Contamination and decontamination of rat and human skin with plutonium and uranium, studied with a Franz's chamber

Purpose : Our work offers a new method of assessing human skin radiocontamination and of appraising its treatment. This in vitro technique stems from methods used in skin pharmacology. Materials and methods : Franz's diffusion chambers, which help maintain the physiological condition of a skin biopsy, are used to study how 233 U and 239 Pu, added to a 0.1N solution of nitric acid, could enter skin. The efficiencies of two different decontaminating agents (Na3Ca)DTPA (25%) and EHBP (0.5 M) are compared. These studies were made on human skin samples, recovered after plastic surgery. Parallel experiments were carried out on hairless rat skin biopsies and on the skin of live hairless rats. Results : Results in vivo and in vitro on the rat were not significantly different which validates the in vitro technique. In human beings, most of the radioactivity was found in the epidermis, with 2-4% found at the level of the dermis. By means of autoradiography we were able to identify that this radioactivity was concentrated in and around hair and sebaceous glands. Local treatments by EHBP seemed more efficient than those by DTPA in decorporating uranium and plutonium but the complexes radionuclide-EHBP seemed to diffuse through the skin more than the radionuclide-DTPA complexes if the skin was not rinsed after application of the chelating agent. Conclusion : This new in vitro technique using human skin has been validated for radiotoxicology. It can be used to quantify the diffusion of radionuclides through the various skin layers and to assess the effciency of decontaminating agents.