+2
8 years post exposure it was noted that two boys
were particularly stunted in growth (Figure
97),10.16 They had been exposed at one year of age
and gradually developed atrophyof the thyroid
gland and signs of myxedema with puffy faces,
dry skin, sluggish reflexes, and bony dysgenesis of
the humerus and femur (see Figure 28:. These two
bovs (Nos. 3 and 5) were considerably shorter
than their brothers (Nos. 83 and 8+) who were
vounger and had been exposed in uler>. In 1963, a
satisfactory methodfor serum thyroxine analysis
by ion exchange column becameavailable. Studies by 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 protein-bound iodine (PBI)determinations. It became
apparent onlythen that low thyroxine (T4)levels
in some of the children had probably been masked
by high levels of iodoprotein.!8-73 Several children
with slight growth retardation had lowered T,
levels. The hypothyroidism appeared tobe from
primary thyroid 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 years after exposure, a 12-year-old
girl was found to have an asymptomatic nodule of
|
Percent dhyroaid
lesions (cumulative)
-
30
#0
10
e@
.
:
Ailingnae
4
Control
if
:
7
i
Rongelap
5
oO
‘
7
Utink
on woh.
12
be
#13
T
ele
14
ook
#150
a ee
the thyroid gland. Development of thyroid abnormalities in other subjects continued during subsequent years.!3-?3 Ar present (1974) 29 of 86 exposed people of Rongelap are affected, including
the two stunted boys who developed thyroid
atrophy without nodularity. One of 4 children exposed m utero developed thyroid nodules in 1974.
Fig..e 29 showsthat, considering the population
remaining at risk (persons living in 1964, at the
ume 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
some of the children nodular glands wereassociated with low thyroxine levels and slight growth
retardation. The two stunted boys (Nos. 3 and 5)
showed markedly reduced thyroxine levels. None
of the adults with nodularity had low thyroxine
levels prior to surgical exploration. The growth retardation with reduced thyroxine levels appears to
be the result of radiation injury to the thyroid 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 oflesions (89.5%) has been
noted amongthose in the heavily exposed group
who were <10 years old at the time of the accident. The absence oflesions among those ofcorresponding ages in the less exposed Utirik group and
the unexposed groups is notable, but 2 of 6 exposed children in the Ailingnae group have recently developed lesions. The incidence of thyroid
lesions among the exposed Rongelap adults is considerably lower than that amongthe children but
higher than among the Utirik or unexposed
groups. The Utirik group does not appear to have
had a higherincidence of thyroid lesions than the
unexposed groups, but one Utirik individual developed cancerof the thyroid.
«160~6«17)«18
Years after exposure
Figure 29. Cumulative percentages of persons with thyroid lesions in exposed Rongelap, Ailingnae, and Utirik
groups and in unexposed Rongelap control group since
1964, based on numbers of persons in the groups in 1964,
the time when radiation-induced lesions were first noted.
C. SURGICAL EXPLORATION
In view of the possibly malignantnature of the
thyroid nodules in the exposed population, surgical exploration of the affected thyroids, with removalof nodules, was considered necessary. Thy-