Figure 9. Typical Marshallese living conditions at Utirik. tal examinations were carried out on all persons >40 years of age. This included in the case of men palpation of the prostate gland. Radiographs of the chest and other parts of the body were ob- tained as indicated. Hematological data were obtained and were available for evaluation. ’ In detection of possible leukemia (or preclinical evidence of incipient leukemia) the lymph nodes and spleen were carefully examined; hematological data were analyzed, including routine hemograms and percent basophils in 4000 white cell count; and alkaline phosphatase smears of the white blood ceils where done wereavailable for review. LABORATORY PROCEDURES Hematological studies included white cell counts with differentials, red blood counts, hematocrits, hemoglobins, piatelet counts, serum proteins, blood smears for alkaline phosphatase, and baso- phil countstudies. Techniques for these procedures have been described in previous reports.''? Bone marrow aspirations for differential study werecollected on 4 exposed and 2 unexposed individuals. Considerable effort was spent on chromosome studies in the past two surveys. Of particular interest was the possibility of studying the chromosomes of cells cultured from the “beta burn”’ areas of the skin. Some 50 skin biopsies were obtained and successfully grown in most cases. However, contamination of these cultures occurred under the field conditions of these studies, and unfortunately all were lost before they could be broughtto the stage of chromosomepreparations. Chromosome studies of peripheral blood cuitures, however, have been considerably more successful. During 1963 a large numberof bloods were cultured suc- cessfully. However,the final chromosomespreads in Many cases were not completely satisfactory, and the study was repeated during the 1964 survey. At this time successful 2- and 3-day blood cultures were obtained on 64 exposed people and 11 unexposed. Excellent growth and chromosome spreads were obtained, and the slides are now being evaluated.* Sera were collected both years on most indi- viduals, and the following examinations were carried out in U.S. laboratories: prote:n-bound iodines on 9 exposed and 8 unexposed people and a few blood sugar determinations; ** serum folic acid levels on 52 exposed and 85 unexposed peopie.*** During the 1963 survey 38 urine samples were collected, and during the 1964 survey 27 sampies, for radiochemical analyses.” Most of these were 24-hour samples, though several pooled samples were obtained. Most were from people living on Rongelap Island, but some were obtained at Ebeye. “Assisting in these studies are Dr. Shields Warren and Dr. HermannLisco at the New Engiand Deaconess Hospicai. Miss ’ Agnes Stroud at Argonne National Laboratory, and Miss Patricia Crurnrine at the Women’s Medical College, Philadelphia. We are grateful to Dra. Michael Bender and Carolyn Gooch of Oak Ridge, W.M. Court-Brown of Edinburgh, Scotland, and Kurt Hirshorn of New York University for advice. **Dr L.V. Hankes and the Clinical Chemistry Group in the Medical Department of Brookhaven National Laboratory were responsible for these analyses. ***Dr. Thomas Lynch, Hackensack Hospital, Hackensack, N. J., did the folic acid determmations. tDr. Edward Hardy and others at the AEC Health and Satetv Laboratory, New York, N.Y., carried out these analyses.