IRIS Toxicological Review of Trimethylbenzenes (External Review Draft)
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Abstract
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.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 (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-11/012Aa-Ab, 2012.History/Chronology
| Date | Description |
|---|---|
| 01- Feb 2012 | EPA hosted an interagency science consultation meeting on the review of the draft Toxicological Review of Trimethylbenzenes. |
| 02- May 2012 | EPA 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 2012 | EPA released the external peer review draft of the trimethylbenzenes assessment for public review and comment. [Federal Register Notice June 29, 2012] |
Download(s)
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.
- IRIS Toxicological Review of Trimethylbenzenes (External Review Draft) (PDF) (138 pp, 1.9 MB, about PDF)
- Supplemental Information for Trimethylbenzenes (External Review Draft) (PDF) (220 pp, 9.3 MB, about PDF)
- Draft Charge to External Peer Reviewers (PDF) (6 pp, 213.9 KB, about PDF)
Notices
Docket
Comments on the assessment may be submitted and reviewed using the Docket ID EPA-HQ-ORD-2012-0459