Office of Environmental Health Hazard Assessment

Air Toxicology and Epidemiology

Potential Health Risks of Ethanol in Gasoline

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On March 25, 1999, Governor Gray Davis issued Executive Order D-5-99 which stated that, while the gasoline additive, methyl tertiary-butyl ether (MTBE), has benefited California by decreasing air pollution, it also poses an environmental threat to groundwater and drinking water. Weighing all of the evidence, the Governor declared that there is significant risk to the environment from using MTBE in gasoline in California. As a result, the Governor assigned tasks, by way of the Executive Order, to various designated state agencies, regarding the reformulation of gasoline in the State. Task 10 required the California Air Resources Board (CARB) and the State Water Resources Control Board (SWRCB) to conduct an environmental fate and transport analysis of ethanol in air, surface water, and ground water. It further requires the Office of Environmental Health Hazard Assessment (OEHHA) to prepare an analysis of the health risks of ethanol in gasoline, the products of incomplete combustion of ethanol in gasoline, and any resulting secondary transformation products. This final report, prepared by OEHHA, is the analysis of the potential public health impacts of ethanol as an oxygenate in gasoline.

The final versions of the volumes and chapters included in the evaluation of the potential air, groundwater, and health impacts that may be associated with the use of ethanol as a fuel oxygenate in California are available from the Lawrence Livermore National Laboratory Web site.

OEHHA's report (Volume 5 of "Health and Environmental Assessment of the Use of Ethanol as a Fuel Oxygenate") is based on analyses undertaken by CARB and SWRBC. Those analyses appear in volumes 1-4 of the Report. In order to meet the timetable of the Executive Order, OEHHA was obliged to work from the Review drafts of the other Boards' documents. In the case of the CARB document, significant additional work was performed in response to peer reviewers' comments and the availability of new data, which was not completed in time for incorporation of these additional results into OEHHA's analysis. The new model results appear in the final version of the Air Board's document, Volume 3 of the Report, along with the original results. An Addendum was therefore prepared by OEHHA to take account of these additional modeling results, which extend (rather than necessarily replace) the earlier calculations.

Phone inquiries regarding the document can be directed to Dr. Andrew Salmon or Dr. Melanie Marty at (510) 622-3150.

Click here to download a copy of the Final Report on Potential Health Effects of Ethanol in Gasoline as a PDF file (includes Appendix B, Response to Comments)

Click here to download Appendix A - Toxicity Summaries as a PDF file.

Click here to download the Addendum as a PDF file.

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