Lung clearance and retention of toner, utilizing a tracer technique, during chronic inhalation exposure in rats.

Male and female F-344 rats were exposed 6hr/day, 5 days/week for up to 24 months to a special test toner at 0, 1, 4 and 16 mg/mhigh3 by the inhalation route. 59Fe-labeled iron oxide and 85Sr-labeled polystyrene particles were periodically inhaled by the nose only route and used to measure alveolar clearance rates during the course of the study. The final pulmonary burdens of toner at the three exposure levels were 0,22, 1,73, and 15,6 mg/lung, respectively. Alveolar clearance of both tracers was substantially impaired at the toner high-exposure level, and moderately slowed at the toner middle-exposure level.