| Widespread concern about anthropogenic climate change has increased interest in biodiesel as a carbon-neutral or reduced carbon alternative fuel. Research regarding potential health impacts that may result from the introduction of biodiesel is timely and necessary. This review of published literature focuses on comparing the toxicity of biodiesel exhaust to diesel exhaust emissions from the same or similar engine configurations. We address the health implications of a large-scale shift to biodiesel from petroleum diesel by reviewing and summarizing the relevant literature directly comparing the toxicity of their emissions. The studies are classified by toxicity outcome or test subject: mutagenicity, cytotoxicity, oxidative potential, and live animal studies. In general, the brake-specific mutagenicity of emissions was found to be lower for biodiesel than for diesel, usually by a factor of 2-3. Polycyclic aromatic hydrocarbon (PAH) exposure burden will be reduced, and long-term cancerous outcomes in exposed populations may be reduced with a large-scale shift to biodiesels, because PAH content and mutagenicity of the exhaust particulate is lower than for petroleum diesel. Cytotoxicity and oxidative potential studies had inconsistent results, although there is some concern for increased toxic carbonyl emission with biodiesel exhaust and increased oxidative potential of biodiesel soot. The live animal studies found that cardio-respiratory health effects of biodiesel exhaust exposure are essentially the same as diesel exhaust exposure. The extant research suggests that in the medium- to long-term, a large-scale shift to biodiesel should reduce cancer rates in exposed populations, with little or no differences in short-term cardio-respiratory health outcomes. |
