Methods to measure the cutaneous transfer of radionuclides across the intact or lesioned epidermis,application to radiotoxicology

Although skin contamination by radionuclides is the most common cause of nuclear workers accidents, few studies dealing with the penetration of radioactive contamination through the skin are available. This work is a review of experimental methods that allow to assess transfer of radionuclides through the skin in occupational conditions, with or without skin trauma. The first section describes the different methods applied for skin transfer assessment of chemicals used in pharmacology. Major radionuclide contamination accidents can be associated with skin traumas. Thus, the second section describes the adaptation of these methods to radiotoxicology. Finally, the third section is an in vivo investigation of cobalt transfer (57CoCl2) through undamaged and damaged skin which simulates different industrial accident conditions (excoriation, acid or alcalin burn, scalding, branding).     

The effect of dose distribution on risk of lung cancer after inhalation of actinide oxides

The aim of this work was to estimate risk of lung tumour occurrence after inhalation of actinide oxides from published studies and rat studies in progress. For the same delivered dose, the risk increases when homogeneity of irradiation increases, i.e., the number of particles deposited after inhalation increases (small particles and (or) low specific alpha activity). The dose-effect relationships reported appear linear up to a few gray, depending on the aerosol considered, and then the slope decreases. This slope, which corresponds with the risk, can vary over one order of magnitude depending on the aerosol used. An effective threshold at about 1 Gy was not observed for the most homogeneous dose distributions. A dosimetric and biological approach is proposed to provide a more realistic risk estimate.     

Specific parameters for the calculation of dose after aerosol inhalation of transuranium elements

A review on specific parameter measurements to calculate doses per unit of incorporation according to recommendations of the International Commission of Radiological Protection has been performed for inhaled actinide oxides. Alpha activity distribution of the particles can be obtained by autoradiography analysis using aerosol sampling filters at the work places. This allows us to characterize granulometric parameters of "pure" actinide oxides, but complementary analysis by scanning electron microscopy is needed for complex aerosols. Dissolution parameters with their standard deviation are obtained after rat inhalation exposure, taking into account both mechanical lung clearance and actinide transfer to the blood estimated from bone retention. In vitro experiments suggest that the slow dissolution rate might decrease as a function of time following exposure. Dose calculation software packages have been developed to take into account granulometry and dissolution parameters as well as specific physiological parameters of exposed individuals. In the case of poorly soluble actinide oxides, granulometry and physiology appear as the main parameters controlling dose value, whereas dissolution only alters dose distribution. Validation of these software packages are in progress.     

In vitro liberation of lymphocytic factors inhibiting migration of human leukocytes induced by gold, cadmium and mercury chlorides]

The presence of 300 microgram gold and cadmium and 10 microgram mercury chloride per millitre of survival medium, during the process of T.I.M.L., results in the release by human lymphocytes of soluble factors which inhibit migration of leucocytes (L.I.F. and M.I.F.). This stimulation of cellular immunity suggests that the anti-infectious therapeutic effect of gold and mercury inorganic salts results from activation of the histiocytary system, through the release of these lymphokins.