US EPA

In August 2013, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for ETBE to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in comments on the following:

• Draft literature search strategies
• The approach for identifying studies
• The screening process for selecting pertinent studies
• The resulting list of pertinent studies
• Preliminary evidence tables
  • The process for selecting studies to include in evidence tables
  • The quality of the studies in the evidence tables

The literature search strategy, which describes the processes for identifying scientific literature, contains the studies that EPA considered and selected to include in the evidence tables. The preliminary evidence tables and exposure-response arrays present the key study data in a standardized format. The evidence tables summarize the available critical scientific literature. The exposure-response figures provide a graphical representation of the responses at different levels of exposure for each study in the evidence table.

Ethyl tertiary butyl ether is used as a fuel additive for gasoline to increase octane rating and has been used to meet air pollution reduction goals 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 for the purpose of increasing octane rating in gasoline. Ethyl tertiary butyl ether has been used extensively in Europe and 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. Plastic plumbing pipe, particularly silane cross-linked polyethylene (PEX), represents an additional potential source of ethyl tertiary butyl ether in drinking water.

The draft Toxicological Review of Ethyl Tertiary Butyl Ether provides scientific support and rationale for the hazard and dose-response assessment pertaining to chronic exposure to ethyl tertiary butyl ether.

U.S. EPA. IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (Preliminary Assessment Materials, 2013). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-13/108, 2013.