Table l.
Description of Radioisotope-Labeled Sand Fed to Dairy Cows
Isotope
Weight per
Particle**
Label
(mg)
(g)
20
14la.
9.7 x 107°
19
173
80
855,
6.2 x 10°
15
116
200
Aun
9.7 x 10°
16
85
450
466.
1.5x 10!
40
96
Nominal Size*
(ym)
size is used in discussing
*The nominal
the results.
Dose per Cow
(uCi)
The size descriptions are:
20 um -— 95% of mass between 15 and 20 um, and no particles greater than
25 um; separated by liquid sedimentation.
80 um - pass 88 ym and retained on 74 um sieves.
200 um
pass 246 um and retained on 175 um sieves.
450 um - pass 495 um and retained on 417 um sieves.
**Weight of nominal spherical size particle with specific gravity of 2.3.
Table 2.
Characteristics of Isotopes Used to Label Sand Particles
Isotope
Gamma
Half-Life
Energy
(Days)
(MeV)
Branching
Ratio
141c.
32.5
0.145
48%
825,
64.0
0.514
100%
oA Mn
312.5
0.835
100%
465,
83.9
0.889
1.120
1002
100%
153