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Considerations for Developing Alternative Health Risk Assessment Approaches for Addressing Multiple Chemicals, Exposures and Effects; External Review Draft

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Information about this document as published in the Federal Register.

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Environmental Protection Agency (EPA).


Notice of public comment period.


EPA is announcing a 45-day public comment period for the draft document titled, “Considerations for Developing Alternative Health Risk Assessment Approaches for Addressing Multiple Chemicals, Exposures and Effects” (EPA/600/R-06/013A). The draft 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.


The 45-day public comment period begins March 31, 2006, and ends May 15, 2006. Technical comments should be in writing and must be received by EPA by May 15, 2006.


The draft document, “Considerations for Developing Alternative Health Risk Assessment Approaches for Addressing Multiple Chemicals, Exposures and Effects,” is available primarily via the Internet on the NCEA home page under the Recent Additions and the Data and Publications menus at​ncea.

A limited number of paper copies are available from Ms. Donna Tucker, Technical Information Manager, NCEA-Cincinnati; telephone: 513-569-7257; facsimile: 513-569-7916; e-mail: If you are requesting a paper copy, please provide your name, your mailing address, and the document title, “Considerations for Developing Alternative Health Risk Assessment Approaches for Addressing Multiple Chemicals, Exposures and Effects,” and its EPA publication number, EPA/600/R-06/013A.

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

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For information on the public comment period, contact the Office of Environmental Information Docket; telephone: 202-566-1752; facsimile: 202-566-1753; or e-mail:

For technical information, contact Linda K. Teuschler, NCEA-Cincinnati; telephone: 513-569-7573; facsimile: 513-487-2539; or e-mail:

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I. Information About the Document

In EPA's 2003 “Framework for Cumulative Risk Assessment,” cumulative risk assessment is defined as the evaluation of risks from exposures to multiple chemicals and other stressors, and having a population focus rather than a source-to-receptor focus. Several reports and environmental justice concerns published over the past 11 years have highlighted the importance of estimating cumulative risks. EPA has published several guidance documents dealing with specific aspects of cumulative risk, such as chemical mixture risk assessment, planning and scoping, stakeholder involvement, and the toxicity from a mixture of pesticides sharing a common mode of action. This draft document is one contribution to EPA's efforts to address issues related to cumulative health risk assessment.

Existing EPA guidance addresses some of the combination aspects of cumulative risk, but none addresses all of the multiples included in this report, such as consideration of the composite impact of multiple health effects. Among the distinctive new approaches are those for grouping chemicals based on exposure characteristics and toxic endpoints, multi-route combination of relative potency factors, integration of categorical regression modeling of multiple effects with additivity approaches, and the emphasis on the iteration and collaboration between exposure assessment and dose-response assessment to ensure compatible and relevant information. Major findings and conclusions in this document are as follows:

  • This draft report provides a set of approaches that deal with certain complications in cumulative risk assessment, specifically those caused by multiple chemicals, exposures and effects, including toxicological interactions and environmental Start Printed Page 16307transformations of mixture component chemicals.
  • The scope is focused on the evaluation of health risks from exposures to multiple chemicals, including multiple exposure routes and times as well as multiple health endpoints.
  • Areas of cumulative health risk assessment emphasized in this report can often be performed with existing information.
  • Exposure and toxicity characterizations of mixtures are strongly dependent on mixture composition (chemicals and concentrations) and timing of exposures and health effects.
  • Qualitative and semiquantitative approaches provided can simplify the number of potential combinations of chemicals, exposures, and effects to make the cumulative health risk assessment more feasible.

II. How to Submit Technical Comments to

Submit your comments, identified by Docket ID No. EPA-HQ-ORD-2006-0223 by one of the following methods:

  • Follow the on-line instructions for submitting comments.
  • E-mail:
  • Fax: 202-566-1753.
  • Mail: Office of Environmental Information Docket (Mail Code: 2822T), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460. The phone number is 202-566-1752; facsimile: 202-566-1753.
  • Hand Delivery: The Office of Environmental Information (OEI) Docket in the EPA Headquarters Docket Center, Room B102, EPA West Building, 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 202-566-1744, and the telephone number for the OEI Docket is 202-566-1752; facsimile: 202-566-1753; or e-mail: 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-2006-0223. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at, 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 or e-mail. The 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, 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​epahome/​dockets.htm.

Docket: All documents in the docket are listed in the 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 or in hard copy at the OEI Docket in the EPA Headquarters Docket Center.

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Dated: March 27, 2006.

Peter W. Preuss,

Director, National Center for Environmental Assessment.

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[FR Doc. E6-4746 Filed 3-30-06; 8:45 am]