Selection Criteria The whole Sody counting and urine anal-tical service programs area can ducted under contract with the J.5. Deparztment of Energy for individuals liviag on atolls or islands in the Marshall Islands chain which were radiolozically contaminated by the U.S. Mid Pacific Nuclear Weason Testing Program. Individuals currently particivating in the program are residents of Enewetak, Gjelang, Rongelap and Ucirix Atolls plus former rasidents of Bikini Atoll curtently residing on Majuro Atoll, Jaluit atoll and Kilt Island. Each atoll is monitored differently. At Rongelap and Utirik, the size or the population participating in the program is approximately 29 individuals per age and sex subgroup. There ara six subgroups consisting of male adulscs, adolescents and juveniles plus female adulcs, adolescents and juveniles. The nuaber 20 is the aumber of individuals required in the sample to provide an estimate of the mean body burden at the 90% confidence limit. Normally, the same population is sample overtime to determine any trends in the data. For the former Bikini Atoll population, individuals who resided on Bikini Island during the final two year residence intarval were nonitorad until July 1980 to follow the decline of 137Cs in their bodies. Speciai interest was given te individuals present on Bikini Island during the 3NL April 1973 field survey and to individuals who were present at the time of the Bikini population resetclement in September 1978. It is unlikely that these tadividuals will be monitored again relating to the 3ikini experience 1969-1978. However, persons participating in the repatriation of Eneu [Island which is to commence in 1981 will be monitored initially on a six month basis

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