PROTRACTED EXPOSURE TO FALLOLT ttoring team stationed at nearby Rongenk Atoll. the 64 residents of Rongelap Atoll and an additional 18 Rongelapese who were gathenng food neurby at Snfo Isiand. Ailinginae Atoll. were removed to Kwajalein Atoll. some 300 km to the south on 3 March 1984. Or March 3 anc 4. the more distant 157 Ltink Atoll residents were moved. Durmng the first few weeks anc at jeast once every sear from 1957 to the present. a Brookhaven Nationa! Laboratory (BNL: medical team. orgamized bv the AEC (and ns successor organizations; and tne Department of Defense. has regularly conducted medical exammations to monitor the health and to evaluate the radiobiological status of persons affected by tropospheric failout from the BRAVO nuclear test. Reports of their findings including whole- body counting data and urine activity concentration data are available in Cr56, DuS6, Du”. Wo59, CoS6. Co5&. Cod9, Co60. Co62, Co63. Co65, Co6"?, Co7G. Co7S and Co&80a. These reports may be consulted in order to easily follow the information presented here. Esti- mates of the immtial body burdens of internal emitters were presented in Co55, Coh56 and Coh60 and will not be discussed here. A reassessment of thyroid absorbed dose from the iniual 1954 exposure is currently being made and will be reported in a separate study. Since April 1978. the bicassav program and whole- body counting studies have been performed by members of the Safety and Environmental Protection Division of BNL. Reports of their findings maybe found in Gr77a. Gr77b, Le8Ga. Le80b. Mi80, Mi8l and Na80. The report by Lessard (Le80b) contains more detail on the development of the equations used here. The Utirik and Rongelap inhabitants were returned to their homeatoll in June 1954 and in June 1957, respectively. The earlier repatriation of Utink Atoll was based on the low measured level of external radiation exposure overa threemonth observation period. The Utink population was subsequently examined by a Brookhaven medical team during 1957; 144 people received comprehensive physical examinations. In 1957, the Rongelap inhabitants were also returned to their atoll to occupy new homes, community structures and otherfacilities which had been constructed during their three-year 9012603 residence at Mauro and Kwajalein Atolls. Following the 1987 medical survey. Measurements were made on two men from Lunk Atoll using the whole-bods counter at Argonne National Laboratory (ANL». Radiochemical analyses of the:r urine sampies were also made. Four per- sons from Rongelap Atoll also visited Argonne for whole-body counting in 1957. In addition. pooled urine samples from both atoll popu- lauons were anaivzed radiochemucally for "Cs and “Sr. The dody burdens measured at ANL were corrected for 10 davs of biologic elim- nauon and radiologic decay to estimate the body burden while living on the atoll. Startimg in May 1958. Conard and Cohn (CoSG), measured whole-body levels of Cs. “Zn and *Co in about 100 Rongelap adults, adolescents and juveniles as part of the Brookhaven medical examination program. A portable whole-body counter with a standard chair geometryin a shielded steel room was employed (Cones). Whole-body counts were obtained in the Rangelap and Lturnk populations in 1959 (Cohé0). 196) 1Co62). 1965 (Co67). 1974 (Co7Si and 1977 (Co80a). The counting geometry was converted to a scanning type shadowshield geometry starting in 1968 (Co67). Urine samples were also collected in these surveys and in additional medical surveys conducted in in- tervening years. The samples were analyzed for their radiochemica} content by both USNRDL and the NYO-AEC Laboratones. From 1978 to the present time. whole-body counung measurements were performed with the bed-type shadow shield whole-body counter (C067). In 1980, a standard chair geometry was once again used. All three counting systems were intercalibrated and also calibrated against the large BNL 54-detector whole-body counting facility to ensure consistency of the whole-body counting data over the past 28 yr. A summary of the sequence of events affecting the whole-body and urine activity measurements on the Rongelap and Utink people is given in Fig. !. The detonation of BRAVO in 1954 was followed by the evacuation of Ron- gelap Atoll at 2.2 days post-detonation and then Utink Atoll at 3.5 days post-detonation. After a three-month wait, the Utink people returned in June 1954 and after three years Rongelap Atoll was rehabilitated and occupied in June 1957. mee gene re ee Siz