1-156
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The prob-
lern is that, under a number of conditions (Anderson, B.V., et al., 1967;
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insoluble they may reside in the alveoli fer a considerable lime.
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particles tend to be deposited here by gravitational settling, and if they are
Fraser, D.C., 1967; Kirchner, R.A., 1966; Mann, J.R., et al., 1967;
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dy
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Stewart, K., 1963; ‘Wilson, R.H. etal., 1967) plutonium tends to form
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eer
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ES A OSS TSS SSS
aerosois Of a size that are preferentially deposited in deep .ung tissue.
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.
2
Plutonium dioxide, which is a principal offender, is insoluble and may be
immobilizedin the lung for hundreds of days before being cleared to the
throat or to the lymph nodes around the lungs (Health Physics, 1966).
An aerosol is comprised of particles of many different sizes, and
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IT will
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simplify the argument and sav that there is a class of these particles, the
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largest ones deposited in the deep lung tissue, that can be expected to have
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“a different potentiat of cancer induction than the particles of the smaller
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This is because they are sufficiently radioactive to disrupt cell .
populations in the volumeof cell tissue which they expose (Geesaman,
D.P., 1968a). An example might be a particle that emits 5000 helium
t
. Nuclei per day.
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.
It would subject bétween 1 and 20 alveoli to intense radi-
ation, sufficient to inflict substantial cell death and tissue disruption.
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For reference, the alveoli are the basic structural units of the deep lung.
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They are shaped and bunched roughly like hollow grapes 0.3 millimeter
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in diameter.
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re.
‘Theie walls are thin, a few thousandths of a roilimeter,
and they are a highly structured tissue with many ccll types.
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their radioactivity may differ by factors of thousands or even more.
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Intense ex-
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“~~. parure of local tissue by arediouetive particle is referred to aus the hot
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