CHAPTER 2
INTERNAL CONTAMINATION IN HUMAN BEINGS
The internal contamination study was begun 15 days postdetonation with the collection of
pooled 24-hr urine samples from the Marshallese and American groups. Maximum activity
in the urine occurred during the first few days after internal contamination. By one week an
approximate equilibrium state was reached in which the contaminants remaining in the body
were firmly fixed, chiefly in the skeletal tissues. The activity in the urine then was derived
from radioelements which were replaced in the natural process of biological turnover. Thus
the study made is essentially that of an equilibrium condition.
All the urine samples were sent back to laboratories in the United States for analysis
since the high background encountered in the field masked the relatively low levels of activity
in the aliquot samples used. A field laboratory is most desirable for a rapid survey and was
shown to be feasible if adequate facilities are provided for the counting of the samples.
The first urine samples, mentioned above, were collected by the Los AlamosScientific
Laboratory (LASL). Similar samples collected 44 days postdetonation were also sent to LASL.
On the 23d, 24th, and 47th days postdetonation, 24-hr urine collections from each individual in
the Rongelap and Ailinginae groups were sent to the AEC New York Operations Office (NYOO, AEC) for analysis. In addition, samples from representative individuals in these groups were
collected 2'4, 3, and 6 months postdetonation and sent to NYOO-AEC.
The Naval Radiological Defense Laboratory (NRDL) collected samples from each member
of the American, Rongelap, and Ailinginae groups at 43 to 45 days postdetonation. Samples from
representatives of these groups were also collected at 2'4, 3, and 6 months by NRDL. In addition, samples from a representative group of 6 Americans and 20 Marshallese were collected
for 6 consecutive days beginning 33 days postdetonation.
2.1
METHODS
Since a complete radiochemical analysis of all the urine samples was not feasible, samples
were analyzed only for Sr®, Ba!“°, the rare-earth group, and fissile material. These analyses
are the most useful for evaluating the concentration and identity of all the potentially hazardous
internally deposited radioactive isotopes. Measurement was also madeof the gross beta ac-
tivity of all the samples.
A scanning method for beta measurement, consisting of a basic oxalate precipitation with
a lanthanum carrier, was employed on an aliquot of the 24-hr urine samples in order to facilitate the processing of the large number of urine samples being sent from the field, This
method rapidly concentrates the radioactive elements into a small volume and eliminates the
normally present K* background. A carbonate precipitation of the entire 24-hr sample in-
creased the sensitivity of measurement sufficiently for analysis of samples collected later
than 214 months postdetonation.
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