Comparative Evaluation of Nose-Only Versus Whole-Body Inhalation Exposures for Rats—Aerosol Characteristics and Lung Deposition

Abstract

Two types of rat exposure chambers, nose-only and whole-body, were evaluated simultaneously for their performance for the temporal and spatial distribution of the same test aerosols within the chambers, both with and without animals present. Aerosol deposition in lungs was also determined after 4-h exposures to evaluate whether the types of exposure chambers and/or test aerosols have effects on the deposition of the aerosols in the respiratory tract. The test aerosols were TiO₂ and brass (a Cu-Zn alloy). The TiO₂ was relatively nontoxic under conditions of this study, while the brass caused respiratory-tract lesions. Results indicated that both types of exposure chambers performed well with coefficients of variation less than 10% for both temporal and spatial variations. The lung burden data for TiO₂ agree well with literature values. The lung burden data for the brass, however, were different from the TiO₂ data, and differences were also observed between nose-only and whole-body exposures.