Discrimination of radiotoxic and chemotoxic effects of uranium: Definition of biological markers for occupational risk assessment in the nuclear industry

Titre du congrès :EUROTOX 2007 - 44th Congress of the European Societies of Toxicology
Ville du congrès :Amsterdam
Date du congrès :07/10/2007

Titre de la revue : Toxicology Letters 172 Supplement 1 Pages : S166

Uranium internal exposure is a major risk for the nuclear workers. Uranium is an alpha-emitter radioactive element from the actinides group and is also categorized as a heavy metal. The aim of this work was to find biological markers of internal contamination able to discriminate between chemotoxic and radiotoxic effects of uranium.
The study was carried out in vitro on mouse C3H10T1/2 embryo fibroblasts contaminated either with depleted uranium (DU) or with enriched uranium (EU). EU (12% 235U) has a specific activity 20 times higher than DU (0.3% 235U). Genotoxic effects of both DU and EU were assessed with the cytokinesis-block micronucleus assay.
The normalized to control frequency of binucleated cells with a micronucleus (MN) was higher when cells were contaminated with EU compared to DU (6.8 and 4.10 for a 5 μM EU and DU concentration, respectively). EU induces approximately 6 times more nucleoplasmic bridges (NPBs) than DU normalized to control frequencies of 17 and 2.7 for a 5 μM EU and DU concentration, respectively. By contrast, the normalized to control frequency of mononucleated cells with a MN is lower after a contamination with EU compared to DU (1.1 and 1.5 for a 5 μM EU and DU concentration, respectively).
As a conclusion, our experiments confirm binucleated cells with a MN to be a marker of U genotoxicity (chemical + radiological). Frequency of NPBs seems to be more a marker of a radiotoxic effect whereas the mononucleated cells with a micronucleus seem to be more a marker of a chemotoxic effect.