Pulmonary Effects due to Subchronic Exposure to Oil Fog

Male and in some cases female rats were exposed to an oil fog generated by flash vaporization and subsequent condensation of lightweight lubricating oil. Exposures were for 3.5 h/d, 4d/wk for 13 wk. Males were exposed at concentrations of 1.5, 0.5, 0.2 or 0.0 mg/l (1500, 500, 200, and 0 mg/m3) and a particle size of approximately 1 μm (mass median aerodynamic diameter). A number of biologic end-points were assessed the day after the last exposure and, in some cases, after a 4 wk recovery period. Effects of 1.5 mg/l on male and female rats were compared. Diffuse accumulation of macrophages in the alveoli was observed in all oil fog exposed groups. The degree of severity was concentration dependent. Histopathologic changes were more prominent in males than in females and represented the most notable gender-related differences. Histologic effects observed one day and 4 wk post exposure were similar. Minimal histopathologic changes and minimal increase in lavage fluid protein were the only effects observed at...