US EPA

Oxygenates are chemicals added to fuels (oxyfuels) to increase the oxygen content and thereby reduce certain emissions from use of the fuel. Of the several ethers and alcohols that may serve as oxygenates, methyl tertiary butyl ether (MTBE) is the most commonly used. Although the contamination of ground and surface waters by motor vehicle fuels and fuel additives is not a new problem, recent events have focused attention on what appear to be somewhat different characteristics associated with oxyfuels, including the higher solubility and potentially greater persistence of MTBE in ground water than other components of gasoline.

A key question is whether oxygenates in water pose a significant threat to human health or the environment. If a risk or problem is judged to exist, then information is needed to guide decisions on how best to manage risks or otherwise deal with the problems posed by oxygenate contamination. The purpose of this document is to identify key limitations in current information needed to assess and manage the potential health and environmental risks related to oxygenates in water. Without more definitive scientific information, uncertainties will dominate these efforts. Gaps and limitations in current information are identified in the areas of source characterization, transport, transformation, occurrence, exposure, aquatic toxicity, health effects, release prevention, and contaminant removal. Within each of these areas, a brief background section highlights currently available information on key issues, followed by a section that identifies needed research, analyses, or information. The document also contains an appendix listing Current Projects Related to Oxygenates in Water.