[Federal Register Volume 65, Number 31 (Tuesday, February 15, 2000)]
[Notices]
[Pages 7550-7552]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-3492]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-6537-6]
Superfund Probabilistic Risk Assessment to Characterize
Uncertainty and Variability
AGENCY: Environmental Protection Agency.
ACTION: Notice of availability with request for comment.
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SUMMARY: The Environmental Protection Agency (EPA) has developed and is
requesting public comment on a draft guidance entitled ``Risk
Assessment Guidance for Superfund Volume 3 Part A: Process for
Conducting Probabilistic Risk Assessment (RAGS 3A).'' It is available
electronically on the Internet at http://www.epa.gov/superfund/pubs.htm#r. RAGS 3A addresses the technical and policy issues
associated with the use of probabilistic risk assessment (PRA) in the
EPA hazardous waste sites cleanup program, commonly known as Superfund.
PRA, if applied appropriately, can better characterize uncertainty and
variability in the risk estimates than the traditional point estimate
approach. The guidance presents a recommended tiered process for
conducting both human health and ecological PRA using Monte Carlo
analysis, with emphasis on applying sensitivity analysis to identify
important sources of variability and uncertainty in risk estimates,
applying frequency distributions to characterize variability in
exposure, and quantifying uncertainty in the mean contaminant
concentration. The draft RAGS 3A should not be used or cited until it
is finalized. RAGS 3A provides guidance to EPA staff and also to the
public and to the regulated community on how EPA generally intends that
the PRA be implemented to evaluate risk at more complex Superfund sites
addressed under the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980 (CERCLA). The guidance is designed to
describe EPA's national policy on the use of PRA. PRA is not expected
to be relevant at every site. The document does not substitute for
EPA's statutes or regulations, nor is it a regulation itself. Thus, it
cannot impose legally-binding requirements on EPA, States, or the
regulated community. EPA may change this guidance in the future, as
appropriate.
Further, Executive Order 13132, entitled ``Federalism'' (64 FR
43255, August 10, 1999), requires EPA to develop an accountable process
to ensure ``meaningful and timely input by State and local officials in
the development of regulatory policies that have federalism
implications.'' ``Policies that have federalism implications'' is
defined in the Executive Order to include regulations and regulatory
policies that have ``substantial direct effects on the States, on the
relationship between the national government and the States, or on the
distribution of power and responsibilities among the various levels of
government.''
RAGS 3A does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132. As explained above, RAGS 3A does
not impose legally-binding requirements on the States. It is a
technical risk assessment guidance which discusses a statistical risk
assessment approach that may be used at more complex Superfund sites.
Thus, the requirements of section 6 of the Executive Order do not apply
to RAGS 3A.
DATES: You may submit comments until April 21, 2000. Comments received
after
[[Page 7551]]
that date will be considered to the extent feasible; however, EPA will
not delay finalizing the guidance in order to accommodate late
comments.
ADDRESSES: You are invited to submit written comments to: EPA,
Superfund Docket RAGS 3A-2, Mail Code 5202G, Ariel Rios Building, 1200
Pennsylvania Avenue, N.W., Washington, DC 20460. For cost savings the
draft RAGS 3A document is available electronically on the Internet and
EPA plans to print the document only after it is finalized. The
Superfund Docket containing the RAGS 3A document and public comments is
physically located at 1235 Jefferson Davis Highway, Crystal Gateway I
Building street level, Arlington, Virginia. The docket is available for
inspection between 9:00 a.m. and 4:00 p.m., Monday through Friday,
excluding Federal holidays. Appointments to review the docket can be
made by calling (703) 603-9232. The public may copy a maximum of 266
pages from the docket free of charge, however a charge of 15 cents will
be incurred for each additional page, plus a $25.00 administrative fee.
FOR FURTHER INFORMATION CONTACT: S. Steven Chang, Office of Emergency
and Remedial Response (5204G), U.S. Environmental Protection Agency,
Ariel Rios Building, 1200 Pennsylvania Avenue, N.W., Washington, DC
20460, at (703) 603-9017, by E-Mail at [email protected], or the
RCRA/Superfund Hotline at (800) 424-9346 (in the Washington, DC
metropolitan area, (703) 412-9810). The Telecommunications Device for
the Deaf (TDD) Hotline number is (800) 553-7672 (in the Washington, DC
metropolitan area, (703) 412-3323).
SUPPLEMENTARY INFORMATION:
Introduction
The U.S. Environmental Protection Agency (EPA) responds to releases
and threatened releases of hazardous substances under the authority of
CERCLA. Regulations governing such responses are found in the National
Oil and Hazardous Substances Pollution Contingency Plan or NCP. The
process for remedy selection in the NCP generally involves performance
of a remedial investigation to identify the nature and extent of
contamination at National Priorities List sites. In general, sampling
results and site observations obtained in the field are used in the
baseline risk assessment to identify specific contaminants and exposure
pathways of concern and to determine whether remedial action is
warranted.
Today's Federal Register notice introduces a draft guidance on use
of a tool which could evaluate the uncertainty and variability
associated with risk estimates developed as part of the baseline risk
assessment for hazardous waste sites. The RAGS 3A document builds upon
basic concepts of risk assessment outlined in the RAGS Volume 1 (U.S.
EPA, 1989),\1\ the ``Guiding Principles for Monte Carlo Analysis'' and
the ``Policy for Use of Probabilistic Analysis in Risk Assessment''
(U.S. EPA, 1997).\2\ PRA is not a requirement, and will not be
appropriate at many sites. The guidance focuses on Monte Carlo analysis
as a method of quantifying uncertainty and variability in risk.
Primarily targeted toward the risk assessors, it is intended to be most
accessible to those readers who are familiar with risk assessment and
basic statistic concepts. The development of a PRA could involve
significant investment of time by the risk assessor and risk manager to
determine the extent and scope of the assessment. A tiered approach to
PRA is advocated, beginning with evaluating the results of a point
estimate approach. Important considerations include the time required
to perform the PRA, the additional resources involved in developing the
PRA, the available data on exposure that will be used in the
assessment, and the value added by conducting the PRA.
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\1\ U.S. EPA, 1989, Risk Assessment Guidance for Superfund:
Volume 1: Human Health Evaluation Manual, Part A, Interim Final.
EPA/540/1-89/002. Office of Emergency and Remedial Response,
Washington, DC. NTIS PB90-155581.
\2\ U.S. EPA, 1997, ``Guiding Principles for Monte Carlo
Analysis.'' EPA/630/R-97/001. Office of Research and Development
Risk Assessment Forum, Washington, DC.
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Background
Probabilistic risk analysis, as exemplified by Monte Carlo
analysis, has been in use since 1946. However, the application of PRA
to human health and ecological risk assessment is a more recent
application. As a result, the Agency believes that those using PRA
analysis would benefit from development of additional guidance.
In 1997, the EPA announced the ``Policy for Use of Probabilistic
Analysis in Risk Assessment at the U.S. EPA'' (U.S. EPA, 1997),
indicating the Agency's interest in probabilistic analysis in human
health and ecological risk assessment. This 1997 policy states that
``It is the policy of the U.S. Environmental Protection Agency that
such probabilistic analysis techniques as Monte Carlo analysis, given
adequate supporting data and credible assumptions, can be viable
statistical tools for analyzing variability and uncertainty in risk
assessments. As such, and provided that the conditions described below
are met, risk assessments using Monte Carlo analysis or other
probabilistic techniques will be evaluated and utilized in a manner
that is consistent with other risk assessments submitted to the Agency
for review or consideration. It is not the intent of this policy to
recommend that probabilistic analysis be conducted for all risk
assessments supporting risk management decisions. Such analysis should
be a part of a tiered approach to risk assessment that progresses from
simpler (e.g., deterministic) to more complex (e.g., probabilistic)
analyses as the risk management situation requires. Use of Monte Carlo
or other such techniques in risk assessments shall not be cause, per
se, for rejection of the risk assessment by the Agency. For human
health risk assessments, the application of Monte Carlo and other
probabilistic techniques has been limited to exposure assessments in
the majority of cases. The current (1997) policy, Conditions for
Acceptance and associated guiding principles are not intended to apply
to dose response evaluations for human health risk assessment until
this application of probabilistic analysis has been studied further. In
the case of ecological risk assessment, however, this policy applies to
all aspects including stressor and dose-response assessment.''
Based on this (1997) Policy the Superfund program is developing
guidance for implementation of PRA to better characterize variability
and uncertainty in fate and transport, and exposure assessment for
human health and ecological risk assessments, and dose-response
assessment for ecological risk assessments.
Goals
EPA welcomes feedback on today's draft RAGS 3A document. EPA will
review public comments received on the draft RAGS 3A document and,
where appropriate, incorporate changes responsive to those comments.
EPA is seeking public comment at this time in order to ensure
hearing the widest range of views and obtaining all information
relevant to the development of policy, not because doing so is a legal
requirement. EPA does, however, expect to respond to the principal
comments received on the draft RAGS 3A document as a matter of public
information.
[[Page 7552]]
Dated: February 9, 2000.
Stephen Luftig,
Office Director, Office of Emergency and Remedial Response.
[FR Doc. 00-3492 Filed 2-14-00; 8:45 am]
BILLING CODE 6560-50-U