-ll(b)
The worst years seem to be 1953 and 1957.
(c}
Many Utah children have received thyroid doses of several rads.
(d)
The St. Geerge exposures were sizable.
(e)
These dose estimates need to be improved.
In particular, field gamma
data should be released; air beta concentrations should be made available
for 1951, 1952, 1953 and 1955; and if not contrary to the interests of
national security, kiloton yields for the July 1962 tests are needed.
Perhaps a future "incident" will provide the needed calibration check?!
PREDICTED THYROID CANCERS
I realize that any attempt to predict an increase in cancer due to low
doses of radiation is subject to great inaccuracy and criticism.
This is
especially true when the dose estimates are so very approximate.
There-
fore, it should be understood that the following estimates were made pri-
marily to indicate whether or not an effort to search for increased
thyroid cancers would be justified.
Archer and Simpson 1) have tabulated 10 thyroid cancers in 2253
Ae
|
children x-irradiated as infants for "an enlarged thymus" with an average
dose of 225 rads, and an average follow-up time of 14.5 years.
At present
we have no information on how many additional thyroid cancers will develop
at later times, ie after 14.5 years.
They have calculated that 0.05
"spontaneous" thyroid cancers should have been expected normally in this
group during the follow-up period.
NS dose
Assuming a linear relation between
and incidence’, there should be 1 case per 50,000 rad-children.
* To my satisfaction this relation has neither been proved or disproved
adaquately for thyroid cancer.