[en] The gastrointestinal (GI) absorption of plutonium was measured in mice, rats, and dogs under conditions relevant to setting drinking water standards. The fractional GI absorption of Pu(VI) in adult mice was 2 x 10^-4 (0.02%) in fed mice and 2 x 10^-3 (0.2%) in fasted mice. The GI absorption of plutonium was independent of plutonium oxidation state, administration medium, and plutonium concentration; absorption was dependent upon animal species, state of animal fasting, state of Pu(IV) hydrolysis, and age of the animal. Fractional GI absorption values ranged from 3 x 10^-5 (0.003%) for hydrolyzed Pu(IV) administered to fed adult mice to 7 x 10^-3 (0.7%) for Pu(VI) administered to fed neonatal rats. From analysis of our data, we suggested values of f₁ (the fraction transferred from gut to blood in humans) for use in establishment of oral limits of exposure to plutonium. For an acute exposure in the occupational setting, we proposed one value of f₁ for fed (2 x 10^-4) and one for fasted (2 x 10^-3) individuals. For the environmental setting, we developed two approaches to obtaining values of f₁; suggested values were 6 x 10^-4 and 4 x 10^-3, respectively. Both approaches took into account effects of animal age and fasting. We discussed uncertainties in proposed values of f₁ and made recommendations for further research. 41 refs., 8 figs., 24 tabs