[en] Beagle dogs received an inhalation exposure to one of two sizes of monodisperse aerosols of ²³⁸PuO₂ to achieve graded levels of initial lung burden. All dogs are being studied for their life spans. Ninety-nine dogs that had initial lung burdens ranging from 0.01 to 1.5 μCi ²³⁸Pu per kilogram body weight (0.37 to 56 kBq/kg) have died, eight with radiation pneumonitis and pulmonary fibrosis, four with lung tumors, 70 with bone tumors, three with liver tumors, and 13 of miscellaneous causes. Four control dogs have died. Forty-five exposed and 20 control dogs survive at 2753-3779 days after exposure. 3 references, 9 figures, 1 table

[en] Immature Beagle dogs have been exposed by inhalation to a monodisperse aerosol of ²³⁹PuO₂ (1.5 μm AMAD) to compare the biological effects with those observed in dogs exposed to a similar aerosol as young or aged adults. The study includes 96 dogs exposed to ²³⁹PuO₂ and 12 controls. The lung burdens of the plutonium-exposed dogs ranged from 0.00030 to 0.80 μCi/kg body weight (0.011 - 30 kBq/kg). During this year, three dogs died; one death was ascribabble to radiation induced injury. With 18 dogs having estimated cumulative radiation doses in excess of 1000 rad (10 Gy), the biological response of the dogs exposed as juveniles appears to be less than that seen in mature dogs. However, major uncertainties in the current estimations of radiation dose exist and these are being addressed in a parallel study. 3 figures

[en] The effects of protracted α irradiation of rat lungs are being studied. Rats have been exposed once or repeatedly to aerosols of ²³⁹PuO₂ to achieve or to re-establish lung burdens of ²³⁹Pu that will result in projected lifetime α radiation doses to the lungs of 20, 60, 200, or 600 rad. The survival of rats exposed once to achieve a projected dose of 600 rad to the lung was decreased compared to controls. However, protraction of this dose by repeated exposure has not decreased survival. Older rats appeared to be more resistant to the toxic effects of ²³⁹PuO₂ than young adult rats. 6 references, 2 figures, 1 table

[en] Dogs were exposed once or repeatedly by inhalation to aerosols of ²³⁹PuO₂ to study the relative doses and effects of these two types of exposures. Dogs still alive in this study have been exposed twelve times and maintained at least 6.7 years after their first exposure. To date 14 dogs have died from radiation pneumonitis and pulmonary fibrosis, of which three had pulmonary carcinomas at death. Two other dogs died from pulmonary carcinomas. Results to date indicate that total accumulated radiation dose may be a good indicator of expected radiation effects for both types of exposures. 4 references, 3 figures, 1 table

[en] To determine the effect of physicochemical form of inhaled curium aerosols on subsequent retention, translocation, distribution, and excretion, 18 young adult Beagle dogs received single pernasal inhalation exposures to a monodisperse aerosol (1.38 μm activity median aerodynamic diameter [AMAD]) of Cm₂O₃, and 18 dogs inhaled a polydisperse aerosol (1.14 μm AMAD; sigma/sub g/ = 1.7) of Cm(NO₃)₃. Through measurement of curium in the tissues and excreta of dogs being serially sacrificed from 0.17 to 730 days after exposure, the biokinetics of curium are being elucidated. Through 132 days after exposure, both aerosol forms of curium cleared from the lung rapidly, less than 20% of the initial lung burden remaining in lung by 60 days after exposure. During the first 14 days after exposure, the nitrate form dissolved and translocated more rapidly than the oxide. 2 references, 3 figures

[en] The influence of total dose and dose rate pattern on the effects of inhaled β-emitting radionuclides is being studied in laboratory animals. The inhaled radionuclides were either in a relatively soluble form (⁹⁰SrCl₂, ¹⁴⁴CeCl₃, ⁹¹YCl₃, or ¹³⁷CsCl), or in a relatively insoluble form in fused aluminosilicate particles. The organs affected depend on the solubility and chemical characteristics of the radionuclides. Studies with young adult dogs are complemented by comparable studies in other species (mice, rats, and Syrian hamsters), with animals of different ages and animals repeatedly exposed to ¹⁴⁴Ce. 12 references, 2 figures, 2 tables

[en] The modifying effects of a pre-existing lung disease (emphysema) on the deposition, distribution, retention, and effects of inhaled ²³⁹PuO₂ in the rat are being investigated. Preliminary observations indicated that the deposition and retention patterns for ²³⁹Pu particles inhaled by rats with emphysema and control rats were similar, but the distribution of inhaled ²³⁹Pu immediately after exposure was different. Respiratory function measured through one year after exposure to ²³⁹Pu was consistent with emphysema and was not altered by the ²³⁹Pu lung burden. Long-term observations are continuing. 4 references, 2 tables

[en] The effect of acute exposure to carbon tetrachloride on the clearance of injected ¹⁴⁴Ce in Chinese hamsters and rats was investigated. Preliminary data indicated that exposure to carbon tetrachloride decreased to whole-body retention of ¹⁴⁴Ce. Data on the retention of ¹⁴⁴Ce in the liver, skeleton, and gastrointestinal tract indicated that the retention patterns of ¹⁴⁴Ce could be altered by acute exposure to carbon tetrachloride in rodents. 5 references, 2 figures, 2 tables

[en] This report updates a study in progress to determine the long-term fate of inhaled 0.7 μm, 1.5 μm, or 2.8 μm activity median aerodynamic diameter (AMAD) or polydisperse (1.5-2.0 μm AMAD) aerosols of ¹³⁴Cs-labeled aluminosilicate using Beagle dogs. Clearance models developed from results obtained during the first 2 yr after inhalation were used to simulate additional data to 4 yr after exposure. The original models fit the new data satisfactorily, with the exception that the smallest particle size might have an increased dissolution rate at the later times after exposure. These results add to a growing data base on deposition and long-term fate of airborne particles inhaled by a laboratory animal. 2 references, 1 figure

[en] The purpose of this study was to determine the effect of benzo(a)pyrene (BaP), Aroclor-1254, coal gas condensate (CGC), nitropyrene (NP), and diesel exhaust extract pretreatment on the binding of radiolabeled aromatic hydrocarbons and/or their mouse metabolites to lung DNA. Pretreatment with BaP, CGC, and Aroclor-1254 was effective in increasing the level of radiolabel bound to DNA following treatment with ¹⁴C-BaP, ¹⁴C-NP, or ³H-2-aminoanthracene. Pretreatment with NP was not effective in increasing the DNA binding of hydrocarbons and diesel exhaust only increased binding of BaP. The highest level of binding was found for NP. These studies suggested that BaP, Aroclor-1254, and CGC induced enzymes which had an effect on the metabolic conversion of specific aromatic hydrocarbons to DNA-reactive species. 5 references, 1 figure, 1 table