E6-22431. Draft Toxicological Review of 2,2,4-Trimethylpentane: In Support of Summary Information on the Integrated Risk Information System (IRIS)

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice of public comment period and external peer review panel meeting.

SUMMARY:

The EPA is announcing a public comment period and an external peer review panel meeting to review the draft document titled, “Toxicological Review of 2,2,4-Trimethylpentane: In Support of Summary Information on the Integrated Risk Information System (IRIS)” (NCEA-S-2202), related to the human health assessment for 2,2,4-trimethylpentane. The document was prepared by the National Center for Environmental Assessment (NCEA) within EPA's Office of Research and Development.

EPA is releasing this draft document solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. This document has not been formally disseminated by EPA. It does not represent and should not be construed to represent any Agency policy or determination. EPA will consider any public comments submitted in accordance with this notice when revising the document.

DATES:

The 45-day public comment period begins on December 29, 2006 and ends February 12, 2007. Technical comments should be in writing and must be received by EPA by February 12, 2007. The peer review panel meeting will be conducted on February 28, 2007, by teleconference and will begin at 1 p.m. and end at 4 pm. Members of the public may call into the teleconference meeting and are invited to provide oral statements at the commencement of the teleconference. (For more information refer to the instructions for registration provided in the ADDRESSES section of this notice.)

ADDRESSES:

The external peer review panel meeting will be held by teleconference. Under an Interagency Agreement with EPA and the Department of Energy, the Oak Ridge Institute of Science and Education (ORISE) is organizing, convening, and conducting the peer review panel meeting. To obtain the teleconference call-in number and access code, register by February 14, 2007, by calling ORISE, P.O. Box 117, MS 17, Oak Ridge, TN 37831-0117, at [phone] or [phone] (facsimile). Interested parties may also register on-line at: http://www.orau.gov/​trimethylpentane. Public comments submitted to the EPA by February 12, 2007 will be provided to the external peer review panel prior to the teleconference meeting.

The draft, “Toxicological Review of 2,2,4-Trimethylpentane: In Support of Summary Information on the Integrated Risk Information System (IRIS)” (NCEA-S-2202) is available primarily via the Internet on NCEA's home page under the Recent Additions menu at http://www.epa.gov/​ncea. A limited number of paper copies are available by contacting the IRIS Hotline at [phone], [phone] (facsimile), or [e-mail]. If you are requesting a paper copy, please provide your name, mailing address, the document title, and the EPA number of the requested publication. Copies are not available from ORISE.

Technical comments may be submitted electronically via www.regulations.gov,, by mail, by facsimile, or by hand delivery/courier. Please follow the detailed instructions provided in the SUPPLEMENTARY INFORMATION section of this notice.

FOR FURTHER INFORMATION CONTACT:

Questions regarding registration and logistics should be directed to Margaret Lyday, ORISE, P.O. Box 117, MS 17, Oak Ridge, TN 37831-0117, at [phone] or [phone] (facsimile), [e-mail] (email).

If you have questions about the document, contact John Stanek, Chemical Manager, National Center for Environmental Assessment; telephone: [phone]; facsimile: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

I. Information About the Document

IRIS is a database that contains Agency scientific positions on potential adverse human health effects that may result from chronic (or lifetime) exposure to specific chemical substances found in the environment. The database (available on the Internet at http://www.epa.gov/​iris) contains qualitative and quantitative health effects information for more than 500 chemical substances that may be used to support the first two steps (hazard identification and dose-response evaluation) of the risk assessment process. When supported by available data, the database provides oral reference doses (RfDs) and inhalation reference concentrations (RfCs) for chronic health effects, and oral slope factors and inhalation unit risks for carcinogenic effects. Combined with specific exposure information, government and private entities use IRIS to help characterize public health risks of chemical substances in a site-specific situation and thereby support risk management decisions designed to protect public health.

2,2,4-Trimethylpentane, also known as isooctane or isobutyltrimethylmethane, is a hydrocarbon used primarily in deriving high-octane fuels. It comprises about 10% of unleaded gasoline. 2,2,4-Trimethylpentane is released into the environment through the manufacture, use, and disposal of products associated with the gasoline and petroleum industry. The current assessment posted on IRIS (1991) does not include an evaluation of the oral non-cancer or the cancer literature; for the inhalation RfC, a message indicates that the health effects data for 2,2,4-trimethylpentane were considered inadequate for the derivation of an inhalation RfC. A review of the more recent literature identified mechanistic studies, gavage studies, and toxicokinetic studies, the majority of which were designed to specifically address and characterize the involvement of alpha_2u-globulin accumulation in the renal toxicity observed in the male rat. Little or no evaluation of other endpoints in tissues/organs other than the kidney was reported. Therefore, the major issues discussed in the draft assessment are: (1) the association of TMP-induced renal effects in male rats with alpha_2u-globulin accumulation, and (2) the lack of studies with sufficient duration and dose-response information for any endpoint from which to derive reference values.

II. How to Submit Technical Comments to the Docket at www.regulations.gov

Submit your comments, identified by Docket ID No. EPA-HQ-ORD-2006-1009 by one of the following methods:

• http://www.regulations.gov: Follow the on-line instructions for submitting comments.
• E-mail: [e-mail].
• Fax: [phone].
• Mail: Office of Environmental Information (OEI) Docket (Mail Code: 2822T), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. The phone number is [phone].
• Hand Delivery: The OEI Docket is located in the EPA Headquarters Docket Center, EPA West Building, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket Center Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is

[phone]. Such deliveries are only accepted during the docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

If you provide comments in writing, please submit one unbound original with pages numbered consecutively, and three copies of the comments. For attachments, provide an index, number pages consecutively with the comments, and submit an unbound original and three copies.

Instructions: Direct your comments to Docket ID No. EPA-HQ-ORD-2006-1009. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at http://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through www.regulations.gov or e-mail. The www.regulations.gov Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through www.regulations.gov, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at http://www.epa.gov/​epahome/​dockets.htm.

Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at the OEI Docket in the EPA Headquarters Docket Center.

Dated: December 20, 2006.

George Alapas,

Deputy Director, National Center for Environmental Assessment.