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RELATIVE TOXICITY OF SIZE-FRACTIONATED PARTICULATE MATTER OBTAINED AT DIFFERENT PROXIMITIES TO A HIGHWAY
Citation:
CHO, S., Q. T. KRANTZ, J. K. MCGEE, J. R. LEHMANN, D. L. DOERFLER, AND M. I. GILMOUR. RELATIVE TOXICITY OF SIZE-FRACTIONATED PARTICULATE MATTER OBTAINED AT DIFFERENT PROXIMITIES TO A HIGHWAY. Presented at American Thoracic Society Annual Meeting, San Francisco, CA, May 18 - 23, 2007.
Description:
Recent epidemiological studies have shown associations between proximity to highways and adverse health effects. Toxicology studies in animals are needed to examine the basis for these observations. Airborne particulate matter (PM) was collected for 2 weeks using a high-volume impactor in three different size ranges (ultrafine: < 0.1 µm; fine: 0.1-2.5 µm; coarse: > 2.5 µm) at two different locations (10 m and 350 m) from an interstate highway in Raleigh, NC. PM of each size range collected from each location was extracted in methanol and the PM suspensions were dried, concentrated, and diluted in 0.9% sterile saline. CD-1 female mice were intratracheally instilled with 25 or 100 µg of each size fraction and necropsied at 4 and 18 hr post instillation. Lung lavage fluid was analyzed for signs of inflammation. Neutrophils were increased at 4 hr and more drastically at 18 hr in the coarse PM from both locations in a dose-dependent manner. Smaller effects were evident in the fine PM, and no effects were seen with ultrafine PM. A similar pattern was also seen for pro-inflammatory cytokines (IL-6, MIP-2 and TNF-α) except these increases were higher at 4 hr than 18 hr. Pulmonary responses to inhaled methacholine in a whole body plethysmograph were also increased after exposure to the coarse PM compared to the other fractions. Biochemical markers of lung injury and edema (lactate dehydrogenase and albumin) showed no significant changes across all the groups. The results confirm previous studies that show that on a mass basis, coarse ambient PM produces greater inflammatory responses than fine and ultrafine ambient PM, and in this instance proximity to the highway did not influence toxicity. Future analyses will investigate the relationship between chemical characteristics and toxicity of size-fractionated PM. (This abstract does not reflect EPA policy.)