IRIS Toxicological Review of Trimethylbenzenes (Interagency Science Consultation Draft)

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Abstract

On June 26, 2012, the draft Toxicological Review of Trimethylbenzenes and the draft charge to external peer reviewers were released 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. 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 consultation materials provided to other agencies, including interagency review drafts of the IRIS Toxicological Review of Trimethylbenzenes and the charge to external peer reviewers, are posted on this site.

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.

Impact/Purpose

EPA is reassessing its IRIS toxicological review of Trimethylbenzenes (1,2,3-;1,2,4-;1,3,5-). This trimethylbenzene reassessment consists of an oral reference dose (RfD), an inhalation reference concentration (RfC), an inhalation unit risk (IUR) and a cancer weight of evidence descriptor. This is the first assessment developing an RfC or IUR for this compound. This assessment is intended to provide human health data to support agency regulatory decisions.

Status

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.

Citation

U.S. EPA. IRIS Toxicological Review of Trimethylbenzenes (Interagency Science Consultation Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-11/012C, 2012.

History/Chronology

Date Description
01-Feb 2012EPA hosted an interagency science consultation meeting on the review of the draft Toxicological Review of Trimethylbenzenes.
02-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.
03-Jun 2012EPA released the external peer review draft of the trimethylbenzenes assessment for public review and comment.

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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