48 burdensof Sr®° have reached equilibrium with the environmental Sr*’. Little or none of the present body burden of the exposed group can beconsidered residual from their initial exposure, since little difference has been noted between the body burdens in exposed and unexposed populations living on RongelapIsland. The possible relation of internal absorption of radioiodinesinitially in the fallout to the recent development of thyroid nodules has been referred to above. Noothereffects of such exposure have been detected. OTHER EXAMINATIONS Ophthalmological examinations showed no clear-cut evidence of radiation-induced changes in the eyes. Slit-lamp studies revealed no increase in incidenceof lens opacities which might beattributed to radiation. Cytogenetic studies of the chromosomesof leukocytes and peripheral blood cultures obtained in 1964 are in progress and will be reported at a later date. Anthropometric studies revealed that young adult Rongelap males were superior in muscular development compared with many populations. This was not true, however, for the young adult females. Blood volume and red cell mass determinationsusing tritiated water and Cr** revéaled values in the Marshallese which were considerably lower than found in American Caucasians. However, there is some indication that Americanslivingin the Islands for more than one year mayalso haveslightly lower values. This finding will be further investigated on future surveys. Protein boundiodine studies during the past two years confirmedthe previousfindingsoflevels higher in the Marshallese than generally found elsewhere. No explanation is apparent. Folic acid levels were found to be somewhat low in the Rongelap population and probably reflected low dietary folic acid. Serum studies for the Ag system reveal that the Rongelapese comparedwith other world populations have a high frequency of C.deB. antiserum reactors and a low frequency of New York antiserum reactors. Acknowledgments The cooperation of many agencies and persons was necessary to carry out these surveys successnN authors are deeply grateful to many 9006831 individuals, too numerous to name, for valuable assistance. Manyofficials of the Atomic Energy Commission, particularly Dr. Charles L. Dunham, Dr. H.D. Bruner, and manyoftheir staff of the Division of Biology and Medicine, and Mr. W.H. Brummett, Jr. and Mr. G.P. Steffy of the San Francisco Operations Office were most helpful in the coordination of arrangements with various governmental agencies and in supporting these surveys in every possible way. Wearegrateful to the officials of the Department’ of the Interior, particularly to Mrs. Ruth Van Cleve andtheofficials of the Trust Territory of the Pacific Islands, including the High Commissioner, Mr. M.W.Goding; the Director of Medical Services, Dr. J.W. Sampson; the District Admin- istrator for the Marshall Islands, Mr. Peter Coleman; the Director of the Marshall Islands Memorial Hospital, Dr. John Iaman, and members of his staff; and the Representative of the High Commissioner at Kwajalein, Mr. R. McKay. Mr. Don Davis and his crew of the Trust Territory Ship Ran Anim and Mr. L. Roberts and the crew of the Roque were most helpful. Asin the past, the Department of Defense, particularly the Departmentof the Navy, contributed most vitally to the mission. The Pacific Missile Range Facility at Kwajalein was of great assistance in furnishing necessary airlifts and materials to be used on the survey. Drs. G. Temple, C. Cunnington, and Y.C. Smith at the Kwajalein Hospital were extremely helpful. Drs. L. Donaldson and E. Held at the University of Washington haveaided in coordination of their studies with these. Weare grateful to Dr. K. Tsuhamoto, Director of the Japanese National Institute of Radiological Sciences, and to Dr. Dunham for arranging the visit of the senior author to Japan to observe the annual examinationsof the irradiated Japanese fishermen and for having Dr. T. Kumatorivisit Rongelap for the 10-year survey. At Brookhaven National Laboratory, contributions were made by manyindividuals in many departments including Medical, Instrumentation and Health Physics, Photography and Graphic Arts, the Shipping Section, and others. We are grateful to the following people for their support and advice: Dr. Maurice Goldhaber, Director; Dr. J.B.H. Kuper, Chairman of the Instrumenta-