americium-oxide and americium-nitrate

To improve the dosimetry of incorporated americium (Am) and to contribute to radiation protection by characterizing the absorption kinetics of inhaled Am compounds.. In vitro dissolution tests, animal experiments and human contamination cases published in the literature were reviewed. The data were analyzed with biokinetic models consistent with the current publications of the International Commission on Radiological Protection.. Material-specific dissolution parameter values with consequent assignment to absorption Types are proposed as well as representative central values for the different chemical forms of Am.. The absorption of Am oxide is consistent with the moderate absorption Type M while Am nitrate appears more soluble. Am associated with plutonium oxide usually follows its slow absorption Type S. However, the large variability observed stresses the value of investigating the specific absorption kinetics for Am compounds which represent a significant risk of internal exposure.

Topics: Absorption, Radiation; Administration, Inhalation; Americium; Animals; Dogs; Humans; Lung; Radiation Dosage; Radiation Protection; Rats; Reproducibility of Results; Respiratory System; Solubility

The metabolic behavior of 239Pu and 241Am present in three industrial dusts has been studied after their inhalation by the rat. A comparative experiment has also been carried out with a mixture of these actinides, inhaled as their nitrates. The aim of this work was to provide an experimental basis for assessing limits on intake and to establish whether the 239Pu content in the lungs could be interpolated from measurements of 241Am. The results (1) demonstrate the wide differences in the lung retention kinetics of the actinides and in the absolute and relative amounts which translocate to the blood that can occur for industrially produced materials; (2) show that the annual limits on intake (ALI) for the different materials vary between those postulated for class W and Y compounds by the International Commission on Radiological Protection; (3) indicate that, depending on the nature of the dust, acute intakes of 239Pu equivalent to the ALI can be estimated from 241Am chest-monitoring data at times from a few days up to about 3 y after exposure.

Topics: Actinoid Series Elements; Aerosols; Air Pollutants, Occupational; Americium; Animals; Humans; Lung; Plutonium; Radiation Monitoring; Radiation Protection; Rats; Species Specificity

Accidental intakes of 241AmO2 and 241Am(NO3)3 can be treated with some success by inhalation of ZnDTPA . The main advantage of this method of treatment is that it can be self-administered very soon after an accidental intake, and it is effective for reducing the lung content of Am at doses about 10 times less than those usually used intravenously. Otherwise the efficacy of injected ZnDTPA is superior since in addition to removing 241Am from the lungs it can deplete appreciably the systemic deposit of the nuclide. There appears to be no advantage in using the lipophilic form of DTPA code-named Puchel , since following the inhalation or injection of the compound decorporation is not significantly increased relative to ZnDTPA .

Topics: Aerosols; Americium; Animals; Chelating Agents; Cricetinae; Drug Evaluation, Preclinical; Injections, Intraperitoneal; Mesocricetus; Pentetic Acid; Radiation Injuries, Experimental; Time Factors; Tissue Distribution