Removal of Inhaled 241Am Oxide Particles of Various Sizes from Beagle Dogs Using Lung Lavage and Chelation Treatment

Abstract

The combined treatments of lung lavage and chelation therapy were evaluated for the removal of inhaled 24'Am02. Twenty-four Beagle dogs were divided into four equal groups; three groups were exposed to aerosols of diff erent-sized monodisperse particles of ='Am02; Group 1, 0.75 pm aerodynamic diameter (AD) particles; Group 2, 1.5 pm AD particles and Group 3,3.0 pm AD particles; and the fourth group was exposed to an aerosol of polydisperse particles of "'Am02 with an activity median aerodynamic diameter (AMAD) of 1.8pm, a, 1.7. In each group, 3 dogs were treated and 3 were untreated. Treatment consisted of 5 lung lavages of the right lung (days 2,7, 14,28 and 42 after exposure) and 5 lavages of the left lung (days 2, 10, 21, 35 and 49 after exposure).Treated dogs were also given 18 intravenous injections of 22pm/kg body weight of trisodium calcium diethylenetriaminepentaacetate (DTPA). The dogs were sacrificed 64 days after inhalation exposure. Tissues, excreta and lavage fluids were analyzed for 241Am activity by radiochemical techniques. The amount of U'Am removed from lung in the lavage fluid for Groups 1, 2, 3 and 4 represented 41, 46, 42 and 33% of the initial lung burden, respectively. The amount of "'Am excreted in the urine from the treated dogs in excess of that excreted by the untreated dogs for Groups 1, 2, 3 and 4 was 20, 19, 8 and 26%, respectively. More 241Am was excreted in the urine from dogs that inhaled smaller particle sized aerosols. As a result of the removal of 241Am activity, the 64-day cumulative absorbed radiation doses to lung, liver and skeleton were reduced by 50, 90 and 85%, respectively.

Animal Models and Medical Countermeasures Development for Radiation-Induced Lung Damage: Report from an NIAID Workshop

“…Studies in a canine (beagle) model have demonstrated that the use of bronchoalveolar lavage (BAL) will facilitate the removal of inhaled 144 Ce, resulting in greatly increased survival times in treated animals when compared to animals not subjected to BAL (105). BAL also removed about 50% of inhaled 241 Am particles and similarly improved survival in dogs (106). Currently, therefore, BAL is the only treatment available to clear nonsoluble radioactive particle in the lung, and has been used following incidents of internal contamination (107); however, it is an invasive procedure.…”