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CHAPTER 1
INTRODUCTION
1.1
OBJECTIVES
The objectives of the study of internal radioactive contamination, Project 4.1, are as
follows:
;
1. To determine the nature and extent of the internal radiation hazard to human beings
exposed to the fallout from the 1 March 1954 detonation of Operation CASTLE.
2. To evaluate the contribution of the internal contamination to the acute and long-term
radiation syndrome.
3. To determine the feasibility of an internal decontamination therapy program.
4. To determine the amount and type of contamination sustained by exposed animals,
food plants, soil, and water of the contaminated atolls.
The nuclear detonation of 1 March wasthe first instance in which a large group of people
received a significant internal contamination from fission products with an accompanying external dose of less than lethal magnitude.
A detailed study of the internal contamination in the exposed human population and in
animals was made to determine the kind and degree of internal deposition. There were three
general problemsto be investigated: (1) The first was to determine the contribution of the
internal contamination to the acute radiation syndrome observed in order to evaluate the importance of internal contamination when combined external and internal irradiation occurs.
(2) The second problem concerned the possibility of long-term effects. (3) The third question
was directly answered by the study made, that is, what was the qualitative and quantitative
nature of the internal contamination produced by exposure of individuals to mixed fission
products. There has been no previous situation in which human beings have been exposed to
an environment contaminated with mixed fission products.
Evaluation of the internal contamination of the human beings was madeby a study of the
radioelements excreted. Since very little information is presently available concerning the
ratio of excreted radioelements to the amount deposited in the body, it was necessary to base
the evaluation on data obtained from animals that had been contaminated in the same event.
Detailed studies of animal tissues and animal excreta then provided data on which estimates
of the human body burden were based.
1.2
GENERAL NATURE OF INTERNAL RADIATION TOXICITY
The nature of the radiation hazard from internally deposited fission products can best be
understood in terms of the biophysical behavior of the radionuclides.
Fission products entering the body through inhalation or ingestion concentrate in various
tissues and act as sources of internal radiation. The ability of a radionuclide to enter the
il
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