The aim of this study is to model plutonium (Pu) excretion from the analysis of a well-documented Pu wound case involving repeated diethylene-triamine-penta-acetic acid (DTPA) perfusions up to 390 d and monitoring up to 3109 d. Three modelling approaches were simultaneously applied involving: (1) release of soluble Pu from the wound, estimated with the ICRP66 dissolution model, (2) systemic behaviour of Pu by using ICRP67 model, but also two new models recently reported and (3) additional 'Pu-DTPA' compartments which transfer Pu directly to urinary compartment from blood, interstitial fluids and liver. The best fit of simulations to biological data was obtained by using the new Leggett's systemic model and assuming the presence of three DTPA compartments. Calculations have shown that DTPA treatments have contributed to a 3-fold reduction of the effective dose. Thus, reduction of doses associated with the DTPA treatments can be estimated by modelling which is useful to improve the efficacy of a DTPA treatment schedule based on a diminution of risk.

RÉSUMÉABSTRACT implication of the occupational physician and of the expert in the management and the dosimetry of an accidental contamination.This case concerns a wound contaminated by plutonium. In managing the consequences of such an incident, the occupational physician of a nuclear installation has to solve various questions in the field of dosimetry, communication and regulation. Dosimetry and risk evaluation of internal contamination are complex. Dose limits are annual limits and it is dificult to explain to the victim that for internal contamination the decision concerning the ability to work in controlled areas is determined on the basis of a commiîted dose on 50 years. Moreover, the notification of such an incident to the employer, to the labour inspectorate and to the govermental organism of control of radiation protection needs an important involvement in the domain of information. This case allows us to describe various practical aspects of medical management and dosimetry. The follow-up of measurements and therapy is given for a period of more than five years.

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Dose per unit intake (DPUI) of radionuclides is obtained using International Commission on Radiological Protection (ICRP) models. After inhalation exposure, the first model calculates the fraction of activity deposited within the different regions of the respiratory tract, assuming that the aerosol contains an infinite number of particles. Using default parameters for workers, an exposure to one annual limit of intake (ALI) corresponds to an aerosol of 239PuO2 containing approximately 1 x 10(6) particles. To reach such an exposure, very low particle number might be involved especially for compounds having a high specific activity. This study provides examples of exposures to actinide aerosols for which the number of particles is too low for a standard application of the ICRP model. These examples, which involve physical studies of aerosols collected at the workplace and interpretation of bioassay data, show that the number of particles of the aerosol can be the main limit for the application of DPUI after inhalation exposure.