Effect of inhaled aerosol of 1-chloroacetophenone (CN) and Dibenz (b,f)-1,4 oxazepine (CR) on lung mechanics and pulmonary surfactants in rats.

Inhalation toxicity following exposure to 1-Chloroacetophenone (CN) and Dibenz(b,f)-1,4 oxazepine (CR) aerosols for 60 min at sublethal concentrations were studied in rats. The dynamic surface tension (gamma max and stability ratio) of lung homogenate increased significantly on CN exposure. The lung mechanics studies revealed a significant increase in compliance in CN exposed rats. CR, on the other hand did not influence any of the above variables except for a decrease in compliance. Total lung phospholipids and sphingomyelin contents decreased significantly following exposure to CN, while CR exposure produced an increase in sphingomyelin, reduction in phosphatidylcholine and ethanolamine, with no change in total phospholipid contents. Histomorphological observations indicated cellular degeneration in the epithelium of the bronchiole and alveolar septal-wall thickening due to the presence of an increased number of mononuclear cells in CN exposed rats. However, CR induced inflammatory reaction and enlargement of respiratory air spaces. It is concluded that of the two sensory irritants (tear gases) examined, CN is potentially more toxic compared to CR in rats.