[Federal Register Volume 71, Number 250 (Friday, December 29, 2006)]
[Notices]
[Pages 78441-78442]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-22388]



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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Agency for Toxic Substances and Disease Registry

[ATSDR-228]


Update to ATSDR Policy Guideline for Dioxins and Dioxin-Like 
Compounds in Residential Soil

AGENCY: Agency for Toxic Substances and Disease Registry (ATSDR), U.S. 
Department of Health and Human Services (HHS).

ACTION: Request for public comments on the revised Policy Guideline 
document used by health assessors to evaluate health hazards associated 
with exposure to dioxins and dioxin-like compounds in residential soil.

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SUMMARY: ATSDR is seeking public comment on the draft revision of its 
1998 Policy Guideline for Dioxins and Dioxin-Like Compounds in 
Residential Soil. The policy is intended to assist health assessors who 
must evaluate the public health implications of dioxin and dioxin-like 
compounds (e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD], 
chlorinated dibenzodioxins [CDDs], chlorinated dibenzofurans [CDFs], 
and other structurally related groups of chemicals from the family of 
halogenated aromatic hydrocarbons) in residential soils near or on 
hazardous waste sites. The 1998 policy established a screening level of 
0.05 ppb TEQ (50 ppt), an evaluation level (>0.05 ppb TEQ, <1 ppb), and 
an action level of 1 ppb TEQ (1,000 ppt) for dioxins in residential 
soil.
    ATSDR revised the 1998 policy because it has been used 
inconsistently over the past eight years. The ATSDR ``action'' level 
has been misinterpreted by health assessors and others as ... (1) A 
soil concentration that defines a public health hazard, (2) an ATSDR 
clean-up level which implies the need for site remediation, and (3) an 
initial screening level that defines a safe level of exposure, below 
which there is no public health concern. In addition, the ``action'' 
level triggered a set of ``potential public health actions'', including 
surveillance, research, health studies, community education, and 
exposure investigations. However, ATSDR believes that these actions 
could be considered in some circumstances when the 1 ppb level in soil 
is not exceeded. In response to these concerns ATSDR has updated its 
Policy Guideline for Dioxins and Dioxin-Like Compounds in Residential 
Soil. The key elements in the updated ATSDR Policy Guideline for 
Dioxins and Dioxin-Like Compounds in Residential Soil are as follows:
     Deletion of the 1 ppb action level as the criteria for 
taking specific public health actions.
    The 1-ppb dioxin soil concentration should not be used as a 
comparison value for defining public health hazards in public health 
assessments and consultations. The 1-ppb action level can be cited by 
health assessors as the Superfund Dioxin Cleanup policy criteria (EPA 
1989, 1998).

Retention of the 0.05 ppb Screening Level

    The minimal risk level (MRL)-based environmental media evaluation 
guide (EMEG) of 0.05 ppb for dioxin TEQ in soil is retained as the 
basis for screening soil concentrations. Levels exceeding this 
screening level should be evaluated as described in the ATSDR Public 
Health Assessment Guidance Manual (PHAGM) (ATSDR 2005). This 
clarification will ensure that evaluation of dioxins and dioxin-like 
compounds in soil will be done in the same manner as all other soil 
contaminants.

Recommendation To Conduct Exposure Pathways Analyses for Dioxins and 
Dioxin-Like Compounds

    The focus of the guideline is the assessment of direct exposure to 
soil contamination, particularly soil ingestion. However, health 
assessors should be aware of the potential impact of indirect exposure 
pathways on exposed populations in site-specific health assessments. 
This document does not provide specific guidance on how these indirect 
pathways should be assessed. However, the PHAGM document does provide 
assistance in evaluating indirect exposure pathways such as food chain 
contamination (ATSDR 2005).

Updated TEFs

    The 2006 World Health Organization Toxicity Equivalency Factors 
(TEFs) for dioxins and dioxin-like compounds have been included in the 
updated document.

Background Information

    In 1998, the Agency for Toxic Substances and Disease Registry 
(ATSDR) adopted a Final Policy Guideline for Dioxin and Dioxin-Like 
Compounds (De Rosa et al. 1999a). The 1998 policy guideline was 
accompanied by a Technical Support Document for ATSDR Policy Guideline 
(De Rosa et al. 1999b). The initiative to develop this policy guideline 
was based on a request from the U.S. Environmental Protection Agency 
(EPA) to evaluate the protectiveness of the EPA Superfund Policy for 
Dioxins in Residential Soils, which established 1 part per billion 
(ppb) (1,000 parts per trillion [ppt]) total dioxin toxicity 
equivalents (TEQ) as the starting point for making clean-up decisions. 
In addition, the 1998 policy guideline was to provide guidance to 
health assessors in evaluating the public health implications of dioxin 
and dioxin-like compounds (e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin 
[TCDD], chlorinated dibenzodioxins [CDDs], chlorinated dibenzofurans 
[CDFs], and other structurally related groups of chemicals from the 
family of halogenated aromatic hydrocarbons) in residential soils near 
or on hazardous waste sites. As stated in the 1998 document, ``these 
guidelines and procedures apply to human exposure for direct ingestion 
of soils contaminated with dioxin and dioxin-like compounds in 
residential areas and may not be appropriate for other exposure 
scenarios.'' The 1998 Policy Guideline established a screening level of 
0.05 ppb TEQ (50 ppt), an evaluation level (>0.05 ppb TEQ, <1 ppb), and 
an action level of 1 ppb TEQ (1,000 ppt) for dioxins in residential 
soil and made recommendations for specific considerations or public 
health actions.
    ATSDR has established environmental screening values for chemicals 
to be used by health assessors to assess exposures. No other chemical 
has an action level as was established for dioxins in soil in the 1998 
policy guideline. This inconsistency alone has led to confusion 
regarding the appropriate screening value for soil dioxin levels.
    The primary objectives of the updated Policy Guidelines are to 
provide greater consistency in ATSDR Health Assessments and to bring 
dioxin assessments in line with how all other chemicals are evaluated 
by the agency.

Summary of Peer Review for Document

    The public comment draft of the revised policy has undergone 
internal review and clearance within ATSDR. In addition, the revised 
draft was reviewed by the National Center for Environmental Health/
Agency for Toxic Substances and Disease Registry (NCEH/ATSDR) Board of 
Scientific Counselors (BSC). Public testimony was received during the 
meeting of the NCEH/ATSDR BSC. ATSDR also received peer review comments 
from health assessors in several state health departments.
    Information about the ``Update to ATSDR Policy Guideline for 
Dioxins and Dioxin-Like Compounds in Residential Soil'', including the 
draft document, fact sheet, peer review

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comments and ATSDR responses, is available on the ATSDR Web site at: 
http://www.atsdr.cdc.gov/substances/dioxin/policy/index.html.

DATES: Comments concerning this document must be received by February 
27, 2007.

ADDRESSES: Public comments should be forwarded to Ms. Athena Gemella, 
ATSDR, Office of Science, 1600 Clifton Road, N.E., Mail stop E-28. 
Atlanta, GA. 30333, or e-mail at [email protected].

FOR FURTHER INFORMATION CONTACT: Ms. Athena Gemella, Office of Science, 
telephone (404) 498-0621.

    Dated: December 22, 2006.
Kenneth Rose,
Acting Director, Office of Policy, Planning and Evaluation, National 
Center for Environmental Health/Agency for Toxic Substances and Disease 
Registry.
 [FR Doc. E6-22388 Filed 12-28-06; 8:45 am]
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