1 52 Table 33 Urinary Sr*° Levels, in ppC/1, of Marshallese, 1959 Males Age 1-15 Rongelap exposed Rongelap unexposed Ailingnae Utirik Ebeye Females Age >15 2.4 (2)* 7,142.0 (3) - Age I-15 Age >15 +5.1 (8) 72.8 (9) 3.9 (2) - 3.4 42.2 (9) 4.2 42.3 (6) +0.9 (5) 0.56+0.37 (4) 3.9 (1) - 2.5 (2) 0.70+0.70 (3) (t) - - 3.0 (1) *The numbers in parentheses are the numbers of people in the groups. Table 34 Cs'*? Body Burdens, in muC/kg, of Marshallese as Measured by Whole-Body Gamma Spectroscopy, 1959 Males Rongelap exposed Rongeiap unexposed Ailingnae Utirik Females Age 1-15 Age >15 Age 1-15 Age >15 12.4+6.2 (9)* 11.824.8 (20) 8.9 (2) 14.2-5.1 (10) 14.02%4.7 (37) 11.5%3.6 (4) 11.3%2.7 (12) 9.92.1 (15) 10.0%3.1 (4) 1102:3.4 (16) 9.8>=2.8 (33) 114445 (5) 4.61.2 (14) 4.51.6 (15) 4.51.9 (14) 3.61.3 (15) *The numbers in parentheses are the numbers of people in the groups. on an average 24-hr urine output of 1660 ml(see Table 33). No significant difference was found between the Rongelap exposed and unexposed groups, although the exposed adult group hada slightly higher mean value than the unexposed group. Females tended to have a lower mean Sr*° value than males, but the difference was not sta- tistically significant. Relatively few children <15 years of age weretested for urinary Sr®°; therefore, it was not possible to comparetheir levels statistically with those of the adults. The mean Sr® urinary value for an adult inhabitant ofUtirik was 1.8 puC/I, which is about 35% that of the Rongelap group. The control group on EbeyeIsland (not contaminated) hadstill lower values, 0.62 puC/l. The lack ofsignificant difference between the exposed and unexposed groups on Rongelap seems to indicate that essentially no residual Sr*° from the initial exposure is detectable in the exposed group. Cesium-137. The Cs'*' urinary excretion levels of the Marshallese people for the period from 50 to 180 days following exposure can be expressed as a single exponential function with a half-life of 70 days (see Figure 56). This figureis not in agree- ment with the value of 140 days obtained by Anderson,**? but a biological half-time of 31 to 59 days was obtained ina clinical study made over a 4-month period following injection of Cs'Cl, Into two patients. ** The estimates of body burden of Cs'** in 1958, derived indirectly from urinalysis, are presented in Table 32. The urinary excretion of Cs'*’ of 34 puC/l in 1957 indicates that the Rongelap people were exposed to a continuing low level of Cs'*’ from stratospheric fallout during 1956 while residing on Majuro. By contrast, the mean body burden of Cs'*" in 1957 of the Utirik people (who werereturned to their atoll in 1954) was 334 mpC, considerably higher than that of the Rongelap people whowereresiding on Majuroat that time.*° This higher burden among the Utirik people in 1957 can be attributed to the higher level of Cs**’ contamination on Utirik than on Majuro at that time. Zinc-65. Zn** urinary levels were not measured before 1958. With the assumptions that excretion of Zn® is exponential and urinary excretion is 10% of total excretion (urinary/fecal ratio=), the March 1958 urinary excretion level of 175