Figure 25 demonstrates.the external exposure following the 1958 testing se- Since return to Rongelap followed 3 years after the BRAVO contamination, ries. this 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 atolle Rongelap and Utirik. Evacuation from Rongelap commenced 50 hours after detonation and from Ucirik $5 hours after detonation. During June 1954 and June 1957 the return of the Utirikese and Rongel gpese, occurred resper- tively. Body burden data for dosimetrically significant nuclides were obtained throughout the residence interval post return primarily by direct in vivo gamna atts * spectroscopy and by indirect radiochemical analysis of urine and blood. 3 4 The dosimetric models peed in this analysis were representative of a declining continuous uptake fosine. Dietary decline of radioactivity ine luded $ Ast a radioactive decay of the source and a conglomerate of other factorg which mighr + have included increased use of imported foods and weathering of the source. [)!- 10 if Ryd i etary loss rate constants were estimated from sequential body burden data ani oly re it ay Variation in body burden history data for a particular nuclide on a paitic~ ular atoll was observed in whole body counting deta and urine bioassay resulis. 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 the laboratory analysis of samples. Daily activity ingestion rates were determined for al] measured In general, infants, children, and adults between 20 and 40 50 naan at he eee vans PS ee a he erewie AN tee . ts f This was attributed principally to the statistical variation encountered when radionuclides. beat72 rt >i i + 2p. were comparable for both atolls. rouytl whe