Deposition of monodisperse particles in small rodents

Hamsters and rats have been exposed to monodisperse aerosols of spherical aluminosilicate particles (rho = 2.2) labeled with 169Yb to determine the inhalation deposition and organ distribution with respect to particle size. Ten animals of each species were exposed to five aerodynamic equivalent diameters: (a) 3.15 μm, (b) 2.19 μm, (c) 1.14 μm, (d) 0.61 μm, and (e) less than 0.3 μm. Five animals were exposed simultaneously for twenty minutes with automatic recording of respiratory rates and volumes using individual whole-body plethysmographs. Three were sacrificed immediately after the exposure and the remaining 2 after 20 hours had elapsed for radioanalysis of selected tissues to determine deposition quantities and organ distribution. The deposition fractions for the various aerosols in the various parts of the respiratory tract are summarized. Relative deposition among the various lung lobes showed remarkable consistency with respect to particle size. (U.S.)