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Characterization of Soy Biodiesel Exhaust and Toxicological Effects in Mice
Citation:
GILMOUR, M. I., Q. T. KRANTZ, C. King, D. G. Nash, W. Preston, W. P. Linak, AND E. H. Boykin. Characterization of Soy Biodiesel Exhaust and Toxicological Effects in Mice. Presented at Society of Toxicology (SOT) Annual Meeting, San Francisco, CA, March 11 - 15, 2012.
Impact/Purpose:
This study characterizes fuel and exposure conditions of soy biofuel used as an altervative to conventional petrodiesel, and describes toxicological effects of this biofuel exhaust in healthy Balb/cJmice. Minimal inflammation after exposure up to 500ug/m3 was found after exposures of 1day, 5days,or 4weeks. These effects will be compared to those from other biofuel exhaust and conventional petrodiesel.
Description:
Although biofuel use across the world is increasing, very little is known about possible health effects resulting from biofuel exhaust (BE) from this relatively new source of transportation fuel. The U.S. EPA has instigated an in vivo screening approach in rodents to examine whether BE can induce lung and cardiopulmonary responses in healthy and compromised animal models. In our combustion facility, biofuel exhaust is generated by a 0.32 L Yanmar engine driving a 3.8 kW Pramac generator with a load of 3 kW. Initial studies tested soy biodiesel, either 100% (S100) or a 20% mix with conventional petrodiesel (S20). Organic solvent extracts of S100 fuel were composed of about 70% methyl esters (e.g. linoleate, oleate) and 15% organic acids (e.g. hexadecanoic). Exhaust from combustion of S100 or S20 was diluted to target concentrations of 0, 50, 150, or 500 ug/m3 as determined by TEOM. Average CO, NO (ppm) at the 500 ug/m3 level were 12.3, 18.7 (S100) and 13.9,13.2 (S20), respectively, while S02 and N02, were not above instrument background <1 ppm). Female Balb/cJ mice (8/group) were exposed whole body to these emissions 4 hr/d, for 1 d, 5 d, or 4 wk (5 d/wk), and necropsied 2 or 24 hr after each of these exposures. Lung inflammation was minimal as neutrophils in BAL fluid were < 3% with both S20 and S100 at all concentrations and time points. However, significantly fewer BAL macrophages (62% of control) were found 2 hr after 5 d exposure to 500 ug/m3 S100. At the same time point, MIP-2a levels in BAL fluid were significantly higher in mice exposed to 500 ug/m3 S100 (mean ± SE: 52 ± 5 vs. 12 ± 6 pg/ml at 0 level). No significant changes in BAL protein, LDH, albumin, or NAG were found. Future studies comparing these effects of soy BE with those generated by exposure to exhaust from other biodiesel preparations or pure petrodiesel will enable athorough understanding of the toxicology of BE.(This abstract does not represent U.S.. EPA policy.)