275 rad
69 rad
nodules in spite of a higher dose to the children’s glands.
During the past ten vears, a disturbing findiag has been the further
development of thyroid hypofunction, even in some Rongelaup people
without other detectable abnormalities. Table 3 showsthe present status
of thyroid hypofunction. The positive category represents individuals
who have exhibited two TSH (thyroid-stimulating hormone) levels of 6
14 rad
ire was not
s began to
.ed dose of
J rad in the
loses were
qe children
The largest
wUrml or greater. The suggestive category represents individuals who
have two TSH levels of 4 to 6.
The association of radiation exposure with the developmentof thyroid
abnormalities in the Rongelap population seems apparent though ‘the
Utink findings are less clear-cut. The development of thyroid tumors
following radiation exposure is well documented in the Japanese exposed
to the atomic bomb and in patients, particularly children. following
radiation therapy.
On a risk per rad basis, the induction of thyroid nodules and cancer in
the Marshallese appears to be about equal to that following X-ray
exposure. Since '!} is believed to be only about one-tenth as effective as
culariy‘°],
of growth
later corre‘gsed func-
X irradiation in producing thyroid abnormalities, it seems likely that ir
the Marshallese the exposure to the short-lived isotopes of iodine 7],
83], and 'I, which have more energetic betas and deliver a faster dose
rate than ''], might account for the high incidence.
The findings in the Marshallese emphasize the importance of thyroid
was about
larly in the
110 appear
967, in the
» have had
exposure to radioiodines that may result from warfare or accidents in
which radioiodines are released. Exposure to penetrating gammas or
v increased
neutrons is a more serious hazard not only because of their acute effects.
but also because of the fatal nature of malignancies such as leukemia
which may develop. Deaths due to thyroid abnormalities including cancer
tirik group
unexposed
Table 3.
Cancer?
4.7%
(4/86)
1.9%
(3/158)
‘aSES are
Sf eet
rarer
Group
Positive
Rongelap + Ailingnae
(135-1150 rads)
15%
(13/86)
Utirik
0.8%
(1/158)
(6/158)
Unex posed
0.6%
(1/155)
(30-95 rads)
eet Ps ra? Se tp be
0.9%
(4/437)
Thyroid Hypofunction in Marshallese Populations
Suggestive
Total?
9.3%
(8/86)
24.4%
(21/86)
3.8%
4.4%
1.5%
(1/67)
3.0%
(2/67)
(7/158)
“Some of these subjects appear also in the nodule table, ie., they have both hypofunction
and nodularity.
ena.eaea a a
AY
1 ane “ThalRR SI i
we
Estimated
gamma dose
people. In the Rongelap-Ailingnae group, 65% of those exposed as
children had nodules compared with 27% of those exposed as adults.
Paradoxically. in the Utink population a greater percentage of adults had