170
Health Physics
colon from chronic intakes for each of the 26 population groups considered were calculated as the products
of the annual intakes and the annual dose coefficients
developed for the purposesof this paper Asthe doses
result from the consumption of seafood and ofterrestrial foodstuffs primarily contammated through root
uptake, the radioactive materials were assumed to be
im soluble form and the alimentary tract absorption
fractions (f, values) that we selected for the calculation
of the annual dose coefficients were those recommended by the ICRP 1m tts Publication 72 (ICRP 1996)
August 2010, Volume 99, Number 2
exception of the year 1954 for the population groups that
were evacuated asa result ofthe fallout from the Bravo test,
which took place on 1 March 1954 In thatcase, the chronic
dosecalculation for the Bravo test was done separately from
the calculation of the dose resultmg from all other tests that
took place m 1954
FINDINGS
The primary purpose of the models and calculations
described here were to estrmate (1) empirically-based acute
for ingestion by membersofthe public, rather than for
particulate fallout as used for acute mtakes
intakes of "I by adults among the Marshallese and Amer-
that for a given test giving rise to a given mtakerate of
nuclides by representative Marshallese of six age groups
from mfancy to adulthoodatall mhabited atolls from each
of 20 nuclear tests (plus acute mtakes by adult military
The calculation of the doses takes mto account (1)
a given radionuclide soon after the test, the anual mtake
of a person of a given age varies from year to year due to
radioactive decay and environmentalloss, (2) the dose
for a given intake1s delivered over several years, and (3)
both the mtakes and the dose coefficients varied as a
function of age The formulation shown im eqns (12a)
through (12c) was used
Forthe year of thetest, called yl
D(o, 1, age, yl) = g(z, age, yl)
X DC(o, 1, age, yl) (12a)
Forthe following year, called y2
D(o, 1, age, y2) = qt, age, yl) X DC(o, 1, age, y2)
+ g(t, age, y2) X DC(o, 1, age, yl)
(12b)
For the following year, called y3
D(o, 1, age, y3) = q(t, age, yl) X DC(o, 1, age, y3)
+ q(t, age, y2) X DC(o, 1, age, y2) + q(t, age, y3)
X DClo, 1, age, yl), (12c)
where
D =the absorbed dose (mGy),
1 =the radionuchde under consideration,
age = the age at intake,
o=one of the four organs considered (RBM,
thyroid, stomach wall, or colon wall),
q =the annualintake (Bq), and
DC =the annual dose coefficient (mGy Bq”')
Given the large uncertamties m the annual intakes
resulting from eachtest, we judged 1t sufficient to group the
intakes from the tests that occurred m a given year and to
assume that the summed mtake was due to a single test that
was detonated on | July of that year This procedure was
used for all population groups and for all years, with the
ican military weather observers on Rongerk using urme
bioassay data, (2) acute mtakes of '*'l and 62 other radio-
weather observers on Rongerik at the ome of Bravo), (3)
chrome itakes of residual fallout radioactivity m_ the
environment at all mhabited atolls during the years 1948
through 1970, and (4) mternal doses to four ussues or
organs (RBM,thyrord, stomach wall and colon wall) from
all estimated mtakes The following sections describe fmdings from the mtake models and dose calculations
Acute intakes of “I from urine samples
As a necessary step to estimating intakesofall the
radionuclides considered in this analysis, by persons of
all ages, we first derived emprrically-based estimates of
the mtake of "I by adults on three atolls where bioassay
was conducted (Marshallese on Rongelap Island, Marshallese on Ailmgmae, and American military weather
observers on Rongerk) usmg data from Harris (1954)
and Harms et al (2010) via eqn (1) Four different
average values of the ‘I mtake were estimated smce
urme samples from the Rongelap Island group were
collected on two different days The data used to estrmate
"31] mtake, as well as the results of the calculations, are
shown im Table 7 Estrmated average takes of "I by
adults on Rongelap Island and Ailinginae were about
3,600 and 1,300 kBq, respectively Intakes of “I by
younger ages were assumed to have been smaller as
described bythe scalmg factors discussed m the previous
section and presented m Table 2 For the age groups
13-17 y, 8-12 y, 3-7 y, 1-2 y, and <I y, the estimates
of acute mtake of “"I on Rongelap were 3,150, 2,100,
1,400, 1,050, and 1,400 Bq, respectively Corresponding
™'T acute mtakes at Ailmgmae were about 37% of the
intakes at Rongelap Only adults were on Rongenkat the
time ofthe Bravo test, their mtakes of "I were about
1,700 kBq
Estimates of acute mtakes of '*'I were converted to
"Cs intakes for the purposeof estrmatmg the intakes of