less than 200 rads, are below the lowest dose:
which caused adverse biological effects seen i
experiments using beagles.
For example, Bair
colleagues at Battelle-Northwest have not obse
lung effects below about 2000 rads in dogs 10
12 years following a single inhalation exposur
?39pu0,.79
However, these animal data must be
interpreted with caution, as lung tumor incide
is essentially 100 percent at the lowest plutc
exposure levels.
Recently beagles have been exposed to low
initial alveolar depositions, but additional <4
Fig. 9.
?
on the dose-response function will not be avai
al
for many years.
The tn vivo counter with detectors in position for counting the
chest.
The estimated initial alveola
deposited plutonium in beagles which developed
tumors ranged from 0.2 to 3.3 uCi per total or
or ahout 3 to 45 nCi per gram of bloodless dog
counting time, the comparable value is about 3.5 n-
Park and his associates !® estimate that this a
ci.
of plutonium is 100 to 1500 times the estimate
Positive counts were obtained for 14 of 21 per-
sons measured.
These counts suggested chest burdens
ranging from 3 to about 10 nCi.
However, in no case
maximum occupational lung burden in man (i.e.,
0.016 uCi or about 0.03 nCi per gram of blood1l
lung).
As a conservative estimate based upon
did the estimated chest burden exceed the MDA at the
extrapolation of their data to the 15-year mea
95 percent confidence level.
life span of beagle dogs, these authors feel t
jects with positive
chest
Seven of the 14 sub-
counts had estimated chest
initial deposits of about 70 nCi in the lung (
burdens of 7 nCi or greater and may be considered
i nCi per gram), which cause premature death i:
(at the 68 percent level of confidence) to have
beagles, are about 30 times the concentration
statistically significant chest burdens of from 7
alent to the maximum permissible occupational
to 1O-nCi.
burden for man.
For reference, 10 nCi is about 2/3 of
the maximum permissible lung burden for occupational
workers (16 nCi).
If maintained indefinitely, this
This
conclusion,
of course,
based on the assumption that lung tumor develo
is related to plutonium concentration and not
burden will deliver about 15 rem per year to the
the total amount of plutonium in the lung.
lung, assuming uniform distribution of energy
example,
throughout the organ.
the
If one uses the 68 percent confidence level,
i:
Fo:
if tumor induction is somehow related
total number of cells
at
risk
(therefore,
t
number and size of plutonium particles), then i
certain qualitative statements can be made about
relative sizes of human and dog lungs may be ur
the chest measurements.
important and the 70 nCi which causes premature
For example, the estimates
of lung burdens of subject Nos. 1 and 2, who most
death from lung cancer in the dog may be about
likely received exposure to plutonium oxide, were
5 times
approximately 10 nCi.
sidered to be the maximum occupational lung bur
Subject Nos. 4 and 9, who
worked in the Recovery Group, each had a chest
burden ox about 8 nCi.
These relatively small
the total amount of plutonium (70/16)
«
for man. 28
The experimental data obtained from rodent
values are not surprising, in view of the known
are not as
translocation of plutonium from the lung to other
reports that the frequency of malignant neoplas
tissues as a function of time following inhalation.
of the lungs of rats exposed to plutonium by in
The cumulative radiation doses to the lungs
clear nor as encouraging.
Moskalev™
halation is 2 or 3 times higher than in the con
of some of our subjects have been estimated pre-
group at doses ranging from 41 to 234 rads.
viously by Langham? (Table V).
alev states that, assuming the biological effec
16
The values, all
Mo