o9
induced activities (59Fe, 57-58.60Co 54Mn, 144Cs144Pr, 95Zr-95Nb, and !8Ru-!06Rh), Radiological
assessment has included surveys for gammaradiation levels on the islands; radiochemicalstudies of
soil profiles, lagoon bottoms, marinelife. plants, animal life (e.g., rats, coconut crabs), food items, and
urine samples: and gamma spectrographic analysis
of internallv deposited gammaemitters in personnel. The medical team has been responsible since
1969 for monitoring the body burdens of the people
returning to Bikini, as well as of the Marshallese ex-
posed to fallout and their controls, and morerecently also of the people returning to Eniwetok.
The 1974 studies of environmental radiation on
Rongelap, Utirik, and Bikini are being published
separately. 185
Until 1965 gammaspectroscopy was done ina
2l-ton steel chamber built at BNL for shielding,
with additional housing for the counting equipment( Figure 53). The subject to be counted took
a soap and water shower, put on paper pajamas,
and then stayed in the chamberfor about 15 min,
during which soft music was piped in. Only a few
small children were apprehensive during the pro-
cedure. More recently whole-body counting has
been done with a smaller “‘shadow-shield” arrangement of lead bricks,.a modification of the
Hanford model!®6 (Figure 54). In 1974 spectroc
30.000 =
+
,
10,000
Activity (Counts/ 15 min)
+
r
,
r
13TCs
i
4
4
—— Rongelap male
~--- BNL medical team —[
male
4
1,000 —
=
300 —
3
|
100 =
5
ot
30 ~
ij
4
~
|
10 0
4
0.4
0.8
Energy (MeV)
1.20
|
t 60
Figure 55. Gamma spectra obtained by whole-body
counting, males, 1974 (——, Rongelap; ---~, BNL medical team).
the low levels present in the people (see Figure
53).187.168 Annual collections of 24-hr urine samples from a numberof people have been madefor
radiochemical analvsis.
The results of radiochemical analysesof urine,
water, and crabs over the past 3 vears are summarized in Tables 37 to 40; the results of individual urinalyses are given in Appendix 12.* By
1974 the only detectable gamma emitter was
137Cs; its levels are given for Rongelap, Utirik.
and Bikini individuals in Appendix 12 and for
groups in Table 41. Since the returr to Rongelap.
no differences have been seen between exposed
and unexposed groups.
Figures 56 and 57 show the estimated body
burdensof gamma emitters and 9Sr for the Rongelap people at various timesaftertheinitial exposure in 1954. After their return to Rongelapthe
body burdens increased. Zn was present for a
few years, apparently from fish in the diet; the reason for its rapid decrease was not immediately apparent but maybe related to movements of marine
life in and out of the lagoon. Small amounts of
Co wereidentified in personnel during the earlv
years after the return (the highest concentration
was in clams). 99Sr body burdensreached their
highest level during 1962 to 1965 at about 12 nCi
*Weare indebted to Mr. Edward P. Hardv, Jr.. Director, Environmental Studies Division. AEC Health and Safetv Laboratorv, New York, N.Y., for carrying out the radiochermcal
analvses.
Table 40
4
3,000 —
-
-
graphs showeda characteristic peak for 37Cs and
65Zn, but ®°Co was barely discernible. if at all. at
Radionuclides in Coconut Crabs From Rongelap
Year
137Cs, pCi/kg
1961
90Sr,pCi’g Ca
1,140
1962
1,224 (1.317: 1.086;
1,113; 1,378)
1964
50,281 (39.292: 45,318;
758 (865; 628; 780)
1965
1969
12,700
7,775 (8,540; 7,010)
724
705 (910; 500)
{973
37,065 (64,700: 9,430)*
1972
1974
66,234)
5,900 (5.600; 6,100;
6,800; 5,100)
12,900*
6,600 (5,000; 8,200)
4,800*
353 (376; 419; 359;
259)
933*
3.950 (6.639; 1,267)*
448 (290; 606)
290*
*From northernislands of Rongelap Atoll, where radi-
ation dose was much higher.