- 10 attention should he paid to assessment of medical x-irradiation.
Is this
factor important since 1950 for Utah children?
I do not pretend that refinement of dose estimates would be easy.
It
is a difficult task, but one which must be done to get maximum scientific
value from the study.
Otherwise, one is forced to use less satisfactory
estimates, such as those presented in this paper.
|
6)
Other conditions should be considered, such as the benign thyroid
tumors which appear more frequently than thyroid cancers.
In 73 children and
adolescents treated with I? for hyperthyroidism (an overactive thyroid) and
followed for 2-14 years, there were S thyroid tumors, of which only one {a
papillary adenocarcinoma) was malignant ©) ,
In a different study, out of 15
children treated with I'°+ for hyperthyroidism, 6 thyroid tumors were observed
5-14 years later 19) |
More cases may appear after longer follow-up times.
A very high incidence of adenomatoid goiter (a benign thyroid tumox)) has
been observed in 29 children in the Marshall Islands who were exposed to.
heavy fallout in 1954 G1) |
The external gamma-ray dose was about 175 rads,
while the internal dose from I'31 is estimated to be roughly 1000 rads for
the younger children.
No thyroid abnormalities have been observed in the 75
unexposed comparison children.
7)
The Utah study has motivated careful examination of thyroid condi-
tions in a general population.
The medical information gained may be among
the most important aspects to emerge from this investigation.
SUMMARY
For the 250,000 Utah infants exposed to fallout P°?, the average
thyroid dose received by age 2.5 years is estimated to be 1.3 to 10 rads.
The resulting numbers of thyroid cancer are predicted for each of 3 doseresponse models.
These predictions
indicate that the Utah study should be
continued, with additional effort devoted to improving the estimates of thyroid
dose. .