Effect of SO2 on the pathogenesis of viral upper respiratory infection in mice.

Abstract

Epidemiologic studies have consistently shown an association between respiratory infection and air pollution. Most of these studies have been concerned with effects on the mucous membranes of the tracheobronchial tree. Among the many airborne contaminants to which the Yokkaichi industrial area of Japan was heavily exposed from about 1960 to 1966, SO/sub 2/ was the major pollutant, with levels ranging from 0.2 to 2.5 ppM, and during those years the incidence of respiratory diseases was significantly increased over that of nonpolluted areas. In 1968, after rigorous control measures, the range was lowered to 0.071 to 1.0 ppM. Nonetheless, Ohyana and Miyoshi found in 1972 that the incidence of rhinitis and tonsillitis in school children in Yokkaichi was still significantly higher than that of children in nonpolluted areas. Previous reports of increased respiratory disease had been concerned with industrial workers in the United States and in England after exposure to SO/sub 2/ levels as high as 55 and 36 ppM, respectively. There have been several histopathologic studies of lower respiratory mucosae in experimental animals after exposure to various levels of SO/sub 2/ and three studies of experimental exposure of nasal mucous membranes to high (10 to 36 ppM) concentrations of SO/submore » 2/, but the effects of continued exposure of nasal tissues to low levels of SO/sub 2/ have not been reported. Since the inhaled gas initially impinges on nasal tissues and may interact with other factors to enhance respiratory tract infections, it seemed important to follow the pathogenesis of intranasal virus infection in association with low levels of exposure. The present study was designed to determine the effects of constant exposure of nasal mucous membranes of mice to low levels of SO/sub 2/ on the pathogenesis of influenza virus infection in these animals.« less