Ethanol Fuel May Pose Health Risks

Ethanol is a renewable alcohol fuel hyped as environmentally friendly solution to air pollution. Proponents claim that ethanol burns cleanly and produces less toxic emissions. It is a linchpin in President Bush's plan to reduce gasoline consumption in the United States by 20% with 10 years. The president announced the plan during the State of the Union address in January 2007.

The most common form is ethanol currently available in the US is E10, a mixture of 90% gasoline and 10% ethanol. E10 is used primarily in urban areas that do not meet clean air standards. All vehicles that use gasoline can run on E10 without a modified engine. The California Air Resources Board (CARB) has been considering the impact of ethanol on air quality. So far, CARB seems ambivalent toward ethanol. It recently applied for a waiver from the U.S. Environmental Protection Agency's rule requiring the use of E10 during the winter months.

That is a valid concern according to Dr. Mark Jacobson, an atmospheric chemist at Stanford University. In the 1970s, Brazil heavily promoted ethanol fuel. At the same time, for reasons that are still unclear, air quality deteriorated. Using that knowledge, a NASA research grant for computational development, and a sophisticated atmospheric computer model, he compared two air quality scenarios for the year 2020: a vehicle fleet fueled entirely by gasoline versus a fuel flexible vehicle (FFV) fleet, which should be common by then. FFVs are vehicles that can run on 100% unleaded gasoline or a mixture of gasoline and up to 85% ethanol. The next generation of ethanol is E85, a blend of 85% ethanol and 15% gasoline. It contains approximately 80% less contaminants than gasoline. The National Ethanol Vehicle Coalition (NEVR) maintains that E85 will reduce greenhouse gas emissions as much as 46%, is non-toxic, water soluble and biodegradable. They claim that the cleaner exhaust will mean less smog and fewer respiratory illnesses. The American Lung Association of the Upper Midwest also endorses E85 as a CleanAirChoice.

However, Dr. Jacobson's study, "Effects of Ethanol (E85) Versus Gasoline Vehicles on Cancer and Mortality in the United States", produced results that contradict NEVR's assertions. This is the first study that examined not just tailpipe emissions, but also "chemical reactions, temperatures, sunlight, clouds, wind and precipitation." He found that E85 emissions did reduce atmospheric levels of two carcinogens, benzene and butadiene. Unfortunately, the atmospheric levels of two other carcinogens, formaldehyde and acetaldehyde, actually increased. Dr. Jacobson adds that "we have found that using E85 will cause at least as much health damage as gasoline, which already causes about 10,000 U.S. premature deaths annually from ozone and particulate matter."

The Renewable Fuels Association published a review** that challenged these results. It was written by Dr. Gary Z. Whitten, who has worked in the field of gas-phase photochemistry since the 1960s. He has testified as an expert witness before Congress, State Legislatures, and the U.S. EPA as an expert witness on the subject of various emission sources and the impact on air quality. While both scientists agree that the future is uncertain with regard to emission technology, regulations and other fuel formulations, they reach entirely different conclusions. Dr. Whitten's primary objection to this study centers on the data Dr. Jacobson entered into the computer model. "The methodology used to assemble existing data... is not described in sufficient detail to assess... that methodology or the range of data variability." He also believes that rapidly developing technology make long-term projections unreliable.

Responding to the review, Dr. Jacobson says, "Dr. Whitten did not realize that simulations were done for present day conditions as well, as reported in the paper. Almost his entire argument centered around uncertainties in future emissions when, in fact, simulations indicated an even greater effect under current emission conditions, which are extremely reliable. Further, four sensitivity tests were run examining different possible future (2020) emission scenarios, and regardless of the uncertainty, the future results held. Dr. Whitten did not realize these results were also stated in the paper. He hypothesized incorrectly that conclusions would change if emissions changed."



This article is based on information from an article entitled "Clearing the Air On Ethanol" published in the April 18 online edition of the journal Environmental Science & Technology (ES&T) and input directly from Dr. Mark Jacobson.