488 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



(alfalfa hay), we assumed a sixfold dilution of soil concentration due to plowing to a 

 depth of 30 cm; i.e., the plant/soil ratio for cultivated plants is 0.017 instead of 0.1. In 

 preparing Table 1 , we assumed that 90% of the external contamination of "leafy 

 vegetables" and that 99% of the contamination associated with "other food plants" 

 would be removed by washing, peeling, etc., during preparation for consumption. In spite 



TABLE 5 Estimation of Standard Man's Plutonium 

 Ingestion Rate 



*See Eq. 29 and explanation in text. 



fAssumed accidental ingestion rate. 



$From U. S. Department of Agriculture (1973). 



§From Organization for Economic Cooperation and Development (1970). 



of this assumed reduction, leafy vegetables and other food plants account for 90% of 

 Standard Man's estimated plutonium ingestion rate (Table 5). 



Muscle, liver, and milk. The model beef cow weighs about 275 kg. Its plutonium 

 ingestion rate (ly), owing to ingestion of 6.2 kg native vegetation/day and 0.25 kg 

 soil/day, is about 870 Cs (pCi/day). Given this ingestion rate and the parameters noted in 

 Fig. 2, the discrimination ratios for muscle and liver (Table 5) were estimated as follows: 



Cmuscle_(870)(3x 1 0" ' )(0.07) / 1 - exp {-730 [In (2)/2000] } 



( \ -exp {-730 [In (2)/2000] } \ 

 \ ln(2)/2000 / 



Cs 125,000 \ ln(2)/2000 



= 9.4 X 10"^ 



Ciiver_(870)(3 X 10-')( 



Cs 4800 



= 4.7 X 10" 



0.12) / i - exp {-730 [In (2)/30,000| } \ 

 \ ln(2)/30,000 / 



In these examples t was set equal to 730 days (2 yr), and this is the assumed average age 

 of beef cattle at the time of slaughter. 



The method of estimating the discrimination factor for milk was described earlier in 

 the description of the model milk cow (see Eq. 27). 



