42
8 vears post exposure it was noted that two boys
were particularly stunted in growth (Figure
the thyroid gland. Development of thyroid abnor-
and gradually developed atrophy of the thyroid
gland and signs of mvxedema with puffy faces.
drvskin. sluggish reflexes, and bony dysgenesis of
the humerus and femur(see Figure 28). These two
posed people of Rongelap are affected. including
the two stunted boys who developed thvroid
atrophy without nodularitv, One of 4 children exposed in utero developed thyroid nodules in 1974.
Figure 29 showsthat. considering the population
27).10.18 They had been exposed at one vear of age
boys (Nos. 3 and 5) were considerably shorter
than their brothers (Nos. 83 and 84) who were
younger and had been exposed zn utevo. In 1965, a
satisfactory method for serum thyroxine analysis
by ion exchange colurnn becameavailable. Stud-
ies bv this method showed that some ofthe children did indeed have low serum thyroxinelevels.
Control studies on normal Marshallese revealed
that manyof them had unusually high iodoprotein levels. leading to a false interpretation of pro-
tein-bound iodine ( PBI) determinations. It became
apparent only then that low thyroxine (T,) levels
in some of the children had probably been masked
by high levels of iodoprotein.18-23 Several children
with slight growth retardation had lowered Ty
levels. The hvpothyroidism appeared to be from
primary thvroid damage and not secondary to
pituitary damage, since tests for growth hormone
in several growth-retarded children were normal,
and their serum thyroid-stimulating hormone
(TSH) levels were elevated.
B. DEVELOPMENT OF THYROID NODULES
In 1963, 9 vears after exposure, a 12-year-old
girl was found to have an asymptomatic nodule of
’
Percent thyroid
|
> 30/2
2 Or
5 30h
e
2
=
-
T
T
~
TOOT
|
Rongelap
Arlingnae
Ununk
4
Control
gO!
5 20r
Z
+
1
1
10
ti
oh,
12
absaande
13
[4
TieregeoF
[5
16
17
18
19
malities in other subjects continued during subse-
quent years.!8-23 At present (1974) 29 of 86 ex-
remaining at risk (persons living in 1964, at the
time of appearance of the thyroid abnormalities).
the trend is for continued developmentoflesions
with recent increases among the lower-exposure
Ailingnae group. Table 24 lists the thyroid status
of all exposed Rongelap people and of people with
positive findings in certain other populations.
The thyroid nodules were usually multiple.
were not tender. and varied in size from several
millimeters to several centimeters in diameter. In
someof the children nodular glands wereassoci-
ated with low thyroxine levels and slight growth
retardation. The two stunted boys { Nos. 3 and 3)
showed markedly reduced thvroxinelevels. None
of the adults with nodularity had low thyroxine
levels prior to surgical exploration. The growthretardation with reduced thyroxine levels appears to
be the result of radiation injury to the thvroid in
the children (see Section E, below).
Table 25 lists the incidence of benign and malignant lesions and the estimated dose of radiation
to the thyroid glands in the various populations
The highest incidence of lesio-
(89.5%) has been
noted among those in the heavily exposed group
who were < 10 years old at the time of the acci-
dent. The absenceoflesions amongthoseof corresponding ages in theless exposed Utirik group and
the unexposed groups is notable, but 2 of » exposed children in the Ailingnae group have recently developed lesions. The incidence of thy raid
lesions amongthe exposed Rongelap adults is considerably lower than that amongthe children but
higher than among the Utirik or unexposed
groups. The Utirik group does not appearto have
had a higherincidence of thyroid lesions than the
unexposed groups, but one Utirik individual developed cancerof the thyroid.
20
Years after exposure
Figure 29. Cumulative percentages of persons with thy-
roid lesions in exposed Rongelap, Ailingnae, and Utirik
groups and in unexposed Rongelap control group since
1964, based on numbers ofpersons in the groups in 1964,
the ume when radiation-induced lesions were first noted.
C. SURGICAL EXPLORATION
In view of the possibly malignant nature of the
thyroid nodules in the exposed population, surgical exploration of the affected thyroids. with removal of nodules, was considered necessarv. Thy -