wa
1.
Introduction:
The adequacy of the biomedical basis of standards
for occupational and public exposure to plutonium and other internal
alpha emitters have been widely discussed (145) and seriously questioned ‘© 8) |
The serious uncertainties in the cancer risks attributable to
internal alpha emitters must be resolved before we are irretrievably
committed co a nuclear energy program.
This is a matter of immediate
concern in the western suburbs of Denver due to plutonium and americium
.contamination of surface soils in public areas around the Rocky Flats
Plutonium Plant ©?) ,
Many other localities are similarly affected by
tranuraniun element contamination and its attendant cancer risks.
Recent controversy regarding the adequacy of plutonium standards
has
centered on several aspects of the problem of the cancer risxs
attributable to inhaled plutonium oxide particles, including such aqueetions .
- as which organ and how small a tissue volume constitutes the “eritical” |
organ (i.e., that experiencing the highest cancer risk), and whether the
average alpha radiation dose
to the critical organ or the tumor risk
attributed to a given number of individual hot plutonium oxide particles
provides the best guidance for the assessment of risks and standards
for plutonium. , Geesaman
(6)
has discussed possible mechanisms of cancer
induction by hot particles and concludes that the tumorigenic risk may
be as high as 1/2000 per particle for submicron particles of plutonium
.oxide.
A recent examination of hot particle risks by Tamplin and Cochran °®),
based largely on the Geesaman study, led these suthors to recommend that
the occupational MPLB (maximum permissible lung burden) be reduced by a
factor of 115,000, to a value of 0.14 pCi.
A recent study 20) was
carried out by Bair, Richmond and Wachholz at the request of the U.S.
Atomic Energy Commission with the specific objective of providing an
updated review of the evidence bearing on the problem of uniform vs