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###### Environmental Protection Agency

          - [EPA-HQ-ORD-2009-0605; FRL-9248-4]

# AGENCY:

Environmental Protection Agency (EPA).

# ACTION:

Notice of document availability.

# SUMMARY:

                        The U.S. Environmental Protection Agency (EPA) is announcing the availability of the final “Recommended Toxicity Equivalence Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8-Tetrachlorodibenzo-                        *p*                        -dioxin and Dioxin-Like Compounds” (EPA/100/R-10/005). The purpose of this document is to assist EPA scientists in using the toxicity equivalence methodology to assess health risks from dioxins and dioxin-like compounds, as well as inform EPA decision makers, other agencies, and the public about this methodology. This guidance document summarizes the toxicity equivalence methodology, provides background information and assumptions on how the methodology has evolved, and recommends an approach for health risk assessors to use to apply the methodology. EPA's Risk Assessment Forum (RAF) oversaw the development of this document. Input was obtained from scientists throughout the Agency, from interested members of the public, and from external experts from a range of scientific disciplines via a contractor-led peer review.                    

# ADDRESSES:

                        The final document is available electronically through the EPA Office of the Science Advisor's Web site at:                         *http://www.epa.gov/​osa/​raf/​hhtefguidance/​*. A limited number of paper copies will be available from EPA's National Service Center for Environmental Publications (NSCEP), P.O. Box 42419, Cincinnati, OH 45242;                         *telephone number:*                         1-800-490-9198 or 513-489-8190;                         *facsimile number:*                         301-604-3408;                         *e-mail: NSCEP@bps-lmit.com.*                         Please provide your name, mailing address, and title of the requested publication.                    

# FOR FURTHER INFORMATION CONTACT:

                        Julie Fitzpatrick, Risk Assessment Forum Staff, Mail Code 8105R, Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Washington, DC 20460;                         *telephone number:*                         (202) 564-4212;                         *facsimile number:*                         (202) 564-2070;                         *e-mail: fitzpatrick.julie@epa.gov.*

# SUPPLEMENTARY INFORMATION:

Dioxin and dioxin-like compounds (DLCs), including polychlorinated dibenzo-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs), are structurally and toxicologically related halogenated dicyclic aromatic hydrocarbons. Dioxins and DLCs are released into the environment from several industrial sources, including chemical manufacturing, combustion, and metal processing. There is global contamination of air, soil and water with trace levels of these compounds. Typically, dioxins and DLCs occur in the environment as chemical mixtures. Dioxins and DLCs do not readily degrade; therefore, levels persist in the environment, build up in the food chain, and accumulate in the tissues of animals. Human exposures to these compounds occur primarily through eating contaminated foods. The health effects from exposures to dioxins and DLCs have been documented extensively in toxicological and epidemiological studies.

Risk assessments have relied on the dioxin toxicity equivalence factors (TEFs) approach. Various stakeholders, inside and outside the Agency, have called for a more comprehensive characterization of risks. Therefore, EPA's RAF identified a need to examine the current recommended approach for application of the toxicity equivalence methodology in human health risk assessments. An RAF Technical Panel developed the draft guidance document, “Recommended Toxicity Equivalence Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Dioxin-Like Compounds,” to assist EPA scientists in using this methodology to assess health risks from dioxins and dioxin-like compounds, and inform EPA decision makers, other agencies, and the public about this methodology.

An external expert peer review was conducted by both letter and an open, public teleconference in October 2009. The peer review panel was provided with the public comments received in the official public docket for this activity under docket ID number EPA-HQ-ORD-2009-0605. The peer review panel also had the opportunity to hear public comments provided during the peer review teleconference. In preparing the final document, EPA considered the public comments submitted to EPA's docket during the public comment period and during the public teleconference, and the recommendations from the external peer reviewers provided in the peer review report and during the public teleconference.

                    EPA is currently addressing several issues related to dioxins and dioxin-like chemicals in the environment. More information on these activities is located at:                     *http://www.epa.gov/​dioxin/​scienceplan/​.*

Dated: December 22, 2010.

Paul T. Anastas,

EPA Science Advisor.

[FR Doc. 2011-20 Filed 1-5-11; 8:45 am]

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