70 EFFECTS OF IONIZING RADIATION Table 5.2.—Summary of Human Urine Analysis, Gross Beta Activity mEFost 14 MontHs No. ; Rongelap Age in vears 7 B (5-16) ll C (> 16) 31 Ailinginae | A (<5) j; B (5-16) C (> 16) American D/M 24 HRS No. VOLUME (Q48R3) ML 3 Montus p/m 24 HRS No. VoLuue (24 HRS) ML 6 MontHs D/M 24 HRS No. VOLUME (24 HRS) ML DiM 24 HRS 8 360 12 33 625 0 400 655 0 0 ! | A (<5) Age in years VOLUME (24 HRS) wL 2}4 MontHs | 404 581 1208 758 2 10 275 722 150 217 | 25 1158 309 , | i 1 165 439 | 10 824 705 10 126 553 379 339 12 3 12 510 5 } I All values corrected for decay. highest activity was in the Rongelap group (Table 5.2). The Ailinginae group had less than half that of the Rongelap group, and the Americans had about one-quarter the activity of the Rongelap group. The mean gross betn activity of the urine of the three groups above was roughly proportional to the external dose each group received. However, x comparison of the mean beta activity of the urine of Ailinginae and American groups indicated that the latter had a somewhat lower amount of internal contamination, even though both groups received about the same ex- ternal dose. This may be accounted for by the fact that the Ailinginae group drank contam- inated water from open containers and ate contaminated food up to the time of evacuation, wherens the Americans ingested much less contaminated food and water, since both were largely stored in closed containers. Indoctrination of the Americans concerning radiation hazards probably was also a factor in reducing the amount of contamination which they received, The variation of gross activity among the individuals in any of the three groups is quite large (Tables 5.8 and 5.4). This is chiefly the result of variations in the quantity of water and both the kind and quantity of food ingested. The degree of exposure of the individual to air-borne activity is also a factor in determining the individual degree of contamination. While there were Jarge variations among individuals, the day-to-day levels of activity for each individual were fairly consistent. Further information on the source of individual variations was obtained by grouping the individuals from the Rongelup and Ailinginae groups uccording te age ( Tables 5.3 and 5.4). While the activity excreted per unit volume of urine is about the same for both children and adults, the mean activity of the urine excreted in 2+ hours by children under 15 years was signiticantly lower than that excreted by adults. The data available do not indicate definitely whether the lower total excretion indicates a smaller total body burden in the children resulting from Jower inhalation and ingestion, or whether it represents a higher de- vree of fixation of the radio-elements by growing bone,