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o
>
So
on
9
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Cumulative fraction
20, and was assumed to pertain| to every
individual in the modeled exposed population.
The local food items appearing in Talfle 20 were
divided into three types (and thell indicated
corresponding sampling periods werelassumed):
pork-related items (n, = 12 y1), chicHen-related
o
o
rh
items (nm, = 52 y!), and other items
0.5
1
1.5
(nz = 182.5 y"1).
2
Model-uncertainty (i.e., missppcification
Meandaily intake (Bq/kg-d)
Figure
16.
Sample
distribution
of
interindividual variability in daily intake of
137Cs per unit body weight based on survey data
for 34 adult Ujelang females (bold), fit to a
lognormal distribution (light) with mean = 0.447
Bq kg! d-1 and a geom. stand. dev. = 2.274.
Watson tests (Stephens, 1970; Pearson and
Hartley, 1972).
We used this lognormal
distribution as the basis of our model of
variability in (R)= 365{Ry) for a hypothetical
Rongelap population of arbitrary size N. The
distribution has a corresponding CV with respect
to modeled variability equal to gp = 0.9821.
Uncertainty due to random dietary sampling
associated with daily 137Cs intake for any given
individual about that individual’s mean daily
level (presumed constant for each individual)
was estimated under the assumptions stated
above that food imports are available and that
local foods of type j are randomly and
independently sampied nj; times per year from
among Rongelap sources, using LLNL-model-diet
assumptions discussed previously, along with
the information summarized in Table 20 about
predicted amounts and measured inter-sample
variability of 137Cs in different food items local
to Rongelap. For this analysis, the activities
associated with the items listed in this table
(accounting for ~99% of 137Cs intake associated
with local foods) were scaled to correspond to an
assumption that these items comprise 100% of
the local-food_diet. Each corresponding CV,
YRy = OR, / (Ry), with respect to presumed
dietary sampling error was assumed to be the
measured value appearing in column 6 of Table
error) was estimated directly from] the data
shown in Figure 3 relating LLNL thodel-diet
predictions assuming imported foods are
available, and corresponding BNL measurements
of whole-body dose amongdifferent famples of
Marshallese people tested during the period
1977-1983. The mean of the six megsured- to
predicted-burden ratios shown is 125 + 0.37
(differing insignificantly from 1, p > P).16 by Ttest). Based on these data, an uncerta[nty-CV of
~40% was assumed, and model unceftainty for
the LLNL model diet assuming impofted foods
are
available,
was
characteriz@d
as
a
corresponding lognormally distributefi factor B
with expectation 1 and SD, = 1.47.
Predicted population risk I (her@ taken as
the numberof fallout-induced cancey fatalities)
necessarily depends on the size,
and age
distribution of the population involved in any
Rongelap resettlement. To reasonably estimate
_I, it was assumed that N = 500 In a 1995
resettlement, wherein 40% of this population
would be exposed for 70 y (i.e., be present upon
birth) and the remainder (of adultB of 40-y
average age) for 30 y. Calculation of J was by
the method of Bogen and Spear (1987)] treating [
as compound-Poisson-distributed [with an
uncertain parameter (population-average dose),
here approximated as 500W D(Lifetim®), where
W is an uncertain risk-per-unit dose dbnversion
- factor and D(Lifetime) was assumed
]to be the
weighted functional (not stochastic) qverage of
D(70) and D(30) using 0.4 and 0% as the
respective weights. For this purpose, (70) was
taken to be 1.63 D(30) based on the corresponding
LLNL/ICRP model predictions (Table 1). Based
on the BEIR V (NRC, 1990) predictioh of total
cancer (leukemia + nonleukemia) fatplities for
47