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

Sensitivity coefficients S i
Figure 3.1.24 Systemic sensitivity coefficients S i for the Plutonium activity in blood assessed
with the Model-b. Only the transfer rates with | S i|>0.1 at least for one time
point are shown.
The sensitivity analysis of the parameters of respiratory tract and gastrointestinal
models was performed just for the most important and common bioassay, i.e. the activity in
urine. In case of contamination via ingestion it turns out that the most important parameter is
the uptake factor f 1, whose sensitivity coefficient is always equal to +1.0 at any time point.
This was observed in similar sensitivity analysis [166]. The transfer rate from the small
intestine to the upper large intestine (ULI) is also significant for some time points because it
affects the value of the f 1.
In case of inhalation the sensitivity coefficients for the transfer rates of the respiratory
tract model that have an absolute value greater than 0.1, at least for one time point and for one
absorption type, are presented in Figure 3.1.25 and Figure 3.1.26 for type M and S,
respectively. It turns out that for type M the only significant parameters are the absorption
parameters s p, s pt and s t and the transfer rate from the ET2 extrathoracic compartment to the
gastrointestinal tract. In case of inhalation of a compound with a slow rate of absorption into
blood (type S) the transfer rates from the three compartments of the alveolar-interstitial region
to the bb1 compartment of the bronchiolar region become significant, particularly at long time
after inhalation. In any case the sensitivity analysis seems to indicate that the urinary
excretion of Plutonium is not particularly sensitive to the clearance rates of all the other
compartments related to the particle transport in the bronchial and bronchiolar regions.
126