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Environmental Assessment

IRIS Toxicological Review of Trimethylbenzenes (External Review Draft) (Jun 2012)

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Archived files are provided for reference purposes only. The file was current when produced, but is no longer maintained and may now be outdated. Persons with disabilities having difficulty accessing archived files may contact the NCEA Webmaster for assistance. Please visit http://epa.gov/ncea to access current information.

Report Information

EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessment of trimethylbenzenes that will appear in the Integrated Risk Information System (IRIS) database. Please refer to IRISTrack for the latest schedule updates: IRISTrack - 1,2,3-Trimethylbenzene, IRISTrack - 1,2,4-Trimethylbenzene, and IRISTrack - 1,3,5-Trimethylbenzene.

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J. Allen Davis
  • by phone at:   919-541-3789
  • by fax at:   919-541-0245
  • by email at:  davis.allen@epa.gov


Trimethylbenzenes (TMB) are a mixture of three isomers: 1,2,3-, 1,2,4- and 1,3,5-TMB. TMBs are produced during petroleum refining, and 1,2,4-TMB makes up approximately 40% of a certain petroleum product (the C9 fraction) which is used as a component of gasoline. Because of this, vehicle emissions are a major source of TMBs. Other uses of TMBs include solvents in research and industry, dyestuff intermediate, paint thinner, and as a UV oxidation stabilizer for plastics.


Feb 2012EPA hosted an interagency science consultation meeting on the review of the draft Toxicological Review of Trimethylbenzenes.
May 2012EPA sent an abbreviated version of the toxicological review containing only information on 1,2,3-trimethylbenzene for Interagency Science Consultation at the recommendation of reviewers.
Jun 2012EPA released the external peer review draft of the trimethylbenzenes assessment for public review and comment. [Federal Register Notice June 29, 2012]

Next Steps

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

Additional Information

Comments on the assessment may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select Environmental Protection Agency and the key word EPA-HQ-ORD-2012-0459 (for the docket ID).


U.S. EPA. IRIS Toxicological Review of Trimethylbenzenes (External Review Draft) (Jun 2012). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-11/012Aa-Ab, 2012.


This download(s) is distributed solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. It has not been formally disseminated by EPA. It does not represent and should not be construed to represent any Agency determination or policy.

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