Influence of Pollutant Gases on Benzpyrene Hydroxylase Activity

Previous studies have shown that exposure to concentrations of ozone as low as 1.4 mg/cu m (0.75 ppm) depresses the activity of benzpyrene hydroxylase In lung parenchyma. Because most pulmonary cancers occur in the tracheobronchial area rather than in the lung itself, the present study was conducted to evaluate the effect of two atmospheric pollutant gases, ozone (O3) and nitrogen dioxide (NO2), on benzpyrene hydroxylase activity in the tracheobronchial mucosa of rabbits. The results show an inhibition of enzyme activity by several concentrations of O3, and no demonstrable early or delayed effect of NO2 inhalation. These findings are consistent with previous reports that have suggested a cocarclnogenic role for O3. The role of NO2 in carcinogenesis remains uncertain, but it is apparent from this and other studies that NO2 is chemically less active than