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Environmental Assessment

IRIS Toxicological Review of 1,4-Dioxane (Interagency Science Consultation Draft)

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On September 9, 2011, the Toxicological Review of 1,4-Dioxane (with inhalation update) (External Review Draft) was posted for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Offices before public release. In the new IRIS process, introduced by the EPA Administrator, all written comments on IRIS assessments submitted by other federal agencies and White House Offices will be made publicly available. Accordingly, interagency comments with EPA's response and the interagency science consultation draft of the IRIS Toxicological Review of 1,4-dioxane and the charge to external peer reviewers are posted on this site.

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Norman Birchfield
  • by phone at:   703-347-0174
  • by fax at:   703-347-8699
  • by email at:  birchfield.norman@epa.gov


1,4-Dioxane is commonly used as a solvent, cleaning agent, chemical stabilizer, surface coating, adhesive agent, and an ingredient in chemical manufacture. The IRIS Program completed the assessment for oral exposure to 1,4-dioxane on August 11, 2010 and noted that new inhalation studies would be evaluated separately. Additional information regarding 1,4-dioxane toxicity resulting from exposure via inhalation has now been incorporated into the 2010 assessment without changing the oral toxicity conclusions of the previous assessment.


Aug 2010EPA released the final assessmentof 1,4-dioxane on the IRIS Web site.
May 2011EPA initiated the interagency science consultation on the draft Toxicological Review of 1,4-Dioxane.
Sep 2011EPA released the external review draft of the 1,4-dioxane assessment (with inhalation update) for public review and comment. EPA concurrently released the interagency science consultation draft toxicological review and charge, and interagency comments with EPA's response.

Next Steps

Following external peer review the assessment will be revised taking into consideration external peer review and public comments. The revised assessment will undergo a final EPA internal review and review by other federal agencies and White House offices, then the final assessment will be posted to the IRIS database.


U.S. EPA. IRIS Toxicological Review of 1,4-Dioxane (Interagency Science Consultation Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-11/003C, 2011.


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