ABSTRACT
Ultrafine metal oxide particles (diameters less than 0.1 microns) and sulfur dioxide are important products of coal combustion. Interaction of these products in the effluent stream results in formation of ultrafine particles with adsorbed sulfur compounds, including sulfuric acid. The toxicity of ultrafine zinc oxide particles with adsorbed sulfuric acid was evaluated by comparing pulmonary lavage fluid from guinea pigs exposed for 1, 2, 3, 4, or 5 consecutive daily 3-h periods to ultrafine zinc oxide generated in the presence of sulfur dioxide (ZnO + SO2) to pulmonary lavage fluid from guinea pigs exposed to an equivalent concentration of ultrafine ZnO. Two groups of guinea pigs exposed either to SO2 or to particle-free furnace gas served as additional controls. Cells, protein, and activities of lactate dehydrogenase, acid phosphatase, and alkaline phosphatase were increased in lavage fluid obtained from guinea pigs exposed to ZnO + SO2 as compared to guinea pigs exposed to ZnO. These results demonstrate the potential importance of ultrafine metal oxides as carries of sulfuric acid derived from fossil fuel combustion.
Subject(s)
Bronchoalveolar Lavage Fluid/analysis , Sulfuric Acids/toxicity , Zinc Oxide/toxicity , Zinc/toxicity , Acid Phosphatase/analysis , Air Pollutants/toxicity , Alkaline Phosphatase/analysis , Animals , Bronchoalveolar Lavage Fluid/enzymology , Glucuronidase/analysis , Guinea Pigs , Male , Neutrophils/analysis , Proteins/analysisABSTRACT
Metal oxide particles with diameters of less than 0.1 micron (ultrafine particles) are important products of fossil fuel combustion. Pulmonary lavage fluid was obtained from guinea pigs given 1, 2, or 3 consecutive, daily, 3-h, nose-only exposures to 0, 2.3, 5.9, or 12.1 mg/m3 of freshly generated zinc oxide (ZnO) particles with a projected area diameter of 0.05 micron. Exposure to ZnO at 5.9 or 12.1 mg/m3 was associated with increased protein, neutrophils, and activities of angiotensin-converting enzyme, alkaline phosphatase, acid phosphatase and lactate dehydrogenase in lavage fluid, and with histologic evidence of pulmonary damage characterized by centriacinar inflammation. The severity of inflammation, graded by the number of inflammatory foci per square centimeter of lung, correlated with the amount of protein and the activity of angiotensin-converting enzyme and other enzymes in lavage fluid. These results indicate that analysis of pulmonary lavage fluid is a useful and sensitive method for quantitative evaluation of pulmonary damage caused by inhalation of low levels of ultrafine ZnO.
