C.W. Mays - Page 9
incidence of 425 thyroid cancers per million infants
each receiving one rad; (B) a linear dose response, but
iodine 131 irradiation only one tenth as effective as
X-irradiation; and (C) a high threshold.
Assumption (A)
probably sets an upper limit,for it is unlikely that
iodine 141 is more effective than X-rays.
Assumption
(C) certainly sets the lower limit -- the number of
induced cancers cannot be less than zero!
Assumption
(B), while between the upper and lower limits, is not
necessarily the best estimate but it yields reasonable
values for planning the experimental search for thyroid
cancer.
Estimates of the number of radiation-induced
thyroid cancers which night appear during the lifespan
of the 250 oan infants for doses of 1.3 - 10 rads
are compared in Table 3 to their expected natural
incidence by age fifteen.
Table 3
ESTIMATED THYROID CANCERS
FOR THE 250,000 IRRADIATED UTAH INFANTS
ASSUMPTION
(A)
(B)
(C)
NUMBER OF CANCERS
Iodine 131 effect equals
x-ray effect
Effect equals 1/10 of
X-ray effect
High Threshold
ii
-
88
1
-
9
0
"NATURAL" INCIDENCE BY 15 YEARS OF AGE
6
Similarly, it is instructive to calculate the
anticipated number of radiation-induced thyroid cancers
which might appear during the lifespans of the 565
infants in Washington County, Utah,
exposed to higher
thyroid doses (estimated at 120-440 rads”) following the
"Harry" shot of 19 May 1953.
in Table 4.
These estimates are shown
DOE ARCHIVES