o9
induced activities (°9Fe, 57.58.80Co, 54Mn, 144Cs144Py, 95Zr-95Nb, and }°6Ru-106Rh). Radiological
assessment has included survevs for gammaradia-
tion levels on the islands; radiochemical studies of
soil profiles, lagoon bottoms, marinelife, plants, animal life (e.g., rats, coconut crabs), food items, and
urine samples; and gammaspectrographic analvsis
of internally 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 exposed to fallout and their controls, and morere-
cently also of the people returning to Eniwetok.
The 1974 studies of environmental radiation on
Rongelap, Utirik, and Bikini are being published
separately. 165
Until 1965 gammaspectroscopy was done in a
21-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,
andthen stayed in the chamberfor about 15 min,
during which soft music was piped in. Only a few
small children were apprehensive during the procedure. More recently whole-body counting has
been done with a smaller “‘shadow-shield” ar-
rangement of lead bricks,.a modification of the
Hanford model?66 (Figure 54). In 1974 spectroE
T
30.000 —
T
T
T
T
137g
3
4
graphs showed a characteristic peak for 137Cs and
65Zn, but °°Co was barelydiscernible, if at all, at
the low levels present in the people (see Figure
55),167.168 Annual collections of 24-hr urine sam-
ples from a numberof people have been madefor
radiochemical analysis.
The results of radiochemical analyses of urine,
water, and crabs over the past 5 vears are summarized in Tables 37 to 40; the results of indi-
vidual urinalyses are given in Appendix 12.* Bv
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 return to Rongelap,
no differences have been seen between exposed
and unexposed groups.
Figures 56 and 57 show the estimated body
burdens of gamma emitters and Sr for the Rongelap people at various timesafter theinitial exposure in 1954. After their return to Rongelap the
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
60Co were identified in personnel during the earlv
years after the return (the highest concentration
was in clams). 9°Sr body burdens reached their
highest level during 1962 to 1965 at about 12 nCi
*Weare indebted to Mr. Edward P. Hardy, Jr.. Director, Environmental Studies Division.AEC Health and Safety Labora-
tory, New York, N.Y., for carrying out the radiochemical
Activity (counts/15 min)
analyses.
10,000
“OE
—— Rongelap male
5,000
1000 =
~---- BNL medical team J
male
|
\
\
\
500
-
.
100 =_
‘
“S
¥ \f
=
¥
Figure 55.
0.4
=
1961
1962
4
7
1964
1
1965
1969
1972
s
50 —
10 0
Year
=
an)
Ay
‘
iy
VA
4
0.8
Energy (MeV)
1.20
1.60
Gamma spectra obtained by whole-body
counting, males, 1974 (——, Rongelap; ---, BNL medi-
cal team).
Radionuclides in Coconut Crabs From Rongelap
.
4
‘\
Table 40
|
4
1973
1974
137Cs, pCi/kg
Sr, pCi/g Ca
1,140
1,224 (1,317; 1,086;
50,281 (39.292; 45,318;
66,234)
12,700
7,775 (8,540; 7,010)
5,900 (5,600; 6,100;
6,800; 5,100)
12,900*
37,065 (64,700: 9,430)*
6,600 (5,000; 8,200)
4,800*
1,113; 1,378)
758 (865; 628; 780)
724
705 (910; 500)
353 (376; 419; 359;
259)
933*
3,950 (6,639; 1,267 )*
448 (290; 606)
290*
*From northern islands of Rongelap Atoll, where radi-
ation dose was much higher.