Acute Cardiovascular Effects of Controlled Exposure to Dilute Petrodiesel and Biodiesel Exhaust in Healthy Volunteers: A Crossover Study
Background Air pollution derived from combustion is associated with considerable cardiorespiratory morbidity and mortality in addition to environmental effects. Replacing petrodiesel with biodiesel may have ecological benefits, but impacts on human health remain unquantified. Objectives To compare acute cardiovascular effects of blended and pure biodiesel exhaust exposure against known adverse effects of petrodiesel exhaust (PDE) exposure in human subjects. Methods In two randomized controlled
... domized controlled double-blind crossover studies, healthy volunteers were exposed to PDE or biodiesel exhaust for one hour. In study one, 16 subjects were exposed, on separate occasions, to PDE and 30% rapeseed methyl ester biodiesel blend (RME30) exhaust, aiming at PM 10 300 µg/m 3 . In study two, 19 male subjects were separately exposed to PDE and exhaust from a 100% RME fuel (RME100) using similar engine load and exhaust dilution. Generated exhaust was analyzed for physicochemical composition and reactive potential. Following exposure, vascular endothelial function was assessed using forearm venous occlusion plethysmography and ex vivo thrombus formation was assessed using a Badimon chamber technique. Results In study 1, PDE and RME30 exposures were at comparable PM levels (314 ±27 µg/m 3 ; (PM 10 ± SD ) and 309 ±30 µg/m 3 respectively), whereas in study 2, the PDE exposure concentrations remained similar (310 ±34 µg/m 3 ) , but RME100 levels were lower in PM (165 ±16 µg/m 3 ) and PAHs, but higher in particle number concentration. Compared to PDE, PM from RME had less oxidative potential. Forearm infusion of the vasodilators acetylcholine, bradykinin, sodium nitroprusside and verapamil resulted in dose-dependent increases in blood flow after all exposures. V asodilatation to vasoactive infusions and ex vivo thrombus formation were similar following exposure to exhaust from petrodiesel and the two biodiesel formulations (RME30 and RME100). Conclusions Cardiovascular impairment did not differ following controlled exposure to biodiesel exhaust as compared to PDE, despite differences in PM composition and particle reactivity. We suggest that the potential adverse health effects of biodiesel fuel emissions should be taken into account when evaluating future fuel policies.