Research report (Health Effects Institute)
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Res Rep Health Eff Inst · Jan 1991
Synergistic effects of air pollutants: ozone plus a respirable aerosol.
Rats were concurrently exposed to mixtures of ozone or nitrogen dioxide and respirable-sized aerosols of sulfuric acid, ammonium sulfate, or sodium chloride, or to each pollutant individually. Their responses to such exposures were evaluated by various quantitative biochemical analyses of lung tissue or lavage fluids, or by morphometric analyses. Such studies were performed in the acute time frame, generally involving exposures of from one to nine days, depending on the assays used. ⋯ A hitherto unexpected synergistic interaction between nitrogen dioxide and sodium chloride aerosol was found during these studies; it is hypothesized that this was due to formation of their acidic (anhydride) reaction product, nitrosyl chloride, in the chambers during exposure to the mixture. Preliminary experiments treating exposed animals in vivo with various free-radical scavengers suggested that dimethylthiourea, a hydroxyl-radical scavenger, might be protective against effects of ozone on rat lungs. This observation might have mechanistic implications, but further studies will be necessary to determine the significance of these findings.
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Res Rep Health Eff Inst · Oct 1989
Influence of experimental pulmonary emphysema on the toxicological effects from inhaled nitrogen dioxide and diesel exhaust.
This project examined the influence of preexisting, experimentally induced pulmonary emphysema on the adverse health effects in rats of chronic inhalation exposure to either nitrogen dioxide or automotive diesel-engine exhaust. Previous reports indicated that humans with chronic lung disease were among those most severely affected by episodic exposures to high concentrations of airborne toxicants. There were no previous reports comparing the effects of chronic inhalation exposure to components of automotive emissions in emphysematous and normal animals. ⋯ Airway fluid indicators of cell damage and oxidant protective mechanisms were increased. Similar effects of nitrogen dioxide exposure were superimposed over the effects of emphysema in emphysematous nitrogen dioxide-exposed rats. Several parameters were affected similarly by nitrogen dioxide exposure and emphysema (for example, increased lung volume), and the combined effects tended to be additive.(ABSTRACT TRUNCATED AT 400 WORDS)
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Res Rep Health Eff Inst · Jan 1987
Effects of inhaled nitrogen dioxide and diesel exhaust on developing lung.
This study examined age-related differences in the physiological responses of rats to inhaled automotive emissions. Previous reports suggested that lung development of animals exposed to oxidant gases early in life might be impaired, or that developing lungs might be more susceptible than adult lungs to inhaled toxicants. There were no previous comparisons in developing and adult lungs of the effects of atmospheres containing particles. ⋯ Particularly striking was an almost sixfold increase in the percentage of neutrophils, a class of highly phagocytic leukocytes, in the airway fluids of adults after six months of exposure. Exhaust-exposed adults had increased numbers of cells in pulmonary lymph nodes, delayed clearance of both diesel soot and 134Cs-labeled particles, and increased lung weight. These changes did not occur in the rats exposed during development.(ABSTRACT TRUNCATED AT 400 WORDS)