[en] The retention of thorium in liver, bone, and other tissues subsequent to its gastrointestinal absorption has been determined in fasted mice. The value obtained for fractional retention was 1.0 x 10^-3, which is about a factor of two lower than the values for plutonium and neptunium. The tissue distribution and the value for fractional excretion of absorbed thorium were the same as those for intravenously injected thorium. 5 references, 1 table

[en] An investigation is being made of the absorption of plutonium from the gastrointestinal tract of rodents. In the mouse it has been found to be essentially independent of the oxidation state of plutonium and the administration medium. In the rat the absorption was higher than it was in the mouse, but not appreciably so. The values obtained for both mice and rats are about two orders of magnitude higher than the value adopted for the gastrointestinal absorption factor for plutonium in man

[en] The retention of neptunium in liver and bone subsequent to its gastrointestinal absorption has been determined in both fasted and fed mice. The values obtained for fractional retention were 3 x 10^-₃ and 1 x 10^-₄, respectively, and are within a factor of two the same as those for plutonium in fasted and fed mice

[en] In mice that are consuming food ad libitum the gastrointestinal absorption of plutonium (and its subsequent retention in liver and skeleton) has been shown to be a factor of about 10 lower than it is in the fasted anaimal. It has been found that the time required to achieve the fasted state is less than two hours for mice that are at the end of their diurnal, inactive phase and between 4 and 8 hours for mice that are 4 hours into their active phase. The absorption of plutonium appears to depend on the nature of materials in the G.I. tract, i.e., properties of the food consumed, rather than amounts present. The fractional absorption of plutonium from the G.I. tract by the rat decreases with age in the unweaned animal, from 7 x 10^-₃ on day 1 to 3 x 10^-₃ on day 19 (the latter value being the same as that for the fasted adult) and with weaning to 1 x 10^-₄ on day 29

[en] Individual isotopes of plutonium and uranium were administered both intragastrically and intravenously to a baboon. Samples of urine, faces, blood, and tissues were taken and are now being analyzed. Preliminary results indicate that the fractional absorptions of plutonium and uranium were 1 x 10^-3 and 1 x 10^-2, respectively, and their retentions about one month later were about 20% and 10%, respectively, of the amounts absorbed. The fractional retentions of the intravenously injected plutonium and uranium at that time were 0.90 and 0.07. 13 references, 1 figure, 3 tables

[en] Studies have been performed to provide data needed for the development of an optimal protocol for the clinical application of DTPA (diethylenetriaminepentaacetic acid) for treatment of humans accidentally exposed to certain actinide radioelements such as plutonium (Pu). Groups of two or three beagle dogs previously injected intravenously with 0.3 μCi/kg monomeric ²³⁹Pu-citrate were treated twice weekly, beginning at 6 hr, with either 0.18 or 0.036 mmol/kg Na₃CaDTPA or, beginning at 6 or 89 days, with 0.18 mmole/kg DTPA. The animals were sacrificed 12 weeks (in one case, 4 weeks) after the beginning of therapy, and selected soft tissue and bone samples were analyzed radiochemically for Pu content. DTPA treatment initiated at 6 hr after Pu injection was superior to treatment begun at 6 to 89 days; much of the additional benefit of the 6-hr treatment was derived from increased removal of circulating Pu, hence prevention of deposition. When treatment was begun at 6 hr (the latter being the currently accepted blinical dose). When the initiation of therapy was delayed for 6 days, a 3-month regime of twice-weekly treatment at 0.18 mmole/kg was superior to similar treatment for 1 month

[en] Two isotopes of plutonium were administered simultaneously to a baboon and two to a dog, one intragastrically and one intravenously. Samples of urine, blood, and tissues were taken and analyzed. The results indicate that the metabolism of absorbed plutonium is the same as that of injected plutonium. They also show that the value for the fractional absorption of plutonium from the GI tract can be calculated from the amounts of the isotopes administered and the value of the ratio of their concentrations in a single sample of urine, blood, or tissue. 3 references, 1 table

[en] The gastrointestinal absorption of plutonium in the beagle has been determined to be 0.066 +- 0.014% of the amount administered. This result is quite comparable with the results reported for the dog by other workers, and a factor of 3 smaller than that observed by us for mice. On the average, the retained plutonium was found to be almost equally divided between the liver and the skeleton

[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

[en] In the mouse the gastrointestinal absorption of hexavalent plutonium (the form present in chlorinated drinking water) is (1) a factor of about ten lower in the fed animal than in the fasted one (0.015 vs 0.15%), (2) independent of plutonium concentration over a range that broadly brackets the MPC for plutonium in drinking water, and (3) independent of the time of day the solution is administered to fasted animals. Other factors related to the determination of G.I. absorption which have been investigated are: (1) the adsorption of plutonium onto teeth of animals during both gavage and ad libitum administrations, (2) the formation of polymeric tetravalent plutonium during and subsequent to solution preparation, and (3) the relationship between the metabolic behavior of plutonium solutions, administered both intragastrically and intravenously, and their ultrafilterability