Cancer Deaths among Radiation Workers
907
ig. 2 displays these time distributions. Calculations have been performed
with A and B spread over 50 years as well as 30 years as in the figure and these
ave distinguished as Ago, Aso, etc. This permits some estimate of the difference
between leukaemia cdeaths—all of which may be expected to have occurred
within 30 ycars—and other cancer deaths where the risk may spread over a
longer period following exposure.
5
~
@
o
a.
%
<=
%
<
S
3
S
sa
4-00
5a
on
0-07
0-06
0-05
0-04p
0-03
0-0?
0-0i0
5
{l
c
oe
B
—
10
a
15
a
20
at
25
30
Time following exposure lyears }
Tig. 2. The three risk-time relations Aj, By, and C,,. Wo also consider Agg and Bago
(i.c. the same form as Ay and Byg but spread over 50 years).
Having established the three factors (1), (1) and (iit) we may now calculate
the expected age-specific racdiation-induced deaths in our work foree. The
munbers of workers in cach 10-year age group are shownin column B of tables 2
and 3 and the corresponding ‘non-radiation’ deaths in columns C, D and Is.
Columns I? and @are calculated by summing a man’s risk of dying in any
particular year arising from cach year of exposure up to that tine. Henee we
caleulate the number of deaths in a group of the same age and exposure.
This is repeated for all age and exposure groups and the results summarized in
columns Pand G. Both columns Jf and G (Ag, and Az, vespeetively) have been
evaluated with a risk cocfiiciont of LO-4 per rad so to find the expected number
of radiation-induced leukacmia deaths we must seale column Tf appropriately
fsce eqn 1).
While the age-specific numbers of radiation-indueced deaths shown in tables 2
and 3 are applicable to a population of 100000 workers cach exposed to Lrad/
yeav with an associated risk of 10! per rad, we ean deduce the corresponding
numbers for any other parameters from
=mx i
fe
ALif =
105°x io-4
D=mP,
= INL, RD{LO
4h
(1)
where m is the number of deaths shown in the table, 2, is the working population, & is the risk per rad and / is the average annual dose per worker. ‘This
simple sealing is possible because of the negligible effect of radiation-induced
deaths on the population distribution.
The calculations described are for the steady state and ib would take 50 years
for the exposure distribution to be reached. Since this is longer than the
nuclear power industry has been in existence, it is of interest to consider the
approach to the steady state situation. We have maintained the same work