34
The increase in cancer mortality resulting from the dosages of Table
4.5 #1 can be calculated as follows.
Suppose that 500 persons w
live continuously on Rongelap Island for the period 1978-2008.
average each would accumulate a committed dose (whole-body) of 1
over that 30-year period. For simplicity, I will assume that ea
receives the dose all at once.
Then, taking an overall cancer m
e to
the
5 ren
tality
factor of 5 x 10-4 per rem (Shimizu et al, 1987; Preston and Pie ce,
1987), I find the increment to be:
500 x 1.25 x 5 x 10-* = .31 extra cases.
The factor for first generation genetic defects is smaller
for cancer mortality (National Academy of Sciences, 1972; NCRP,
being approximately 1 x 10-4.
han that
987a),
The foregoing comments apply to the future.
But what about the
past? The Rongelap residents exposed to the Bravo shot received an acute
dose of 190 rem in 1954 and during 1957-1978 they received a chr nic dose
of 1-3 rem. My opinion is that the addition to these past doses of
something like 1.25 rem during the next 30 years will not apprec ably
increase detectable health and genetic risks in a way that shoul
preclude return to Rongelap Island.