Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK

excreted by individuals aged sixty and twenty-five, respectively. For the other f 1 values the
deviations are even slightly smaller.
On the basis of the previous considerations a forty years old subject can be assumed as
a reference subject for evaluating the average urinary excretion of occupationally exposed
workers. Such an assumption also has the advantage to be coherent with the E(50)
coefficients previously calculated and referring to a forty years old subject.
ratio
1,20 1.2
1,10 1.1
1,00 1.0
0,90 0.9
0,80 0.8
Figure 3.1.21 Ratio of 239 Pu urinary excretion curves for a 40 years old subject to the
excretion for ages 25 to 60 years (5 years interval) (e.g. 40/25 = ratio of age 40
years to age 25 years excretion curve). Type of absorption M. AMAD = 5 m.
The analytical functions of the urinary excretion of Plutonium for a forty years subject
were calculated in case of both inhalation and ingestion. The excretion of Plutonium in urine
(equation 3.1.8) is described by a product of an exponential term, that represents the
radioactive decay of the radioisotope, with a sum of seven exponential terms that follow from
the biokinetic transfers of the radionuclide in the body:
e u(t) = e − R t
40/25 40/30 40/35 40/40
40/45 40/50 40/55 40/60
0 5000 10000 15000 20000
Days post intake
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7
∑ci e
i=1
− i t
119
[Bqd -1 per Bq of intake]
equation 3.1.8
where:
e u(t) is the daily urinary excretion of a Plutonium radioisotope;
λ R is the physical decay costant of a Plutonium radioisotope;
λ i and ci are the exponents and coefficient of the exponential terms used to describe the
biokinetic transfers.
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