scores into 5-year age groups was doneto reduce possible errors due to the uncertaintyof the exact age of someindividuals. DENTAL SURVEY Dental examinations were carried out on most of the people on theisland. particularlythose requiring dental attention. LABORATORY PROCEDURES Hematological Examinations Complete routine blood counts were carried out with repeat counts on anvpersons showing abnormalities. White blood counts and red blood counts were obtained with the electronic Coulter, which again proved to be a verysatisfactory instrument for examinationsofthis type in the field, Differential counts were performed in the usual manner after staining with Wright’s fluid. Platelet counts were done by phase microscopy. Hemoglobin was determined by the cvan-hemoglobin technique with the Lumitron colorimeter. but only 49 deter- minations were possible because of breakdown of the Lumitron. Hematocrits were obtained by the microhematocrit method. Reticulocyte counts were carried out in 16 people who had low hemoglobin values. Serum proteins were determined with the Hitachi refractometer. Blood and serum samples for certain studies to be described below were collected and kept underrefrigeration and finally shipped back for study. Urine Analysis Routine urine analyses were done on almostall people receiving physical examinations. Thesein- cluded determinations of protein and hyperglucosuria by reagent paperstrips. * Serum Examinations for Calcium, Phosphorus, and Protein Bound lodine These studies were carried out in six of the children in the exposed group of the growth and development studv.** *Combistix, Ames Company, Inc., Elkhart, Indiana. **We are grateful to Drs. D.D. Van Slvke and L.V. Hankes of this Laboratoryfor carrying out these determinations. Serum Iron Serum iron determinations were performed in the 16 people who were found to have an anemic tendencyto see whether deficiencyof this element might be responsible. * Serum Gamma Globulin Studies In previous surveys extensive studies have been made on certain genetically inherited character- istics such as blood groupings. haptoglobin and transferrin, hemoglobin types, glucose-6-phosphate dehydrogenase activityof red cells, B-amino-iswbutyric acid excretion, etc. One type of gamma globulin had not been previously studied in the Rongelap people, and 149 sera were collected during this survey for determination of the Gm tvpe of gamma globulin. The determinations were car. ried out by Dr. A.G. Steinberg of Western Reserve University and his collaborators and reported along with the same observations on other popula- tions,” the methods used werealso reported. Radionuclide Body Burden Evaluation The methods used in the radionuclide bodys burden evaluation are described later in a separate section. Results and Discussion The census of Rongelap people in March | was 334, of which 81 were in the exposed yvroup (including + children exposed in udero at the time of the accident); 33 were children of exposed parents. and 220 were unexposed people: Table | shows their location. In Table 2 the population is broken down according to percent distribution in various age groups and comparedwith that of the Mar- shall Islands as a whole for 1948-1950 and ol the United States for 1960. The table also shows the median age. The lower median age of the Murshallese would tend to support the impression that their life span is shorter than that of people in the continental United States, but there has been a “population explosion” in those islands which might accountfor this discrepancy. *We are erateful to Mrs. Ruth Saart of South Nassau Coun munities Hospital, Rockville Centre, L.1., N.Y. for cares oni cuit the serum iron determinations.