V. Chazel

Bioaccumulation and behavioural effects of depleted uranium in rats exposed to repeated inhalations

Depleted uranium has numerous industrial and military uses. Contamination by inhalation of airborne compounds is probably the most important route of exposure. In humans, there are no data clearly demonstrating neurotoxicity of uranium, yet some experimental studies suggest a link between neurological toxicity and uranium exposure. In this work, the bioaccumulation of uranium in male rats after exposure to repeated depleted uranium dioxide inhalation (30 min inhalation at 197 mgm(-3), 4 days a week for 3 weeks) has been studied, together with the behavioural effects. The uranium concentrations in the brain 1 day after the end of the exposure period varied as follows: olfactory bulb>hippocampus>frontal cortex>cerebellum, subsequently decreasing rapidly. The spontaneous locomotion activity of exposed rats was increased 1 day post exposure and the spatial working memory was less efficient 6 days post exposure, compared with control rats. These data suggest that depleted uranium is able to enter the brain after exposure to repeated inhalation, producing behavioural changes.

Distribution and Genotoxic Effects After Successive Exposure to Different Uranium Oxide Particles Inhaled by Rats

In nuclear fuel cycle facilities, workers may inhale airborne uranium compounds that lead to internal contamination, with various exposure scenarios depending on the workplace. These exposures can be chronic, repeated, or acute, and can involve many different compounds. The effect of uranium after multiple scenarios of exposure is unknown. The aim of this study, therefore, was to investigate the genotoxic and biokinetics consequences of exposure to depleted insoluble uranium dioxide (UO2) by repeated or acute inhalation on subsequent acute inhalation of moderately soluble uranium peroxide (UO4) in rats. The results show that UO2 repeated preexposure by inhalation increases the genotoxic effects of UO4 inhalation, assessed by comet assay, in different cell types, when UO4 exposure alone has no effect. At the same time, the study of UO4 bioaccumulation showed that the UO4 biokinetics in the kidneys, gastrointestinal tract, and excreta, but not in the lungs, were slightly modified by previous UO2 exposures. All these results show that both genotoxic and biokinetics effects of uranium may depend on preexposure and that repeated exposure induces a potentiation effect compared with acute exposure.