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Draft Recommended Interim Preliminary Remediation Goals for Dioxin in Soil at CERCLA and RCRA Sites

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Environmental Protection Agency (EPA).


Notice of availability and announcement of public comment period.


The Environmental Protection Agency (EPA or the Agency) is announcing a 50-day public comment period for draft recommended interim preliminary remediation goals (PRGs) developed in the Draft Recommended Interim Preliminary Remediation Goals for Dioxin in Soil at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA) Sites. EPA's Office of Solid Waste and Emergency and Emergency Response (OSWER) has developed the draft recommended interim PRGs for dioxin in soil. These draft recommended interim PRGs were calculated using existing, peer-reviewed toxicity values and current EPA equations and default exposure assumptions.

This Federal Register notice is intended to provide an opportunity for public comment on the draft recommended interim PRGs. EPA will consider any public comments submitted in accordance with this notice and may revise the draft recommended interim PRGs thereafter.


Comments may be submitted in writing by February 26, 2010.


Submit your comments, identified by Docket ID No. EPA-HQ-SFUND-2009-0907, by one of the following methods:

  • Follow the on-line instructions for submitting comments.
  • E-mail:
  • Mail: EPA Docket Center, Environmental Protection Agency, Mail Code: 5305T, 1200 Pennsylvania Ave., NW., Washington, DC 20460.
  • Hand Delivery: EPA Docket Center (EPA/DC), Room 3334, EPA West Building, 1301 Constitution Avenue NW., Washington, DC 20460, Attention Docket ID No. EPA-HQ-SFUND-2009-0907. Deliveries are only accepted from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. Special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-SFUND-2009-0907. 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 by statute 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.

Docket: This Federal Register notice and supporting documentation are available in a docket EPA has established under Docket ID No. EPA-HQ-SFUND-2009-0907. 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 Start Printed Page 985copy. Publicly available docket materials are available either electronically in or in hard copy at the OSWER Docket, EPA West, Room 3334, 1301 Constitution Avenue,. NW., Washington, DC. The 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 OSWER docket is (202) 566-0270.

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Marlene Berg, Office of Superfund Remediation and Technology Innovation, 1200 Pennsylvania Avenue, NW., Mail Code: 5204P, Washington, DC 20460; by telephone/voicemail at (703) 603-8701; Fax: (703) 603-9112; or via e-mail at

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Preliminary remediation goals (PRGs) generally are chemical-specific concentration goals for specific media (e.g., soil, sediment, water and air) and land use combinations at CERCLA sites. They are intended to serve as a point of departure in the remedy selection process and generally are used as a target in conjunction with site-specific information (e.g., exposure frequency) during the initial development, analysis, and selection of cleanup alternatives. As discussed in the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) (40 CFR 300.430(e)(2)(i)) preliminary remediation goals are typically developed from readily available information. Preliminary remediation goals should be modified, as necessary, when more site-specific information becomes available (e.g., exposure frequency).

In May 2009, EPA Administrator Lisa P. Jackson committed to accelerating the Agency's work currently underway to reassess the human health risks from exposures to dioxin. EPA's Science Plan for Activities Related to Dioxins in the Environment (​ncea/​cfm/​recordisplay.cfm?​deid=​209690) details a plan, with interim milestones, for completion of the Agency's dioxin reassessment. By the end of 2010, EPA expects to complete the dioxin reassessment and release it to the public, subject to further consideration of the science and the scope and complexity of the revisions.

Several site-specific investigations and decisions involving dioxin may need to be made before the dioxin reassessment is finalized. Therefore, Administrator Jackson directed the Office of Solid Waste and Emergency Response (OSWER) to develop draft recommended interim PRGs by the end of 2009 that are informed by the best available peer-reviewed science. The recommended interim PRGs, when finalized, will allow EPA to continue to make progress on key site-specific investigations and decisions while the dioxin reassessment is on-going. Also, development of the recommended interim PRGs at this juncture allows EPA to include the dermal absorption pathway of dioxin. The information to estimate the dermal pathway was not available when EPA last recommended PRGs for dioxin in soil in 1998.

OSWER reviewed the Agency's current dioxin cleanup guidance and related work by other entities, including the states, other countries, and other federal agencies with the goal of developing guidance containing recommended interim PRGs informed by the best available peer-reviewed science. Once the recommended interim PRGs are finalized, they are intended to be considered by EPA regions until the Agency issues its final dioxin reassessment; at that time, OSWER may issue updated recommended PRGs based on the final dioxin reassessment. After publication of the final dioxin reassessment and any subsequent updated PRG guidance, EPA regions would then re-evaluate, as appropriate, cleanup decisions at CERCLA sites to ensure that cleanups are still protective. States which apply the final recommended interim PRGs to RCRA sites may choose to re-evaluate, as appropriate, cleanup decisions based on the recommended interim PRGs as well.

The draft guidance presents current OSWER technical and policy recommendations regarding PRGs for soil contaminated with dioxin. While OSWER developed the draft guidance for facility response actions under CERCLA and RCRA corrective action, other regulators, including the States, may find it useful in their programs, although they may choose to use alternative assessments consistent with their own programs and policies. In addition, EPA may use and accept other technically sound approaches after appropriate review, either at its own initiative or at the suggestion of other interested parties. The draft guidance does not impose any requirements or obligations on EPA, the States, other Federal agencies, or the regulated community. It is important to understand that the draft guidance does not substitute for statutes that EPA administers or their implementing regulations, nor is it a regulation itself. Thus, the draft guidance does not impose legally binding requirements on EPA, the States, or the regulated community, and may not apply to a particular situation based upon the specific circumstances. Rather, the draft guidance suggests approaches that may be used at particular sites as appropriate, given site-specific circumstances.

In developing these draft recommended interim PRGs, OSWER, EPA's Office of Research and Development and other EPA offices reviewed current soil cleanup levels and dioxin toxicity values used by the states, the U.S. Department of Health and Human Services' Agency for Toxic Substances and Disease Registry and other countries (see docket #EPA-HQ-SFUND-2009-0907 for State Soil Cleanup Levels for Dioxin and Review of International Soil Levels for Dioxin). Based on this evaluation, OSWER considered EPA's currently recommended PRGs for CERCLA and RCRA sites (​superfund/​resources/​remedy/​pdf/​92-00426-s.pdf), which are 1 ppb (parts per billion) (or 1,000 ppt (parts per trillion)) for dioxin toxicity equivalents (TEQs) [1] in residential soil, and a level within the range of 5 ppb (or 5,000 ppt) and 20 ppb (or 20,000 ppt) in commercial/industrial soil, where exposure is due to direct contact. Three key components of EPA's current recommended PRGs were re-evaluated: available toxicity values, generic exposure assumptions and the cancer risk level.

These draft recommended interim PRGs are informed by the best available peer-reviewed science, as well as the work of states and other agencies. Based on a consideration of oral and dermal exposures to dioxin, EPA has developed the following draft recommended interim PRGs for dioxin in soil: 72 ppt for residential soil and 950 ppt for commercial/industrial soil. EPA believes that these draft recommended interim PRGs would generally provide adequate protection against non-cancer effects, and generally should protect against cancer effects at approximately the 1E-05 risk level (1 in 100,000). These recommended interim PRGs are within EPA's protective risk range of 1E-04 to 1E-06 (see 40 CFR 300.430(e)(2)(i)(A)), and are more protective than the 1998 PRGs.

In addition, consistent with the NCP (40 CFR 300.430(e)(2)(i)(A)), EPA is considering (and requesting comment Start Printed Page 986on) an alternative concentration of 3.7 ppt TEQ in residential soil and 17 ppt TEQ in commercial/industrial soil as draft interim PRGs. These alternative draft interim PRGs would be protective for cancer and non-cancer effects and are consistent with the NCP provision for PRGs reflecting a 1E-06 risk level as a point of departure for determining remediation goals. OSWER notes that PRGs based on a 1E-06 cancer risk level would likely be within or possibly below the average concentration of dioxins in rural U.S. soils. Generally, it is OSWER's policy not to clean below background (for more information about this policy visit​ncea/​CFM/​recordisplay.cfm?​deid=​150944).

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Dated: December 30, 2009.

Mathy Stanislaus,

Assistant Administrator, Office of Solid Waste and Emergency Response.

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1.  Toxicity equivalents consider the toxicity of the less toxic dioxin-like compounds as fractions of the toxicity of the most toxic compound (2,3,7,8-TCDD). Each compound is attributed a specific “Toxic Equivalency Factor” (TEF). This factor indicates the degree of toxicity compared to 2,3,7,8-TCDD, which is given a reference value of 1.

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[FR Doc. 2010-16 Filed 1-6-10; 8:45 am]