Health effects of long-term inhalation of sulfuric acid mist-carbon particle mixtures

Abstract

The effects of exposures of mice 3 hr/day, 5 days/week for up to 20 weeks to 1.4 mg/m 3 sulfuric acid mist and 1.5 mg/m 3 carbon particle mixtures as well as 1.5 mg/m 3 carbon only were investigated. The immunologic state of the animals was examined directly by the primary response of spleen cells after specific antigen stimulation, and indirectly by infectivity studies. A quantitative measure of the effects on the immune system without the antigenic stimulation was obtained by determination of serum immunoglobulin concentrations. Significant alterations of immunoglobulin titer, depression of primary antibody response in spleen cell antigenic stimulation, and decreased resistance to respiratory infection as measured by mortality, survival time, and pulmonary consolidation after 20 weeks of exposure to acid mist and carbon particle mixtures were noted. In addition, bactericidal capacity of lungs was reduced in mice exposed to either sulfuric acid and carbon mixtures or to carbon alone, and subtle morphological changes in the respiratory tract were detected by scanning electron microscopy. Thus the alterations of the defense system suggest that prolonged exposure to low concentrations of sulfuric acid and carbon particle mixtures reduces the ability of mice to resist the secondary stress of respiratory infection.