ment data during the twenty-three year residence interval. The results indicate that because of urine activity concentration variability, a probability of 6 out of 10 existed such that the male value for Ke would be different from the female ‘value by the factor observed. Thus differences in the derived activity inges- tion rates and dose equivalents were not significant. Figure 14 shows a semi-log plot of the 6574 and 1370, activity ingestion rate histories for adults on Rongelap. A smooth curve was drawn between points and the appearance of an increasing 1376, ingestion rate during the 1960's indi- cates the possibility of another contaminating event. The Hardtack Phase I se- ries 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 sup- port the conclusion that recontamination was sipnificant. These are as follows: 1) the increase in !3’¢s5 ingestion rate was not in conjunction with an increase of 65 20 however, since 6 on is an activation product it may have not been produced in the same proportions 2) the peak 1375 body burden at Utirik occur red nearly three years after the initiating event, Castle BRAVO, while the peak body burden at Rongelap followed six years after the potentially contaminating experiments of the Hardtack series in 1958 3) the activity ingestion rate at Utirik demonstrated a continuously declining pattern versus the humped pattern observed 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 Health Service on both Rongelap and Utirik (Un 59). These facts suggest that the Hardtack series was not a major factor influencing the Rongelap body burden patterns. Thus it is assumed that persons who had body burdens siynificantly different from the mean body burden for the population 14