TABLE 16. -Comparison of the predicted and measured body burdens of '"Cs for three
atolls in the Marshall fslands.
Predicted adult body burdens using dose
models and various diet options (u(r)
Atoll
MLSC diet
Imports
available
Bikini
5.5
Imports
unavailable
11
used are:
N
Measured average body burden in
197K by BNL (eu)
|
BNE. diet
Community
~20
N
q(th=q() Y Ae+01 ¥ AG - e/a,
Average
2.4 (M)"
1.7 (F)P
Rongelap
0.19
0,42
0.58
0.17 (A}
Utirik
0.043
0.098
0.18
0.053 (A)
Maximum
1
N
Q(t) = { q(t) = q(@) ¥ AW — ev") /a;
5.7 (M)
‘1
2.7 (F)
i-|
* Male.
* Female.
Distribution of Doses Around the Estimated Average Dose
The doses presented herein are calculated using the mean value of
the data available for each parameter in the dose models. For example,
mode] parameters include body weight, residence time of radionuclides
in the body, radionuclide concentrations in either foodsorsoil, dietary
intake (measured in grams per day), and fractional deposition of
radionuclides in body organs or compartments. Data for all of these
parameters have a lognormal!distribution as shownin Figs. 5-11. The
meanvalues fall between the 60 to 70th percentile; that is, for a given
parameter, approximately 60 to 70% of the data pointsfall below the
mean value. Thus, if the mean values for the parameters are used in
the dose models and the data sets are lognormally distributed, the
ual
The method for calculating the distribution in the final dose is based
on the distribution of each of the model parameters and is briefly
reviewed here. The 30-y integral dose equivalent for the ingestion of
"Cs has been simulated using Monte Carlo techniques. The equations
70
A:
irl
&®
R= 51.2E x q(t)
© Adult.
was 0.17 wCr [49]. The models predict an average body burden of 0.19
uCi for the MLSC diet when imported foods are available and 0.42
uCi when unavailable and 0.58 »Ci for the BNL diet. At Utirik Atoll,
the predicted average body burden using the MLSCdiet is 0.043 pCi
when imported foods are available and 0.098 »Ci when unavailable;
the predicted body burdens are 0.18 uCi using the BNL diet. The
BNL-measured average body burden was 0.053 Ci for adults in 1978
[49].
N
+ f,f5] z —[t -— 1 -— e")/ay},
M
'
5L2E x Qit)
Dp = ————_
M
,
where
I
= intake rate («4Ci/d)—concentration (yCi/g) x dietary
intake (g/d),
q(@) = initial organ burden (uCi) at time t = ty,
q(t) = organ burden (Ci) at timet,
Q(t)
cumulative activity at time t (uCi) since ty,
f,
= fraction of ingested activity from gut. to blood,
f.,
A,
B,
= fraction of activity in blood to organ of interest,
= fraction of q(t) in compartment i of organ,
= biological elimination rate for compartment i of organ
(d''),
r
N
a;
M
E
=
=
=
=
=
51.2
= units conversion factor,
R
D
radioactive decay rate of nuclide (d~'),
numberof organ compartments,
+ B; = effective decay rate of compartmenti (d°'),
organ mass(g),
effective energy of nuclide for organ (MeV),
= dose rate at time t (rem/d), and
= integrated dose at time t (rem).
The distributions of variables of interest I, B,, and M are lognormal,
generated using International Mathematics and Statistical Laboratory
routines for lognormal and random (uniform) deviates. Each run
generates the appropriate random numbersfor each variable for calculating the dose. After storing the dose in the proper histogram bin,
71