Table 1.3-—- EFFECTS OF 10-FOLD DIFFERENCES IN DUST
CONCENTRATION ON INITIAL PULMONARY RETENTION IN
RABBITS FOLLOWING SINGLE INHALATION EXPOSURES
OF INCREASED DURATION TO TWO DUST CONCENTRATIONS
Total activity in lungs,* d/sec
Duration of
Dust concentration
Dust concentration
exposures, hr
of 2« 10° d/min/m?
of 2 x 108 d/min/m*®
1
2
4
8
6.84
21.6
39,2
85.6
118
224
370
402
*Each value for lung radioactivity represents an average
from four separate animals exposed simultaneously.
Table 1.4-—- PARALLEL RELATION BETWEEN RATES OF PULMONARY
AND GASTROINTESTINAL-TRACT CLEARANCE OF RADIOACTIVE
SILICEOUS PARTICLES* FOLLOWING A SINGLE 4-HR INHALATION
EXPOSURE OF RABEITS
ete.
days
0
2
4
7
28
56
84
112
Total beta-gamma activity
tn ashed specimens, d/sec
Lungst
Gastrointestinal tractt
372
2330
282
106
55.7
9.01
4.96
4.35
0.80
1750
534
202
40.6
22.7
10.9
21.0
-
*Density of siliceous material = 2.5.
tAverage of four rabbits.
{Stomachonly.
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rer’
.
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