The effect of titanium dioxide inhalation on the pulmonary clearance of Pasteurella haemolytica in the mouse.

Four inhalation exposure chambers were designed and built in which up to 80 mice per chamber could be accommodated. Exposure for several weeks to an inert inorganic particulate aerosol of titanium dioxide at a respirable aerosol concentration of 20 mg m-3 impaired the clearance of Pasteurella haemolytica in proportion to the duration of exposure. Other groups exposed to a lower respirable concentration of 2 mg m-3 exhibited similar clearance rates relative to mice maintained in clean air. A recovery experiment showed that inhalation of TiO2 at 20 mg m-3 for 10 days impaired bacterial clearance at least 10 days after cessation of exposure to TiO2.