Charles E. Land,* André Bouville,* Iulian Apostoaei,' and Steven L. Simon*
estimated by the National Cancer Institute in a more simplistic
analysis conducted in 2004, these estimates of cancer risk are
the best available as they are based on the most detailed dose
reconstruction to date and comprehensively include populations at all locations and dose contributions from all nuclear
Health Phys. 99(2):201-215; 2010

Abstract—Radioactive fallout from nuclear test detonations
during 1946-1958 at Bikini and Enewetak Atolls in the
Marshall Islands (MI) exposed populationsliving elsewhere in
the MI archipelago. A comprehensive analysis, presented in
seven companion papers, has produced estimates of tissuespecific radiation absorbed dose to MI residents at all historically inhabited atolls from internal (ingested) and external
irradiation resulting from exposure to radioactive fallout, by
calendar year, and by age of the population at time of
exposure. The present report deals, for the first time, with the
implications of these doses for cancer risk among exposed
members of the MI population. Radiation doses differed by
geographic location and year of birth, and radiation-related
cancer risk depends upon age at exposure and age at observation for risk. Using dose-response models based on committee reports published by the National Research Council and
the National Institutes of Health, we project that, during the
lifetimes of members of the MI population potentially exposed
to ionizing radiation from weapons test fallout deposited
during the testing period (1948-1958) and from residual
radioactive sources during the subsequent 12 y (1959-1970),
perhaps 1.6% (with 90% uncertainty range 0.4% to 3.4%) of
all cancers might be attributable to fallout-related radiation
exposures. By sub-population, the projected proportion of
cancers attributable to radiation from fallout from all nuclear
tests conducted in the Marshall Islands is 55% (28% to 69%)
among 82 persons exposed in 1954 on Rongelap and Ailinginae, 10% (2.4% to 22%) for 157 persons exposed on Utrik, and
2.2% (0.5% to 4.8%) and 0.8% (0.2% to 1.8%), respectively,
for the much larger populations exposed in mid-latitude
locations including Kwajalein and in southern locations including Majuro. By cancer type, point estimates of attributable
risk varied, by location, between 12% and 95% for thyroid
cancer, between 2% and 78% for leukemia, and between 0.8%
and 55% for all cancers combined. Thelargest projected risks
pertain to the Rongelap Island community and the lowest risks
pertain to the populations resident on the southern-mostatolls.
While the projected cancer risks are smaller than those


Key words: cancer; fallout; Marshall Islands; nuclear weapons

PREVIOUSLY ADMINISTERED by Japan under a League of
Nations mandate, the Marshall Islands (MI) archipelago
was occupied by the United States (U.S.) during World
War II. The group of atolls and islands was administered
by the U.S. as a United Nations Trust Territory until 1986
when the Republic of the Marshall Islands (RMI) was

established as a sovereign nation in free association with
the U.S.
After World WarII, the U.S. established the Pacific
Proving Grounds, essentially the atolls of Bikini and

Enewetak and the nearby ocean at the northwestern end
of the archipelago, for testing nuclear weapons. The
populations of Bikini and Enewetak were relocated to
other atolls prior to testing. Between 1946 and 1958, 66
nuclear test detonations were carried out on or near to the
atolls of the Marshall Islands. As discussed in four of the
companion papers (Becket al. 2010; Bouville et al. 2010;
Simon et al. 2010a and b), 20 of these tests resulted in

varying levels of radiation exposure from radioactive
fallout to residents of the inhabited islands in the archipelago. Significant exposures to radioactive fallout began
in 1948, and exposures to residual fallout radioactivity
continued after the cessation of testing in 1958, until
about 1970. The highest exposures by far were from the

* Division of Cancer Epidemiology and Genetics, National CanInstitute,





* SENES Oak Ridge, Inc., Oak Ridge, TN.



For correspondence contact: Steven L. Simon, National Cancer
Institute, National Institutes of Health, 6120 Executive Blvd., Bethesda, MD 20892, or email at

thermonuclear test (code name Castle Bravo) detonated

on Bikini on | March 1954, which unexpectedly resulted
in very substantial radiation exposure to 82 members of
the Rongelap community who were on Rongelap Island
and nearby Sifo Island (Ailinginae Atoll) and substantial

(Manuscript accepted 5 March 2010)

Copyright © 2010 Health Physics Society

DOI: 10.1097/HP.0b013e3 18 Ldc4e84

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