Health Effects of Biodiesel
EPA researchers examine biodiesel emissions
That converted bus rumbling up next to you at the red light during your morning commute and smelling like a roving fast food restaurant may be running on old French fry grease. The quest for more sustainable, domestically produced alternatives to petroleum-based fuels has sparked a growing interest in biodiesel—fuels made from vegetable oils (mainly soybean and rapeseed), animal fat, or recycled restaurant grease.
The benefits of biodiesel are many. Biofuels can be used alone, or blended with petrodiesel (conventional diesel fuel) to power vehicles and as a low carbon alternative to fuel cars and heat homes. These domestically produced fuels are generally safe to handle, naturally biodegradable, and often help convert waste—such as used cooking grease—into a marketable commodity.
But while the allure of biodiesel is powerful, there are important questions about their long-term health impacts that are being addressed by EPA researchers.
"Our research is focused on assessing the full impacts of this emerging technology. We hope to be able to better understand the health effects of biodiesel—from producing the fuel, to burning it—and to make comparisons with petrodiesel," says EPA scientist Ian Gilmour, Ph.D.
Gilmour and a team of EPA researchers, including Michael Madden, Steve Gavett, Bill Linak, Mike Hays, Urmila Kodavanti, Aimen Farraj, and David DeMarini, are using previous exposure studies such as diesel exhaust and smoke from forest fires to guide them in studying biodiesel combustion.
"We are comparing how the fuels burn and the amount and type of pollutants in the exhaust along with evaluating their toxicity," explains team member Michael Madden.
Biodiesel fuels are quite complex and are still not fully understood. "The chemistry is tricky —we don't have a complete understanding of how chemicals interact with each other when they are burned in an engine, and how the emissions will affect our health," Madden says.
The researchers are looking to see if components of biodiesel emissions are likely to have properties that trigger adverse health effects, including changes in gene structures, lung and cardiac reactions such as altered electrocardiogram (or EKG, a measure of the heart's electrical activity), heart rate variability (HRV), blood pressure (BP), and lung function in both normal and susceptible individuals.
"One of our key concerns is the emission of polycyclic aromatic hydrocarbons (PAHs)," says Gilmour. PAHs are one of the most widespread organic pollutants and released into the air when things are burned or cooked. PAH compounds have been identified as being able to change DNA structure, an indicator that it may potentially cause cancer.
EPA researchers are also studying the potential health effects of biodiesel blends (e.g. soybean oil mixed with petro-diesel). Biodiesel fuel sources and the amounts used to create blends are a constantly moving target because innovative technologies and market forces can dramatically change the fuel type or blend.
"Today in the US, soybean oil is the most widely available biofuel on the market. However, if oilgae (algae-based fuels) or some other alternative fuel source proves to be more cost-effective, it's going to be very important to characterize them. We are working to develop the ability to create tests that we can use to quickly evaluate the health and environmental impacts of emissions from emerging fuel sources," says Gilmour.
What the EPA team is learning will help inform important decisions and guide research in the quest to develop alternative fuel sources that don't bring with them the unintended consequences of harmful emissions.
EPA Biodiesel Technical Highlights (3 pp, 109K)