Percutaneous diffusion of uranium: what is the best experimental model for occupational risk assessment in the nuclear industry?

Titre du congrès :EUROTOX 2007 Ville du congrès :Amsterdam Date du congrès :07/10/2007

Uranium uptake represents an occupational risk in the nuclear industry. Uranium intoxication can occur accidentally by inhalation, ingestion, injection or absorption through intact or wounded skin. Uranium absorption via intact skin route received little attention and experimental data are needed. This work aims at comparing the percutaneous diffusion of an uranyl nitrate solution (0.01 M) through several skins, using different approaches. Hairless rat and human skin were tested in vitro using Franz's cells meanwhile in vivo experiments were performed with hairless rat and nude mouse with human skin biopsy grafted onto its back. Uranium absorption rate through skin and uranium fraction retained in skin were calculated for each model after 24 hours of exposure to uranyl nitrate. No significant differences were observed between in vitro and in vivo hairless rat model concerning uranium absorption rate, respectively 2.7x10-4 and 2.1x10-4 cm-2.h-1. Rat models slightly overestimate uranium percutaneous diffusion data obtained through human skin in vitro (1.4x10-4 cm-2.h-1). However, using the grafted nude mouse, uranium absorption rate was higher, reaching 9.9x10-4 cm-2.h-1. Uranium fraction retained in the human grafted skin was 1.8 times lower than the one retained in the skin from all other described models. As a conclusion, the grafted nude mouse model seems not to be adapted to the study of kinetics of uranium diffusion. The assessment of uranium percutaneous diffusion kinetics will be made using human and hairless rat skin in vitro. Hairless rat in vivo will be used to obtain data concerning biokinetics of uranium after topical exposure. Acknowledgements This study was initiated to answer a request of the physicians of AREVA medical department and was supported by grants from AREVA.