Comparison between whole-body inhalation and nose-only inhalation on the deposition and health effects of nanoparticles.

Objectives: We performed the two inhalation exposures, whole-body inhalation and nose-only inhalation, to investigate the pulmonary deposition and health effects of the two inhalation methods. Methods: In both methods, we exposed rats to the same TiO nanoparticles at almost the same exposure concentration for 6 h and compared the deposited amounts of nanoparticles and histopathological changes in the lungs. Rats were exposed to rutile-type TiO nanoparticles generated by the spray-dry method for 6 h. The exposure concentration in the whole-body chamber was 4.10 ± 1.07 mg/m, and that in nose-only chamber was 4.01 ± 1.11 mg/m. The particle sizes were 230 and 180 nm, respectively. A control group was exposed to fresh air. Results: The amounts of TiO deposited in the lungs as measured by ICP-AES after acid digestion just after the exposure were: 42.6 ± 3.5 μg in the whole-body exposure and 46.0 ± 7.7 μg in the nose-only exposure groups. The histopathological evaluation was the same in both exposure groups: no infiltration of inflammatory cells in the alveolar space and interstitium, and no fibrosis. Conclusion: The two inhalation methods using the same material under the same exposure conditions resulted in the same particle deposition and histopathology in the lung. [ABSTRACT FROM AUTHOR]