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

activity values by a factor of 2 smaller and by a factor 2.5 higher, respectively, than ICRP 67.
At 10,000 days post intake the amount of activity in the blood compartment doesn’t
significantly differ in relation to the adopted skeletal model. On the basis of such
considerations it can be concluded that, by predicting greater amounts of Plutonium in the
transfer compartment at intermediate and long time, Polig’s model seems to be able to correct
the low urinary excretion of Plutonium calculated with the ICRP 67 model when no transfer
of activity from ST0 soft tissue compartment to urinary bladder content is assumed (ICRP67a
curve in Figure 3.1.4). This can be verified by substituting the ICRP skeletal model in the
ICRP67-a version with Polig’s skeletal model and then calculating the urinary excretion of
Plutonium (ICRP67-a-Polig curve in Figure 3.1.11).
Fraction of initial activity
1E+1
1E+0
1E-1
1E-2
1E-3
1 10 100 1000 10000 100000
Days post intake
Figure 3.1.10 Fraction of initial activity retained in blood and skeleton for a study model
composed by a blood compartment connected to a skeletal model (ICRP 67 or
Polig’s skeletal model).
As expected from Figure 3.1.8 the substitution of the skeletal model doesn’t
significantly affect the activity in blood compartment up to 100 days post injection and
therefore doesn’t modify the urinary excretion in this time range. At long time the increase of
available activity in blood compartment following the introduction of Polig’s skeletal model
(observed in Figure 3.1.10) enhances the urinary excretion of Plutonium: In Figure 3.1.11 the
urinary excretion is closer to the reference data set up to about 2,000 days post injection. In
this time range Polig’s skeletal model has effected a lift of the excretion curve by a factor 2.5
in comparison with the excretion of ICRP67-a model. This seems to support the claim that
Polig’s skeletal model is a more realistic description of Plutonium biokinetics in skeleton than
the skeletal model adopted in ICRP 67. After 2,000 days post injection the model predictions
underestimate the reference data set. For example at 10,000 days the model calculations are
low by nearly a factor of two, if compared to ICRP 67 (0.0011%/d -1 ), Khokhryakov
(0.0011%/d -1 ) and Langham’s subject HP-6 (0.0014%/d -1 ).
100
ICRP67: blood compartment
ICRP67: skeleton
Polig: blood compartment
Polig: skeleton