Shawki A. Ibrahim,* Steven L. Simon,’ André Bouville,’ Dunstana Melo,’
and Harold L. Beck*
located in equatorial waters in the Pacific. During
roughly the same period (1951-1958), the U.S. also
conducted 119 nuclear tests at the Nevada Test Site

Abstract—This paper presents gastrointestinal absorption
fractions (f, values) for estimating internal doses from local
and regional fallout radionuclides due to nuclear tests. The
choice of f, values are based on specific circumstances of
weaponstest conditions and a review of reported f, values for
elements in different physical and chemical states. Special
attention is given to fallout from nuclear tests conducted at the
Marshall Islands. We makea distinction between the f, values
for intakes of radioactive materials immediately after deposition (acute intakes) and intakes that occur in the course of
months and years after deposition, following incorporation
into terrestrial and aquatic foodstuffs (chronic intakes). Multiple f, values for different circumstances where persons are
exposed to radioactive fallout (e.g., local vs. regional fallout
and coral vs. continental tests) are presented when supportive
information is available. In somecases, our selected f, values
are similar to those adopted by the International Commission
on Radiological Protection (ICRP) (e.g., iodine and most
actinides). However, f, values for cesium and strontium derived from urine bioassay data of the Marshallese population
are notably lower than the generic f, values recommended by
ICRP, particularly for acute intakes from local fallout (0.4 and
0.05 for Cs andSr, respectively). The f, values presented here
form the first complete set of values relevant to realistic dose
assessments for exposure to local or regional radioactive
Health Phys. 99(2):233-251; 2010

(NTS) (U.S. DOE 1988). All together, over 500 atmo-

spheric nuclear weaponstests took place at varioussites

around the world from 1945 to 1980 (Beck and Bennett

2002). These tests resulted in the deposition of significant quantities of radioactive debris to the local, regional
and global environments resulting in human health consequences that have ensued over the decades since
(Simon 1997; Simon et al. 2006). Since nuclear testing

ceased, a number of dose reconstruction assessments
have been conductedfor specific populations (Becketal.
2006). Depending on the level of detail considered and
the degree of realism sought in assessment calculations,
dose estimation parameters may require evaluation and
interpretation based on the available historical data for
each assessment.
The assessment of internal dose from the ingestion
of radionuclides for the general public requires knowledge on the fraction of the radioactive material absorbed
from the alimentary tract to blood, using a model

parameter usually termed the “f, value.” Literature
information for f, values vary significantly depending on
the origin of the measurements or assumptions made
about the chemical and physical properties of the ingested form in addition to other biological and environmental factors. Metabolic investigations on radionuclide
uptake using soluble compoundsused in laboratories and
some industries often produced higher f, values compared to other less soluble forms in both animal and
humanstudies. Typically, the International Commission
on Radiological Protection (ICRP) and other radiation
protection organizations tend to adopt conservative f,
values to ensure a margin of safety for protection of
humans exposedto a wide range of radionuclide forms
in the workplace and to members of the public. The

Key words: fallout; Marshall Islands; radionuclide; nuclear

From 1946 through 1958, 66 nuclear weaponstests were

conducted by the U.S. in or near the Marshall Islands

* Department of Environmental and Radiological Health Sci-

ences, Colorado State University, Fort Collins, CO; * Division of

Cancer Epidemiology and Genetics, National Cancer Institute, Na-

tional Institutes of Health, Bethesda, MD; * New York City, NY.
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 June 2009)

Copyright © 2010 Health Physics Society

use of generic f, values, however, may not be desir-

able in dose reconstructions, particularly where “best

DOI: 10.1097/HP.0b013e3 18 1b186ff

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