Reversibility of clearance impairment after subchronic test toner inhalation

In a chronic study of a test toner in F-344 rats an impairment of alveolar clearance and increased toner retention were observed at the high and, to a lesser degree, at the middle exposure level throughout the study. The objectives of the present study were: 1. To investigate the nature and the time course of test toner and surrogate tracer alveolar clearance and toner retention behaviour following a subchronic exposure interval. 2. To investigate the dependence of the response upon the pulmonary burden of the test toner.