63 hypothyroidism in the two most growth-retarded bovs with subsequent growth response to thyroid hormone treatment. Thyroid function tests in cases with thyroid abnormalities also indicated reduced thyroid function in someother children. Preliminaryindicationsare that thyroid hormone treatment instituted in the exposed population in September 1965 is having a beneficialeffectin reducing thyroid nodules and stimulating growth of children. The importance of these thyroid developments in the Marshallese is discussed. OTHER STUDIES Hematological studies show that the leukocyte and platelet levels of the peripheral blood of the exposed Rongelap people seem to have recovered to levels equal to those of the unexposed population. The blood levels of the Utirik population showed no obvious abnormalities and were similar to those previously noted. Chromosome studies of white cells of 51 peripheral blood cultures showed a low incidence of 2-hit burden and about “oeo this much for *"Co body burdens. These levels are about the same as orslightly lower than those reported previously for the 1961 survey. Urine specimens werealso ana. lyzed radiochemically for *°Sr and '*'Cs. The *°Sr levels remain nearly the same as those found in 1961. In a comparison of the '*'Cs excretion rate with the body burdens, a mean fractional excretion rate of 0.00553/day was found. Acknowledgments The cooperation of many agencies and persons was necessary to carry out these surveys successfully. The authors are deeply grateful for valuable assistance to many individuals too numerousto name. Weare particularly grateful to the people of Rongelap and Utirik Atolls for their coopera- ogy and Medicine, and Mr. W.A. Bonnet and Mr. Neil Rassmussen of the Honolulu Operations Of- tion of several new parameters (vibratory sense, fice, were most helpful in coordination of arrange- ESTIMATION OF INTERNAL BODY BURDENS OF RADIONUCLIDES ee 1954 and the unexposed residents wereindistin- guishable by this method, both groups showing elevated '''Cs body burdens of 10 to 20 nCi;kg body weight, orslightly less than 1 wCi total body aberrations in the exposed people which was quite significant in view of the absence of any such aberrations in the comparison population. Blood volume and red blood cell volume studies showed that people of Rongelap have significantly reduced levels as compared with Americans. Caucasians living in the Marshall Islands did not generally show this phenomenon. A ging studies have been repeated with the addilight extinction test, body potassium levels, and blood serum cholesterol) and with more refined statistical analysis. Curves of response for each - aging parameterand anover-all biological age score curve are presented. No significant increase in aging effects in the exposed population compared with the unexposed population could be detected. The over-all correlation of the biological age scores with chronological age was good. It was concluded thatthe tests employed may not have been sensitive enoughto detect subtle effects of aging at this exposurelevel. ene Nal (Tl) crystal in a portable shadow-shield type of counter. The Rongelap residents exposed in In the 1965 survey whole-body counting was done on 179 people with an 11%-in.-diameter I0083449 tion in these examinations. Manyofficials of the Atomic Energy Commission, particularly Dr. Charles L. Dunham and Dr. H.D. Bruner andtheirstaff of the Division ofBiol- ments and in supporting the surveys in every way possible. Weare grateful to the officials of the Department of the Interior, particularly Mrs. Ruth Van Cleeve and the officials of the Trust Territory of the Pacific Islands, including High Commissloners Mr. W.M. Goding and Mr. W.R. Noorwood; the Acting Director of Medical Services, Dr. L.A. Howe; the District Administrator for the Marshall Islands, Mr. Dwight Heine, and his Assistant, Mr. Danny Akimoto; the Director of the Majuro Hospital, Dr. John Iaman, and members of his staff; the Trust Territory Representative at Kwajalein, Mr. R. McKay, and Dr. Ezra Riklon at the Ebeye Hospital; all were most helpful. The Pacific Missile Range Facility at Kwajalein was of great assistance in furnishing necessaryairlifts and materials. Mr. Frank Granich and others