Ethyl Tertiary Butyl Ether (ETBE)

Overview

EPA has finalized the IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) [CASRN 637-92-3]. This assessment addresses the potential cancer and noncancer human health effects from exposure to ethyl tertiary butyl ether (ETBE). EPA’s program and regional offices may use this assessment to inform decisions to protect human health.

Background

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 ETBE in reformulated gasoline in the U.S. 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 U.S. prior to 2006. The main source of exposure to ETBE in the U.S. is from exposure to contaminated groundwater due to leaking underground storage tanks.

History/Chronology

Date	Description
Aug 2013	EPA released preliminary assessment materials (draft literature searches and associated search strategies, evidence tables and exposure response arrays) for discussion at an IRIS Public Science Meeting.
Dec 2013	EPA discussed tert-butanol at the December 2013 IRIS public science meeting.
Sep 2014	EPA sent an interagency science consultation draft for review and comment.
May 2016	EPA released the public comment draft for public review and comment.
Jun 2016	EPA convened a public science meeting June 29-30, 2016 to discuss the public comment draft.
Sep 2016	EPA announced the availability of the draft assessment of ETBE for public comment and discussion and released the interagency science consultation draft, EPA response to select comments, and comments from reviewers. [Federal Register Notice Sep 1, 2016]
Oct 2016	EPA convened a public science meeting to discuss the public comment draft of the IRIS assessment of ETBE.
Jun 2017	EPA released the external review draft and charge to reviewers prior to the public peer review meeting.[SAB FR Notice Jun 16, 2017]
Jul 2017	EPA's Science Advisory Board (SAB) hosted a public teleconference to discuss the draft assessment.
Aug 2017	EPA's SAB hosted a 2-day public meeting on August 15-17, 2017, to discuss the draft assessment.
Feb 2019	EPA's SAB released a final report of their review of the draft IRIS assessment (see related links).
Aug 2020	EPA submitted the revised interagency science discussion draft for final Agency and Interagency review.
Aug 2021	EPA posted the final reportIRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) and released the interagency science discussion draft and comments to the IRIS database.

This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (EPA/635/R-20/400Fa) (PDF)  (200  pp, 4.2 MB, about PDF)
• Errata Sheet for IRIS Assessment of ETBE (Oct 2022) (PDF)  (1  pp, 116.2 KB, about PDF)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) - Supplemental Information (EPA/635/R-20/400Fb) (PDF)  (175  pp, 3.7 MB, about PDF)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) - Executive Summary (EPA/635/R-20/400Fc) (PDF)  (8  pp, 316.4 KB, about PDF)

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Document Related Link(s)

• Review of EPA’s Draft Assessments titled Toxicological Review of Ethyl Tertiary Butyl Ether and Toxicological Review of tert-Butyl Alcohol (tert-Butanol)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (Interagency Science Consultation Draft, 2016)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (Preliminary Assessment Materials, 2013)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (Public Comment Draft, 2016)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (External Review Draft, 2017)
• IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) (Interagency Science Discussion Draft, 2020)