Effect of styrene and fiber glass on small airways of mice

Three groups of 20 mice each were exposed to respirable glass fibers, to 300 ppm styrene vapor, and to glass fibers plus 300 ppm styrene. The glass fiber concentration was congruent to 1070/cm3; fiber diameters were under 3 micron and fiber lenths under 10 microns. The 5 h/d, 5 d/wk inhalation experiment lasted 6 wk. Glass fibers did not cause any lung damage when inhaled separately but combined styrene and glass fibers induced a change in the cellularity of the bronchiolar lining, where aprocrine-type cells became predominant. The same type of bronchiolar epithelial change was found in 10% of the styrene-exposed mice, while most of the styrene-exposed animals (90%) presented thickened bronchiolar walls becasue of stratification of the bronchiolar epithelium.