Health Physics

exposures The subject of cancer nisks 1s addressed m a
companion paper by Land et al (2010)
Wehave attempted to collect and use the available
data and information to conduct a dose reconstruction m
a manner webeheve to be relatively free of mtentional
biases To accomplish that, m a companion paper (Beck

August 2010, Volume 99, Number 2
doses to the most exposed populations m the northern
Marshall Islands immediately downwind from the 1954
Bravo test (James 1964, Lessard et al 1984, 1985) Much

of the earher work was reported m a special issue of
Health Physics (Simon and Vetter 1997) and focused on

fallout radionuchdes determmed to have contributed over
99% of the acute mternal doseat all 32 mhabited and

monitoring of the most 1mpacted 1slands and people,
developmg land remediation strategies, and assessing
contemporary and possible future doses that might be
received by mhabitants of certam atolls of the northern

Bikim and Enewetak Atolls where the tests were con-

ysis has ever been completed on the mtakes and mternal

et al 2010), we estimated the deposition densities of 63

ummhabitated atolls of the Marshall Islands, excluding
ducted, and developed a method to estimate acute and

chronic intakes of radioactive materials from the nuclear

tests for representative persons of various age groups at

all mhabitedatolls and the related doses to four organs
Acute mtakestook place during the period of the trme the
fallout was bemg deposited at each atoll Gf durmg the
day) or shortly afterwards if the fallout arrived at mght
The assumption was made that acute mtakes were pnmarily the result of eatmg superficially-contaminated
food, using contammated eating utensils, mgestmg contamination deposited on the hands and face, and to a

lesser degree, drmking contammated water (Lessard et
al 1985) Followmg the deposition of radionuchdes on
the ground, protracted or chrome intakes took place by
imgestion but at rates much smaller than those due to the
acute mtakes The environmental pathways resultmg in
chromic mtakes are substantially different from the direct
deposition of fallout on ground surfaces and materials
accountng for acute intakes Chromic intakes among
Marshallese were primarily a result of consumption of
seafood and oflocally grown terrestrial foodstuffs and, to
a lesser degree, madvertent consumption of soil (Simon
1998, NCRP 1999)

Doses estimated mthis work are atoll and age-group

annual and Iifetrme radiation absorbed doses (Gy) to four
organs, red bone marrow (RBM), thyroid gland, stomach
wall, and colon wall, and presented as best estimates and

with 90% uncertamty ranges Doses pertammg to representative persons residmg at every mhabited atoll and for all
relevant birth years have been estimated for the analysis of
cancer risk (Land et al 2010) In this paper wepresentthe
dosimetric fmdmgs for four commumities (Mayuro, Kwayalem, Utrik, and Rongelap) that represent the overall range of
doses recetved across the Marshall Islands as well as
represent the populations of the two atolls with the largest
number of residents (Mayuro, the capital and largest popu-

Marshall Islands However, to our knowledge, no analdoses from al] fallout radionuchdes, from all tests, and at

all mhabited atolls The primary goal of this publication

and the compamon papers was to carry out a compre-

hensive dose assessment and cancer risk projection
Historical context

Of all the Pacific nuclear tests, the 1954 Castle

Bravo test at Bikim Atoll caused the most serious
exposures Followmg the Bravo detonation on | March
1954, heavy early fallout was unexpectedly deposited on
nearby atolls in the Marshall Islands to the east of Bikim
begmmmg at about 4 h post-detonation and resultmg m
moderate to high radiation exposures to small groups of
Marshallese and Americans living or staymg on those
atolls 64 Marshallese on Rongelap, 18 Marshallese from
Rongelap staying on Sifo Island m Ailinginae Atoll, 159
Marshallese on Utnk Atoll, 28 military weather observ-

ers on Rongertk Atoll, and 23 sailors on the Japanese
fishing vessel, the Lucky Dragon (see Cronkite et al

1997 and Srmon 1997 for additional hstory) The magmitudes of mterna] doses recetved bythe thyroid gland of
the Marshallese and American weather servicemen were
not completely understood at the tme of the Bravo test,
primarily because there was little experience at estimatimg the many factors that are smportant to the determnation of radiation dose, e g , fission y1elds, atmospheric

dispersion and deposition-related factors, quantitative
understanding of modes of mtake (inhalation vs mgestion), solubility of different nuclides, doses received per
umt activity mtake of each radioiodme,etc

The earliest estimates of mternal dose to the nghly
exposed Rongelap and Ailmgmae populations were mm a
Los Alamos Scientific Laboratory (LASL) memo to the
US Atomic Energy Commission (USAEC) (Hams
1954) In that document, a summary of measurements of

urmary excretion of "I and several other nuchdes were

lation center, and Kwayalem, home to a US muhitary base

reported from population pooled urine samples collected

As far as we know, there are no publications in the

James (1964) estrmated thyroid doses to Rongelap chil-

and the secondlargest population center)

peer-reviewed literature on mternal doses to all the
Marshallese from fallout on a yearly basis from 1948
through 1970 Previous reports focused primarily on

from adults at 16, 17, and 19 d post-detonation Later,
dren based on the LASL excretion data (Harris 1954),

though James mistakenly reported that the LASL pooled
urme sample contamed 201% (by volume) from ages

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