The hypothesis that ingestion was the chief source of internal contamination is supported
by the finding that the gastrointestinal tract, its contents, and the liver of autopsied chickens
and pigs sacrificed at early intervals following 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 Rongelap pigs. These animals had about ten times the
body burden of the human population. Since the airborne 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.
2.4
INTERNAL RADIOACTIVE DECONTAMINATION THERAPY
Since there is no method of counteracting the effects of radiation from internally deposited
emitters, treatment consists of removing the nuclides from the body as rapidly as possible.
TABLE 2.6—Internal Radioactive Decontamination Calcium EDTA
Treatment of Rongelap Group
{Beta Activity (dis /min/24 hr)*]
Patient No.
Pretreatment
(Day 35-41)
Post-treatment
52
63
66
WW
Daily
av.
612
2190
2291
3610
3255
2074
5885
3583
6356
4284
3190
4775
7
14
39
1750
810
6206
3922
(Way 55—59)
*All values corrected for decay to day 35.
The ability of ethylene-diamine-tetra-acetic acid (EDTA) to mobilize certain of the fission
products from the skeleton and to increase the rate of their excretion has previously been
demonstrated (Foreman and Hamilton,® Cohn et al.%). It is most effective with the rare-earth
group, but it has no effect on strontium (Cohn and Gong’). These studies have shown that most
of the biologically hazardous material remaining in the body is firmly fixed in bone within a
short time, so that effective systemic decontamination by chemical agents can occur only in a
short period following exposure. Nevertheless, an attempt to effect internal decontamination
was made at 7 weeks postdetonation, since it was felt that whereas optimum decontamination
could not be accomplished at this time, any procedure which enhancedthe elimination of some
of the radioelements from the body was valuable in reducing theultimate hazard to the contaminated individual.
A representative group of seven individuals from Rongelap were selected for this study.
During a control period of 5 days, 24-hr urine samples were collected daily for radioanalysis
in order to establish a basal excretion rate. During the next 3 days, calcium EDTA was administered daily (1 g per 25 lb of body weight) by oral administration. (Although the slow-drip
intravenous administration of sodium EDTA in 5 per cent dextrose is the method of choice,
only the oral administration of calcium EDTA wasfeasible in this situation.)
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 radioelements.
No side effects from the use of EDTA were observed. Blood counts and blood pressure
remained unchanged throughout the treatment.
The meanactivity of the urine during the EDTA treatment period was 2.5 times the pretreatment activity (Table 2.6). The probability that the differences observed are due to chance
is less than 0.01. Thus the oral administration of EDTA for a period of 3 days beginning 52
20