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Synergistic effects of exposure to concentrated ambient fine pollution particles and nitrogen dioxide in humans
Citation:
Huang, Y., A. Rappold, A. Ghio, R. Devlin, AND D. Graff. Synergistic effects of exposure to concentrated ambient fine pollution particles and nitrogen dioxide in humans. INHALATION TOXICOLOGY. Informa Healthcare USA, New York, NY, 24(12):790-7, (2012).
Impact/Purpose:
THIS MANUSCRIPT WAS ORIGINALLY CLEARED THRU PAPER FILE EPHD-12-033 AND ENTERED IN THE SCIENCE INVENTORY.
Description:
Exposure to single pollutants such as ambient particulate matter (PM) is associated with adverse health effects. It is unclear, however, if simultaneous exposure to multiple air pollutants (e.g. PM and ozone or nitrogen dioxide), a more real world scenario, results in non-additive (e.g. synergistic) interactions. In this study, healthy young volunteers were exposed to either clean air, nitrogen dioxide (N02, 0.5 ppm), concentrated fineparticlesfromChapelHillair(PM2.5CAPS,89.5±IO.7ug/rrr'),or N02 + PM2.5 CAPS for two hours. Each subject performed intermittent exercise on a cycle ergometer during the exposure. Holter monitoring was initiated prior to exposure and continued for 24 hrs to measure changes in time and frequency domain ofheart rate variability (HRV) as well as changes in repolarization. Blood was drawn and lung function performed immediate prior to exposure, and one and 18 hours after exposure. Bronchoalveolar lavage was performed 18 hours after exposure. Effects driven primarily by N02 included increases in total cholesterol and HDL cholesterol 18 hours after exposure, decreases in high frequency component ofHRV one and 18 hours after exposure, decreases in QT variability index one hour after exposure, and increases in LDH in BAL fluid. PM2.5 CAPS resulted in only an increase in HDL cholesterol one hour after exposure, likely due to the low concentrations ofthis pollutant in the exposure chamber. Exposure to both N02 and PM2.5 CAPS increased BAL eel-antitrypsin levels, mean t wave amplitude, the low frequency components ofHRV and the LF/HF ratio. Thesechangeswerenotobservedfollowingexposuretoeither N02orPM2.5CAPS alone, suggesting possible synergistic effects. We conclude that N02exposure may produce and enhance acute cardiovascular effects ofPM2.5 CAPS. Assessment ofhealth effects by ambient PM should consider its interactions with gaseous co-pollutants.