Comparing Biofuel Toxicity to that of Conventional Fuels

With biofuels, such as ethanol-gasoline blends and biodiesel, being used on a wider scale globally, there is a range of implications related to their use. These issues were discussed during the session titled “Are Biofuels More or Less Toxic Than Conventional Fuels and What Are the Implications for Human Exposure and Risk?” on March 27, 2014 at the SOT 53rd Annual Meeting.

After an introduction by session Co-chair Annemoon M. van Erp, Kent Hoekman presented information on exhaust emissions. He described the changes to the emissions from vehicles using biofuels, showing that biodiesel blends provide modest reductions in emissions of carbon monoxide, total hydrocarbons, and fine particulate matter and slight increases or no change in nitrogen oxides.

Next, Norman Kado talked about a multi-investigator, multi-institutional study that used a toxicity screening approach to assess the emissions resulting from biodiesel, renewable diesel, and ultra-low sulfur diesel fuels. Testing emissions from heavy-duty trucks using different blends, Dr. Kado and his team looked into both regulated and unregulated emissions and found that their testing process provided a way to efficiently compare the toxicity of the complex mixture of vehicle emissions.

Different blends of diesel fuel also were the focus of Ian Gilmour’s presentation. His research compared the toxicity of a 100 percent biodiesel, a 20 percent biodiesel mix, and conventional petroleum diesel. He found that petroleum diesel had the greatest pro-inflammatory effects in normal mice, whereas both 100 percent biodiesel and petroleum diesel caused changes in heart rate variability and systemic inflammatory responses in hypertensive rats.

Miriam Gerlofs-Nijland discussed the difficulties inherent in testing toxicity of emissions associated with combustion biofuels due to the increasing number of different fuel blends and engine types. Compounding the matter is the lack of common testing guidelines and standards.

Health Canada’s approach to assessing the potential health impacts of new transportation fuels was described by Marika Egyed during her presentation. Health Canada’s risk assessment looked at whether biodiesel emissions were more or less toxic than conventional diesel emissions and how the emissions might change air pollution levels. The result of the assessment was that biodiesel blends in on-road vehicles in Canada is expected to have minimal impacts on air quality and human health compared to conventional diesel.

Prior to the session, Dr. van Erp told me that “We hope to show that the risks of using biofuels are not all that different from the risks associated with the use of conventional fuels—at least not in terms of people being exposed to fuel blends at the production factory, in transporting or pumping them, and being exposed to the exhaust gases.” The session’s other co-chair was Michael C. Madden.

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