a
a
ws
T-156
of particies deposited (that is those emitting several thousand helivin nuclei
This is reasonable.
pec ery),
Thore would be sorvething like a thousand of
these particles and each would chronically expose J] to 20 alveoli to intense
.
would cevelop lung cancer.
Put another way,. about 1 cubic centimeter of the lung is receiving
high doses of radiation. It would not be surprising if intense exposure of
such a localized volume led to acancer one time in ten.
we eee ee ee
atbehe Shere ebe bie
ticle, then the total risk in this situation is one in ten, i.e., one man in ten
boas
If the risk of canceris like 1 in 19,000 for one disruptive par-
Oo
radiation.
The guestionis:
-
It is rauch easier to find two cancers
using 50 exposures of 1 cubic centimeter each, than it is to find a couple
of cancers in 50,000 single particle exposures.
Certainly the length scales
of injuc; are long enough that a disruptive carcinogenic pathway cannot be
disregarded for isolated hot particles {(Geesaman, D.P., 1968b).
. One can lock to the relevant experience for reassurance.
In an
experiment done at Hanford by Dr. Bair and his colleagues, beagle dogs
>
~
_Wwere given Pu23%, lung burdens of a few hundred thousandthsof a gram
(Bair, W.J., et al., 1966; Ross, D.M., 1987). At 9 years post exposure,
or after roughly half of an adult beagle life span, 22 of 24 deaths involved
lung cancer, usually of multiple origin.
Five dogs remain alive.
For
conipurison, these exposures are about 100 times larger than the presen
thaniimum permissible burdens tnoaman,
There are two unsatislactory aspeets of this experiment.
First,
Diebt. WEA Sek
-protection afforded? No one knows.
ee
if the individual volumes are separated from each other, is substantial