Steven L. Simon,* André Bouville,* Dunstana Melo,* Harold L. Beck,’
and Robert M. Weinstock*
available anywhere and were used to makeprojectionsof lifetime
cancer risks to the exposed populations, which are presented in a
companion paperin this volume.
Health Phys. 99(2):157-200; 2010

Abstract—Annualinternalradiation doses resulting from both
acute and chronic intakes of all important dose-contributing
radionuclides occurring in fallout from nuclear weaponstesting at Bikini and Enewetak from 1946 through 1958 have been
estimated for the residents living on all atolls and separate reef
islands of the Marshall Islands. Internal radiation absorbed
doses to the tissues most at risk to cancer induction (red bone
marrow, thyroid, stomach, and colon) have been estimated for
representative persons of all population communities for all
birth years from 1929 through 1968, and for all years of
exposure from 1948 through 1970. The acute intake estimates
rely on a model using, as its basis, historical urine bioassay
data, for members of the Rongelap Island and Ailinginae
communities as well as for Rongerik residents. The model also
utilizes fallout times of arrival and radionuclide deposition
densities estimated for all tests and all atolls. Acute intakes of 63
radionuclides were estimated for the populations of the 20
inhabited atolls and for the communities that were relocated
during the testing years for reasons of safety and decontamination. The model used for chronic intake estimates is based on
reported whole-body, urine, and blood counting data for residents of Utrik and Rongelap. Dose conversion coefficients relating
intake to organ absorbed dose were developed using internationally accepted models but specifically tailored for intakes of
particulate fallout by consideration of literature-based evidence
to choose the most appropriate alimentary tract absorption
fraction (f,) values. Dose estimates were much higher for the
thyroid gland than for red marrow, stomach wall, or colon. The
highest thyroid doses to adults were about 7,600 mGy for
the people exposed on Rongelap; thyroid doses to adults were
muchlower, by a factor of 100 or more, for the people exposed on
the populated atolls of Kwajalein and Majuro. Theestimates of
radionuclide intake and internal radiation dose to the Marshallese that are presented in this paper are the most complete

Key words: dose, internal; fallout; Marshall Islands; nuclear

INTERNAL RADIATION doses to residents of the Marshall
Islands during the years of nuclear testing at Bikini and
Enewetak (1946-1958), as well as in later years, were a

consequence of inadvertent intake of radioactive materials from nuclear tests that were deposited as fallout.
Doses were received both from acute intakes, 1.e., those
intakes occurring at the time of fallout or immediately
afterwards, and from chronic intakes of residual radioactivity in the environment, i.e., intakes occurring contin-

uously for manyyears after deposition. But deriving and
understanding the true range of organ doses received by
the Marshallese specific to each nuclear test and at each
atoll of residence has remained an unmet challenge for
many years. Understanding radiation doses to the Marshallese is important for several reasons that include
providing to the Marshallese a complete account of the
radiation doses they received and the related health
consequences, increasing our overall understanding of
the health impact of nuclear testing conductedin the past,
and increasing our understanding and ability to prepare
against fallout events in the future.
A companion paper addresses external doses received by representative persons in the Marshall Islands
from nuclear testing (Bouville et al. 2010). This paper
addresses internal doses. The sum of the internal and

* Division of Cancer Epidemiology and Genetics, National Can-

cer Institute, National Institutes of Health, Bethesda, MD 20892;
* New York City, NY (retried from U.S. DOE); * Consultant,
Bethesda, MD.
For correspondence contact: Steven L. Simon, National Cancer
Institute, National Institutes of Health, 6120 Executive Blvd., Bethesda, MD 20892, or email at

(Manuscript accepted 5 May 2010)

external doses (Simon et al. 2010), when estimated as

Copyright © 2010 Health Physics Society

age-specific annual doses at each atoll, can be used to
predict the excess cancer burden that resulted from the

DOI: 10.1097/HP.0b013e3181dc4e51

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