Effects of inhaled diesel emissions and coal dust in rats.

Rats were exposed to coal dust and diesel exhaust emissions, separately and in combination, for 20 months to evaluate the potential health effects of these specific mine air materials. The diesel exhaust was produced by an engine operated in a load, no-load mode and acceleration, deceleration cycle. It was also modified to simulate an inefficiently tuned engine. Exposure to coal dust was performed in a whole-body rodent inhalation system. Mortality, body weight and hematologic parameters examined were normal compared with those of control rats. Lesions observed were primarily restricted to the lungs and were similar to those described for simple coal workers' pneumoconiosis (CWP). Lesion progression and severity was related to exposure duration and exposure material. Alveolar bronchiolization, though not reported in human CWP, was present in the lungs of some rats in all exposure groups except the control animals.