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Cardiopulmonary Toxicity of Size-Fractionated Particulate Matter Obtained at Different Distances from a Highway
Citation:
CHO, S., H. TONG, J. K. MCGEE, R. W. BALDAUF, AND M. I. GILMOUR. Cardiopulmonary Toxicity of Size-Fractionated Particulate Matter Obtained at Different Distances from a Highway. Presented at Annual American Thoracic Society, San Diego, CA, May 15 - 20, 2009.
Impact/Purpose:
This study was initiated to determine the effect of size fractionated particulate matter (PM) obtained at different distances from a highway on acute cardiopulmonary toxicity in mice.
Description:
This study was initiated to determine the effect of size fractionated particulate matter (PM) obtained at different distances from a highway on acute cardiopulmonary toxicity in mice. PM was collected for 2 weeks using a three-stage (ultrafine: <0.1µm; fine: 0.1-2.5µm; and coarse: 2.5-10µm) high-volume impactor 10m (NR) and 275m (FR) from an interstate highway in Raleigh, North Carolina. Collected samples were sonicated in methanol, concentrated to dryness by evaporation, diluted in physiological sterile saline, and analyzed by ICP-OES. Female CD-1 mice were intratracheally instilled with saline, 25 or 100μg of each size fraction, then assessed for airflow limitation and markers of lung injury and inflammation at 4 and 18 hours post-instillation. In both the NR and FR samples, fine particles comprised approximately 55% of total mass while coarse and ultrafine contributed 30% and 15%, respectively. Certain elements (Ba, Ca, Cr, Cu, Fe, Pb, Sb, Si, Ti, Zn) and endotoxin levels were 50% to 100% higher in NR-PM than FR-PM, respectively, suggesting potential for increased toxicity at this location. Pulmonary endpoints (inflammatory cells, cytokines, total protein and responsiveness to methacholine) however showed that only the coarse PM was associated with significant inflammatory responses regardless of distance from the highway. On the other hand, cardiac ischemia/reperfusion injury (%LVDP, infarction, coronary flow) was induced by the ultrafine fraction without significant differences between the NR-PM and FR-PM. The results show that on a comparative mass basis, coarse and ultrafine particles affect different organ systems presumably due to differences in physical size and chemical composition. Further studies will determine translocation of particles and associated chemicals from the lung to the systemic vasculature system. (This abstract does not reflect EPA policy.)