58
FALLOUT EFFECTS—MARSHALL ISLANDERS
TABLE 1. Estimated radiation doses in exposed populations
Atoll
No.
affected*
Est. whole-body
gamma dose
(rem)
Rongelap
67
175
Ailingnae
Utirik
19
164
69
14
Est. thyroid dose (rem)
by age at exposure
<10 yr
10-18 yr
> 18 yr
800-2,000(?)
334-810
335
275-450
60-95
190
30-60
135
30
2 Includes in utero exposures (3 on Rongelap, 1 on Ailingnae, and 6 on Utirik).
doses were due to gammaradiation plus radioiodines.! Because of the smaller
size of the thyroid gland in children, their exposure from radioiodines was
considerably greater. Although the estimated dose in a 3-year-old Rongelap
child was 700 to 1,400 rads, the dose to a 1-year-old child was perhaps 2,000
or more rads. These dose estimates unfortunately had to be based on single
pooled 24-hr urine sample from Rongelap people collected 15 days after exposure,
with the assumption that the I-131 excreted in this sample represented 0.1%
of the I-131 initially taken in (33). The short-lived radioiodines (I-132,1-133,I' 135) were not measurable but were estimated to have contributed 2-3 times
the dose from I-131 to the thyroid. The possible importance of these isotopes
will be referred to later. The thyroid doses to the Ailingnae and Utirik groups
were arrived at by extrapolation based on relative gammadose estimates.
COMPARISON POPULATIONS
About 200 Rongelap people who were not on Rongelap at the time of the
accident, matched as nearly as possible with the exposed group with respect
to age and sex, have been examined regularly for comparison purposes. In addi-
tion, during the past decade, about 400 other unexposed Rongelap people in
the same age range as the exposed people and about 500 younger Marshallese
have had thyroid examinations in order to establish the prevalence of thyroid
abnormalities in unexposed Marshallese people. Though someofthese ‘“‘controls”
have been exposed to slight residual radiation while living parttime on Rongelap
and Utirik, any effects of such low levels of exposure would not be detectable
and would not nullify their use for comparative purposes (13).
FINDINGS DURING THE FIRST DECADE
Theearly findings in the exposed Rongelap and Ailingnae groups(14) included
transient nausea and vomiting, and depression of peripheral blood elements to
1 Reevaluation of early dosimetry, now under way at Brookhaven National Laboratory with
additional data that have becomeavailable, indicates that thyroid doses may be higher than previously
estimated (39). In this report the earlier estimates shown in Table | are used.
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