3}
tea, it became evetrtifore difficult to extrapolate
to body burden fromfood.
The excretion rate of Sr?’ maybe expressed as
the sum of two exponential functions for the Arst
the transport of low levels of Sr’ and other prod-
Sr’? is excreted eariy, with a biological half-life of
environmental data alone ofthe internal radia-
respond to those reported by Cowan! in a case of
contamenated area.
More reliable estimates of the Marshallese body
extrapolating back to the one-day Sr8® bodvburden of the Marshallese.**,
spectrometry and by radiochemical urinalysis.
and Zn** are presented in Table 32. and also
It is obvious that further data are required on
ucts through the ecological cycle in this and other
communities to make possible assessment from
tion hazard to human beingsliving in a falloutburdens can be obtained by whole-body gamma
Radiochemical Analysis of Urine
Strontium-90. The urinary excretion levels of
Sr°*° for the 5 years following exposure to fallout
are shown tn Figure 55. The +- and 5-yearlevels
were much higher, after the return of the Marshallese to Rongelap in July 1957, the mean being
higher by a factor of 20 in March 1958 than in
ee Nenean eer es ee oe ne cee ee en on ee ee
eR Ree ee ee
March 1957.
3 years following exposure. The major fraction of
+0 davs. The smaller fraction is excreted witha
half-life of 300 days. These excretion rates cor-
accidental inhalation of Sr?’, and were used in
The 1958 Rongelap body burdens of Sr®, Cs!*",
figures for percent of equilibrium and equilibrium
value, estimated by Woodward* from urinary excretion data. These values are subject to some uncertainties, since they are based on a number of
assumptions; however, they can be checked by use
of other methods. For example, the estimated
body burden of Sr*° in March 1958 was 2 wuC/g
Ca, based on the 24-hr Sr*® output in urine (1 hrer
per 24 hr), and this appeared to be of the right
order of magnitude compared with data from
10
ie ‘5
2
|
bone analysis. Two bone samples of vertebra aad
tleumvars
from a deceased 35-year-old
Rongelap
Y
geiap male
at this time indicated a level of about 3.7 puCfreg
7
4
oO
4
Ca, which gives, upon application of the normali.
te
J
zation factor of 2 from vertebra to average
skele&
F 1.0
58
7
1
the mean body burden of Sr*° for exposed Rongelap people in 1958 was estimated to be =2 muC,
S
o
BO2b
a
O
th~40 pay$
.
«
a
|peTORN TORONGELAP
R
Eee AYP aye, ay
.
300 800 900 1200 1500 1800
TIME IN DAYS ~ AFTER MARCH 1, 1954
ton,** an average skeletal value of 2 uuC/g. Thus
:
or about 9% of the estimated equilibrium value of
4
23 mpC.*°
.
.
The estimated Sr** body burden increased from
2 mpC in 1958 to 6.0 mzeC in 1959, or 26% of the
estimated equilibrium value. The 1959 Sr9° mean
urinary value in the exposed Rongelap inhabitants was 6.3 upC/! or 10.5 puC/24-hr urine, based
Figure 55. Urinary excretion of Sr”?
in exposed Marshallese.
Table 32
Estimation®® of Body Burden, in muC, of Rongelap Population From Urinary Excretion Levels, 1958
Cs'3?
Sr”, Exposed
Body burden
. Equilibrated body burden
Percent of equilibrium
Daily intake
cS Exposed
2
23
9
0.015**
*3.7 Strontium units (SU) determined by bone biopsy.
**15 SU assuming daily calcium intake = 1 g.
118560!
“900
1300
69
2(?)
Zn
Control
Exposed
1200
280
1600
75
330
85
Control
540
2.1-4.1
650
83