Toxicity of Chemical Components of Fine Particles Inhaled by Aged Rats: Effects of Concentration

摘要

This study tested the hypothesis that exposure to mixtures containing fine particles and ozone (O_3) would cause pulmonary injury and decrements in functions of immunological cells in exposed rats (22-24 months old) in a dose-dependent manner. Rats were exposed to high and low concentrations of ammonium bisulfate and elemental carbon and to 0.2 ppm O_3. Control groups were exposed to purified air or O_3 alone. The biological end points measured included histopathological markers of lung injury, bronchoalveolar lung fluid proteins, and measures of the function of the lung's innate immunological defenses (macrophage antigen-directed phagocytosis and respiratory burst activity). Exposure to O_3 alone at 0.2 ppm did not result in significant changes in any of the measured end points. Exposures to the particle mixtures plus O_3 produced statistically significant changes consistent with adverse effects. The low-concentration mixture produced effects that were statistically significant compared to purified air but, with the exception of macrophage Fc receptor binding, exposure to the high-concentration mixture did not. The effects of the low- and high-concentration mixtures were not significantly different. The study supports previous work that indicated that particle + O_3 mixtures were more toxic than O_3 alone.