FALLOUT EFFECTS—MARSHALL ISLANDERS
61
than 5 years of age. Retrospective analyses of the frozen serum samples revealed
that many of the children, prior to thyroid surgery, had elevated TSH levels
and in somecases reduced T, levels, though except for the two myxedematous
boys, the hypofunction was not severe enough to be clinically evident.
In 1965 T, (synthroid) treatment was instituted in exposed Rongelap and
Ailingnae populations with the objectives of retarding thyroid nodule formation
and enhancing growth and development in growth-retarded children. It was
given to surgical cases only in the Utirik and control populations. Results of
this treatment will be discussed below.
In view of the early hypofunction of the thyroid noted in the children, the
groupstested for hypofunction have included, in addition to the exposed Rongelap-Ailingnae groups, the exposed Utirik people and many unexposed people.
On the basis of control studies in the unexposed Marshallese, an increase in
TSH level to 26 »U/mi on at least two occasions was considered positive
evidence of hypofunction and levels between 3 and 6 ~»U/mi were considered
suggestive evidence. In some of the exposed children, the evaluation was based
on only one available presurgical sample (13,37). These are very sensitive criteria
and represent subclinical or “biochemical” hypofunction. In addition to TSH
analyses, results of stimulation tests with TSH and TRH were used in many
cases to confirm the findings. Table 2 summarizes these findings.
The most marked TSH elevations were noted in the Rongelap people exposed
at less than 10 years of age, who had received the highest thyroid doses. Only
two of these had clinical hypothyroidism, and most of the others subsequently
TABLE 2. Thyroid hypotunction (1981)
Hypofunction
Group
age 1954
Rongelap
1 yr
2-10
210
Ailingnae
<10
210
Utirik
< 10
= 10
Controls
<10
210
Est.
dose
(rads)
No.
Positive
OO
No.
%
Positive + Suggestive
No.
%
2 1500(?)
800-1500
335-800
;
275-450
135-190
6
16
45
5
4
4
83
25
9
5
8
6
83
50
13
7
12
0
1
0
8
0
2
0
17
60-95
30-60
64
100
0
1
0
1
4
4
6
4
229
371
1
1
0.4
0.3
2
2
0.8
0.5
2 The levels in the exposed groups have not been corrected for control levels, since the
correction would be small. Includes presurgical data.