BASES FOR CALCULATION OF RISK ESTIMATES USED
IN
410044
“THE MEANING OF RADIATION AT BIKINI ATOLL”
I.
R
ASSUMPTIONS
Estimates of cancer and birth defect risks for the Bikini populations
were based on a number of assumptions.
Some of these assumptions
re-
sulted from consultation with other scientists including members of the
,,
BEIR committees.
Risk coefficients
1.
from BEIR-I were used because BEIR-111 had
not been accepted by any U.S. government agency.
values as given in
BEIR-I rather
age of the population shown
2.
We elected to use the
than the revised values based on increased
in Table V-4 of BEIR-111.
For estimates of cancer risk both the relative risk coefficient
and the absolute risk coefficient were used to give a range of estimated
risk.
The absolute risk coefficient
gives a lower value, is less vari-
able with the population and is not dependent upon the spontaneous
cancer incidence, which is not known for the Bikini population.
The
relative risk coefficient gives a high value, but since it is based on
the spontaneous cancer incidence,
population,
which is unknown for the Bikini
it is probably less reliable than the estimates calculated
from the absolute risk coefficients.
3.
For estimating
increased cancer incidence,
the bone marrow
dose was used because it was slightly higher than the whole body dose.
This probably introduced a small element of conservation.
4.
For estimating
birth defects neither BEIR-I or BEIR-111 is very
clear about what is meant by parental dose, thus it is not clear whether
birth defects should be based on the dose to one parent or both parents.
In the latter case, the 30-year whole body dose would be doubled. We
assumed the BEIR-I risk of 0.2% rem was based on both parents being
irradiated.
Also because we believed the risk coefficient
from
BEIR-I