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BIOLOGICAL EFFECTS OF CO-EXPOSURE TO FINE PARTICLES AND NITROGEN DIOXIDE IN HEALTHY YOUNG ADULTS
Citation:
SOUKUP, J. M., M. W. CASE, J. HYSENI, R. B. DEVLIN, AND Y. T. HUANG. BIOLOGICAL EFFECTS OF CO-EXPOSURE TO FINE PARTICLES AND NITROGEN DIOXIDE IN HEALTHY YOUNG ADULTS. Presented at American Thoracic Society Annual Meeting, San Diego, CA, May 18 - 24, 2006.
Description:
Exposure to particulate matter (PM) is associated with adverse health effects. It is unclear if co-exposure to NO2, a common pollutant gas, potentiates the PM effects. Healthy young volunteers were recruited and exposed to either filtered air (FA), NO2 (0.5 ppm), concentrated Chapel Hill fine particle (PM2.5) (average 121 ± 16 µg/m3) or NO2+PM2.5 (average 126 ± 24 µg/m3) for 2 hours. The subject performed intermittent exercise on a cycle ergometer at 75 Watts during the exposure. For each exposure, the subject performed pulmonary function test and had blood samples drawn before exposure, immediately and 18 hours post-exposure. Bronchoscopy with bronchoalveolar lavage (BAL) was performed at 18 hours post-exposure. The expression of surface markers for peripheral blood monocytes and BAL monocytes (CD11b, CD14, CD86 and HLA-DR) were quantified by flow cytometry. A total of 31 exposures were available for analysis from 16 subjects. There were no differences in spirometry (FEV1, FVC, FEV1/FVC and FEF25-72) for NO2, PM2.5 and PM2.5+NO2 exposure compared to FA. DLCO increased by approximately 5% immediately post-exposure to FA and returned to the baseline at 18 hours. The increase in DLCO immediate post-exposure was not seen in subjects exposed to PM+NO2. Exposures to NO2, PM2.5 and PM2.5+NO2 similarly increased CD11b, CD14, CD86 and HLA-DR on alveolar monocytes while they had no effects on the expression of surface markers on blood monocytes. Our results showed that co-exposure to NO2 and PM transiently decreased DLCO response, possibly due to an inability to vasodilate and recruit pulmonary capillaries. PM2.5 and NO2 exposure increased the expression of surface markers on alveolar monocytes, co-exposure did not result in greater increase than the single exposures. (Abstract does not reflect EPA policy).