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SUMMARY
i The Problem
; The present study was designed to reproduce in the laboratory an acute
‘exposure of mice to early fallout (2 days old) such as might result from
fa land-based nuclear detonation.
Biological data are required on the
,uptake, distribution and retention of the inhaled fallout simulant, Fur-
ither, as a basis for comparing the effects of different types of simulants,
ithe metabolic behavior of this dry-particle fallout simulant of limited
solubility must be compared with that of two previously studied fallout
;simulants, The simulant administered by gavage provides data on the
uptake of fallout by ingestion as compared with inhalation,
{
These data are required for an evaluation of the radiation dose to in-
4 dividual tissues and organsifrom inhaled fallout as compared with the
{concomitant external radiation dose that the animals would receive if
exposed to the same airborne simulant,
t Findings
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Following a 3-hr exposure to a dry-particle simulant of a land-based
i nuclear detonation, the activity was quickly cleared from the lungs and
‘ appeared primarily in the gastrointestinal (Gl) tract.
Lesser concen-
roid, The radioactivity was removed very rapidly from the Gl tract, as
compared to the rate of loss of the simulant from the respiratory syste,
The ratio of activity in the GI tract to that in the respiratory system
following exposure to the ionic, mud-slurry and dry-particle simulants
was 3.2, 12, and 80, respectively. The rate of biological elimination
, of the dry-particle simulant material from the skeleton and liver was
4 considerably greater than was noted with the previously studied lonic
¥ simulant. In terms of total respiratory and GI tract activity at | hr,
i the skeletal activity was twice as high for the ionic simulant as for the
4 dry-particle simulant, while the reverse was true for the liver activity.
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trations of activity were algo found in the head, liver, skeleton and thy-