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

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. In both methods, we exposed rats to the same TiO2 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 TiO2 nanoparticles generated by the spray-dry method for 6 h. The exposure concentration in the whole-body chamber was 4.10 +/- A 1.07 mg/m(3), and that in nose-only chamber was 4.01 +/- A 1.11 mg/m(3). The particle sizes were 230 and 180 nm, respectively. A control group was exposed to fresh air. The amounts of TiO2 deposited in the lungs as measured by ICP-AES after acid digestion just after the exposure were: 42.6 +/- A 3.5 mu g in the whole-body exposure and 46.0 +/- A 7.7 mu g 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. The two inhalation methods using the same material under the same exposure conditions resulted in the same particle deposition and histopathology in the lung.