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Comparative In Vivo and Ex Vivo Toxicity Studies of Wildfire Particulate Matter
Citation:
Kim, Y., M. Daniels, E. Boykin, Todd Krantz, J. Mcgee, M. Hays, J. Dye, AND Ian Gilmour. Comparative In Vivo and Ex Vivo Toxicity Studies of Wildfire Particulate Matter. Presented at Society of Toxicology Meeting, Phoenix, AZ, March 23 - 27, 2014.
Impact/Purpose:
This abstract will be presented at the Society of Toxicology Meeting March 23-27, 2014, Phoenix, AZ
Description:
Inhalation of particulate matter (PM) generated from biomass burning is of concern particularly as the frequency and severity of wildfires have been increasing. Size-fractionated PM samples (ultrafine, <0.2 µm; fine, 0.2-2.5 µm; coarse, 2.5-10 µm) were collected downwind from a peat-bog wildfire in Eastern North Carolina from 6/26/2008 – 7/11/2008 when the fire was smoldering (ENCF-1), or at a later time from 8/8/2008 – 8/19/2008 after the fire had been controlled but not fully extinguished (ENCF-4). Wildfire PM samples were extracted in methanol for toxicity studies and chemical analysis, and then given by oropharyngeal aspiration to mice at 100 µg/50 µl saline or cultured with lung tissue slices at 11 µg per lung slice (8 mm diameter). At 4 h and 24 h post-exposure, biomarkers of lung injury and inflammation were assessed in lung lavage fluid from mice, and in conditioned medium from the lung slices. In addition, lung slices were also exposed to wildfire PM pre-treated with the endotoxin inhibitor (polymyxin B). The results showed that both ENCF-1 and -4 coarse PM had 4-8 times greater endotoxin content than the fine and ultrafine PM. Moreover, only the coarse PM significantly increased neutrophils and biomarkers of inflammation (e.g., interleukin-6) in the lung lavage fluid at any time point, and similar patterns of pro-inflammatory effects were observed in the lung tissue slice model. Finally, the inflammatory effects in the lung slices were significantly diminished after exposure to the PM pre-treated with polymyxin B. We conclude that exposure to wildfire coarse PM caused substantial acute toxicity in the mouse lung in association with endotoxin content, and that the lung slice ex vivo model provides a good alternative for in vivo lung toxicity testing. (This abstract does not represent U.S. EPA policy).