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INTERNAL DEPOSITION OF RADIONUCLIDES
detonation were more active than the alveolar
tissue.
The importance of ingestion as a continuing
source of contamination is evidenced by the
level of internal contamination of the pigs from
Ronegelap. These animals had about ten times
the body burden of the human population in
the same locality. As the air-borne activity
had already- dropped to a low value at the time
of evacuation of the humans, the contamination
of the pigs during their prolonged stay on the
island necessarily derived from ingestion of
radioactive food and water.
,
el
Radioanalysis of water and soil samples from
Rongelap indicated high levels of contamination from the fallout at early times following
detonation.
It appears that during the first month a
linited amount of fission products was available to plants growing on the contaminated
soil. Significant amounts of beta activity as
well as small amounts of alpha activity were
present on the external surface of plants at 42
days post detonation. Only very snl amounts
of beta activity and no alpha activity were de-
tected in the edible portions of fruits such as
—
pandanus, papayas and coconuts.
MWowever,
hich levels of activity were found in the coconut
tree sap, and the isotopic concentration was
very similar to that of water.
High Jevels of activity were found in fish
taken from Rongelap lagoon. Tt appears that
the ingestion of contaminated water and fish
were the principal sources of internal contamination of human beings. Of the individual
radionuclides, Sr, because of its high solubility and relatively long radioactive half-life
was probably the isotope of preatest potential
hazarilin the environment.
Internal Radioactive Decontamination Ther-
apy.
Since there is no method of counteract-
ing the effects of radiation from internally deposited emitters, treatment consists of removing the nuchdes from the body as rapidly as
possible. The ability of ethylene-dianiine-
tetra-acetic acid (EDTA) to mobilize certain
of the fission products from the skeleton and
5002180
75
(o increase the rate of their excretion has pre-
viously been demonstrated (11-13).
It js mast
effective with the rare earth group, but has
no effect on strontinin (13). These stucties have
shown that. most of the bicloyically hazardous
material remaining in the badyis firmly fixed
in bone within a short time, so that effective
systemic decontamination by chemical agents
can occur only in a short period following exposire. Nevertheless, an atrempt to effect internal decontamination was male 7 weeks post
detonation, since it would mobilize and make
detection of isotopes easier, even though it was
realized that the procedure would have limited
value at this time.
A representative group of seven individuals
fram Rongelap were selected for this study.
During a control period of 5 days, 24-hoururine
samples were collected daily for radioanalysis
in order to establish a basal excretion rate.
During the next 3 days, calcium EDTA was administered orally, 1 @m per 23 Ibs of budy
weicht daily instead of the preferable intravenous drip because parenteral therapy was not
practical under the circumstances.
Twenty-four hour urine samples were collected daily during the treatment period and
for 5 days following treatment to determine the
effectiveness of EDTA in accelerating the excretion rate of the radioelenents.
,
No side effects from the use of EDTA were
observed. Blood counts and blood pressure remained unchanged throughout the treatment.
The mean activity of the urine during the
EDTAtreatment period was 2.5 times the pretreatment activity, The probability that the
differences observed are due {o chance is less
than 0.01. Thus the oral administration of
EDTAfora period of 3 davs beginning 52 days
post detonation incrensed the excretion rate of
internally deposited fission products, but the
over-all effect on decreasing the body burden
was slight, as the excretion rates were very low
at this time.
Summary. The first instance of internal deposition of mixed fission products in hunins
occurred asa result of fallout. following a Cher-