US EPA

In August 2021, EPA finalized the IRIS assessment of ethyl tertiary butyl ether (ETBE). The Toxicological Review was reviewed internally by EPA and by other federal agencies and White House Offices after public release in June 2017. Consistent with the May 2009 IRIS assessment development process, all written comments on IRIS assessments submitted by other federal agencies and White House Offices are made publicly available. Accordingly, interagency comments and the interagency science discussion materials provided to other agencies, including interagency review drafts of the IRIS Toxicological Review of Ethyl Tertiary Butyl Ether are posted on this site.

ETBE is used as a fuel additive for gasoline to increase octane rating and has been used to meet air pollution reduction goals in the U.S. under the Clean Air Act. The use of ether oxygenates such as ethyl tertiary butyl ether in reformulated gasoline in the United States was effectively eliminated in 2006; however, use and production of these oxygenates has continued in Europe and Asia for the purpose of increasing octane rating in gasoline. ETBE may be used as a substitute to replace the volume and oxygenate properties of methyl tertiary butyl ether, an oxygenate widely used in the United States prior to 2006. The main source of exposure to ETBE in U.S. is from exposure to contaminated groundwater due to leaking underground storage tanks.

EPA is undertaking an new health assessment for ethyl tertiary butyl ether (ETBE) for the Integrated Risk Information System (IRIS). The outcome of this project will be a Toxicological Review and IRIS Summary of ETBE that will be entered on the IRIS database. IRIS is an EPA database containing Agency scientific positions on potential adverse human health effects that may result from chronic (or lifetime) exposure to chemicals in the environment. IRIS contains chemical-specific summaries of qualitative and quantitative health information in support of two steps of the risk assessment process, i.e., hazard identification and dose-response evaluation. IRIS assessments are used nationally and internationally in combination with specific situational exposure assessment information to evaluate potential public health risks associated with environmental contaminants. The IRIS database is relied on for the development of risk assessments, site-specific environmental decisions, and rule making.

Now that the interagency review draft has been completed and finalized, the ETBE assessment has been loaded into the IRIS Web site and Database.

U.S. EPA. IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (Interagency Science Discussion Draft, 2020). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-20/106, 2020.