CHAPTER 3
INTERNAL CONTAMINATION IN ANIMALS
The internal contamination of a number of animals collected on the Marshall Islands was
studied. The activity in their urinary excretion was studied, and radiochemical analyses were
madeof various tissues. These data provided the bases for estimating the body burden of the
radioisotopes in human beings. In addition, hematological and pathological studies were made,
and autoradiographs of selected tissues were prepared. A numberof the animals are also being
studied for the appearance of possible long-term effects of radiation.
A special study was carried out to determine the effect of the radiation on the fertility of
chickens and the hatchability of their eggs.
The animals collected on Rongelap and Utirik Islands included 41 chickens, 9 baby chicks,
11 swine, 4 ducks, and ! cat. These were all shipped alive to NRDL. Three fish and one large
clam were taken from the Rongelap lagoon. Collection dates and mortality data for these animals are presented in Table 3.1. In addition, a boar, a cat, and two chickens were autopsied in
the field, and representative tissues were collected.
3.1
METHODS
Tissue samples were taken from all animals that died spontaneously or were sacrificed.
Specimens were obtained from the lung,liver, gastrointestinal tract, and the skeleton. The
samples were ashed at 550°C in a muffle oven, and the ash madeup to volume with 2N HCl. An
aliquot was then dried for beta measurement. The beta activity was determined by means of a
thin end-window Geiger-Miiller counter. Strontium-89 was used as the basis for the mass ab-
sorption correction for the samples, since it was the major radioelement deposited. The cor-
rection calculated is an approximation, since mass absorption is a function of the average energy
of the sample. Beta activity was measuredin total disintegrations per minute, and this value
was converted to microcuries, “Sr*? equivalent.”
The gammaactivity of the tissue samples was measured in a well-type sodium iodide scintillation counter, which has an efficiency of about 40 per cent for a Co™ standard. The gamma
activity was obtained in total disintegrations per minute, and this value was converted to microcuries, “Co™ equivalent.”
Samples were analyzed radiochemically for sr®, Bal@? the rare-earth group, y's! | and
fissile material.
For excretion studies the animals were caged individually, and their excreta were collected
at 24-hr intervals. The feces and urine were ashed together for the chickens, whereas they were
collected separately for the pigs. Beginning 5 weeks postdetonation, the excreta of a representative group of chickens were collected at weekly intervals for a period of 24 months. Collection
of pig excreta was begun at 6 weeks postdetonation, and the collection was made at weekly inter-
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