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RESPIRABLE PARTICLES AND MISTS IN MOUSE PULMONARY INFECTIVITY MODEL. EFFECT OF CHRONIC OR INTERMITTENT EXPOSURE
Citation:
Bradof, J., J. Fenters, AND R. Ehrlich. RESPIRABLE PARTICLES AND MISTS IN MOUSE PULMONARY INFECTIVITY MODEL. EFFECT OF CHRONIC OR INTERMITTENT EXPOSURE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/1-78/036.
Description:
The effects of respirable-sized sulfuric acid mist or mixtures containing acid mist and carbon particles (A-C) on the susceptibility to bacterial and viral respiratory infection were studied in mice and hamsters. Both species showed mortalities upon single 3-hour exposure to 600 mg/cu m but not 400 mg/cu m acid mist. Scanning electron microscopic examination indicated that the most severe changes, including emphysemic-like areas in alveoli, were found after five daily 3-hour exposures to 200 mg/cu m A-C. Significantly increased mortality and decreased bacterial clearance from lungs were also observed in mice challenged with Streptococcus sp. Significantly increased mortality and pulmonary consolidation, with concomitant decreased survival time, occurred in mice challenged with influenza virus aerosol and exposed to 50 mg/cu m A-C, 3 hr/day, 5 days/week for 4 weeks. Depressed secondary immune responses, as measured by serum antibody levels, were observed in various groups of vaccinated mice exposed to pollutant. The effects of long-term exposure to mixtures of approximately 1.4 mg/cu m sulfuric acid mist and 1.5 mg/cu m carbon particles as well as carbon only were determined. Significant alterations of immunoglobulin concentration, depression of primary antibody response in spleen cells and decreased resistance to respiratory infection as measured by mortality, survival time, and pulmonary consolidation after 20 weeks of exposure were evident.