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METAL-INDUCED LATE PULMONARY INJURY IS REDUCED BY OZONE (O3) COEXPOSURE
Citation:
Kodavanti, U P., M. Schladweiler, W P. Watkinson, J. P. Nolan, P A. Evansky, E. R. Lappi, G. Ross, J H. Richards, AND D L. Costa. METAL-INDUCED LATE PULMONARY INJURY IS REDUCED BY OZONE (O3) COEXPOSURE. Presented at ATS International Conference, San Francisco, CA, May 18-23,2001.
Description:
METAL-INDUCED LATE PULMONARY INJURY IS REDUCED BY OZONE (O3) COEXPOSURE. UP Kodavanti, MCJ Schladweiler, WP Watkinson, JP Nolan, PA Evansky, ER Lappi, G Ross, JH Richards, and DL Costa. NHEERL, ORD, US Environmental Protection Agency, Research Triangle Park, NC USA.
Ambient particulate matter (PM)-associated metals are postulated to interact with gaseous air pollutants such that the potential of PM to cause lung injury would be modified. We tested the hypothesis that the toxicity of a given combustion-derived metal mixture will be potentiated by a concomitant and/or a prior exposure to O3. Male Sprague-Dawley rats ( 60-70 d old) were pre-exposed to either air or O3 (0.5 ppmx6 h/dx1 d) prior to their exposure to a mixture of particulate vanadium sulfate (0.46 mg/m3; V)+ nickel sulfate (0.46 mg/m3; Ni)+ ferrous sulfate (0.21 mg/m3; Fe), with or without 0.5 ppm O3 for 6 h/dx4 d. In a separate study, rats were either exposed to air or Ni+V with or without 0.5 ppm O3, 6 h/dx4 d. One or 4 d later, pulmonary tissues were examined. O3 pre-exposure or exposure, by itself, was not associated with increases in BALF protein and albumin, or neutrophilic inflammation at the time of analysis. Exposure to Ni+V+Fe caused ~4-fold increases in BALF protein and albumin and ~50-fold increases in neutrophils. This effect of Ni+V+Fe seemed to be more persistent in rats pre-exposed to O3. Simultaneous exposure to O3 resulted in a decrease in the toxicity of this metal mixture (only a 2-3 fold increase in BALF protein and 4-10 fold increase in neutrophils). Lung injury in Ni+V-exposed rats appeared to be slightly greater than that of rats exposed to Ni+V+Fe. Injury caused by Ni+V was similarly, but less markedly attenuated by simultaneous exposure to O3. Lung histology revealed airway and perivascular inflammation and interstitial edema following metal mixtures exposure. Simultaneous exposure to O3 appeared to be protective. This study demonstrates that a mixture of two or more reactive particulate components and gaseous air pollutants may interact to reduce biological effects of PM, and not necessarily result in additive or exacerbated pulmonary responses (Does not reflect USEPA policy).