[sac rificed at periods ranging from 1 hr to 15 days following exposure,
is shownin Pig. 2. At lhyafter exposure, approximately 90 per cent
Jof the internal ac tivity (ag determined by’ gamnia activity measurements)
was found in the Gf tract, although all the activily originally entered the
body by inhalation, It appaars that most of the radioactive maferial was
Jassociated with large particles which presumably were rapidly moved
pack up.fhe respiratory tract by ciliary action and swallowed, while the
famallerjparticles penetrated to the alveolar tissue, A small but signi-
ficant fraction of the material in the Gl tract was absorbed into the body
‘ {following either inhalation‘or gavage; the remaining material was excreted,4
¥By the third day only LtPe
remained,
gent of the maximum activity in the GI tract
N
i,
The major portion of ¢ radioactive sibstance which entered the
systemic circulation did qgin a matter ef hours, Loss of activity from
the blood was very rapidAt ] hr the activity in the liver was approximately 2 per cent of the agtivity in the Gl tract, while both the respiraftory tract (including lung}@nd skeleton contained approximately |.2 per cent ae
tof the activity. ‘The thy d contained 0,2 per centof the Gl tract activity
and the head 9 per cent,
The high level of activity in the head probably
rreflectsithe presenceof:" pa rticles-which were inhaled and trapped
tin the nasal passages,
'
The initial distribution‘
activity ‘differs markedlyfrom that observed
following een re of migerto the ionic liquid acrosol* and the slurry type
‘aerosol
(see Table 1), Qn the basis of the activity found in the respira- ..
story tract being |, the acthyity of the Gi'tract was 80 +13 far the dry -
Fparticle simulant (ype TH), as compared to 3.2 + 0,3for the liquid ae resol| oy ‘
(Type 1), and ta t 1,1 for e jonic-emud ‘slurry aerosol (Type 1),
If the total activity found in both the respiratory tract and the Gl) tract
Fis usedags the basis for cgmpar ison, the amount of activity retained at
Lhr inthe skeleton is 2.34 O.b per cent with the Type l simulant and
only 1.3 £0. per cont with Type Il, suggesting that the dry particles
may not be as available tq:bone as the ionic form, On the other hand, —
the activily retained by the liver when the animal is exposed to Type It
simulant (again in terme ef total Gland respiratory tract activity) was
“169 £ O,) per cont as compared to d,) + 0.1 per cent for Typed,
The
higher retention of the particulate simulant by the liver is probably
-associated with the natura} function of particle entrapment by the reticulos.4
‘ endothelial system, 7 hese findings sugges | that the particulate aerosol
S retaing its adsorbed fisstgn products inthe body,
initial Uptake of Inge sted sieiulant
.
In the experiment in which the dry-particle simulant was fed the mice
by stomach lube, the initéal distribution of aativity in the GI tract and
in the soft lissues and akgjeton is very similar to that following inhalation
eeeten”
£
~5e
UNG LASSER ERD
~~
}