Figure 25 demonstrates. the external exposure following the 1958 testing a-~ ties. Since return to Rongelap followed 3 years after the BRAVO contamination, thie series contributed in large part to the external exposure post return. SUMMARY The Castle BRAVO shot of March 1954 caused the contamination of the inhabited atolls Rongelap and Utirik. Evacuation from Rongel ap commenced 50 hours after detonation and frow Utirik 55 hours after detonation. During Jun: 1954 and June 1957 the return of the Utirikese andRongelapese; occurred tresper.~ tively. Body burden data for dosimetrically significant nuclides were obtained throughout the residence interval post return primarily by direct ip vivo gama spectroscopy and by indirect radiochemical analysis of urine and blood. psed in this analysis were representative of a declining continuous uptake fesine. Dietary decline of radioactivity inc lude | radioactive decay of the source and a conglomerate of other factorg which mighi have included increased use of imported foods and weathering of the source. |): ~ etary loss rate constants were estimated from sequential body burden data anil were comparable for both atolls. Variation in body burden history data for @ particular nuclide on a paiticular atoll was observed in whole body counting data and urine bioassay resuli + This was attributed principally to the statistical variation encountered when small groups are sampled from a heterogeneous group of body burdens in peopl, and in the case of urine bioassay additional variation was introduced during ite laboratory analysis of samples, Daily activity ingestion rates were determined for all measured radionuclides. In general, infants, children, and adults between 20 and 40 50 rae. a 1 ee gg fa ctw te aa GeCFLwe vet oJ 7 e@ + < santas “aes . sg a PEE 2 ete wets ronal, wo 2 aee Seem: ehpacedBackes ohes aaage The dosimetric models