Comprehensive Health and Environmental Effects of Biodiesel As an Alternative Fuel. Sasha Koo-Oshima, Project Manager/Senior Scientist, EA Engineering, Science, and Technology, Inc.,* 8401 Colesville Road, Suite 500, Silver Spring, Maryland 20910, telephone (301) 565-4216, fax (301) 587-4752, e-mail sk@eaest.com
Biodiesel fuel which is defined as the mono alkyl esters of long chain fatty acids derived from renewable lipid feedstock, i.e., rapeseed or soybean oils or animal fats, is used in diesel (compression ignition) engines as an alternative fuel. Registration of biodiesel in the U.S. requires full compliance with regulations of Section 211 (b) of the Clean Air Act, requiring comprehensive reporting on the health and welfare (environmental) effects pertaining to the types of emission from biodiesel fuel. Under this regulation, manufacturers of fuels and fuel additives are required to conduct certain tests and submit information regarding the composition of emissions produced by such fuels and fuel additives and the effects of these emissions on the public health and welfare. As a result, search and review of relevant scientific literature in the public domain and private studies were conducted on biodiesel's chemical, toxicological, and environmental information. These results were compiled into abstracts, summary tables by routes of exposure, and summary texts in accordance with registration requirements.
Biodiesel offers, significant advantages as an alternative fuel in meeting U.S. Federal clean air standards in reducing targeted emissions. Commonly used blend of 20% biodiesel and 80% diesel fuel yielded percent reductions ranging from: 16-33% in total particulates, 11-25% in carbon monoxide, and 19-32% in total hydrocarbons. Emissions of polyaromatic hydrocarbons were lower for biodiesel blended fuels compared with diesel. Mutagenicity studies on Salmonella typhimurium, for a variety of test fuels (e.g., rapeseed methyl ester, rapeseed ethyl ester, soy methyl ester), all showed substantial reductions in mutagenicity for biodiesel compared with diesel fuel. Biodiesel blends were less mutagenic than diesel fuel and were more mutagenic than 100% biodiesel. Persistence and environmental fate information was found for a single soil/water system and several water studies. In the soil/fresh water system, degradation was monitored by increased bacterial growth and disappearance of methyl esters. Biodiesel (soy diesel) underwent faster biodegradation than diesel, with a faster rate under aerobic conditions than anaerobic, conditions. In aquatic environments, the predominant method for evaluation of degradation was evolution of CO2. In general, 100% biodiesel and high biodiesel blends degraded rapidly and fairly extensively, having C02 evolution percentages ranging from. 64-91%. This degradation was more extensive than diesel fuel, which had C02 evolution percentages from 15-18% in the same time periods of 14-28 days. BOD values were also higher for biodiesel than that for diesel.
*Formerly OCDE/OECD International Scientific Secretariat, EA Engineering, Sci., and Technology.
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