These studies were of interest in evaluating the homogeneity of the Rongelap people and learning something of their anthropological background. Blood grouping studies. Studies of the blood groupings and genedistributions in the blood of 129 Marshallese were carried out by Dr. L.N. Sussman of the Beth Israel Hospital, New York City. The following systems were studied: ABO, MN, Rh-Hr, and Duffy, Kell, and Diegofactors. Haptoglobin studies. The method of Smithies was used, in which electrophoresis is carried out with a starch gel slab as supporting medium.” This analysis was made on 126 Marshallese blood samples by Dr. B.S. Blumberg of the NationalInstitutes of Health, Bethesda, Maryland. Hemoglobin types. The determination of hemoglobin types was made on 45 Marshallese blood samples by the method of Smithies" (starch gel zone electrophoresis). These studies were carried out by Dr. R.L. Engle, Jr. and Dr. G. Castillo of the Cornell University MedicalCenter, NewYork, N.Y. Plasma proteins. Plasma protein determinations were carried out on all sera by the proteinometer technique. Thyroid metabolism. In view of the exposure of the thyroid glands to radiation from the internally absorbed radionuclides, the metabolic state of the thyroid gland wasofinterest. These studies were madeby Dr. J.E. Rall at the National Institutes of Health, Bethesda, Maryland. Proteinboundiodine determinations were carried out on 36 people in the exposed group and 24 in the comparison population. Butanol-extractable iodine content was measured in three people in each group, and thyroxine-binding proteins were determined in 12 persons in the comparison population.’ Serum vitamin B,, concentrations. In view of the general tendency to anemia in the population, serum vitamin B,. contents were measured to see whether they could be related to anemia. These determinations were carried out on thesera of 44 exposed Marshallese and 58 unexposed by Dr. whetherparasitism might be responsible for these findings. Because of the generally accepted view that blood pictures of anemia andeosinophilia are more likely to be associated with helminthicrather than with protozoaninfectionsof the intestinal tract, the methods used were directed primarily to detecting the former. The Beaver method of egg counting’ and formalin-ether concentration” was used to obtain quantitative information on helminth infections. This is a simple, direct technique which is also useful in revealing protozoan infections, particularly when trophozoites are present. In addition,all stools were concentrated by the formalin-ether method to pick up infections too light to be detected by direct examination. One stool specimen per person was examined in each of 69 exposed persons and 112 unexposed. Specimens were broughtto the laboratory shortly after being passed, and were generally examined within | hr. The methods used probably revealed % to % of the protozoan infections and perhaps 80% of the helminth infections likely to be found in these individuals had they been subjected to repeated examinations. Serum and food sodium and potassium deter- minations. Because the Marshallese seem to have generally lower blood pressures and in view of the possibility that salt intake bears a causal relationship to essential hypertension in humans,'':!? correlations between salt intake and incidence of hypertension were investigated by Dr. L.K. Dahli of Brookhaven National Laboratory. A morning sample (before breakfast) of urine was obtained on 13 exposed and 14 unexposed persons and analyzed for sodium andpotassium level by flame spectrophotometry. A sample prepared meal was also obtained for similar analysis of the several items. Determination of Body Burdens of Radionuclides Radiochemical urine analyses. Urine samples, 24-hr as well as cumulative, were collected from 15 Rongelap people for radiochemical analyses D.W. Watkin of the National CancerInstitute, National Institutes of Health, Bethesda, Maryland. carried out underthe direction of Maj. K. Wood- specifically for vitamin B,, assay in serum.* this survey about 200 people were examined in the whole-body counter (21-ton steel room constructed at Brookhaven National Laboratory and carried out to the Islands) for body levels of gamma emitting nuclides. Unfortunately, the The method used was a modification of the USP XV Lactobacillus lecchmannit method developed a Lal J cD Csi cm Intestinal parasite survey. The generally high eosinophil counts and tendency to low hematocrits noted in both the exposed and unexposed Rongelap people led to an intestinal parasite survey to see ward and Col. J. Hartgering at the Walter Reed ArmyInstitute of Research, Washington, D.C. Whole-body gamma-ray spectroscopy. During