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Ethanol: Literature Review - page 10 / 17





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6.1.5 Ozone

Because of its effect in reducing hydrocarbons and carbon monoxide in exhaust (that causes respiratory problems), adding ethanol to gasoline results in an overall reduction in exhaust ozone-forming potential. (http://www.comalc.com/fuel ethanol.htm)

Adding ethanol to gasoline can potentially increase the volatility of gasoline. This potential is controlled if all ethanol-blended gasoline sold in Canada meets the volatility standards required for other types of gasoline. In contrast, the U.S. Clean Air Act allows gasohol (gasoline plus 10% ethanol) to have a higher volatility than that of gasoline. This results in greater “volatile organic compounds” emissions. Therefore, the Canadian ethanol blend has less potential to form ozone than the American counterpart.

Adding of ethanol to gasoline does create slightly greater amounts of aldehydes during fuel combustion. Yet the resulting concentrations are extremely small and are effectively reduced by the three-way catalytic converters in the exhaust systems of all recent-model cars. The Royal Society of Canada termed the possibility of negative health effects caused by aldehyde emissions with the use of ethanol-

blended gasoline as being “remote.”



Environmental behavior

Recent reviews of the environmental behavior of gasoline oxygenates generally note that ethanol is not likely to accumulate or persist for long in the environment. For example, the Interagency Assessment of Oxygenated Fuels observes that ethanol is expected to be rapidly degraded in groundwater and is not expected to persist beyond source areas. Ethanol in surface water is also expected to undergo rapid biodegradation, as long as it is not present in concentrations directly toxic to microorganisms. The half-life of ethanol in surface water is reported to range from 6.5 to 26 hours. Atmospheric degradation is also predicted to be rapid. http://www.ethanolrfa.org/544 er 1999.html


Health Effects Ethanol, the active ingredient of alcoholic beverages, has been part of the

human diet — and the human environment — for thousands of years. It is produced by fermentation by fungi and other microorganisms, and is found at low levels in the blood and breath of persons who do not drink alcohol. Ethanol is widely ingested in alcoholic beverages, usually with only mild effects. However, at sufficiently high doses, ethanol can cause toxic effects in humans, both short-term (such as inebriation) and long-term (such as cirrhosis of the liver). If ethanol becomes a common fuel additive, there may be opportunities for exposure by inhalation: ethanol vapors might be inhaled at gasoline stations or in automobiles, for example. Thus, concern has been raised about the possible health consequences of using ethanol for this purpose.

The scientific literature contains virtually no reports of injury to humans from inhaled ethanol. The apparent lack of harm may be attributable to rapid metabolism of ethanol and the difficulty in significantly raising blood ethanol concentrations by

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