90
The value OR,.,=0.25 is an approximate value
obtained experimentally on rats fed a stock laboratory diet.*? The discrimination factor of 4 for
.calcium against strontium from diet to bone in
man has been reported by Schulert*? and Bryant.**
A more appropriate valuefor therats in this situa-
Tt is obvious that use of this technique to estimate the Sr** body burdens of the Marshallese
people is also complicated by the uncertainty of
their diet, The estimates of average dictaryintake
of the Marshallese since their return to Rongelap
are approximate, because the diet has varied during the past several years. A study made in 1958
yielded daily Sr®°/Ca intake levels of 67.5 Sr units
(uC Sr*°/g Ca), provided that coconut crabs (see
Figure 4) were excluded from their diet.**:** The
tion might be the OR,ne-die: = 0.16 obtained by a
study of wild kangaroorats living in the Nevada
desert.**
The Sr** body burdenis then
Sr®°/Ca levels in the various foods are shown in
(Sr°°/Ca), = (Sr°°/Ca),(OR,.,(OR,.,)
Table 31. This study was based on the analysis of
various food samples in what may be considered
an average diet. The data were obtained froma
study of the diets of 14 males on Rongelap.*' It
was assumedthat half the calcium in the diet was
derived from food not native to RongelapIsland.
From the discrimination factor of 4 and the daily
intake of 67.5 Sr units, the equilibrium Sr®° body
burden for the Rongelap people ts calculated as
217 mpC. This is very close to the equilibrium
body burden (23 mpC) estimated by Woodward
from the urinalysis data.*°
Anothereffort was madein the 1959 survey to
gather samples of meals to be assayed for Sr*°/Ca
= (8.4 10*)(0.7)(0.16) =924 pC Sr°*/g Ca.
The value obtained in this manneris approximately twice the value 470 to 545 uC Sr°°/g Ca
obtained by direct radiochemical analysis of the
tissues of rats living on the island during the 2year period following detonation.** This difference
between the indirect environmental estimate of
the body burden of Sr*°/Ca and the results of
direct analysis mayreflect either errors in the discrimination ratios or perhaps lack of equilibrium
between the Sr*°/Ca in the animals and in the
soil at 2 years. The latter possibility exists, since,
although the 13 adult rats analyzed by Held‘ at
content. However, since the Marshallese were
found to subsist to a large extent on foods notindigenous to the area, such as C rations, rice, and
4 years had values close to the 2-year level, 443
181 ppC Sr°°/g Ca,the life span of the rat is only
—=2 years.
Table 31
Estimate of Sr*° in Diet of Rongelap Adults, 1958
Meat from mature coconut
Meat from drinking coconut
Milk from green coconut
Pandanus, edible portion
Arrowroot
Breadfruit
Fish
Clams
Crabs, land
Total
A
Daily
intake,* gg
(wet wt)
B
Ca
content,
mg/g
89
75
0.075
0.14
116
79
58
-45
0.15
0.15
2.10
0.60
14
4.00
139
45
AXB
Daily
D
Fraction
of total
Caintake**
E
Sr*°
content,
pyC/gCa
6.7
10.5
0.008
0.013
1,200
210
18.1
180.0
0.023
0.225
280
5
intake,mg
17.4
11.9
121.8
27.0
0.13
4.00
56.0
660
DOE ARCHIVES
449
0.022
0.015
0.152
0.034
0.070
22.0
14.0
2.9
8.8
(4,000)
(280.0)
0.56
6.4
1.)
67.5
* Based on average daily diet of 14 Rongelap males.’
** Based on total calcium intake of 0.8 g/day.
aa
9.6
2.7
1,000
930
19
260
The diet also included imported foods: rice,
canned C rations. flour, tea, milk. salt, and sugar.
Soa ee
DXxE
Contribution to
total daily
Sr** intake, puC/g Ca
Se