Effect of U308 specific surface area on in vitro dissolution, biokinetics, and dose coefficients

The purpose of this study was to investigate the effect of the specific surface area (SSA) of U3O8, sampled from different processes, on its irt vitro dissolution, its biokinetics in rats, and dose coefficient. A knowledge of the manufacturing process as well as the physico-chemical properties of uranium oxides are necessary to understand why the solubility and consequently the dose may vary for the same chemical form of a compound. Eight preparations of U3O8 with different SSA, have been characterised. In vitro chemical dissolution tests, in culture medium, have shown an increase of solubility with SSA. In vivo experiments involving intratracheal deposition of a suspension of the oxides showed that the amount of uranium absorbed into blood increased 3-fold when the SSA increased 5-fold. Calculations of the dose coefficients from in vitro dissolution parameters, have shown a decrease from 4.30 to 1.75 mu Sv.Bq(-1) when the SSA increased from 0.7 to 15.5 m(2).g(-1). Dose coefficients calculated from in vivo absorption parameters varied from 5.5 to 4.2 mu Sv.Bq(-1), when the SSA increased from 0.7 to 3.2 m(2).g(-1).