Nine male beagle dogs were exposed by inhalation to 0, 6 and 10.5 mg/cu.m sulfuric acid aerosols with normal ammonia, increased blood ammonia, and increased inhaled ammonia to determine whether the addition of ammonia affected the toxicity of sulfuric acid aerosols. Exhaled concentration of ammonia, sulfuric acid and ammonium bisulfate were measured to determine the neutralization of inhaled aerosol by ammonia in the lung. Unneutralized sulfuric acid aerosol was detected in exhaled air only during exposure to 10.5 mg/cu.m H2SO4 with approximately 25 percent of the total exhaled sulfate measured as H2SO4. No unneutralized H2SO4 was measured after a tenfold increase in blood ammonia by ammonium acetate infusion. Increased blood ammonia resulted in a slightly decreased irritant effect of 10.5 mg/cu.m H2SO4 in the lung using residual volume and functional residual capacity as endpoints. The results indicate that neutralization of inhaled sulfuric acid aerosols can be increased by increasing blood ammonia concentrations. However, the increased neutralization does not seem to markedly affect the toxicity of the inhaled and aerosols.

"Biology Department, Battelle Memorial Institute, Pacific Northwest Laboratories." Dec. 1979. Includes bibliographical references (pages 36-37). "Contract No. 68-03-2665."