ body burden in 1958 was about 0.68 pC, about 60 times as great as in 1957, and the urinary Cs**” Jevel rose by a factor of 140; the mean body burden for 1959 was 0.57 uC. The mean bodybur- den of Zn®* estimated from whole-body counting data was, in 1958, after the return to Rongelap, 0.36 pC, 8 times as high as in 1957, and 0.44 pC in 1959. Thus, whereas the Cs'*” levels appear to have reached a maximum and actuallyto have dropped in 1959, the Zn® levels have showna continued increase which is probablyrelated to the long biological half-life of the latter. The Sr*° level in 1958 estimated from excretion data was 2 mpC, about 20 times as high as in 1957 before the return to Rongelap. The estimated body bur- den in 1959 increased to 6.0 muC, about 20% of the estimated ultimate equilibrium value. Little of the body burden of the exposed group is apparently due to their initial exposure, since at presentthereis little difference between the levels of the exposed and unexposed populations living on Rongelap Island. Whenthese three isotopes have reachedtheir estimated equilibrium values, the body burdenswill still be of small significance in terms of radiation hazard. i This studyof the internal contamina(ion ofthe Marshallese has provided information (1) on the movement of Cs'3", Zn**, and Sr*from the en- vironment to man; (2) on the rate of equilibration of these isotopes with the environment; and (3) on the discrimination factors between food and man. DOE ARCHIVES IMPORTANCE OF MEDICAL SURVEYS The Japanese populations of Hiroshima and Nagasaki being studied by the Atomic Bomb Casualty Commission and the Marshallese population of Rongelap comprise the only large groups of people exposed to acute doses ofionizing radiation. The two studies parallel each other but differ in certain importantrespects. The smaller number of people in the Marshallese population and the paucity of vital statistics make statistical analysis of data on this group much moredifficult. However, the Marshallese studies have the advantages that the dose of radiation received by the people is better known; that the findings duringthe early, acute period after exposure are well documented; and that the people did not suffer from trauma, thermal] burns, or marked psychic disturbance, al- though theydid have the complications of beta burns and internal absorption of radionuclides. Studyof both groups has yielded valuable information on the acute effects in human beings of radiations from atomic bomb detonations. Examinations for the more subtle late effects of radiauon exposure are nowreceiving considerable emphasis. In the case of the Japanese, increased incidence of leukemia and possibly other malignancies as well as cataracts alreadyhas been reported. In viewof this finding, the next 5 years will be the critica] period for the development of leukemiain the Marshallese. Animal experimentation has indicated the possibility that still other late effects mayoccur in the humanbeing such as premature aging, shorteningoflife span, increase in degener- ative diseases, genetic changes, etc. Therefore, con- tinued careful examination of these populations is extremely important in order that such effects maybe documented, and therapeutic procedures instituted wherever possible, should such effects develop. In addition, in the case of the Marshal- lese, continued evaluation is indicated of the in- fluence of persisting lowlevels of radioactive materials on Rongelap Atoll on the body burdensof radionuclides of the people living there. ae ee ee ee eee ee ee eee ee