Table
5.
Estimation of Standard Man's Plutonium
Ingestion Rate
1,
i
Substance Suggested
1
Sot
2
Leafy vegetables
81
3
Other food plants
22
9)
Faiz x 10?
3.8 x 1077
19.441
4
Beef muscle
273,
©)
9.4 x 1078
2.6 x 1073
1.322
5
Beef liver
3
Yl
a7zx 107
61 x 10?
3.148
6
Cow milk
436
©
14 x 108
6.1 x 10°
0.003 |
0.01)
(c)
po,
ID,
1.0
1.0 x 107?
Muscle,
1.7 x 10
-3
1.4 x 10
Percent
-1
r TD, = 1.9 x 10
(a)
(b)
{c)
(d)
See Equation (29) and explanation in text.
Assumed accidental ingestion rate.
U.S.D.A., Agricultural Statistics, 1973. U.S. GPO (1973).
Food Consumption Statistics 1960-1968.
Organization for
Economic Cooperation and Development (1970).
5.151
Liver,
“wus ~ (870){3 x 107>) (0,07) [ tere H2ontzy/2000)) |
CSOrL
125,000
1n(2)/2000
70.935
100.000
and Milk
The model beef cow weighs about 275 kg.
Its plutonium ingestion rate (T_),
due to ingestion of 6,2 kg (native vegetation)/day and 0.25 kg (soil)/day, is
about 870 C_ pCi/day. Given this ingestion rate and the parameters noted in
Figure 2, the discrimination ratios for muscle and liver (Table 5) were estimated as follows:
= 9.4 x 10-6
Cry = 487023 x 1077) (0.12) [1-eup(-730C1n(2)/30,000)) |
a
4800
In(2)/30, 000
SOIL
= 4.7 x 107"”
In these examples, t was set equal to 730 days (2 years), and this is the
assumed average ape of beef cattle at the cime of slaughter.
The method of estimating the discrimination factor for milk was described
earlier in the description of the model milk cow (see Equation (27)}.
Discussion
Models for calculating organ burdens and cumulative organ doses due to ingestion
and inhalation of 73%Pu are discussed later in this report in considerable
detail. Based on the ICRP-2 model for ingestion and the ICRP-19 model for
inhalation, radiation doses to the respiratory system would be entirely due to
inhalation and doses to the gastrointestinal tract would be primarily due to
ingestion.
Dose to organs receiving the radionuclide from blood (bone, liver,
kidney, etc.) would be due c6 both ingestion and inhalation.
The relative
importance of inhalation versus ingestion can be compared by comparing the two
components of organ burden after a period of chronic exposure.
Such a compari-~
son is provided in Tabie 6.
Based on our estimates for the hypothetical Standard Man at NTS (inhalation =
0.002 C_ pCi/day and ingestion = 0.2 C. pCi/day), the ingestion/inhalation
ratio would be 100 and ingestion would contribute about 5 percent of the
50-year bone burden.
As indicated by Table 6, the relative importance of
ingestion versus inhalation increases as the ingestion/inhalation ratio increases. Any factor tending to increase the transfer from the gastrointestinal
tract to blood would have the same effect as an increase in the ingestion/
inhalation ratio,