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One versus five-days of exposure to varying concentrations of B100 soya biodiesel exhaust reveals a threshold concentration for increased sensitivity to aconitine-induced arrhythmia
Citation:
WINSETT, D. W., T. Krantz, C. King, D. L. Costa, A. FARRAJ, AND M. S. HAZARI. One versus five-days of exposure to varying concentrations of B100 soya biodiesel exhaust reveals a threshold concentration for increased sensitivity to aconitine-induced arrhythmia. Presented at Society of Toxicology (SOT) Annual Meeting, San Francisco, CA, March 11 - 15, 2012.
Impact/Purpose:
This study describes the effects of a single exposure to soya biodiesel exhaust (BDE) on aconitine-induced arrhythmogenicity in spontaneously hypertensive (SH) rats. A lower cumulative dose of aconitine was needed to elicit arrhythmia in rats exposed to BDE (500ug/m3) when compared to air-exposed controls.
Description:
Although biodiesel (BD) is rapidly being considered as an alternative to diesel fuel, its health effects have not been thoroughly characterized. We previously used the aconitine challenge test to demonstrate that a single exposure to petroleum diesel exhaust (DE) increases the risk ofarrhythmia being triggered in hypertensive rats. Here we hypothesized that inhalation ofbiodiesel exhaust (BDE) increases the risk of arrhythmia, particularly with repeated exposures. Spontaneously hypertensive rats surgically implanted with radiotelemeters were exposed for one or five days to 50, 150 or 500 ug/m3 of B100 soya BDE or filtered air (FA) (4 hours). Arrhythmogenesis was assessed 24hrs after the last exposure in urethane-anesthetized animals by continuous intravenous infusion of aconitine while heart rate (HR) and electrocardiogram (ECG) were monitored. Rats exposed to BDE had lower HR when compared to air-exposed animals but no ECG changes when compared to controls. Sensitivity to arrhythmia was measured as the threshold dose of aconitine required to produce ventricular premature beats (VPB), ventricular tachycardia (VT), and ventricular fibrillation (VF). There was no effect of 50 ug/m3 BDE. Rats exposed to five days of 150 ug/m3 BDE successively developed VPB's, VT, and VF at significantly lower doses of aconitine than FA, however a single exposure had no effect. Both one and five days of 500 ug/m3 BDE significantly, and comparably, increased sensitivity to aconitine-induced arrhythmia when compared to FA. These findings suggest that below a certain concentration, exposure to BDE does not increase arrhythmogenic sensitivity. Furthermore, given the effects of 500 ug/m3 BDE were still lower than 150 ug/m3 DE, BDE might be a safer alternative, particularly if exhaust levels are kept below a certain threshold concentration. (This abstract does not reflect EPA policy.)