Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK
Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK
Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK
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The k<strong>in</strong>etics of <strong>Plutonium</strong> <strong>in</strong> the kidneys is modelled by two compartments: One<br />
represents the kidney tissue exchang<strong>in</strong>g activity with the blood, and another describ<strong>in</strong>g the<br />
ur<strong>in</strong>ary path through which the <strong>Plutonium</strong> reaches the ur<strong>in</strong>ary bladder.<br />
The activity accumulated <strong>in</strong> the ur<strong>in</strong>ary bladder is excreted with the ur<strong>in</strong>e. Three paths<br />
contribute to the activity <strong>in</strong> this compartment: The direct transfer from the blood, the blood<br />
contribution through the ur<strong>in</strong>ary path and the transfer of activity from the soft tissue<br />
compartment ST1.<br />
The fecal excretion of <strong>Plutonium</strong> is also modelled. The systemic activity is transferred<br />
to the gastro<strong>in</strong>test<strong>in</strong>al tract via two pathways: From the first liver compartment to the small<br />
<strong>in</strong>test<strong>in</strong>e (biliary secretion), and from the blood to the upper large <strong>in</strong>test<strong>in</strong>e. These paths<br />
describe the contribution to the fecal excretion of <strong>Plutonium</strong> at short and long times after<br />
exposure.<br />
The model is appropriate to simulate the metabolism of <strong>Plutonium</strong> both <strong>in</strong> male and<br />
female subjects. As mentioned before, gender specific transfer rates are given only for the<br />
gonads (testes and ovaries). Age specific transfer rates are def<strong>in</strong>ed by ICRP for six age<br />
classes: 3 months, 1, 5, 10 and 15 years and adults. Here an adult is a person at least 25 years<br />
old, whereas <strong>in</strong> previous publications of the ICRP concern<strong>in</strong>g the biok<strong>in</strong>etics of other<br />
radionuclides, an adult was def<strong>in</strong>ed as at least 20 years old. The 25-rule is also used here for<br />
the development of new models, because the skeletal transfer rates are equated with bone<br />
formation rates, which are still elevated with respect to the mature skeleton at the beg<strong>in</strong>n<strong>in</strong>g<br />
of the third decade of life. The transfer rates for an adult subject, useful for the monitor<strong>in</strong>g of<br />
an <strong>in</strong>ternal contam<strong>in</strong>ation from an occupational exposure, are given <strong>in</strong> Table 1.4.1.<br />
soft tissue<br />
ST2<br />
soft tissue<br />
ST0<br />
soft tissue<br />
ST1<br />
gonads liver 2 liver 1<br />
kidney<br />
tissue<br />
ur<strong>in</strong>ary<br />
path<br />
bladder<br />
content<br />
ur<strong>in</strong>e<br />
blood<br />
cortical<br />
marrow<br />
cortical<br />
surface<br />
cortical<br />
volume<br />
Figure 1.4.1 The ICRP systemic model for <strong>Plutonium</strong> biok<strong>in</strong>etics. The affected<br />
gastro<strong>in</strong>test<strong>in</strong>al compartments are also shown.<br />
26<br />
trabecular<br />
marrow<br />
trabecular<br />
surface<br />
trabecular<br />
volume<br />
small<br />
<strong>in</strong>test<strong>in</strong>e<br />
upper large<br />
<strong>in</strong>test<strong>in</strong>e<br />
lower large<br />
<strong>in</strong>test<strong>in</strong>e<br />
feces