., .’ Bioassy and external exposure monitoring programs were initiated for Bikini Island residents in anticipation of the changing dietary situation, and with the realization that it was essential to do personnel monitoring on those individuals living on Bikini Island. Extensive external radiation monitoring was performed in 1975 through the joint efforts of Brookh’Lven National Laboratory and . Lawrence Livermore Laboratory. Data were collected using an environ- mental ionization chamber to quantify exposure rates, portable NaI scintillation survey meters to map the external radiation fields, a portable gamma spectroscopy system to defj.ne the major energy components of the external field and to determine energy dependence correction factors for the ion chamber, and LiF thcrmoluminc.scent dosimeters to measure long term integral exposures. External expo- sure estimates were developed based on these measurements and an assumed living pattern (GU 76, GR 79). Urine samples for radionuclide bioassay were collected during RIO.medical field trips to Bikini between 1.970and 1976 (CO 75, unpublished results). This program was reinstated by BNL Safety and Environmental Protection Division in 1978 with systematic 24 hour urine collections from all adult Bikinians. were used to calculate 90sr- g“y and 137C5- Urine bioassay results 137mBa body burdens and resultant radiation dose equivalents for all Bikinians from whom a satisfactory urine sample was obtained. Whole body counting was performed in 1974 and 1977 by the BNL Medical Department (CO 75, CO 77), and the pro~ram continued in 1978 2