48 burdens of Sr’* have reached equilibrium with the environmental Sr”. Little or none of the present body burden of the exposed group can be considered residual from their initial exposure, since little difference has been noted between the body burdens in exposed and unexposed populations living on Rongelap Island. The possible relation of internal abeorption of radioiodines initially in the fallout to the recent development of thyrosd nodules has been referred to above. No other effects of such exposure have been detected. Ophthalmological examinations showed no clear-cut evidence of radiation-induced changes in the eyes, Slit-lamp studies revealed no increase in incidence oflens opacities which might be atunbuted to radiation. Cytogenetic studies of the chromosomes of 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 Rongeiap males were superior in muscular development compared with many populations. This was not tru+, however, for the young adult females. Blood volume and red cell mass determinations using tritiated water and Cr*' revealed values in the Marshallese which were considerably lower than found in American Caucasians, However, there is some indication that Americans living in the Islands for more than one year may also have slightly lower values. This finding will be further investigated on future surveys. Protein bound iodine studies during the past two years confirmed the previous findings of levcis higher in the Marshallese than generally found elsewhere. No explanation is apparent. Folic acid levels were found to be somewhat low in the Rongciap population and probably reflected low dietary folic acid. Serum studies for the Ag system reveal that the Rongelapese conipared with other world populations have a high frequency of C.deB. antiserum reactors and a low frequency of New York antiserum reactors. individuals, too numerous to name,for valuable assistance. Manyofficials of the Atomic Energy Commis- sion, particularly Dr. Charles L. Dunham, Dr. H.D. Bruner, and manyo.their 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 possuble way. Weare grateful to the officials of the Departmentof the Interior, particularly to Mrs. Ruth Van Cleve and the officials 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 Administrator for the Marshall islands, Mr. Peter Coieman; 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 Anam and Mr. L. Roberts and the crew of the Roque were most helpful. Asin the past, the Departmert 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 airiifts 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 have aided 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 examinations of the irradiated Japanese fishermen and for having Dr. T. -.umator visit Rongelapfor the 10-vear survey. At Brookhaven National Laboratory contnbutions were made by many individuals in many de- Acknowledgments The cooperation of many agencies and persons was necessary to carry out these surveys successfully. The authors are deeply grateful to many partments including Medical, Instrumentation and Health Physics, Photography anc 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-