The beta activity was counted with a thin end-window Geiger-Miiller counter. The counter
was calibrated with a U,O, standard, and an appropriate correction for self absorption was
made using a Sr® standard.
2.2
RESULTS AND DISCUSSION
2.2.1
Beta Activity of the Urine
Internal deposition of radioactive elements was evidenced by the presence of significant
amounts of beta activity in the urine. This activity decreased rapidly as a function of time,
Since it was derived chiefly from short-lived radioisotopes. For example, at 3 months postdetonation, the mean activity of the urine of the Rongelap adults was 28 per cent of the value
measured 45 days postdetonation, and at 6 months the activity in the urine was barely detectable in most of the individuals.
TABLE 2,1—Summary of Human Urine Analysis, Gross Beta Activity*
Rongelap
Time
(postdetonation)
1'4 months
Case No.
24-hr vol. (ml)
Dis /min/24 hr
Ailinginae
(age)
(age)
<5
5-16
>16
<5
5-16
>16
American
7
165
404
11
439
758
31
581
1208
1
150
217
2
275
126
10
722
553
25
1158
309
244 months
Case No.
24-hr vol. (ml)
Dis /min/24 hr
10
824
705
3 months
Case No.
10
24-hr vol. (ml)
379
Dis /min/24 hr
339
6 months
Case No.
24-hr vol. (ml)
Dis /min/24 hr
8
360
12
12
510
5
33
625
0
3
400
0
12
655
0
*All values corrected for decay.
Comparison of the means of the urine samples for the adults of the Rongelap and Ailinginae
groups and the American groupindicates that the highest activity was in the Rongelap group at
45 days postdetonation (Table 2.1). The Ailinginae group had less than one-half the activity
present in the Rongelap group, and the American group had about one-fourth the activity of
the Rongelap group.
The mean gross beta activity of the urine of the Rongelap, Ailinginae, and American
groups was roughly proportional to the external dose each group received. However, a com-
parison of the mean beta activity of the urine of the Ailinginae and the American groupsindicated that the latter had a somewhat lower amount of internal contamination although both
groups received about the same external dose. This may be accounted for by the fact that the
Marshallese drank contaminated water from open containers and ate contaminated food up to
the time of evacuation at 55 hr postdetonation. The American personnel ingested much less
contaminated food and water, since both were largely stored in closed containers. Indoctri15