[Federal Register: December 29, 2006 (Volume 71, Number 250)]
[Notices]
[Page 78441-78442]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr29de06-80]
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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
[[Page 78442]]
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 AGemella@cdc.gov.
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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