and
Table 4.
0.12 is the fraction cleared from lungs to the gastrointestinal tract
with a l-day half-life,
Ag = In(2)/1 day),
0.667 is the fraction cleared from lungs to the gastrointestinal
tract with a 500-day half-life.
Note that Equation (22) consists of four terms.
These terms represent transferg
of itnhated plutonium to blood from the upper respiratory tract, the lungs, the
pulmonary lymph, and the gastrointestinal tract, respectively. Equations (23),
(24), and (25) are the differential equations for the long-term components of
the lungs and lymph nodes and for the gastrointestinal tract, respectively.
The solution to Equation (22) is:
Thatt) = I, { 0.0021 + 0,015(1 - e7Ayt)
(26)
+ 5.61 x 1079 (e 2 - ely
+ 3x 107 (0.381 + 0.1201 - e711}
Concentrations of 233°249py (pCi/kg) in Tissues
of Cattle Grazed in Area 13 (NTS)
Tissue
1
Outer Compound ‘2
4
6
Inner Compound ‘>?
2
M
Lunge
74.5
51.4
18.2
48.0
nef?
Liver
14.5
15.8
10.9
13.7
38.9
Muscle
0.05
Data extracted from:
0.195
lost
0.12
(a)
Smith et al., 1976
(c)
Not reported
(b}
Smith, 1977
Integration of Equation (26) and evaluation of the integral from t = Oto t =
177 days gives the amount reaching the blood in 177 days as 0.676 I_. Applying
this result to the Area 13 cow, the total 233py expected to have enfered the
blood via inhalation would be 0.676 x 5.56 pCi/day = 3.76 pCi. Compared to
3,000 pCi for ingestion (see above), this is a negligible quancity.
Based on this comparison, we shall assume that plutonium concentrations in cow
milk, muscle, and liver are due to ingestion only, or conversely, that the
contribution from inhalation is negligible.
Even after 10 yeara of exposure
in Area 13, the contribution from inhalation would be no more than 0.56 percent
of the total,
Comparison of Model Predictions and Field Data
Plutonium concentrations in lungs, liver, and muscle are given in Table 4 for
four cows included in the Area 13 grazing study. Cow 2 (Smith et al., 1976)
Cows 1, 4, and 6 grazed the
was placed in the inner compound for 177 days.
outer compound for 433 days (Smith, 1977),
Cow 1 weighed 252 kg.
Cow 4 weighed 300 kg, the weight of cow 6 is not known. We shall assume that
the average weight of the outer compound cows was 275 kg. Tissue weights for
these cattle were not reported; but we estimate, for a 275-kg cow, the average
lung weight is about 2.1 kg and the average liver weight is 4.8 kg, based on a
study made by Smith and Baldwin (1974).
Avg.
At 45 percent of body weight (Smith,
1977), the muscle weight for a 275-kg cow would be about 125 kg.
651
0.17
NR
6.13 kg
189 kg