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A study was conducted in rats to determine solubility and subsequent metabolism of an inhaled aerosol of curium treated at high temperatures. Young adult Fischer-344 rats received a single inhalation exposure to one of three monodisperse aerosols of 244Cm2O3 (0.70, 1.3, or 2.6 micron activity median aerodynamic diameter) heat-treated at 1150 degrees C. Animals were maintained individually in metabolism cages for excreta collection and serially sacrificed in groups of two male and two female rats from 2 to 33 days after inhalation exposure. Additionally an injection study with curium citrate was done to define the systemic behavior of Cm in this rat model. The in vivo solubility was inversely related to the aerosol particle size. The relationship of the results of this study to results from other experimental inhalation studies with curium oxide aerosols is discussed, as is the relevance to bioassay interpretation and risk assessment in man.

A simple, reliable, rapid and efficient method for the radiochemical analysis of polyvalent nuclides in biological samples is described. The method consists of homogenizing, prefiltering at pH 1 and separating the nuclide as the hydrogen phosphate by filtering through a 0.3 p membrane filter paper at pH 5.0. Optimum conditions were established with respect to pH, carrier concentration, filter paper pore size, and the elimination of chelating agents such as EDTA. The particulate matter filtered was of colloidal size (diameter 0.1 p). Chemical analysis and isotope dilution studies established that for Y the particulate matter was Y2(HP04),. Radiometric yield for in dog urine was 97 & 1.0%. Yields for 144Ce(IV), 155E~(III) and 147Pm(III) were about 97%. Contamination of Y particulate matter by both Ca and Sr was about 1% at pH 5.0 and about 35% at pH 8.0. This procedure eliminates tedious wet ashing steps, yields thin counting samples and minimizes radiochemical and counting errors. It is an excellent procedure for weak beta emitters such as 14'Pm. Since it is fast and simple, this method is well suited for routine analysis of large numbers of radio-THE biological samples.