X EPA Protocol for the Review of
% Existing National Primary Drinking
C3>
T
Water Regulations
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Office of Water
Office of Ground Water and Drinking Water (4607M)
EPA815-D-02-004
www.epa.gov/safewater
March 2002
Printed on Recycled Paper
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EPA815-D-02-004
EPA Protocol for the Review of
Existing National Primary Drinking Water Regulations
March 2002
United States Environmental Protection Agency
Office of Water
Office of Ground Water and Drinking Water
Standards and Risk Management Division
Targeting and Analysis Branch
1200 Pennsylvania Avenue, NW (4607M)
Washington, DC 20460
This report is issued in support of the preliminary revise/not revise decisions for the Six-Year
Review Notice of Intent. It is intended for public comment and does not represent final agency
policy. EPA expects to issue a final version of this report with the publication of the final notice
in 2002, reflecting corrections due to public comment on the preliminary notice and the
supporting documents.
Protocol for the Review ofNPDWRs
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Acknowledgments
This document was prepared in support of the 1996-2002 Six-Year Review of Existing National
Primary Drinking Water Regulations (NPDWRs) for EPA's Office of Ground Water and
Drinking Water with James Taft as Targeting and Analysis Branch Chief. Judy Lebowich served
as EPA co-team lead for the Six-Year Review and as the Work Assignment Manager for the
development of this document. At different times throughout the process, Marc Parrotta and
Wynne Miller have, also served as co-team leads for the project. The Six-Year Review Work
Group consists of representatives of the Office of Ground Water and Drinking Water, the Office
of Science and Technology, the Office of General Counsel, the Office of Pesticide Programs, the
Office of Research and Development, the Office of Policy, Economics and Innovation, the Office
of Solid Waste and Emergency Response, and EPA Regions I, V, VJJ, DC, and X. Work Group
members provided technical guidance throughout. The National Drinking Water Advisory
Council (NDWAC) and many stakeholders provided valuable advice to improve the review
process and this document. The Cadmus Group, Inc., served as the prime contractor for
developing this document.
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TABLE OF CONTENTS
ACRONYMS VI
EXECUTIVE SUMMARY vm
SECTION I: INTRODUCTION 1
A. WHAT Is THE PURPOSE OF THE Six-YEAR REvmw? 1
B. WHAT Is THE PURPOSE OF THIS PROTOCOL DOCUMENT? 1
C. WHAT INFORMATION WILL I FIND IN THIS DOCUMENT? .2
SECTION II: OVERVIEW OF THE SIX-YEAR REVIEW PROCESS 4
A. WHAT BASIC PRINCIPLES DID EPA FOLLOW DURING THIS REVIEW? 4
B. WHATTYPES OF ANALYSES DID EPA CONDUCT? , ;.. 5
1. Initial Technical Review 5
2. In-Depth Technical Analysis 6
C. WHAT TYPES OF REGULATORY REVISIONS DID EPA CONSIDER? 9
1. Changes to MCLGs , 9
2. Changes to MCLs 9
3. Changes to Treatment Technique Requirements 9
4. Changes to Other Treatment Technology 10
5. Changes to Other Regulatory Provisions 11
SECTION III: DETAILED DISCUSSION OF THE SIX-YEAR RE VIEW PROCESS ... 12
A. HEALTH RISK ASSESSMENTS 12
1. What Are the Objectives of the Health Effects Review? 12
2. How Does EPA ReviewHealth Effects Data for ChemicalContaminants? 13
3. Ho-w Does EPA Review Health Effects Data for Microbiological NPDWRs? .. 15
B. TECHNOLOGY ASSESSMENTS 15
1, What Are the Objectives of the Technology Assessment? .. 15
2. How Does EPA Review Analytical Methods? 16
3. How Does EPA Review Treatment Technologies? 75
C. OTHER REGULATORY REVISIONS 19
7. What Are the Objectives of Reviewing Other Regulatory Revision Options? 19
D. OCCURRENCE AND EXPOSURE ANALYSIS : 20
7. What Are the Objectives of the Occurrence and Exposure Analysis? : . . 20
2. How Did EPA Conduct the Occurrence and Exposure Analysis? 20
E. CONSIDERATION OF ECONOMIC FACTORS 21
7. What Were the Objectives ofEPA's Evaluation of Economic Impacts? 21
2. How Did EPA Consider Economic Impacts? 22
Protocol for the Review of NPDWRs
IV
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TABLE OF CONTENTS, continued
SECTION IV: STAKEHOLDER INVOLVEMENT 23
A. WHO ARE THE KEY STAKEHOLDERS IN THE Six-YEAR REvmw PROCESS? 23
B. How HAVE STAKEHOLDERS BEEN INVOLVED IN THE Six-YEAR REVIEW PROCESS? 23
C. How DOES EPA PLAN TO INVOLVE THE S;CIENCE ADVISORY BOARD? 24
REFERENCES \ .25
APPENDICES
APPENDIX A: LIST OF PRE-1997 NATIONAL PRIMARY DRINKING
WATER REGULATIONS (NPDWRs) : A-l
APPENDIX B: DIFFERENCES BETWEEN THE NATIONAL DRINKING WATER ADVISORY
.COMMITTEE'S (NDWAC's) RECOMMENDATIONS AND THIS PROTOCOL B-l
AppENDixC: OVERVIEW OF THE IRIS ASSESSMENTS C-l
APPENDIX D: OVERVIEW OF THE OPP PROCESS FOR TOXICITY ASSESSMENTS D-l
APPENDIX E: OVERVIEW OF THE ANALYTICAL METHODS REVIEW PROCESS E-l
i
i
LIST OF FIGURES
Figure 1: Overview of the Protocol and Making the Revise/Not Revise Decision 8
Protocol for the Review of NPDWRs
IV
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ACRONYMS
ASTM
ATP
ASDWA
ATSDR
AWWA
BAT
CFR
CMR
EPA
FACA
FIFRA
FQPA
FR
IRIS
LOAEL
MCL
MCLG
MDL
mL
MOE
NAS
NDWAC
NERL
NIST
NOAEL
American Society for Testing and Materials
Alternate test procedure
Association of State Drinking Water Administrators
Agency for Toxic Substances and Disease Registry
American Water Works Association
Best Available Technology
Code of Federal Register
Chemical Monitoring Reform
U.S. Environmental Protection Agency
Federal Advisory Committees Act
Federal Insecticide, Fungicide, and Rodenticide Act
Food Quality Protection Act
Federal Register
Integrated Risk Information System
Lowest-Observed-Adverse-Effect Level
Maximum contaminant level
Maximum contaminant level goal
Method detection limit
milliliter
Margin of Exposure
National Academy of Sciences
National Drinking Water Advisory Council
National Exposure Research Laboratory
National Institute of Standards and Technology
No-Observed-Adverse-Effect Level
Protocol for the Review ofNPDWRs
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ACRONYMS
i
''
NPDWR National Primary Drinking Water Regulation
OGWDW Office of Ground Water and Drinking Water
i
OPP Office of Pesticide Programs
OW Office of Water i
PAD Population Adjusted Dose !(aPAD - acute; cPAD - chronic)
i
PE Performance evaluation '
PQL Practical quantitation level
PT Proficiency Testing
PWS Public water system
RfD Reference dose (aRfD - acute RfD; cRfD - chronic RfD)
RSC Relative source contribution
SAB Science Advisory Board
SDWA Safe Drinking Water Act
I
SM Standard Methods |
TCR ' Total Coliform Rule >
TT Treatment technique '
USGS United States Geological Survey
WS Water Supply
Protocol for the Review ofNPDWRs
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EPA Protocol for the
Review of Existing National Primary
Drinking Water Regulations
EXECUTIVE SUMMARY
The Safe Drinking Water Act (SDWA), as amended in 1996, requires that the U.S.
Environmental Protection Agency (EPA) review existing National Primary Drinking Water
Regulations (NPDWRs) no less often than every sue years and, if appropriate, revise them. This
document describes the systematic approach that EPA used to review 68 chemical NPDWRs and
the Total Coliform Rule (TCR) which were promulgated prior to the 1996 Amendments. This
review is scheduled to be completed by August 2002. EPA developed this document based on
recommendations of the National Drinking Water Advisory Council (NDWAC), through internal
Agency deliberations, and discussions with the diverse stakeholders involved in drinking water
and its protection.
As long as an NPDWR revision maintains or provides for the same or greater protection
of public health, the SDWA 1996 Amendments give the Administrator discretion to determine if
revision is appropriate. In order to determine that a revision is appropriate, EPA believes the
revision must continue to meet the basic statutory requirements of the SDWA and present
significant opportunities to improve the level of public health protection; and/or to achieve cost-
savings while maintaining, or improving, the level of public health protection.
EPA applied the following basic principles to the review process:
• Health effects, analytical feasibility, treatment data, and analyses underlying existing
regulations remain adequate and relevant, except in those instances where reliable,
peer-reviewed, new data were available that indicated a need to re-evaluate an
NPDWR (e.g., where a change in health risk assessment has occurred).
• If new data were available, EPA determined whether changes in existing standards
were warranted. For example, in determining whether there was a change in
analytical feasibility, the Agency applied the current policy and procedures for
calculating the practical quantitation level for drinking water contaminants.
EPA was unable to complete evaluation of certain new data within the time available
for the review. For example, if a new health risk assessment for a contaminant was
not completed during the review cycle, EPA generally made a "not revise" decision
on the rationale that it was not appropriate to revise the regulation while the
assessment was ongoing. When an updated assessment is completed, EPA will
review the update and any new conclusions or additional, information associated with
the contaminant during the next review cycle. The Agency may make a determination
to revise a particular NPDWR before August 2008 where justified by new public
health risk information.
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• During the review, EPA identified areas where information was inadequate or
unavailable ("data gaps") and is needed before an NPDWR may be considered as a
candidate for revision. 'Where EPA has been unable to fill such gaps during the
review process, the Agency has provided information about the data gaps to the
appropriate Agency group(s) for consideration and prioritization so that further
research and data collection can be cpnsidered as part of a subsequent review.
i
• During the review process, the Agency did not consider potential regulatory revisions
that were already the subject of otheij rulemaking activities.
• EPA applied the Agency's peer revieyv policy (USEPA, 2000e), where appropriate, to
any new analyses. |
To most efficiently utilize limited resources and assure continued public health
protection, the Agency conducted the review in jtwo phases: (1) an initial technical review of all
69 NPDWRs (see Appendix A for a list); and (2) an in-depth technical evaluation of those
NPDWRs identified during the initial review as (potential candidates for revision. The key
elements of the review included: health effects, technology assessment (i.e., analytical
measurement feasibility and treatment feasibility), and consideration of other regulatory
requirements (e.g., monitoring). If the Agency identified a potential health or technological basis
for a revision during the initial screening, EPA also conducted occurrence and exposure analyses
and evaluated available economic information as a part of the in-depth review.
i
After completing these comprehensive analyses, EPA identified those NPDWRs that
remain appropriate at this time, and those NPDWRs that may be appropriate for revision. The
Agency will publish its preliminary determinations in the Federal Register and will seek public
comment on them. After considering the public' comments received and any new peer-reviewed
data that may become available to the Agency, EPA will publish its final decision in the Federal
Register. \
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EPA Protocol for the
Review of Existing National Primary
Drinking Water Regulations
SECTION I: INTRODUCTION
A. What Is the Purpose of the Six-Year Review?
Under the Safe Drinking Water Act (SDWA), the U.S. Environmental Protection Agency
(EPA) must periodically review existing National Primary Drinking Water Regulations
(NPDWRs) and, if appropriate, revise them. This requirement is contained in Section 1412(b)(9)
of SDWA, as amended in 1996, which reads:
The Administrator shall, not less often than every 6 years, review and revise, as
appropriate, each national primary drinking water regulation promulgated under this
title. Any revision of a national primary drinking water regulation shall be promulgated
in accordance with this section, except that each revision shall maintain, or provide for
greater, protection of the health of persons.
Prior to the 1996 Amendments, the SDWA required EPA to review NPDWRs at least
every three years to determine whether any changes in technology, treatment techniques (TTs) or
other means might provide better health protection. EPA was required to publish its findings in
the Federal Register and provide an explanation, after opportunity for public comment, of any
finding that such new technology, TT, or other means would not be feasible. Although the
Agency did revise existing NPDWRs on occasion when new data became available, EPA did not
have a systematic process for reviewing NPDWRs on a regular basis.
B. What Is the Purpose of This Protocol Document?
This protocol defines the systematic process EPA used to review most of the NPDWRs1
promulgated prior to the 1996 Amendments during the 1996-2002 review cycle. Although this
document is specific to the initial review under the 1996 SDWA Amendments, the Agency plans
to adopt a similar approach, modified as appropriate and with stakeholder involvement, for
subsequent review cycles.
EPA presented its initial ideas for the regulatory review protocol at a stakeholder meeting
in November 1999. Based on the comments made at that meeting, EPA revised the draft
1 Several NPDWRs promulgated prior to 1997 have been the subject of recent rulemaking or are the subject
of ongoing rulemaking activity. The review of these NP DWRs has been incorporated into those rulemaking
activities. Appendix A identifies each of the pre-1997 NP DWRs and indicates whether it is being reviewed in
accordance with this protocol or whether it has been or will be reviewed as a part of a separate rulemaking activity.
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protocol. Among other changes, the revised draft clarified the role of research in the process and
expanded the discussion of the potential need to review/revise an NPDWR. The Agency
provided its revised draft to a National Drinking Water Advisory Council (NDWAC) Working
Group2 that met during the Summer of 2000 to develop recommendations regarding the protocol
process. The NDWAC Working Group submitted their recommendations to the full NDWAC in
November 2000, which approved the recommended guidance and presented it to the Agency
(NDWAC, 2000). EPA incorporated the majority of the NDWAC's recommendations into this
document. In a few cases, however, EPA either decided not to incorporate a NDWAC
recommendation, or to revise it, because of practical considerations and/or resource constraints.
Appendix B contains a summary of those NDWAC recommendations that were not incorporated
or that were substantially revised. \
The systematic planning process used to develop this protocol satisfies the Agency's
quality assurance requirements (USEPA, 2002c). The process described in this protocol
addresses critical aspects of health protection and the setting of standards under the SDWA. In
addition, this protocol allows for the fact that numerous types of regulatory changes may be
considered and therefore, contains an element oif flexibility to allow EPA the opportunity to
consider a range of possible issues. The review! process described in this protocol document
culminates with decisions of whether or not to revise each of the reviewed NPDWRs.
The publication of a decision to revise pursuant to a Section 1412(b)(9) review is not the
end of the regulatory process, but is the beginniiig of one. A decision to revise starts a regulatory
process for a contaminant that involves more detailed analyses concerning health effects, costs,
benefits, occurrence, and other matters relevant to deciding whether and how an NPDWR should
be revised. At any point in this process, EPA may find that regulatory revisions are no longer
appropriate and may discontinue regulatory revision efforts at that time. Review of that NPDWR
would continue in future six-year reviews. \
i
Similarly, a decision not to revise at this;tune means only that EPA does not believe that
regulatory changes to a particular NPDWR are appropriate now, based on lack of new data,
ongoing scientific reviews, low priority, or other reasons discussed in this document. Reviews of
these contaminants continue and future six-year reviews may lead to a decision that regulatory
changes are appropriate. j
C. Wlmt Information Will I Find In This Document?
This protocol is divided into three remaining sections as follows:
Section II: Overview of The Six-Year Review Process provides a summary of the
review process. It discusses how potential candidates for regulatory revision were
identified; how this list was refined to develop a final list of NPDWRs nominated for
revision; and the potential types of regulatory decisions that EPA considered.
5W/
2 The NDWAC Working Group and the full NDWAC operate in accordance with the provisions of the
Federal Advisory Committees Act (FACA). All meetings are announced in the Federal Register and members of the
public are welcome to attend as observers. |
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Section III: Detailed Discussion of the Review Process provides an in-depth
discussion of each of the analyses that were conducted (i.e., health effects, analytical
and technology assessments, consideration of other regulatory revisions, occurrence
and exposure, and evaluation of available economic information), and how these
analyses interrelate.
• Section IV: Stakeholder Involvement discusses how EPA involved the public
during the Six-Year Review process.
This protocol also contains five appendices as described below:
• Appendix A: List of pre-1997 National Primary Drinking Water Regulations
(NPDWRs) identifies each of pre-1997 NPDWRs and indicates whether it is being
reviewed in accordance with this protocol or whether it has been/will be reviewed as a
part of a separate rulemaking activity.
• Appendix B: Differences between the National Drinking Water Advisory
Council's (NDWAC's) Recommendations and this Protocol summarizes the
NDWAC recommendations that EPA either modified or did not include in this
protocol.
• Appendix C: Overview of the IRIS Assessments provides a discussion of how
EPA conducts its Integrated Risk Information System (IRIS) health assessments.
• Appendix D: Overview of the OPP Process for Toxicity Assessments contains a
discussion of the Office of Pesticide Programs (OPP) process for conducting toxicity
assessments.
Appendix E: Overview of the Analytical Methods Review Process describes
EPA's process for approving new analytical methods for chemical drinking water
contaminants and how the Agency has derived practical quantitation limits in the past.
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SECTION II: OVERVIEW OF THE
SIX-YEAR REVIEW PROCESS
This section provides an overview of the review process. It contains a discussion of the
basic principles that EPA followed during the review, the types of analyses that EPA conducted,
and the types of regulatory revisions that EPA considered. In addition, this section includes a
figure that illustrates the review process. A more detailed discussion of each of the analyses, that
were conducted under the review, is provided hi Section III.
A. What Basic Principles Did EPA Follow During this Review?
\ . .,;
EPA's primary goal was to identify and prioritize candidates for regulatory revision in
order to target those revisions that are most likely to result in an increased level of public health
protection and/or result in substantial cost-savings while maintaining the level of public health
protection. In conducting the review, EPA applied the following basic principles:
• The Agency assumed that health effects, occurrence, analytical feasibility, treatment
data, and analyses underlying existing regulations remain adequate and relevant,
except in those instances where reliable, peer-reviewed3, new data were available that
indicated a need to re-evaluate an NPDWR (e.g., where a change in health risk
assessment has occurred). |
• If new data were available, EPA determined whether changes in existing standards
were warranted. For example, in determining whether there was a change in
analytical feasibility, the Agency applied the current policy and procedures for
calculating the practical quantitation| level for drinking water contaminants.4
• EPA was unable to complete evaluation of certain new data within the time available
for the review. For example, if a new health risk assessment for a contaminant was
not completed during the review cyc|le, EPA generally made a "not revise" decision
on the rationale that it was not appropriate to revise the regulation while the
assessment was ongoing. When an updated assessment is completed, EPA will
review the update and any new conclusions or additional information associated with
the contaminant during the next review cycle. The Agency may make a determination
• J "Peer review" is a documented critical review of a sp ecific major scientific and/or technical work product.
The peer review is conducted by qualified individuals (or, organizations) who are independent of those who
performed the work, but who are collectively equivalent in technical expertise (i.e., peers) to those who performed
the original work. The peer review is conducted to en sure that activities are technically adequate, competently
performed, properly documented, and satisfy established qua lily requirements. The peer review is an in-depth
assessment of the assumptions, calculation, extrapola tionS, alternate interpretations, methodology, acceptance
criteria, and conclusions pertaining to the specific majo r scientific and/or technical work product and of the
documentation that supports them. [
i
4 See: 50 FR 46880,-November 13,1985 (USEPA, 1985); 52 FR 25690, July 8,1987 (USEPA, 1987); 54
FR 22062, May 22,1989 (USEPA, 1989a).
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to revise a particular NPDWR before August 2008 where justified by new public
health risk information.
During the review, EPA identified areas where information was inadequate or
unavailable ("data gaps") and is needed before an NPDWR may be considered as a
candidate for revision. Where EPA has been unable to fill such gaps during the
review process, the Agency has provided information about the data gaps to the
appropriate Agency group(s) for consideration and prioritization so that further
research and data collection can be considered as part of a subsequent review cycle.
For example, the review may identify a need to better understand new treatment
technologies. Such an information gap will need to be considered in the context of
EPA's overall OGWDW research strategy.
• During the review process, the Agency will not consider potential regulatory revisions
that are already the subject of other periodic rulemaking activities.
• EPA applied the Agency's peer review policy, where appropriate, to any new analyses
(USEPA, 2000e).
B. What Types of Analyses Did EPA Conduct?
To most efficiently utilize limited resources and assure continued public health
protection, the Agency conducted the review in two phases: (1) an initial technical review of all
69 NPDWRs included in this Six-Year Review (see Appendix A for a list); and (2) an in-depth
technical evaluation of those NPDWRs identified during the initial review as potential candidates
for revision. Figure 1, at the end of this section, illustrates the Six-Year Review process.
1. Initial Technical Review
The initial review phase included these three screening and general evaluation steps:
• Health effects review. Identify NPDWRs for which the Agency has revised health
risk assessments that indicate possible changes to the maximum contaminant level
goal (MCLG) and perhaps to the maximum contaminant level (MCL);
Current technology review. Identify NPDWRs where improvements hi analytical
measurement or treatment feasibility might allow the MCL to be established closer to
the MCLG, or where adjustments in TT requirements might be appropriate; and/or
• Other regulatory revisions review. Identify NPDWRs where adjustments to system
monitoring and reporting requirements might be appropriate and where such changes
are not already being considered as a part of another activity.
EPA generally determined that an NPDWR was not a candidate for revision after the
initial review if a health risk assessment was hi process or was initiated as a result of the review,
since the Agency does not believe it is appropriate to revise the NPDWR while a health risk
assessment is underway. The Agency also determined that an NPDWR was not a candidate for
revision after the initial screening if none of the initial screening analyses identified a health or
technological basis for a regulatory revision.
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2. In-Depth Technical Analysis \
The Agency subjected the remaining NPDWRs to more in-depth technical analyses. If
the initial review indicated a possible revision to the MCLG/MCL, EPA further considered
health and technology factors that might affect the development of a revised MCLG/MCL or
revised MCLG/TT requirements. The Agency also estimated potential occurrence and exposure
at public water systems (PWSs) at concentrations of regulatory interest for the chemical
NPDWRs and conducted a qualitative evaluation of available economic information. EPA based
the qualitative economic evaluation primarily o|n available occurrence and exposure data, to
determine whether the possible revision was likely to present an opportunity for significant gains
in public health protection and/or significant cost-savings to PWSs and their customers that could
be realized without lessening the level of public health protection.
If EPA identified data gaps that could not be filled during the current review cycle, the
Agency did not conduct some or all of the remaining analyses. Although, Figure 1, on page 8
shows the identification of data gaps as the final step in the review; in some instances, data gaps
were identified during earlier steps in the process. If the Agency identified data gaps, EPA
determined that a revision to the NPDWR is not appropriate at this time.
After completing these comprehensive analyses, EPA identified those NPDWRs that
remain appropriate at this tune, and those NPDWRs that may be appropriate for revision. If the
Agency decided that it was not appropriate to revise an NPDWR at this time, that decision was
based on one of the following reasons. i
• Health risk assessment is in process', The Agency is currently conducting, or has
scheduled, a detailed review of current health effects information. Because the results
of the assessment are not yet available, the Agency does not believe it is appropriate
to make a "revise decision" at this time. EPA will consider the results of the updated
health risk assessment during the 2002-2008 review cycle. However, if the results of
the health risk assessment indicate a| compelling need to reconsider the MCLG, EPA
may decide to accelerate the review schedule for that contaminant's NPDWR.
• • NPDWR remains appropriate after data/information review: The outcome of the
review indicates that the current regulatory requirements remain appropriate and,
therefore, no regulatory revisions are warranted. Any new information available to
the Agency either supports the current regulatory requirements or does not justify a
revision. j
• New information, but no revision recommended because:
— Negligible gain in public health protection: Any resulting changes to the
NPDWR would not significantly improve the level of public health protection or
result in a major cost-savings. !
'
— Information Gaps: Although results of the review support consideration of a
possible revision, the available data are insufficient to support a definitive
regulatory decision at this tune. |
EPA will publish preliminary review findings and seek public comment on them in the
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Federal Register. After considering the public comments received and any new peer-reviewed
data that may become available to the Agency, EPA will publish its final decisions in the Federal
Register.
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Figure 1: Overview of the Protocol and Making the Revise/Not Revise Decision
NPDWRs under review
Initial Technical Review
Health Effects, Methods and Treatment
Feasibility, and Other Regulatory
Revisions
Tn-aepth Technical Analysis
New risk assessment, methods feasibility,
treatment effectiveness, occurrence and exposure
and economic implications.
Is a significant gain in
public health protection or significant
cost savings likely to occur?
Are the data sufficient to support
regulatory revision?
Pending health
risk assessment
NPDWR remains appropriate
after data/information review
No Revision
at this time
Negligible gain in
public health protection
and/or cost savings
Data gaps - determine
research needs
1. Publish 7*7? notice with preliminary revise/not decisions
2. Review Public Comments and consider revising decisions
in context of new information.
3. Publish .FT? notice with final list of NPDWRs to be
revised.
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C. What Types of Regulatory Revisions Did EPA Consider?
As a part of the review, EPA considered regulatory revisions, with the primary goal of
improving or maintaining public health protection. The types of revisions considered were based
on the various components of each NPDWR. Some NPDWRs set enforceable MCLs for
particular contaminants in drinking water. Others impose TTs to remove chemical contaminants
or microbiological pathogens from drinking water. Most standards also include requirements for
water systems to test for contaminants in the water to make sure standards are achieved.
NPDWRs also specify recordkeeping and reporting requirements, define what constitutes
compliance, and specify language and delivery requirements for public notification.
Some regulatory revisions that are not listed below (e.g., revisions to approved analytical
methods) are already addressed through periodic rulemaking activities of SDWA, and thus, were
not included in the Six-Year Review.
1. Changes to MCLGs
The SDWA requires EPA to establish non-enforceable health-based MCLGs. As .a part
of the Six-Year Review, EPA considered MCLG changes only in those instances where a new
health risks assessment had been completed since the MCLG was promulgated or last revised,
and where the most current assessment resulted in a revised reference dose (RfD) and/or cancer
classification that significantly affected the calculation of the MCLG.
2. Changes to MCLs
An MCL is an enforceable standard for a contaminant. The SDWA generally requires the
MCL to be set as close to the MCLG as is feasible. As a part of the Six-Year Review, EPA
considered MCL revisions under the following circumstances5:
• The health effects review indicated a change to the MCLG that also indicated a
change to the MCL was appropriate; and/or
The current MCL was limited by analytical or treatment feasibility and the review of
these capabilities indicated it might now be feasible to set the MCL closer to the
MCLG.
3. Changes to Treatment Technique Requirements
When it is not economically or technically feasible to set an MCL, or when there is no
reliable or economically feasible method to detect contaminants in the water, EPA sets a TT
requirement in lieu of an MCL. A TT specifies a type of treatment (e.g., filtration, disinfection,
other methods of control to limit contamination in drinking water, etc.) and means for ensuring
5 Although the 1996 Amendments to SDWA allow EPA to set the MCL at higher than the feasible level if
the benefits do not justify the costs, SDWA also pr ecludes the Agency from making an existing standard less
stringent solely on economic considerations. Therefore, EPA does not believe it is appropriate to revise a pre-1997
MCL unless a health or technical basis exists for the revision.
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adequate treatment performance (e.g., monitoring of water quality to ensure treatment
performance, etc.). i
i
Water TTs may improve to the point where more protective drinking water standards may
be considered. Before EPA would consider a revision to TT requirements, the potential methods
must be generally available and must have demonstrated consistent control of the subject
contaminant in drinking water. As a part of the| Six-Year Review, EPA reviewed available
information on TTs for those chemical NPDWRs for which a TT is set in lieu of an MCL and no
health risk assessment was in process to determine if changes to TT requirements might be
warranted. ! •
4. Changes to Other Treatment Technology i
i
When EPA sets an MCL, the NPDWR also contains Best Available Technology (BAT)
recommendations that address drinking water treatment processes. Although not required for
compliance purposes, EPA sets BATs that have Ithe capability to meet MCLs.
As part of the Six-Year Review, the Agency limited its review of BATs to those
NPDWRs for which EPA was considering possible revisions to the MCL based on the health
effects or analytical feasibility reviews. Before|EPA would consider a revision to a BAT, the
treatment technology must be generally available and must have demonstrated consistent removal
of the subject contaminant under field conditions.
EPA has a separate program in place to periodically review specific treatment technology
issues, such as compliance and variance technology for small systems (Le., systems serving up to
10,000 people) for both the MCL-type and the TT-type rules (however, for microbiological
contaminant regulations, no variances are allow.ed).6 As a part of its periodic review of small
system compliance and variance technology, the Agency also plans to include the identification
of: (1) BATs for larger systems in future regulations, and (2) emerging technologies as potential
compliance and variance technologies for all system sizes for existing and future regulations.
EPA believes that this separate review of treatment technologies is appropriate because it
maintains the focus of technology assessment Within one program function (USEPA, 1998a).
6 The 1996 SDWA Amendments identify two classes of technologies for systems serving 10,000 and fewer
persons: compliance technologies and variance t echnologies. A compliance technology is defined in
§1412(b)(4)(E)(ii) as a technology or other means that is affordable and achieves compliance with an MCL or
satisfies a TT requirement. EPA listed compliance technologies in the EPA publication entitled " Small System
Compliance Technology List for the Non-Mi crobial Contaminants Regulated Before 1996 " (USEPA, 1998a).
Variance technologies, defined in §1412(b)(15)(A), are speci fied for those system size category/source water quality
combinations for which there are no listed compliance technologies. Variance technologies, where they are
permitted, may not achieve compliance with a particular MCL or TT requirement; however, they must achieve the
maximum reduction or inactivation efficiency that is affo rdable, taking into consideration system size and source
water quality. Variance technologies must also achieve a le vel of contaminant reduction that is protective of public
health. . i .
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5. Changes to Other Regulatory Provisions
In addition to possible revisions to MCLGs, MCLs, and TTs, EPA considered other
regulatory revisions, such as monitoring and system reporting requirements, as a part of the Six-
Year Review process. EPA focused this review on issues that are not already being addressed, or
have not been addressed, through alternative mechanisms (e.g., as part of a recent or ongoing
rulemaking, in conjunction with possible Chemical Monitoring Reform, etc.). Where appropriate
alternative mechanisms do not exist, EPA considered these implementation-related concerns if
the potential revision met the following criteria:
• It indicated a potential change in the 40 Code of Federal Regulations (CFR) 141
requirements;
It was "ready" for rulemaking - that is, the problem to be resolved has been clearly
identified and specific option(s) have been formulated to address the problem; and
• It met at least one of the following conditions:
— clearly unproved the level of public health protection; and/or
- represented a significant cost-savings while maintaining or improving the public
health protection.
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SECTION III: DETAILED DISCUSSION OF
THE SIX-YEAR REVIEW PROCESS
This section provides a detailed discussion of how EPA conducted its review of health
risk assessments, technology assessments, other regulatory revisions, and, where appropriate,
occurrence and exposure analyses, and economic considerations.
A. Health risk assessments j
1. Wliat Are the Objectives of the Health Effects Review?
The objectives for the examination of health effects under the Six-Year Review were to:
• To identify new health risk assessments for individual contaminants that could change
the MCLG for the contaminant in question and affirm or change the MCL, thus,
affording the same or greater protection of human health provided by the present
MCLG; !
• To use existing Agency health risk assessments in accomplishing the health effects
data review; j
|
• • To ensure that the health effects data, for each contaminant is the subject of a detailed
review at least once in every two, Six-Year Review cycles (with the exception of •
pesticides that are still in active use,[because they are subject to a detailed review that
is conducted on a different schedule?); and
• To accomplish the review within the limitations imposed by Agency resources.
The procedure for review of health effects data differed depending on whether the
substance to be controlled is a chemical contaminant or a microbiological pathogen/indicator,-as
discussed in detail below. The health risk assessment identified a list of NPDWRs that are
possible candidates for regulatory revisions baspd on changes in health considerations. This list
of NPDWRs was combined with those identified by other key elements of the review to develop
a final list of NPDWRs that are candidates for additional evaluation.
7 The health effects for these contaminants are rea ssessed no less frequently than every 15 years. Within
EPA, health risk assessments for pesticides are conduc ted by the OPP under authority of the Federal Insecticide,
Fungicide, and Rodenricide Act (FIFRA), and the Food Qiia lity Protection Act (FQPA) of 1996. A goal of FIFRA is
that EPA reviews each pesticide's registration every 15 yeajrs. Under some circumstances, a pesticide's health effects
may be reassessed more frequently.
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2. How Does EPA Review Health Effects Data for Chemical Contaminants?
EPA uses a systematic approach in reviewing the health effects data for chemical
contaminants. This approach considers the risk assessment policies that link the MCLG and
MCL as well as the data that have become available since the time of regulation. The document,
"Six-Year Review - Chemical Contaminants - Health Effects Technical Support Document"
(USEPA, 2002d), describes how EPA reviewed the chemical contaminants and provides the
results of the health effects technical review.
If there is evidence that a chemical may cause cancer, and if the cancer mode of action is
linear, there is no dose below which the chemical is considered safe, and thus the MCLG is set at
zero. In these instances; the MCL is based on feasible technology (analytical methods/treatment).
If a chemical is carcinogenic and acts by a well-documented, nonlinear mode of action, the
MCLG may be set at a level above zero. As the health risks of nonlinear carcinogens undergo
reassessment, this may provide regulatory options for MCLGs for carcinogens that are greater
than zero.
For non-carcinogenic chemicals, the MCLG is based on an oral R£D. The RfD is an
estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to
the human population (including sensitive subgroups) that is likely to be without an appreciable
risk of deleterious non-cancer effects during a lifetime. A change in an Agency RfD for a
chemical could accordingly lead to a change in an MCLG and MCL. In deriving the MCLG for a
non-carcinogen, the Agency applies a Relative Source Contribution (RSC)-factor to allocate a
portion of the total allowable exposure to drinking water. The RSC is one factor which will
determine whether or not a change in RfD will lead to a change in the MCLG/MCL.
In the past, it was Agency policy to apply a risk management factor to the RfD for
chemicals with equivocal data on carcinogenicity. This policy is a second factor that must be
evaluated to determine the impact of a change in RfD on the MCLG/MCL for these chemicals.
For most of the 68 chemical NPDWRs included in the Six-Year Review, the MCLG is
derived from the cancer classification and/or the RfD. Therefore, the health effects technical
review focused on whether there has been a change to these values. The Agency reviewed the
results of health risk assessments completed under the following programs to determine if there
had been a change in critical effect or dose-response pattern that indicates the possible need for
an MCLG revision.
• EPA's IRIS (see Appendix C)
• OPP (see Appendix D)
• Agency for Toxic Substances and Disease Registry (ATSDR)
• National Academy of Sciences (NAS).
Where possible, an oral RfD or comparable value is derived and an assessment of carcinogenicity
from oral exposure is conducted under each of these programs.
As a result of the health effects review, EPA placed each of the 68 chemical NPDWRs
into one of the folio whig categories:
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New risk assessment 1997 or later. An IRIS, OPP, ATSDR, and/or NAS assessment
has been completed in 1997 or later.; These assessments have considered
developmental and reproductive toxicity as a part of the assessment. The Agency
considers these assessments to be rebent enough that it is not necessary to conduct a
literature search to identify any additional relevant studies that have become available
on the toxicological effects of these contaminants. In cases where the health risk
assessment resulted in a change in the critical effect, or the dose-response pattern for a
regulated contaminant, and where that change could result in a change in the MCLG,
EPA subjected the NPDWR to more| in-depth analysis as a part of the review process.
Where recent assessments were conducted by an agency other than EPA and new
developmental and reproductive data were identified, EPA initiated an update of its
assessment. ;
New risk assessment since promulgation, but prior to 1997. An IRIS, OPP, ATSDR,
and/or NAS assessment has been completed since the NPDWR was promulgated but
prior to 1997. None of these assessments reflected a change in RfD or cancer
classification. However, since these assessments may not have specifically
considered developmental and reproductive health effects, EPA conducted a full
literature search, including developmental and reproductive toxicity, for those
NPDWRs with non-zero MCLGs to identify any relevant studies that might affect the
MCLGs of these contaminants.8 In a few instances, the results of the literature search
indicate that it might be appropriate to revise the RfD and/or cancer classification.
EPA initiated updates to risk assessments for these chemicals, and established a
schedule for then* completion. EPA jdoes not believe it is appropriate to revise the
MCLG at this time. ;
i
i
Agency risk assessment in progress during the six-year health effects review. The
Agency currently is conducting a heklth risk assessment for the contaminant. That
assessment will consider all relevant studies that have become available on the
toxicology of the contaminant, including developmental and reproductive toxicity.
EPA generally does not believe it is appropriate to revise the MCLG for these
contaminants at this time. j
Original NPDWR risk assessment, ll^o health risk assessment has been conducted
since promulgation of the NPDWR. i The Agency conducted a full toxicological
literature search, including developmental and reproductive toxicity, for each of these
contaminants with non-zero MCLGs to identify new toxicological studies that might
have an impact on the MCLGs. In d few instances, the results of the literature search
indicate that it might be appropriate Jo revise the RfD and/or cancer classification.
EPA initiated updates to risk assessments for these chemicals, and established a
8 A zero MCLG is already considered protective of public health and new information on developmental
and reproductive effects would not affect the MCLG. However, for those NPDWRs with a zero MCLG, EPA
reviewed available information to inquire whether data show a non-linearity of the dose-response; EPA did not find
any data to support such a mode of action (USEPA, 2002d).
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schedule for their completion. EPA does not believe it is appropriate to revise the
MCLG at this time.
Thus, only contaminants in the first category might be potential.candidates for an MCLG revision
at this time.
The document,"Six-Year Review - Chemical Contaminants - Health Effects Technical
Support Document" (USEPA, 2002f) describes the process that EPA used to address the health
effects aspect of the current review for the chemical contaminants.
3. How Does EPA Review Health Effects Data for Microbiological NPDWRs?
The Total Coliform Rule (TCR) is one of several EPA regulations that protect the public
from pathogens in drinking water. The TCR requires all PWSs to monitor for the presence of
total coliforms in the distribution system. Total colifprms are a group of closely related bacteria
that are (with few exceptions) not harmful to humans. They are natural and common inhabitants
of the soil and ambient waters (e.g., lakes, rivers and estuaries), as well as in the gastrointestinal
tract of animals. A few of these coliforms (fecal coliforms, including Escherichia coli orE. coli)
only grow within the intestinal tract of humans and other warm-blooded animals. Total
coliforms may be injured by environmental stresses (e.g., lack of nutrients) and water treatment
(e.g., chlorine disinfection) in a manner similar to most bacterial pathogens and many virus
pathogens. Therefore, EPA considers them a useful indicator of bacterial and many viral
waterborne enteric pathogens. More specifically, for drinking water, total coliforms are used to
determine the adequacy of water treatment and the integrity of the distribution system. The
absence of total coliforms in the distribution system minimizes the likelihood that fecal
pathogens are present. Thus, total coliforms are used to determine the vulnerability of a system
to fecal contamination.
The 1989 TCR set an MCLG of zero for total coliforms because EPA was not aware of
any data in the scientific literature supporting a particular value for the concentration of coliforms
below which no known or anticipated adverse health effects occur, with an adequate margin of
safety. . • .
The memorandum, "Six-Year Review of the Total Coliform Rule - Comments Received"
(USEPA, 2002e), describes the process EPA applied to the review of the TCR. Where
appropriate, EPA applied the same approach to reviewing the TCR as it did to the review of the
68 chemical NPDWRs. However, because of the nature of the TCR, the pathogens it controls,
the Agency focused its review on the implementation-related requirements.
B. Technology Assessments
1. What Are the Objectives of the Technology Assessment?
The SDWA generally requires that MCLs be set as close to the MCLG as is feasible.
When determining feasibility, the Agency considers cost and capability of the analytical and
treatment methods to respectively measure and remove/reduce drinking water contaminants, and
the availability of these technologies. In some cases, particularly when the Agency sets a zero
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MCLG, EPA establishes a higher MCL based on the limitations of analytical or treatment
feasibility.
Where these constraints apply to the current MCL, the objectives of the technology
assessment are to determine whether there havjs been improvements in analytical methods or
treatment technologies that may allow EPA to lower the MCL.
i
2. How Does EPA Review Analytical Methods?
As described in Appendix E, EPA's OGWDW has a process in place to approve new
and/or improved analytical methods for drinking water contaminants. The review and approval
of new methods, updates to §§141.23, 141.24, |or 141.25 and the approval of methods through
§141.27 (alternate analytical techniques - also known as alternate test procedures or ATP) is
generally performed through periodic method update rules. The review and approval of new
methods and/or updates to the methods is also performed through the rulemaking process to
regulate a contaminant or revise the standard for a contaminant, when appropriate (e.g. the
January 22,2001 final rule for arsenic, (66 FR\6975 (USEPA, 2001b)). More recent methods
update rules include 62 FR 10167, March 5,1997 (USEPA, 1997a), 64 FR 67449, December 1,
1999 (USEPA, 1999d) and 66 FR 3526, a proposed rule published January 16, 2001 (USEPA,
2001a). i
The Six-Year Review will not duplicate those efforts per se but will use the information
from these method updates in the review process. In those instances where the MCL has been
established based on the limitations of analytical method capabilities and/or where the health
effects analysis suggests that the MCLG/MCL should be lowered, EPA will review the existing
approved methods hi the context of potential changes in analytical feasibility. The goal of this
part of the review is for EPA to determine whether the currently approved methods provide
sufficient analytical capability to reliably measure the contaminant at levels lower than the
current MCL. If it appears that the currently approved method capabilities (i.e., a method
detection limit (MDL)) are the limiting factor for attaining a lower level of quantisation and
therefore, revising an MCL, and if the occurrence/exposure analyses suggest a potentially
significant gain in public health protection, EPA will include a request hi the Federal Register
for potential new and/or improved methods that are technologically and economically feasible.
However, it should be noted that once a more sensitive method is approved for a contaminant,
there may be a time lag between the time of promulgation and the ability of laboratories to begin
using a new method and have an impact on the| feasible level of quantitation.
r
The remainder of this section generally! describes how EPA determines the feasible level
of measurement for chemical and microbiological contaminants for SDWA purposes. It also
discusses how EPA evaluated available, new data to determine if any changes in analytical
feasibility for the chemical contaminants have occurred since promulgation of the NPDWR. The
document,"Analytical Feasibility Support Document for the Six-Year Review of Existing
National Primary Drinking Water Regulations:! Reassessment of Feasibility for Chemical
Contaminants," (USEPA, 2002g) describes the process that EPA used to address the analytical
feasibility aspect of the current review for specific chemical contaminants.
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Chemical Contaminants
OGWDW establishes a practical quantitation level (PQL) to estimate the level at which
laboratories can routinely measure a chemical contaminant in drinking water. Historically,
OGWDW has typically used two main approaches to determine a PQL for SDWA analytes. The
preferred approach used data from Water Supply (WS) studies (which were predominantly used
to certify drinking water laboratories9). In most cases, OGWDW used the WS method when
sufficient WS data were available to calculate a PQL. In the absence of sufficient WS data,
OGWDW used a multiplier method, in which the PQL was calculated by multiplying the
EPA-derivedMDLbyafactorof5or 10. «
Although there are several approaches that could be used for the reassessment or
re-evaluation of the PQLs, to be consistent with the process that the Agency has used in the past,
only the "WS data method" and the "MDL Multiplier method" were considered for this Six-Year
Review process. Of these two approaches, the Agency preferred to use the WS data approach
since it relies oh actual data from a number of EPA Regional and State laboratories. In cases
were the WS data were indicative of a change in the PQL, the MDL multiplier method was only
used only to estimate what the potentially new PQL could be.
EPA reviewed analytical capabilities for contaminants under two circumstances: (1) for
those NPDWRs where the current MCL is set at the PQL and there is no indication that trie
MCLG would change; and (2) for those NPDWRs that have undergone a health effects review ,
and there is a potential change in an MCLG and it may be less than the current MCL. For each
of these chemical NPDWRs, the following steps were taken to evaluate whether changes in
analytical feasibility have occurred:
(1) a methods comparison step was used to identify whether the ability to detect (and
therefore quantify) these contaminants at lower levels has increased;
(2) a methods usage over time step was used to identify the analytical methods that appear
to be the most widely-used for the analysis of particular contaminants.
(3) a Water Supply data analysis step was used to determine if a PQL can be recalculated
.(if sufficient WS information is available) or if there is an indication that a PQL may
be lower using the available information.
The results of these three steps aided hi assessing whether a PQL might change for a
specific contaminant and, if so, estimating what the new PQL might be. Ultimately, the purpose
of this analysis was to determine whether the analytical method capabilities would support a
lower MCL.
9 Because the Water Supply (WS) program has been ex ternalized, the Agency is currently deciding how it
should assess the multiple laboratory data that are used to determine the PQL for chemical contaminants. Appendix
E briefly discusses the extemalization of the Performance Evaluation program.
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Microbiological Contaminants j
I
For microbes, EPA does not have, or currently .envision, a routine pathogen monitoring
requirement, but rather employs indicators of water quality (e.g., total coliforms, E. coif). PQLs
have not been used for microbial indicators because, for approval, the method must be able to
detect a single cell (i.e., MDL and PQL must bJDth be one cell) in a 100 milliliter (mL) water
sample (40 CFR 141.21(f)). In addition, the false-positive and false-negative (i.e., recovery)
rates must be reasonable. EPA is considering whether to define "reasonable" in numerical terms.
In some cases, EPA may require systems to determine the density of a particular pathogen
or indicator in either their source waters or drinking waters. For example, under the future Long
Term 2-Enhanced Surface Water Treatment Rule (LT2-ESWTR), EPA may require surface water
systems to determine the density of Cryptosporiidium in the source water to determine the level of
water treatment the system would need. In this case, the accuracy and precision of the method at
low levels of pathogen density would have to be determined using interlaboratory studies. The
method would have to be sufficiently sensitive to detect a single oocyst. Therefore the PQLs and
MDLs are not meaningful. In addition, it may be appropriate to determine an MDL and PQL for
some required non-microbial measurements associated with microbial water quality such as
turbidity, disinfectant residual, and algal microcystins. Currently, accurate measurement of
microbiological density is problematic. Moreover, regulation of microbiological contaminants
are currently treatment-technique based. Therefore, this protocol primarily focused on the review
of treatment technology related to the regulation of microbiological contaminants.
ah i
3. How Does EPA Review Treatment Technologies?
As discussed previously, an NPDWR either identifies the BAT for meeting the MCL
(even though BAT is not required for compliance purposes), or establishes enforceable TT
requirements. Currently, for all the pre-1997 chemical NRDWRs reviewed in accordance with
this protocol that include an MCL, the MCL is set equal to the MCLG or the PQL. None of these
MCLs are currently limited by treatment feasibility. Thus, although EPA generally reviews
treatment technologies through alternative mechanisms, there are a few scenarios for which EPA
reviewed treatment feasibility as a part of the Six-Year Review process:
• The health effects technical review identified a potential change to the MCLG/MCL;
or
• A health risk assessment is not in process for the contaminant and one of the
following two conditions applied: j
(1) the analytical feasibility review identified a possible change to the MCLG/MCL;
or i
(2)theNPDWRisaTT-typerule. |
EPA also considered revisions that clarify or mddify BAT or TT requirements where existing
requirements were not clear or were incorrectly specified. In addition, and where appropriate,
EPA evaluated the likelihood that systems would discontinue existing treatment if EPA were to
raise the MCL.
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Treatment capabilities of existing BATs and TTs are well documented by EPA and other
organizations. Likewise, small system compliance and variance technologies are well
documented and periodically reviewed by the Agency. During the development of NPDWRs,
EPA provides state-of-the-science and feasibility of treatment information primarily through its
technical support documents (e.g., EPA technologies and costs reports, and guidance materials
published to assist in regulatory implementation). As part of the Six-Year Review process, EPA.
used these same resources, in addition to newer treatment and cost reports, peer-reviewed data,
and other available treatment technology information including that received by EPA from
stakeholders.
The evaluation of treatment technologies will support the regulatory review process by
identifying any known water treatment limitations that might affect a revision of an MCL. In the
case of TT-type rules, this effort supports consideration of whether changes to TT requirements
are warranted. For example, consideration will be given to any new treatment processes that may
now be available and appropriate. If the Agency identifies treatment technology-related research
needs as a part of the Six-Year Review process, those research needs will be forwarded to the
appropriate Agency group(s) for consideration and prioritization as a part of the overall drinking
water research strategy.
The document," Water Treatment Technology Feasibility Support Document for Chemical
Contaminants; In Support of EPA Six-Year Review of National Primary Drinking Water
Regulations" (USEPA, 2002h) describes the process that EPA used to address the treatment
feasibility aspect of the current review for specific chemical contaminants.
C. Other Regulatory Revisions
/. What Are the Objectives of Reviewing Other Regulatory Revision Options?
In addition to possible revisions to MCLGs, MCLs, and TTs, EPA considered other
regulatory revisions, such as monitoring and system reporting requirements, as a part of the Six-
Year Review process. EPA focused this review on issues that are not already being addressed, or
have not been addressed, through alternative mechanisms (e.g., as part of a recent or ongoing .
rulemaking, in conjunction with possible Chemical Monitoring Reform). Where appropriate
alternative mechanisms do not exist, EPA considered these implementation-related concerns if
the potential revision met the following criteria:
• It indicated a potential change in the 40 CFR 141 requirements;
• It was "ready" for rulemaking - that is, the problem to be resolved has been clearly
identified and specific option(s) have been formulated to address the problem; and
• It met at least one of the following conditions:
- clearly improved the level of public health protection; and/or
- represented a significant cost-savings while maintaining or improving the public
health protection.
The document, "Consideration of Other Regulatory Revisions for Chemical
Contaminants in Support of the SixrYear Review of National Primary Drinking Water
Regulations" (USEPA, 2002b) summarizes the specific issues identified during the review
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process. Some of these issues (e.g., the need to specifically define new system/new source
monitoring requirements for chemical contaminants) have already been addressed in the recently
published arsenic and radionuclides NPDWRs (66 FR 6975, January 22, 2001 (USEPA, 2001b);
65 FR 76707, December 7,2000 (USEPA, 2000d)).
D. Occurrence and Exposure Analysis
s
L What Are the Objectives of the Occurrence, and Exposure Analysis?
The objectives of the occurrence and exposure analysis components of the review process
are to estimate the numbers of PWSs at which contaminants occur at levels of regulatory interest
in drinking water, and to evaluate the number ojf people exposed to these levels. This analysis is
not necessary for the TCR, since national data are not available and are not needed. If an
organism is known to be transmitted by the fecal-oral route, and has caused at least one
waterborne disease outbreak in this country, thdt is sufficient reason to control the organism
nationally. The number of systems affected by San organism depends on the characteristics of the
waterborne organism and the type of water source. Therefore, the remaining discussion of the
occurrence and exposure analysis pertains onlyito the chemical NPDWRs under review.
Combined with results of the other technical analyses described in Section III (e.g., health
effects), the results of the occurrence and exposure analysis were used to help determine which
revisions are most likely to provide the greatest! public benefit. In some cases, these results may
also be used as a factor when recalculating RSCs.10 EPA plans to perform further, in-depth,
occurrence and exposure analysis prior to any proposed revision to an NPDWR.
2. How Did EPA Conduct the Occurrence ana Exposure Analysis?
During the current review cycle, EPA used data voluntarily provided by eight States as a
part of the Agency's occurrence analyses for its'Chemical Monitoring Reform (CMR) evaluation
(USEPA, 1999b). EPA augmented this information with other data that were voluntarily
submitted by an additional eight States, based dp. the same geographic diversity and agricultural
and industrial pollution potential analyses utilized in the CMR analyses.
i
The Agency does not believe it is appropriate to revise a pre-1997 NPDWR solely on the
basis that a contaminant is low-occurring or high-occurring at PWSs. However, the estimated
occurrence and exposure to a contaminant at PWSs at concentrations between the current MCL
and any possible MCL is a factor in determining whether there is likely to be a significant gain in
public health protection, if EPA were to revise the MCL. Occurrence and exposure estimates
also may be a factor in determining the likely change in public health protection and/or cost-
savings if EPA were to make changes to other regulatory provisions. Therefore, EPA focused the
detailed occurrence and exposure analysis on those chemical contaminants that have been
10 While occurrence and exposure estimates factoi: into the derivation of an RSC, a much more important
factor is exposure information for other media (air, food, et c.) relative to that for water. Exposure information for
other media will be assessed as a part of the health risk assessment described in Section III.A. of this document, and
not as a part of the occurrence and exposure assessment described in this section.
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identified as potential candidates for revision by the health effects, technology, and/or other
regulatory revisions reviews.
As a part of the Stage 1 analysis, EPA estimated the percent of PWSs (and the total
population served by those PWSs) with at least one analytical result exceeding the following
thresholds: the lowest level of detection reported by the States; one-half the current MCL, and the
current MCL. Of the chemicals review under this first regulatory review cycle, all were analyzed
in this way, except for: contaminants for which not enough data were available; contaminants for
which the NPDWR specifies a TT-type requirement instead of an MCL; and contaminants for
which EPA did not request data, since the Agency determined there was no health or
technological basis for revising, and because these data would have required extra burden for
States to transmit.
Based on the outcome of the health effects, technology, and other regulatory revision
reviews, EPA performed a more detailed, "Stage 2" statistical analysis of occurrence to estimate
the numbers of systems (and the corresponding affected populations) with mean contaminant
concentrations above the levels of regulatory interest. In general, EPA utilized the results of the
other technical reviews to determine the level(s) of regulatory interest for each contaminant for
which the Agency performed Stage 2 analysis.
The document,"Occurrence Estimation Methodology and Occurrence Findings Report
for the Six-Year Regulatory Review" (USEPA, 2002i) describes the process that EPA used to.
address the occurrence and exposure aspect of the current review for specific chemical
contaminants.
E. Consideration of Economic Factors
/. What Were the Objectives of EPA's Evaluation of Economic Impacts?
While SDWA provides the Agency broad discretion to consider economic impacts in the
context of the Six-Year Review, the statute precludes EPA from using economic impacts as the
sole basis for a revision that would provide less health protection than the current standard (anti-
backsliding). However, if new peer-reviewed scientific health effects research indicates that an
MCLG could be raised while maintaining public health protection, then such a change is
permitted. For NPDWRs published prior to the 1996 SDWA Amendments, consideration of
economic factors is of limited use when determining whether revisions are appropriate, except in
those situations where a health or technical basis exists for a potential regulatory revision.
Therefore, EPA qualitatively evaluated available economic information for those NPDWRs
identified as potential candidates for revision by the health and technology reviews. The purpose
of this analysis was to determine whether a potential revision is likely to provide an opportunity
for significant gains in public health protection and/or the potential for significant cost-savings
that at least maintain the current level of public health protection.
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2. How Did EPA Consider Economic Impacts^
i
EPA did not quantify likely costs and benefits as a part of the review, since many of the
factors that are needed for such calculations depend on specific regulatory options that will riot
be defined until EPA begins the actual rulemaking process. EPA therefore qualitatively assessed
likely costs and benefits based on the other technical analyses performed as a part of the review.
For example, in those instances where the health effects and/or technology reviews indicated that
a more stringent MCL may be appropriate, EPA considered the difference between the levels of
occurrence and exposure at the current MCL and the occurrence and exposure at the lower
concentration(s) indicated by those reviews. On the other hand, if the health effects review
indicated it might be appropriate to raise the MCLG/MCL, EPA considered whether such a
revision would be likely to offer an opportunity; for significant cost-savings to PWSs and their
customers. In making this assessment, EPA considered the number of PWSs with concentrations
above the current MCL that are likely to avoid the need to install treatment.
\
For any NPDWR for which the Agency jmakes a revise decision, the Agency will conduct
detailed cost and benefit analyses, as required, prior to proposing specific regulatory revisions.
Protocol for ate Review ofNPDWRs
22
Draft - March 2002
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SECTION TV: STAKEHOLDER INVOLVEMENT
Section IV discusses how the Agency involved the public during the Six-Year Review
process. More specifically, it lists those organizations with which EPA coordinated during the
Six-Year Review process (i.e., key stakeholders), describes the mechanisms EPA used to keep
these stakeholders involved, and discusses the Agency's plans for involving the Science Advisory
Board (SAB) in the review process.
A. Who Are the Key Stakeholders in the Six-Year Review Process?
The key stakeholders include members of the following:
The general public
Congress
Other Federal agencies
State, Tribal, and local officials
Public health/health care providers
Public interest groups
Public water suppliers
National trade associations
Environmental groups
Manufacturers
Agricultural producers.
B. How Have Stakeholders Been Involved in the Six-Year Review Process?
EPA involved stakeholders by: holding periodic stakeholder meetings- participating in
national meetings, workshops, and technical forums; meeting informally with associations and
technical experts; posting information on the Office of Ground Water and Drinking Water's
(OGWDW's) web page (www.epa. gov/safewater/h and publishing Federal Register notices on
the Six-Year Review.
EPA invited representatives from State and Tribal communities, PWSs, public health
organizations, academia, environmental and public interest groups, engineering firms, and other
stakeholders to a stakeholder meeting in Washington, DC, in November 1999 (64 FR 55711,
October 14, 1999 (USEPA, 1999a)). Approximately 50 participants attended, including
representatives from the invited groups. EPA discussed its preliminary strategy for the Six-Year
Review and invited stakeholder comment. Stakeholders generally agreed that EPA had identified
the appropriate key elements for the review; however, hi some cases, stakeholders suggested that
EPA needed to be more proactive in seeking out new information that might affect the regulatory
decision (USEPA, 1999c). The executive meeting summary is available on EPA's drinking water
web page, http://www.epa.gov/safewater/ccl/novmtg.html.
In the Spring of 2000, the NDWAC formed a working group to develop
recommendations regarding th& process the Agency should'apply to conducting a periodic and
systematic review of existing NPDWRs. The Working Group held two meetings and a
conference call during June through September 2000 (USEPA, 2000a-2000c). The NDWAC
approved the Working Group's recommendations in November 2000 and formally provided them
Protocol for the Review of NPDWRs
23
Draft - March 2002
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to EPA in December 2000 (NDWAC, 2000). The NDWAC recommended that EPA's review
include consideration of five key elements, as appropriate: health effects, analytical and treatment
feasibility, implementation-related issues, occurrence and exposure, and economic impacts. The
NDWAC suggested that the Agency conduct a preliminary screening review of each NPDWR to
identify potential candidates for an in-depth analysis. Except where noted in Appendix B, EPA
has followed the protocol recommended by theiNDWAC.
In addition to the November 1999 stakeholder meeting and consultation with the
NDWAC, EPA representatives have delivered presentations at a variety of meetings held by
other organizations, including: American Water Works Association (AWWA) Technical
Advisory Workgroup meetings, held in February 2001 in Washington, DC and in February 2002
in San Diego, CA; a meeting held by the Association of State Drinking Water Administrators
(ASDWA) hi March 2001 in Alexandria, VA; and the annual AWWA meeting held hi
Washington, DC in June 2001. At each of these meetings, stakeholders were given the
opportunity to comment on the protocol by which EPA was planning to perform the review of
existing NPDWRs. EPA received valuable input from stakeholders on the proposed protocol to
reviewing existing NPDWRs. ',
C. How Does EPA Plan to Involve the Science Advisory Board?
EPA plans to consult with the SAB Drinking Water Committee prior to publishing the
final its final revise/not revise decisions hi the August 2002 time frame. The Agency will request
their review and comment on whether the protocol EPA developed based on the NDWAC
recommendations was consistently applied and| appropriately documented.
Protocol for the Review of NPDWRs
Draft - March 2002
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REFERENCES
NDWAC. 2000. Recommended Guidance for Review of Existing National Primary Drinking
Water Regulations. November 2000. Available on the Internet at:
http://www.epa.gov/safewater/ndwac/guidfiil.pdf.
USEPA. 1975. Water Programs: National Interim Primary Drinking Water Regulations.
Federal Register. Vol. 40, No. 248, p. 59566. December 24, 1975.
USEPA. 1976. Interim Primary Drinking Water Regulations; Promulgation of Regulations on
Radionuclides. Federal Register. Vol. 41, No. 133. p. 28401, July 9, 1976.
USEPA. 1979. National Interim Primary Drinking Water Regulations; Control of
Trihalomethanes in Drinking Water. Federal Register, Vol. 44, No. 231. p. 68624,
November 29, 1979.
USEPA. 1985. National Primary Drinking Water Regulations; Volatile Synthetic Organic
Chemicals; Final Rule and Proposed Rule. Federal Register. Vol. 50, No. 219. p. 46880
November 13, 1985.
USEPA. 1986. National Primary and Secondary Drinking Water Regulations; Fluoride; Final
Rule. Federal Register. Vol. 51, No. 63. p. 11396, April 2, 1986.
USEPA. 1987. National Primary Drinking Water Regulations - Synthetic Organic Chemicals;
Monitoring for Unregulated Contaminants; Final Rule. Federal Register. Vol. 52, No.
130. p. 25690, July 8, 1987.
USEPA. 1989a. National Primary and Secondary Drinking Water Regulations; Proposed Rule.
Federal Register. Vol. 54, No. 97. p. 22062, May 22, 1989.
USEPA. 1989b. National Primary Drinking Water Regulations; Filtration, Disinfection;
Turbidity, Giardia Lamblia, Viruses, Legionella, and Heterotrophic Bacteria; Final Rule.
Part 2. Federal Register. Vol. 54, No. 124. p. 27486, June 29, 1989.
USEPA. 199la. National Primary Drinking Water Regulations - Synthetic Organic Chemicals
and Inorganic Chemicals; Monitoring for Unregulated Contaminants; National Primary
Drinking Water Regulations Implementation; National Secondary Drinking Water
Regulations; Final Rule. Federal Register. Vol. 56, No. 30. p. 3526, January 30, 1991.
USEPA. 1991 b. Drinking Water Regulations — Maximum Contaminant Level Goals and
National Primary Drinking Water Regulations for Lead and Copper; Final Rule. Federal
Register. Vol. 56, No. 110. p. 26460, June 7, 1991.
USEPA. 1991c. Drinking Water; National Primary Drinking Water Regulations; Monitoring for
Volatile Organic Chemicals; MCLGs and MCLs for Aldicarb, Aldicarb Sulfoxide,
Aldicarb Sulfone, Pentachlorophenol, and Barium; Final Rule. Federal Register. Vol.
56, No. 126. p. 30266, July 1, 1991.
Protocol for the Review ofNPDWRs
25
Draft-March 2002
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USEPA. 1992. Drinking Water; National Primjary Drinking Water Regulations - Synthetic
Organic Chemicals and Inorganic Chemicals; National Primary Drinking Water
Regulations Implementation; Final Rule. Federal Register. Vol. 57, No. 138. p. 31776,
July 17,1992. I
USEPA. 1996. Performance Evaluation Studiejs Supporting Administration of the Clean Water
Act and the Safe Drinking Water Act. Federal Register. Vol. 61, No. 139. p. 37464, July
18, 1996.
USEPA. 1997a. National Primary Drinking Water Regulations: Analytical Methods for
Radionuclides; Final Rule and Proposed Rule. Federal Register. Vol. 62, No. 43. p.
10167, March 5, 1997. i
!
USEPA. 1997b. National Drinking Water Advisory Council, Occurrence and Contaminant
Selection Working Group; Notice of Open Meeting. Federal Register. Vol. 62, No. 113.
p. 32113, June 12, 1997. i
USEPA. 1998a. Small System Compliance Technology List for the Non-Microbial
Contaminants Regulated Before 1996. EPA 815-R-98-002 (September 1998)
USEPA. 1998b. National Primary Drinking W,ater Regulations: Disinfectants and Disinfection
Byproducts; Final Rule. Federal Register. Vol. 63, No. 241. p. 69389, December 16,
1998.
USEPA. 1998c. National Primary Drinking Water Regulations: Interim Enhanced Surface
Water Treatment; Final Rule. Federal Register. Vol. 63, No. 241. p. 69478, December
16,1998. ;
USEPA. 1999a. Announcement of Stakeholders Meeting on the Drinking Water Contaminant
Identification and Selection Process, and the 6-Year Review of All Existing National
Primary Drinking Water Regulations, as Required by the Safe Drinking Water Act, as
Amended in 1996; Notice of Stakeholders Meeting. Federal Register. Vol. 64, No. 198.
p. 5571 I.October 14, 1999.
I
USEPA. 1999b. A Review of Contaminant Occurrence in Public Water Systems. EPA Report
816-R-99-006. November 1999. Available on the Internet at:
http://www.epa.gov/safewater/occur/nov99_lo.pdf.
USEPA. 1999c. Stakeholder Meeting on the Contaminant Candidate List and the 6-Year
Review of Existing National Primary Drinking Water Regulations. November 1999.
Available on the Internet at: http://www.epa.gov/safewater/ccl/novmtg.html.
USEPA. 1999d. National Primary and Secondary Drinking Water Regulations - Chemical and
Microbiological Contaminants, Analytical Methods; and Laboratory Certification
Requirements Revisions. Federal Register. Vol. 64, No. 230. p. 67449, December 1,
1999. '
Protocol for the Review ofNPDWRs
26
Draft-March 2002
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USEPA. 2000a. Working Group Meeting on Contaminant Candidate List Regulatory
Determinations and the 6-Year Review of Existing Regulations. Office of Water. June
2000. Available on the Internet at: http://www.epa.gov/safewater/ccl/iunemtg.html.
USEPA. 2000b. Working Group Meeting on Contaminant Candidate List Regulatory
Determinations and the 6-Year Review of Existing Regulations. Office of Water. July
2000. Available on the Internet at: http://www.epa.gov/safewater/ccl/iulvnitg.htm1.
USEPA. 2000c. NDWAC Working Group Meeting on Contaminant Candidate List Regulatory
Determinations and the 6-Year Review of Existing Regulations. Office of Water.
September 2000. Available on the Internet at:
http://www.eDa.gov/safewater/ccl/25septmtg.html.
USEPA. 2000d. National Primary Drinking Water Regulations; Radionuclides; Final Rule.
Federal Register. Vol. 65, No. 236. p. 76707, December 7, 2000.
USEPA. 2000e. Science Policy Council Handbook: Peer Review, 2nd Edition. EPA Report 100-
B-00-001. Office of Science Policy, Office of Research and Development. December
2000.
USEPA. 200la. National Primary and Secondary Drinking Water Regulations - Pollutants
Analysis; Test Procedures; Guidelines Establishment. Federal Register. Vol.66 No 10
p.3526, January 16,2001.
USEPA. 200 Ib. National Primary Drinking Water Regulation; Arsenic and Clarifications to
Compliance and New Source Contaminants Monitoring; Final Rule. Federal Register
Vol. 66, No. 14. p. 6975, January 22,2001.
USEPA. 2002a. National Primary Drinking Water Regulations: Long-Tefm 1 Enhanced Surface
Water Treatment Rule; Final Rule. Federal Register. Vol. 67, No. 9. p. 1811, January
14,2002. .
USEPA. 2002b. Consideration of Other Regulatory Revisions for Chemical Contaminants in
Support of the Six-Year Review of National Primary Drinking Water Regulations EPA
Report 815-D-02-003. Draft. March 2002.
USEPA, 2002c. Quality Assurance for the Six-Year Review of National Primary Drinking Water
Regulations. Memo from Judy Lebowich and Wynne Miller, Targeting and Analysis
Branch. Office of Ground Water and Drinking Water. March 2002.
USEPA. 2002d. Six-Year Review - Chemical Contaminants - Health Effects Technical Support
Document. EPA Report 822-R-02-001. Draft. February 2002.
USEPA. 2002e. Six-Year Review of the Total Coliform Rule - Comments Received. Memo
from Kenneth H. Rotert, Standards and Risk Reduction Branch, Office of Ground Water
and Drinking Water. March 2002.
Protocol for the Review ofNPDWRs
21
Draft - March 2002
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USEPA. 2002f. Six-Year Review - Chemical Contaminants - Health Effects Technical Support
Document. EPA Report 822-R-02-001. [Draft. February 2002.
USEPA. 2002g. Analytical Feasibility Support Document for the Six-Year Review of Existing
National Primary Drinking Water Regulations (Reassessment of Feasibility for Chemical
Contaminants). EPA Report 815-D-02-002. Draft. March 2002.
USEPA. 2002h. Water Treatment Technology Feasibility Support Document for Chemical
Contaminants; In Support of EPA Six-Year Review of National Primary Drinking Water
Regulations. EPA Report EPA 815-D-02-001. Draft. February 2002.
USEPA. 20021. Occurrence Estimation Methodology and Occurrence Findings Report for the
Six-Year Regulatory Review. EPA Report 815-D-02-005. Draft. March 2002.
Protocol for the Review ofNPDWRs
,28
Draft-March 2002
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Appendix A:
Appendix B:
Appendix G:
Appendix D:
APPENDICES
Pre-1997 National Primary Drinking Water
Regulations (NPDWRs)
Differences between the National Drinking Water
Advisory Council's (NDWAC's) Recommendations
and the Protocol
Overview of the IRIS Assessments
Overview of the OPP Process for Toxicity
Assessments
Appendix E: Overview of Analytical Methods Review Process
Protocol for the Review of NPDWRs
Draft - March 2002
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Appendix A: List of Pre-1997 National Primary Drinking
Water Regulations (NPDWRs)
Table A-l identifies the NPDWRs promulgated prior to the 1996 SDWA Amendments
(pre-1997 NPDWRs) and the rulemaking by which they were originally promulgated. EPA plans
to review these NPDWRs by 2002 in accordance with the review protocol described in this
document. Table A-2 identifies the remaining pre-1997 NPDWRs which are being or have
already been reviewed in separate actions and the NPDWRs promulgated after the 1996 SDWA
Amendments. The NPDWRs listed in Table A-2 will be reviewed as a part of the 2002-2008
review cycle:
Table A-l: Pre-1997 NPDWRs Reviewed in Accordance with this Protocol
Contaminant
Corresponding NPDWR
Chemical Contaminants
Acrylamide
Atachlor
Antimony
Asbestos
Atrazine
Barium
Benzene
Benzo[a]pyrene
Beryllium
Cadmium
Carbofuran
Carbon tetrachloride
Chlordane
Chromium (total)
Copper
Cyanide
2,4-D
Dalapon
l,2-Dibromo-3-
chloropropane (DBCP)
[,2-Dichlorobenzene (p-
3ichlorobenzene)
[,4-Dichlorobenzene (p-
Dichlorobenzene)
: ,2-Dichloroethane
Ethylene dichloride)
. , 1 -Dichloroethy lene
Phase II Rule
Phase II Rule
Phase V Rule
Phase II Rule
Phase II Rule
Phase IIB Rule
Phase I Rule
Phase V Rule
Phase V Rule
Phase II Rule
Phase II Rule . •
Phase I Rule
Phase II Rule
Phase II Rule
Lead and Copper Rule (LCR)
Phase V Rule
Phase II Rule
Phase V Rule
Phase II Rule
Phase II Rule
Phase I Rule
Phase I Rule .
Phase I Rule
Contaminant
Corresponding NPDWR
Chemical Contaminants (continued)
cis- 1 ,2-Dichloroethylene
trans- 1,2-
Dichloroethylene :
Oichloromethane
(Methylene chloride)
1 ,2-Dichloropropane
Di(2-ethylhexyl)adipate
(DEHA)
Di(2-ethylhexyl)
phthalate (DEHP)
Dinoseb
Diquat
Endothall
Endrin
Epichlorohydrin
Ethylbenzene
Ethylene dibromide
(EDB)
Fluoride
Glyphosate
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Hexachlorocyclopenta-
diene •
Lead
Lindane
Mercury (Inorganic)
Vlethoxychlor
Phase II Rule
Phase II Rule
Phase V Rule
Phase II Rule
Phase V Rule
Phase V Rule
Phase V Rule
Phase V Rule
Phase V Rule
Phase V Rule
Phase II Rule
Phase II Rule
Phase II Rule
Fluoride Rule; Phase II Rule
revised monitoring requirements
Phase V Rule
Phase II Rule
Phase II Rule
Phase V Rule
Phase V Rule
LCR
Phase II Rule
Phase II Rule
Phase II Rule
Protocol for the Review of NPDWRs
A-l
Draft - March 2002
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Table A-l: Pre-1997 NPDWRs Reviewed in Accordance with this Protocol
Contaminant
Monochlorobenzene
(Chlorobenzene)
Nitrate (as N)
Nitrite (as N)
Oxamyl (Vydate)
Pcntachlorophenol
Picloram
Polychlorinated biphenyls
(PCBs)
Selenium
Simazine
Styrene
2,3,7,8-TCDD (Dioxin )
retrachloroethylene
Corresponding NPDWR
Phase II Rule
Phase II Rule
Phase II Rule
Phase V Rule
Phase IIB Rule
Phase V Rule
Phase II Rule
Phase II Rule
Phase V Rule
Phase II Rule
Phase V Rule
Phase II Rule
Contaminant
Thallium
Toluene
Toxaphene
2,4,5-TP (Silvex)
1 ,2,4-Trichlorobenzene
1,1,1 -Trichloroethane
1 , 1 ,2-Trichloroethane
Trichloroethylene
Vinyl chloride
Xylenes (total)
Corresponding NPDWR
Phase V Rule
Phase II Rule
Phase II Rule
Phase II Rule
Phase V Rule
Phase I Rule
Phase V Rule
Phase I Rule
Phase I Rule
Phase II Rule
Microorganisms
Total coliforms
(including fecal coliform
and E. coli)
Total Coliform Rule (TCR)
Dates of original promulgation are as follows: ;
-PhascIIRule: 56 FR 3526, January 30, 1991 (USEPA, 1991a) -L^:^6^26XU^19.91.^S^},9^ ,„„„
- Phase V Rule- 57 FR 31776 July 17 1992 (USEPA 1992) , ' Fl"°nde Rule: 51 FR 1 1396, April 2, 1986 (USEPA, 1986)
-PhSeHBRule: 56^3M^My 1, I»l OJOTPA, 1991c) , -TCR: 54 FR 27544, June 29, 1989(USEPA, 1989b)
- Phase I Rule: 52 FR 25690, July 8, 1 987 (USEPA, 1 987) !
Protocol for the Review of NPDWRs
A-2
Draft - March 2002
_
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Table A-2: NPDWRs Not Covered by this Protocol
Contaminant/Indicator
Corresponding NPDWBJ
Reason Not Included
Chemical Contaminants
Arsenic
Pre-1986 National Interim Primary
Drinking Water Regulation (NIPDWR)
Reviewed/revised under January 22,
2001 Arsenic Rule2'3
Radionuclides
Beta particles and photon emitters
Gross alpha particle activity
Radium-226/228 (combined)
Uranium
Pre-1 986 NIPDWR
2000 Radionuclides Rule
Reviewed/revised under December 7,
2000 Radionuclides Rule2
Promulgated after 1996. NPDWR
established in the December 7, 2000
Radionuclides Rule2
Microorganisms
Cryptosporidium
Giardia lambia
Heterotrophic plate count (HPC)
Legionella
Turbidity
Viruses
Interim Enhanced Surface Water
Treatment Rule (IESWTR)
Long-Term 1 Enhanced Surface Water
Treatment Rule (LT1ESWTR)
Surface Water Treatment Rule (SWTR);
IESWTR; LT1ESWTR
SWTR
SWTR
SWTR; IESWTR; LT1ESWTR
SWTR; IESWTR; LT1ESWTR
Subject of ongoing ralemaking activity -
Long-Term 2 ESWTR (LT2ESWTR)
(November 2003)4
Disinfection Byproducts
Bromate ion
Chlorite ion
Haloacetic acids: Monobromoacetic
acid; Dibromoacetic acid;
Monochloroacetic acid;
Dichloroacetic acid; and
Trichloroacetic acid
Total Trihalomethanes (TTHMs):
Chloroform; Bromodichloro-
methane; Dibromochloromethane;
and Bromoform
Disinfectants and Disinfection
Byproducts Rule Stage 1 (DBPR)
TTHM Rule; Requirements revised
under Stage 1 DBPR
Revised rule promulgated after 1996 and
additional revisions to be considered
under Stage 2 DBPR (July 2003)'1
Revised rule promulgated after 1996 and
additional revisions to be considered
under Stage 2 DBPR (July 2003)"
Disinfectant Residuals
Chlorine
Chloramines
Chlorine dioxide
Stage 1 DBPR
Revised rule promulgated after 1996
Protocol for the Review of NPDWRs
A-3
Draft - March 2002
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Table A-2: NPDWRs Not Covered by this Protocol
1 Dates of original promulgation are as follows:
-ArsenicRule: 40FR59566,December24,1975(USEPA, 1975)
- Radionuclides Rule: 41 FR 28402, July 9, 1976 (USEPA1, 1976)
- IBS WTR: 63 FR 69478, December 16,1998 (USEPA, 1998c)
-LT1ESWTR: 67FR 1811, January 14,2002 (USEPA, 2002a)
- SWTR:.54F.R 27486, June 29,1989 (USEPA, 1989b) ,
- Stage 1 DBPR Rule: 63 FR 69389, December 16,1998 (USEPA, 1998b)
-TTHMRule: 44 FR 68624, November 29, 1979 (USEPA, 1979)
2 Indicates date of rule revision. ;
- Arsenic Rule: 66 FR 6976, January 22,2001 (USEPA, 2J)01b)
- Radionuclides Rule: 65 FR 76707, December 7,2000 (IJSEPA, 2000c)
3 After promulgation of the revised arsenic NPDWR on January 22, 2001, EPA initiated a review of the new maximum contaminant
level (MCL), and postponed the effective date, of the rule until Fpbruary 22,2002. EPA requested independent expert panel reviews
of the science, cost and benefits analyses for the January 2001 rule, and in July 2001, sought additional public comment on a range of
MCLs. Following receipt of the final expert panel reports in the1 Fall of 2001, EPA requested comment on the reports. EPA will
continue to evaluate the expert panel reports, the voluminous comments received during these comment periods, and other relevant
information and comments as they become available as part of the next six-year review; EPA expects to make a final decision on
whether to revise the January 2001 rule as part of that six-year review, which is due in August 2008. In the meantime, as announced
by the Administrator on October 31,2001, EPA will not further postpone the January 2001 rule, and EPA also does not expect to
take any other additional action relative to the July 2001 proposal in the interim. The revised arsenic MCL became effective on
February 22,2002. The date for compliance with the MCL remains January 23,2006.
4 Indicates anticipated date of promulgation.
Protocol for the Review of NPDWRs
L-4
Draft - March 2002
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Appendix B: Differences between the National Drinking Water Advisory Committee's
(NDWAC's) Recommendations and this Protocol
This table indicates those NDWAC recommendations that EPA either did not incorporate or that
EPA changed substantially in this protocol document. Overall, EPA incorporated the majority of
the NDWAC's recommendations.
NDWAC Recommendation
EPA Response
EPA should review the basis of all existing
National Primary Drinking Water Regulations
(NPDWRs) during the first review round (i.e., the
review round ending August 2002)
EPA does not believe that such a review is
practical in light of resource constraints and has
not incorporated it into the protocol. EPA will
review the basis of existing regulations only if
new data suggest the need for regulatory
revision(s).
Effective with review rounds starting after
August 2002, EPA should complete both the
review and the revision within the six-year
window.
This recommendation does not apply to the 1996-
2002 review round.
EPA should fully consider "other regulatory
revisions" (e.g., monitoring requirements system
data reporting requirements, etc.) as a part of the
Six-Year Review process.
EPA believes that many of these issues are best
addressed through mechanisms other than the
Six-Year Review process. Where appropriate
alternative mechanisms to consider these issues
are not available, EPA may consider them as a
part of the Six-Year Review if they meet the
following criteria:
• they indicated a potential change in 40 CFR
141 requirements;
• they are "ready" for rulemaking - that is,
the problem to be resolved has been clearly
identified and specific option(s) have been
formulated to address the problem; and
• they clearly improve the level of public
health protection and/or represent
significant cost-saving while maintaining or
improving public health protection.
EPA should consider non-regulatory options, in
addition to regulatory changes, if the costs of
other regulatory compliance are considered to be
too high or interim measures are needed pending
promulgation of a rule.
EPA agrees that this suggestion has merit but
believes it is outside the scope of the Six-Year
Review effort and should be addressed through
alternative mechanisms. The recommendation
has not been incorporated into the protocol
document.
Protocol for the Review of NPDWRs
B-l
Draft - March 2002
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NDWAC Recommendation
EPA Response
EPA should consider changes in State data-
reporting requirements, as well as changes to
system data-reporting requirements, as a part of
the Six-Year Review process.
EPA believes that revisions to State data-
reporting requirements are best considered
through other mechanisms outside the scope of
the Six-Year Review effort. The
recommendation has not been incorporated into
the protocol document.
EPA should consider multi-media mitigation
options as a part of the Six-Year Review process.
Efforts to pursue multi-media mitigation for
contaminants are outside the scope of the six-year
process, except in those instances where the
SDWA specifically authorizes EPA to consider a
multi-media approach as a part of the NPDWR.
Therefore, consideration of multi-media
mitigation is outside the scope of the 1996-2002
Six-Year Review.
EPA should quantify, to the maximum extent
practicable, costs and benefits associated with
possible regulatory revisions.
EPA does not believe it is practicable to quantify
costs and benefits during the review phase. This
is best done as a part of the rulemaking phase
before EPA proposes actual revisions. Instead,
EPA will conduct a qualitative assessment of
economic considerations for those NPDWRs
where a health or technical basis exists for a
possible regulatory revision.
Protocol for the Review of NPDWRs
B-2
Draft - March 2002
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Appendix C: Overview of the IRIS Assessments
The Integrated Risk Information System (IRIS) is an EPA database containing Agency
consensus scientific positions on potential adverse human health effects that may result from
chronic exposure to chemical substances found in the environment.11 Assessments by IRIS
undergo internal and external peer reviews by health scientists.
The main reasons for including a chemical in the IRIS program are (1) Agency statutory,
regulatory, or program implementation needs; arid (2) availability of new scientific information
or new methodology that might significantly change current IRIS assessment.
IRIS assessments are based solely on scientifically valid studies. Evaluations of original
toxicological and epidemiological studies conducted by the National Toxicology Program,
National Cancer Institute, National Institute of Environmental Health Sciences, EPA's National
Center for Environmental Assessment, industry, universities, etc., are all used in risk assessment.
These studies are individually evaluated for their soundness, methodological strength and
weaknesses, and whether or not they have been conducted according to current quality standards.
IRIS reviews are not based on secondary sources such as reviews conducted by other
national or international organizations (e.g., State of California, World Health Organization or
the International Agency for Research oil Cancer), although such assessments are often examined
as part of the IRIS review.
A full list of chemicals assessed in IRIS and those for which assessments are planned can
be found on IRIS web site (http://www.epa.gov/irisV A large number of these IRIS assessments
are of direct relevance to the regulatory function of Office of Water (OW) and more specifically
to the six-year review. Some of the reviews are being conducted by OW. Others were
nominated for review by OW.
11 IRIS contains chemical specific health effects inform ation. Information on synergistic effects of chemical
mixtures is scarce and is seldom available for inclusion in IRIS.
Protocol for the Review ofNPDWRs
, C-l
Draft-March 2002
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Appendix D: Overview of the OPP Process for Toxicity Assessments
Under the requirements of Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA),
a registrant (manufacturer) is required to submit animal toxicity data on the potential human
health effects that may be posed by pesticide chemicals. Toxicity data are provided during the
initial registration of a pesticide as well as during the periodic re-registration review of the
pesticide as required by FIFRA. The schedule, priority, for when an existing pesticide enters a
re-review is set in part by regulatory requirements which include provisions to give priority to
certain active ingredients. The Office of Pesticides Programs (OPP) will establish the review
schedule taking into account the procedures outlined in the Act. A more complete discussion of
the re-registration process can be found in Section 4(a)-(f) of FIFRA.
In 1998, The Office of Water's (OW's) Office of Ground Water and Drinking Water
(OGWDW) and the OPP established major areas of coordination on cross-cutting scientific
issues. Included in the major efforts was the harmonization of the human health hazard
assessments and dose-response relationships for pesticides. The two offices have agreed to share
health effects data and coordinate activities on the issues such as endpoint selection, dose-
response information, and quantifying risks. Therefore, the OW and OPP are working closely on
establishing consistency in health effects endpoints through resource and information sharing.
The OPP receives health effects data that are generated under specific scientific
guidelines established by the Agency and conducted under the requirements of Good Laboratory
Practices. These guidelines are available on the EPA's Internet site at the following location:
http://www.epa.gov/opptsfrs/OPPTS_Harmonized/870_Health_Effects_Test_Guidelines/indexx.
html. • , . . . ' . ' . ..
In addition to the required guideline studies, the OPP will obtain and review open
literature data on adverse effects to test species. Although these studies are not used in
establishing health end-points (reference doses (RfDs) and cancer potency or threshold values),
they are used in establishing the "weight of evidence" for an adverse effect. Data sources
include, but are not limited to, published, peer-reviewed journal articles in the open literature and
toxicity data submitted to other U.S. federal or international agencies that do not conform to the
OPP's test guidelines.
Below is a brief-overview of end-point selection.
Toxicity Assessment
Non-Cancer Effects:
Reference Dose. For non-cancer effects, toxicity is represented by an RfD; it may be
calculated for acute effects (acute RfD (aRfD)) and chronic effects (chronic RfD (cRfD)). RfDs
are calculated by determining the No-Observed-Adverse-Effeet Level (NOAEL) or bench-mark
dose point of departure from either acute or chronic toxicity studies (the choice of study depends
on which type of RfD is being calculated - aRfD or cRfD) and dividing it by the appropriate
uncertainty factors. Typically, an uncertainty factor is applied to account for: variation within
the human population (i.e., intraspecies); the differences between humans and animals as the
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animal data are extrapolated to humans (interspecies); the duration of the study; the end point
used in the calculation (NOAEL or Lowest-Observed-Adverse-Effect Level (LOAEL)); and the
completeness of the database. |
If the RfD will be used in dietary risk assessment, then it is adjusted to take into account
the Food Quality Protection Act (FQPA) Safety Factor for infants and children. Such an adjusted
RfD is called a Population Adjusted Dose (PAD). Like the RfD, it may be acute (aPAD) or
chronic (cPAD). In making the decision regarding the FQPA Safety Factor, the Agency takes
into account both information on the toxicity of the pesticide and the completeness of the toxicity
and exposure databases. For more information1 on how the Agency applies the FQPA Factor, see
the document "Standard Operating Procedures for use of FQPA Safety Factor," April 26, 1999 at
http://www.epa.gov/pesticides/trac/science/. However, these standard operating procedures are
currently under revision; and notification of the release of these revisions is posted at:
http://www.epa.gov/oppfeadl/trac/science. ; ,
Cancer Effects:
Linear Effect - Cancer Potency Factor {ql *). The cancer potency factor, which is
commonly known as a ql*, is the relative strength of a carcinogen. The bigger the ql*, the more
potent the carcinogen. It is calculated using a computer model that assumes linearity at doses
below which the effect occurred in the studies.
Non-Linear Effect - Margin of Exposure. For some carcinogenic pesticides, it is not
considered appropriate to calculate a potency factor. In these cases, the cancer effect is assumed
to have a threshold, as for non-cancer effects, and as such, a Margin of Exposure (MOE) is
derived. The MOE is a ratio calculated by dividing the toxicity Point of Departure (such as a
NOAEL or benchmark dose) by the estimated or calculated exposure level. EPA has not yet
established a policy on the level of risk that is of no concern for non-linear cancer risk
assessment. .......
!
During the review of the toxicity data and the dose-response assessment, the pesticide
being evaluated undergoes review by several in-house peer review committees.
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Appendix E: Overview of the Analytical Methods Review Process
A. What Section ofSD WA Requires the Agency to Specify Analytical Methods?
The Safe Drinking Water Act (SDWA) directs EPA to promulgate National Primary
Drinking Water Regulations (NPDWRs) which specify either maximum contaminant levels
(MCLs) or treatment techniques (TTs) for drinking water contaminants (SDWA section 1412; 42
U.S.C. § 300g-l). According to SDWA (Section 1401(1)(D)), NPDWRs include "criteria and
procedures to assure a supply of drinking water which dependably complies with such maximum
contaminant levels; including accepted methods for quality control and testing procedures to
insure compliance with such levels." (42 U.S.C. § 300f(l)(D)) Moreover, EPA is to set an MCL
for such NPDWRs "if, in the judgement of the Administrator, it is economically and
technologically feasible to ascertain the level of a contaminant in water in public water systems."
(SDWA section 1401(l)(C)(i); 42 U.S.C. § 3"OOf(l)(C)(i)). Alternatively, if it is not
economically or technologically feasible to so ascertain the level of a contaminant, the
Administrator may identify known TTs, which sufficiently reduce the contaminant in drinking
water, in lieu of an MCL (SDWA section 1401(l)(C)(ii)).
B. What is the Typical Process for Approving Methods for SD WA Analytes?
Methods are initially approved as a part of an MCL or monitoring requirement
rulemaking. Thereafter, as revisions to the approved methods are published or as new
technologies are developed, the Agency, from time-to-time, will group a set of methods for
proposal in a methods update rule. It generally takes 18 to 24 months to promulgate a methods
update rule. This can increase significantly if there is adverse public comment on a proposed
method.
The revised or new methods included in a methods update rule may be from EPA, other
Federal or State agencies, or standards organizations (e.g. American Society for Testing and
Materials (ASTM) or Standard Methods (SM)). These non-EPA entities have independent
review and/or collaborative testing requirements. In addition, under 40 CFR 141.27 (alternate
analytical techniques, also known as alternate test procedures or ATP) methods may also be
developed by private laboratories, vendors or groups. Independent review and collaborative
testing of these privately developed methods is accomplished by requiring submission of the
method to the Agency under the alternate test procedure (ATP) program. An alternate technique
is accepted "only if it is substantially equivalent to the prescribed test in both precision and
accuracy as it relates to the determination of compliance with the MCL." (40 CFR 141.27(a))
Initially, many ATP applications are missing data. Once a completed ATP application is
recorded by the Agency, the ATP pass/fail decision generally takes three to four months. For
successful ATPs, this period is followed by the formal rulemaking process, which was described
above as taking 18-24 months.
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C WJiat Factors Does the Agency Consider in Approving Analytical Methods and in
Determining Feasible Limits?
i .
In deciding whether an analytical method is economically and technologically feasible to
determine the level of a contaminant in drinking water, the Agency generally considers the
following (50 FR 46880, November 13, 1985 (USEPA, 1985); 52 FR 25690, July 8, 1987
(USEPA, 1987); 54 FR 22062, May 22, 1989a)^
• Is the method sensitive enough to address the level of concern (i.e., is quantitation
sufficient to meet the MCL)?
• Does the method give reliable analytical results at the MCL? What is the precision (or
reproducibility) and the bias (accuracy or recovery)?
• Is the method specific? Does the method identify the contaminant of concern in the
presence of potential interferences?
• Is the availability of certified laboratories, equipment and trained personnel sufficient
to conduct compliance monitoring?
• Is the method rapid enough to permit routine use in compliance monitoring?
• What is the cost of the analysis to Water Supply systems?
Regarding the first criteria (i.e., sensitivity), the method detection limit (MDL) and the
practical quantitation level (PQL) are two performance measures used by EPA to estimate the
limits of performance of analytic chemistry methods for measuring contaminants in drinking
water. For SDWA analytes, EPA defines the MDL as "the minimum concentration of a
substance that can be measured and reported with 99% confidence that the analyte concentration
is greater than zero"(40 CFR Part 136 Appendix B). MDLs can be operator, method, laboratory,
and matrix specific. MDLs are not necessarily reproducible within a laboratory or between
laboratories on a daily basis due to the day-to-day analytical variability that can occur and the
difficulty of measuring an analyte at very low concentrations. In an effort to integrate this
analytical chemistry data into regulation development, the Agency uses the PQL to estimate or
evaluate the minimum, reliable quantitation level that most laboratories can be expected to meet
during day-to-day operations. EPA's Drinking Water program generally defines the PQL as "the
lowest level that can be reliably achieved within specified limits of precision and accuracy during
routine laboratory operating conditions" (50 FR 46906, November 13, 1985 (USEPA, 1985))
For several SDWA analytes, EPA has set the MCL at the PQL.
D. How Are PQLs Typically Determined for SDWA Contaminants?
Historically, EPA's OGWDW has used two main approaches to determine a PQL for
SDWA analytes. The preferred approach, the WS method, uses data from WS studies to
calculate the lower limit of quantitation. The WS method was used in most cases when sufficient
WS data are available to calculate a PQL. In the absence of WS data, the second approach that
EPA used was the MDL multiplier method. In jthis approach, the PQL was calculated by
multiplying the EPA-derived MDL by a factor of 5 or 10. The 5 or 10 multiplier was used to
account for the variability and uncertainty that pan occur at the MDL.
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1. How Were Water Supply Studies Conducted?
Water supply laboratory performance evaluation (PE) studies have been an integral part
of EPA's certification program for drinking water laboratories for over 20 years. Historically,
EPA's National Exposure Research Laboratory (NERL) in Cincinnati, Ohio conducted WS
studies for all current and proposed drinking water contaminants. Although EPA conducted the
WS studies semi-annually, for certification purposes, laboratories were only required to
demonstrate acceptable performance once a year (141.23(k)(3) and 141.24(f)(17)).
Each WS study included WS samples (or sample concentrates) that were analyzed for
both SDWA analytes and analytes being considered for regulation under the SDWA. During
these WS studies, EPA-NERL sent participating laboratories a set of the stable WS sample
concentrates in sealed glass ampules, a data reporting form, and appropriate instructions.
EPA-NERL sent WS samples to all laboratories that conducted drinking water analyses,
including utility laboratories, commercial laboratories, and State and EPA Regional laboratories.
With appropriate dilution, the laboratory then analyzed the WS samples using the specified
procedures. Afterwards, the laboratory sent the completed reporting form to EPA for evaluation.
After evaluation, EPA returned a fully detailed report to each participating laboratory.
At this point in time, WS PE studies are no longer performed by EPA. On July 18, 1996
(61 FR 37464 (USEPA, 1996)), EPA proposed options for the externalization of the PE studies
program (now referred to as the Proficiency Testing or PT program). After evaluating public
comment, in the June 12, 1997 final notice EPA stated that the Agency has decided (62 FR
32113 (USEPA, 1997b)):
...on a program where EPA would issue standards for the operation of the program, the
National Institute of Standards and Technology (NIST) would develop standards for
private sector PE (PT) suppliers and would evaluate and accredit PE suppliers, and the
private sector would develop and manufacture PE (PT) materials and conduct PE (PT)
studies. In addition, as part of the program, the PE (PT) providers would report the
results of the studies to the study participants and to those organizations that have
responsibility for administering programs supported by the studies.
2. PQL Determinations - How Are WS Studies Evaluated and What Criteria Are
Used?
The derivation of the PQL involves determining the concentration of an analyte at which
a set percentage of the laboratories achieve results within a specified range of the spiked value.
Historically, the percentage of laboratories was set at 75 percent, while a range of acceptance
limits around the spiked value were used. In many cases, EPA derived PQLs only from the data
submitted by the EPA Regional and State laboratories that participate in the WS studies.
A PQL derived from WS data in such a manner is considered a stringent target for routine
laboratory performance because:
• WS samples are prepared in reagent water and therefore do not contain the matrix
interferences that may occur in field samples.
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Laboratories analyze only a small number of samples for the study and are aware that
the samples are for the purposes of PE (i.e., they are not "blind" samples).
In deriving a PQL from WS study data, the Agency typically sets a fixed percentage or 2
sigma (2 standard deviation) acceptance window around the known concentration (or spike
value) of the WS samples. Then percentage of laboratories achieving results within the specified
acceptance window (y-axis) is plotted against the known spike concentration of the Water Supply
study samples (x-axis). While the acceptance limits for inorganics typically range from 15 to 30
percent, the acceptance limits for organics generally range from 40 to 50 percent. Several
SDWA analytes have acceptance limits of 2 sigma (2 standard deviation). Linear regression or
graphical analysis is performed on the WS datafto determine the concentration at which 75
percent of EPA Regional and State laboratories achieve acceptable results.
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