Management of Commercially Generated Radioactive Waste - U.S. ...

E.2
levels derived by linear extrapolation from data obtained at high doses and dose rates, as
actual risks, and of basing unduly restrictive policies on such interpretation or
assumption" (NCRP 1975, p. 4).
( a )
An alternative approach involves direct comparison of the estimated radiation doses
from CWM activities with the more accurately known radiation doses from other sources. This
avoids the most uncertain step in estimating health effects (the dose-effect relationship)
and provides a comparison with firmly established data on human exposure (i.e., the exposure
to naturally occurring radiation and radioactive materials). Some people prefer to judge a
risk's acceptability on knowledge that that risk is some certain fraction of an unquantifi-
able, but unavoidable, natural risk, than to base this judgement on an absolute estimate of
future deaths that might be too high or too low by a large factor. Because of these judg-
mental problems it is the practice in this Statement to compare estimated radiation exposure
from CWM activities with naturally occurring radiation exposure as well as to indicate esti-
mates of cancer deaths and genetic effects.
E.1 LATE SOMATIC EFFECTS
Recently much literature has dealt with the prediction of late somatic effects of very
low-level irradiation. This literature is not reviewed in detail here because it is recent
and readily available. Instead, the various dose-effect relationships that have been pro-
posed are briefly considered and justification is given for the range of values employed in
this Statement.
Two publications have served as the basis for most recent efforts to quantify late
( b )
somatic effects of irradiation. These are the so-called BEIR Report, issued in 1972
by the National Academy of Sciences as a report of its Advisory Committee on the Biological
Effects of Ionizing Radiations (NAS-NRC 1972); and the so-called UNSCEAR Report, a report
to the General Asembly by the United Nations Scientific Committee on the Effects of Atomic
Radiation, most recently revised in 1977 (UNSCEAR 1977).
Both the BEIR and UNSCEAR Reports draw their conclusions from human effects data derived
from medical, occupational, accidental, or wartime exposures to a variety of radiation
sources: external x-irradiation, atomic bomb gamma and neutron radiation, radium, radon and
radon daughters, etc. These observations on humans were, of course, the result of exposures
to relatively large total doses of radiation at relatively high dose rates. Their extrapolation
to the low doses and dose rates of concern to us is acknowledged by the BEIR Report as
"fraught with uncertainty" (p. 7). The BEIR Report concludes, however, that the assumption
of a linear relationship between dose and effect, extending to zero dose with no threshold
dose below which no effects are predicted, "in view of its more conservative implications,...
(a) EPA commented that this paragraph reflects a bias on the part of the authors. However,
the NRCP quotation was chosen because it represented the negative point of view, and it
was the purpose of this paragraph to reflect that point of view.
(b) A version of this report is in progress.