- 14 -
In obtaining the derived values in Tables I and Iti,
MPLB and MPCa for Pu-239, a QF=10 was employed.
This OF
implies, as mentioned above, that the particles of Pu-239,
which emit alpha particle radiation,
in inducing cancer than X-rays.
are 10
times more effective
Although the irradiation of
tissue by insoluble plutonium particles is highly nonuniform,
no DF value has been assigned to these particles and hence, a
DF=1 was employed in determining the derived values in Tables I
and II.
Ideally, the DF should be determined by the ratio
of the observed effects in an organ Following uniform and
nonuniform radiation of the tissue with the same radicnuclide;
for example:
Number of cancers
DF ~ Number of cancers
(nonuniform irradiation}
(uniform irradiation)
Since direct experimental data are not available, it is
necessary to derive the DF for insoluble Pu-239 particles from
collateral data,
Ina subsequent section, we shall present
the biological evidence that strongly suggests that a DF=1
grossly underestimates the DE for insoluble particulates of
Pu-239 and, consequently, that the derived standards, MPLB
and MPC, for this radionuclide, are greatly in error?°,
|
In fact, it will be shown that the biological data strongly
suggests that for such particles one should use a Dr=].15,0092.
20/
This
app 1 ies
™~
me
- +
in insoluble
a
—
as well to cther alpha-emitting actniccs
particulate
pa
form.