Effects of repeated inhalation exposures to 1-nitropyrene, benzo[a]pyrene, Ga2O3 particles, and SO2 alone and in combinations on particle clearance, bronchoalveolar lavage fluid composition, and histopathology.

The toxicities of 1-nitropyrene (NP) and benzo[a]pyrene (BaP), inhaled alone and in combination with particles and an irritant gas, were examined to evaluate synergisms among the organic compounds, particles, and gas. Groups of F344 rats were exposed 2 h/d, 5 d/wk for 4 wk to atmospheres of pure NP aerosol (7.5 mg/m3), and to these same compounds adsorbed to Ga2O3 particles (27 mg/m3) both with and without coexposure to 5 ppm SO2. Rats were also exposed to Ga2O3 and SO2 alone. Measurements were made of lung burdens of Ga2O3 particles and retention of radiolabeled tracer particles after the cessation of exposure to evaluate effects on particle clearance. Bronchoalveolar lavage fluid was analyzed to assess inflammation and cytotoxicity. Histopathology was examined to assess the nature and extent of lung injury. Particle clearance was significantly impaired (p less than .05) in all groups whose exposure atmosphere included Ga2O3, but was not significantly changed in the other exposure groups.