an a 3 INTERNAL. IRRADIATION <i den for 1959 was 0.57 uC. The mean body burden of Zn" estimated from whole-body counting data y Radiochemital sags was, in 1958,after the return to Rongelap, 0.36 uC, ples of the exposee Bg 8 times as high as in 1957, and 0.44 uC in 1959. Thus, whereas the Cs!’ levels appear to have absorption of radigas brought about largpe ing conta extent through Soe ang Duringsthe first few - days when thebody levels were at their highest, the maximum peFinissible concentrations were approached or slighty exceeded only itt the 1 aseCof strontium-89 @nd theisogspes of iodine. Feathed a maximum andactuaily to have dropped in 1959, the Zn*’ levels have shown a continued inerease which is probably related to the long bio- loiiBal half-life of the laéter. TheSr® level in 1958 estimated from excretion data was 2 miyC, about 20.times as high as in 1957 before the return to Rongelap. The eétimatealbody burden in 1959 in- = “Yeveased to 6.0: myC, aboug,20% of the estimated centrations were beliéVed to be too lo ultignate equilibrium value. Little of the body burden‘of the exposed group if apparently dueto their .. Mygoal exposure, since at Present there is little dif- anyserious effects. ‘BodyJevels fell ae by 2 and 3 years poseexposure. they were-far. be- low the accepted aximum perm, months activity in the urine was’ relydet: the men who died showed 3.7 sree9p. i eee ES) uilibrium values, the body cda calcium. Beginning.in 1937, gamma spectrosg aea byuse of a low-levelcoutiting chanyber was added__: 3 ‘eats! smallnificancein termsof rifee to the techniques ofbadioghefilical analysis. The” return of the Rongetapese.to thetr : <<) = tabdaede hOB (which after careful survey was consideredsafe for OTHER STUDIES active contamination) wasreflected in a rise in their body burdens and increased urinary excre- grouping studies in the Marshallese showed a rela- habitation, despite a persisting low level of radio- tion of certain radionuclides. During the years since the original contaminating event, additional weapons tests held in the area have contributed to the fission products in the environment, 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 circum- stances. Body burdens of gamma-emittingfission prod- ucts (such as Cs'** and Zn **) were measured in a whole-body counter and checked by radiochemical analysis of urine specimens. Body burdens of Sr'’ were estimated from urinary excretion as determined by radiochemical analyses. Both the external dose measurements on Rongelap Island and thelevels of radioactive isotopes in the food on the island indicated that some increase in Cs'*’, Zn”°, and Sr*® body burdens wasto be expected when the people returned there in 1957. The Cs'3” body burden in 1958 was about 0.68 uC, about 60 times as great as in 1957, and the urinary Cs"? level rose by a factor of 140; the mean body bur- Studies ofgenetically inherited characteristics. Blood tively high B gene frequency, a high N genefrequency, an extremely high R' gene frequency. and total absence of Kell and Diego factors. These characteristics differ from those of Polynesians and suggest relationship with Southeast Asians and Indonesians. Haptoglobin studies showed the trequency of the Hp’ gene to be higher than in European populations thus far tested and consistent with populations living near the equator. The distribution of haptoglobin types showed the population to be relatively homogeneous. 7ransferrms in all sera were type CC, the common European type. B-Amino-iso-butyric actd urinary levels showed the Marshallese to be the highest excretors of this acid of any population thusfar reported. Levels in the exposed group were about the sameas in the unexposed group, and nocor- relation was found with body burden level of radionuclides; this indicates that there is probably no correlation with radiation exposure. Hemoglobin types were considered normal. Szckling tests showed no sickling tendency in any of the people. Glucose-n- phosphate dehydrogenase of the red cells appeared to” be deficient in the Marshallese. Considerable cau-