Occupational Intakes of Radionuclides Part 1 - ICRP

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DRAFT REPORT FOR CONSULTATION
simplifies to two or three compartments depending on the physical and chemical form
of the radionuclide specified.
Figure 14. Diagram illustrating the NCRP Model for Wounds
(200) Four retention categories are defined for radionuclides present initially in
soluble form in a wound: Weak, Moderate, Strong and Avid, which refer generally to
the magnitude of persistent retention at the wound site. The criteria for categorisation
are based on: (a) the fraction of the injected radioactive material remaining 1 d after
deposition and (b) the rate(s) at which the initially retained fraction was cleared.
(201) Release of the radionuclide from the wound site occurs via the blood for
soluble materials and via lymph nodes (LN) for particulates. Further dissolution of
particles in LN also results in radionuclide transfer to the blood. The blood is the
central compartment that links the wound model with the respective radioelementspecific
systemic biokinetic model. Once the radionuclide reaches the blood, it
behaves as if it had been injected directly into blood in a soluble form. This is the
same approach as is taken in the HRTM and HATM.
(202) To illustrate the application of the model for bioassay interpretation, the
wound model was coupled to the systemic biokinetic model for 137 Cs (ICRP, 1979,
1989, 1997b). The principal default for Cs in the wound model is the Weak Category.
Accordingly, the parameters for this category were applied to the wound model, and
urine and faecal excretion patterns predicted (Figure 15). The patterns show peak
excretion of 137 Cs in urine at 2-3 days after intake, and for faeces at about 5 days.
Both patterns reflect the rapid movement of 137 Cs from the wound site, and its
distribution in and excretion from the systemic organ sites.
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