THE GASTROINTESTINAL ABSORPTION OF PLUTONIUM AND AMERICIUM IN RATS AND GUINEA-PIGS AFTER INGESTION OF DUSTS FROM THE FORMER NUCLEAR-WEAPONSSITE AT MARALINGA - IMPLICATIONS FOR HUMAN EXPOSURE

The gastrointestinal absorption of plutonium and americium present in dusts from the Maralinga test sites in South Australia has been measur ed as an input to dose assessments. The materials studied were from th ree different areas, designated Taranaki (Q380II), TM100 (10/2) and N. Plume (26). The three dusts were fed to groups of rats, mixed with th eir normal food. The Taranaki and TM100 dusts were also fed to guinea pigs, as a suspension in water. Expressed as fractional absorption fro m the gastrointestinal tract (f1), the values obtained for plutonium w ere 2 x 10(-6) and 8 x 10(-6) for Taranaki dust in rats and guinea pig s, respectively, 3 x 10(-6) and 10(-5) for TM100 dust in rats and guin ea pigs, respectively, and 2 x 10(-6) for N. Plume dust in rats. The f (l) values obtained for americium were 3 x 10(-6) and 2 x 10(-5) for T aranaki dust in rats and guinea pigs, respectively, 10(-5) and 5 x 10( -5) for Taranaki dust in rats and guinea pigs, respectively, and 10(-5 ) for N. Plume dust in rats. On the basis of these results, rounded f( l) values used in the dose assessments were 10(-5) for plutonium and 1 0(-4) for americium, applying to all intakes of dust. These values com pare with the International Commission on Radiological Protection reco mmendations of 10(-3) for unspecified chemical forms of both elements, 10(-4) for plutonium nitrate and 10(-5) for plutonium oxides. The eff ect of changes in f1 values on doses from Pu-239 and Am-241 is conside red.