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PubMed1975

The alveloar deposition of inhaled plutonium aerosols in rodents.

The alveolar burden following nose-only aerosol exposure of rodents to highly toxic radioactive materials depends upon the percentage of the inhaled aerosol that is deposited beyond the animals' ciliated epithelium. The quantity inhaled was estimated from the product of the aerosol concentration (nCi/liter), the exposure time (minutes) and the mean minute volume (liter/min) of the animals. For rats exposed to Pu(NO3)4 and sacrificed within an hour, the mean alveolar deposition was 19.2 plus or minus 9.19% for 36 groups of both -239Pu and -238Pu. No important correlations between any of the measured parameters and this initial percentage deposition were observed, in contrast with the results for -239PuO-2 deposition measured in rats sacrified 24 or 48 hours postexposure. In these, the aerosol activity median aerodynamic diameter (AMAD) was strongly correlated with aerosol concentration and percentage deposition (mean-7.9 plus or minus 3.9% for 32 groups) with AMAD over the range of 1.5 to 4.5 mum. The 200-fold lower mass concentration of -238Pu compared with -239Pu for a given activity level may explain the fact that the AMAD was correlated with concentration for -239Pu oxide and nitrate, but not for -238Pu compounds.

Aerosols↗
PubMed1975

Suggested reduction of permissible exposure to plutonium and other transuranium elements.

The historical development of the value of maximum permissible body burden ot 239Pu is presented and present considerations for the revision of this standard are given. Some evidence is presented that the linear hypothesis may not be sufficiently conservative at low dose rates and especially for the actinide elements. Until certain questions are answered about the particle problem, it will not be possible to set a satisfactory maximum permissible body burden for 239Pu based on lung as the critical organ, but in the meantime some studies suggest that the present maximum premissible body burden based on bone should be reduced at least by a factor of 200.

Body Burden↗
PubMed2000

Comparative biokinetics of plutonium and americium after inhalation of PuO2 and mixed oxides (U, Pu)O2 in rat.

PURPOSE: To compare the biokinetics of Pu and Am in rat after inhalation of PuO2 and two (U, Pu) mixed oxides (MOX), referred to as MIMAS and SOLGEL. MATERIALS AND METHODS: Lung clearance was measured in vivo by X-and y-ray spectrometry. Retention of Pu and Am in femurs, liver and kidneys was measured by alpha-spectrometry. RESULTS: Observed lung clearance was in the same range for all three powders. Extra-pulmonary transfers were expressed as the percent of the initial deep lung deposit (IDLD) measured 7 days after inhalation. After PuO2 exposure, bone retention remained nearly constant throughout the 270-day experiment. It was approximately 0.7% of the IDLD for Pu and Am. By contrast, a gradual increase was observed for the two MOX. After 7 days, bone retention of Pu and Am was respectively 0.05 and 0.08% for MIMAS, and 0.2 and 0.6% for SOLGEL. The retention reached maximal values between 180 and 270 days post-exposure, which were 0.2 and 0.3% for MIMAS, and 1.2 and 2.8% for SOLGEL for Pu and Am respectively. CONCLUSIONS: Different transfer rates of Pu and Am from the lung were observed depending on the chemical composition of the oxides and/or the method of their preparation.

Administration, Inhalation↗
PubMed1980

The wound clearance and distribution of plutonium, americium and curium in rodents.

Wound contamination was simulated by the intramuscular injections of either 239Pu, 241Am or 244Cm nitrate in the hamster and by the subcutaneous injection of either 239Pu or 241Am nitrate in the rat. The actinides moved from the hamster muscle at approximately the same rate after injection of 370 Bq of each radionuclide (approximate 80 per cent cleared after 6 months). Similarly, the rates of translocation of 239Pu and 241Am in the rat were the same after injection of 370 Bq of each radionuclide (approximate 80 per cent cleared after 1 month). The clearance of 239Pu in the rat was slower after injection of 14.8 kBq and more rapid after injection of 20 Bq (approximately 40 per cent and 90 per cent moved after 1 month, respectively) while the movement of 241Am showed no dependence on the administered dose over the same range. The mixing of 239Pu and 241Am prior to intramuscular injection appeared to enhance the clearance of both radionuclides. The levels of accumulation of each actinide in the skeleton and liver of both species showed that they reached the circulation predominantly in soluble form. Some uptake of Pu and Am in regional lymph nodes was also observed, indicating that lymphatic clearance of polymeric material also took place.

Americium↗
PubMed1982

Dominant lethal and ovarian effects of plutonium-239 in female mice.

In two separate experiments (C3H x 101)F1 female mice were injected intravenously with 239Pu in trisodium citrate, then mated in pairs to strain CBA males, to test for dominant lethality. In the first experiment 10 muCi kg-1 and in the second 20 muCi kg-1 body mass was injected. Matings were after 6 days in the first experiment (estimated ovarian absorbed dose of 0.1 Gy) and after 3, 6 or 12 weeks in the second (estimated ovarian doses of 1.11, 2.45 and 5.91 Gy respectively). No evidence of dominant lethal induction was found in the first experiment, but in the second there was a significant increase over controls in pre-implantation loss in all three series. Post-implantation lethality increased significantly (by 12 per cent) only after 12 weeks' exposure. With the 6- and 12-week exposures (especially the latter) luteal counts fell and fewer females became pregnant than in controls. This is attributed to oocyte killing by the alpha-particles. Histological and autoradiographic investigations showed a marked reduction in ovarian size and follicular numbers with fission-tracks clustered mainly over the medullary stroma. The pre-implantation loss may stem from lowered fertilization of oocytes because of their damage, so that the best measure of dominant lethality is that based on post-implantation death. Thus there is only slight evidence for the induction of genetic damage, which is in line with previous findings after chronic exposures of female mice.

Animals↗
PubMed1983

Identification of transferrin as the principal plutonium-binding protein in the blood serum and liver cytosol of rats: immunological and chromatographic studies.

An analysis of 239Pu-labelled protein complexes in serum and liver cytosol fractions prepared from rats injected intravenously with 239Pu-citrate indicated that among the possible metal-binding proteins, ferritin, transferrin and metallothionein, 239Pu was bound almost exclusively to transferrin. The method employed for the quantitative determination of 239Pu-transferrin was chromatography on immobilized rabbit anti-rat apo-transferrin. There was no evidence that transferrins from serum and liver cytosol are serologically different. The residual blood content of perfused and non-perfused liver was measured using 51Cr-labelled red blood cells and the amounts of blood-derived 239Pu and 239Pu-transferrin in the liver cytosol were calculated. The results are discussed with respect to the possible role of transferrin in the uptake of Pu into cells.

Animals↗
PubMed1984

Distribution of plutonium-239 in the skeleton of the tree shrew (Tupaia belangeri) during the first 15 months after injection.

The macroscopic and microscopic distribution of intramuscularly injected, essentially monomeric 239Pu, was studied in the tree shrew (Tupaia belangeri). Data for the first 15 months after injection are presented. About 50 per cent of the absorbed dose is deposited in the skeleton. The microscopic distribution was analysed in femora, humeri, tibiae and lumbar vertebrae. The initial bone surface activity is about 11 Bq/cm2 per 37 kBq/kg injected dose (related to a bone uptake of 50 per cent) and is similar in all four bones. At 462 days after injection the surface activity in the tibiae and humeri is comparable with the initial concentration, whereas only 50 per cent and 37 per cent of the initial surface activity is present in the femora and lumbar vertebrae respectively. A comparison with results from rats and dogs shows that at 5 days after injection the normalized endosteal surface activity is similar but marked species differences are found at 365 days after injection.

Animals↗
PubMed1986

Chelation therapy of incorporated plutonium-238 and americium-241: comparison of LICAM(C), DTPA and DFOA in rats, hamsters and mice.

The carboxylated catechoylamide 3,4,3-LICAM(C) was tested for removal of 238Pu and 241Am from small laboratory rodents. The effectiveness of treatment was compared with that of two ligand preparations approved for clinical use: calcium-trisodium diethylenetriaminepentaacetate (DTPA) and desferrioxamine (DFOA). With early treatment and at the dosage used clinically for the decorporation of actinides with DTPA (30 mumol/kg body weight) LICAM(C) was superior to DFOA but when compared with DTPA, the effect of LICAM(C) on 238Pu was greater only in bone; as little as 1 mumol LICAM(C)/kg was as effective as 30 mumol DTPA/kg. However, in all animals treated with LICAM(C) there was a large increase in the 238Pu content of the kidney. With 241Am the effect of DTPA was always superior to that of LICAM(C). The best overall results early (1 day) after injection of 238Pu and 241Am were achieved by a combination of a single injection of LICAM(C) and DTPA with subsequent continuous administration of DTPA in drinking water. LICAM(C) affected the retention of 238Pu even if given orally; the data suggested that about 3 per cent of ingested LICAM(C) was absorbed. When the beginning of treatment was delayed, LICAM(C) became equally effective or less effective than DTPA even as far as 238Pu retention in bone was concerned, but it still increased the accumulation of 238Pu in the kidneys.

Americium↗