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.