Fe ESLT TT xe aLA ‘ tye nye as 1, 1 3 a t De \ ‘ Dye tT: 5 ‘salt tel ey toy a wing ge Cyt ae Horta! of urine activity concentration variability, there was a 60% probability that 4 we L cet bee Sabo ty i al Py ty Pee Subic. the male value for Ke would’ be‘different from’ the female value by’ the factor observed. Thus differences in the derived activity ingestion rates and dose ‘ . e e 4 equivalents were not significant. Figure 14 shows a semi-log plot of the 65 “Zn and rate histories for adults on Rongelap. gt. 13?"Ca activity’ ingestion A curve was drawn between’ points, and the appearance of an increasing >’ Cs ingestion rate duringthe1960's' indicated the possibility of another contaminating event. The Hardtack Phase1 series was conducted just prior to the observed increase in the curve and fallout from the Cactus, Yellow Wood, and Hickory experiments detonated at Bikini and Enewetak would have reached Rongelap. However, several observations fail to support the conclusion that recontamination was significant. These are as follows: 1) the increase in !3’cg ingestion rate was not in conjunction with an increase of 6570; however, since 6575 is an activation product it may have not been produce} in the same proportions. 2) The peak 1370, body burden at Utirik occurred nearly three years after the initiating event, Castle BRAVO, while the peak bo:ly burden at Rongelap followed six years after the potentially contaminating experi - ments of the Hardtack series in 1958. 3) The activity ingestion rate at Utirik demonstrated a continuously declining pattern versus the humped pattern observe. at Rongelap. This occurred even though there was an equal external exposure rate history following the Hardtack series as measured by the U.S. Public Healtl Service on both Rongelap and Utirik (Un59). 4) The peak exposure rate on Rongelap following the Hardtack series was 10,000 times less than the peak expo~ sure rate following BRAVO. These facts suggest that the Hardtack series was woi a major factor influencing the Rongelap body burden patterns. Thus it is postulated that body burden variations were caused by travel away from the atv] | 29 et AMET _ 3