30
Ir 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 dietary intake
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
ytelded daily Sr*’/Ca intake levels of 67.5 Sr units
(upC Sr*°/g Ca), provided that coconut crabs (see
Figure 4) were excluded from their diet.**:** The
The value OR,., =0.25 is an approximate value
obtained experimentally on rats fed a stock laboratory diet.** The discrimination factorof 4 for
calcium against strontium from diet to bone in
man has been reported by Schulert** and Bryant. **
A more appropriate value for the rats in this situation might be the OR,,,. ge, =0.16 obtained by a
study of wild kangaroo rats living in the Nevada
desert. *°
The Sr*” body burden is 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 assumed that half the calcium in the diet was
derived from food not native to Rongelap Island.
From the discrimination factor of 4 and the daily
intake of 67.5 Sr units, the equilibrium Sr‘? body
burden for the Rongelap peopieis calculated as
=17 myuC. Thisis very close to the equilibrium
body burden (23 mpC) estimated by Woodward
from the urinalysis data.’
Another effort was made in the 1959 survey to
gather samples of meals to be assayed for Sr*”/Ca
=(8.4« 10°)(0.7)(0.16) =924 py Sr’’/g Ca.
The value obtained in this manner1s approxtmately twice the value +70 to 545 puC Sr““/g Ca
obtained by direct radiochemicaianalysis 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 may reflect either errors in the discrimination ratios or perha: ack of equilibrium
between the Sr°’/Cainth
auuimals and in the
sou at 2 years. The latter possibility exists, since,
although the 13 adult rats analyzed by Held“ at
content. However, since the Marshallese were
4 years had values close to the 2-year level, 443+
181 upC Sr’ /g Ca, the life span of the rat is only
m2 years.
found to subsist to a large extent on foods notin-
digenousto the area, such as C rations, rice, and
Table 3|
Estimate of Sr” in Diet of Rongelap Adults, 1958
A
Daily
8B
Ca
intake,“ g@
content,
89
0.075
(wet wt}
Meat from mature coconut
Meai from drinking coconut
Milk from green coconut
Pandanus, edible portion
Arrowroot
Breadfruit
Fish
Clains
Crabs, land
Total
mg/g
AxB
Daily
Ca
intake,mg
content,
6.7
0.008
1,200
18.1
0.023
280
10.5
17.4
1b.9
1218
27.0
45
14
4.00
4.00
180.0
56.0
66U
of total
wuC/g Ca
0.14
0.15
0.15
2.10
0.60
0.13
E
Sr”
Caintake**
75
116
79
58
45
139
D
Fraction
449
0.013
0.022
0.015
0.152
0.034
0.225
0.070
DE
Contribution to
total daily
Sr*” intake, wpC/g Ca
9.6
2t0
1,000
930
19
260
27
22.0
14.0
2.9
83
5
(4,000)
Pl
(280 0)
0.56
b.4
67.5
The diet also included imported foods. rice,
canned C rations, flour, tea, milk, sail, and sugar.
* Based on averave daily chetot 1! Rangclap males
"* Based on total ceborud uidake obO We days
a
6 Mee A
ee