[Federal Register Volume 68, Number 138 (Friday, July 18, 2003)]
[Notices]
[Pages 42908-42929]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18152]
[[Page 42907]]
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Part VI
Environmental Protection Agency
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National Primary Drinking Water Regulations; Announcement of Completion
of EPA's Review of Existing Drinking Water Standards; Notice
Federal Register / Vol. 68, No. 138 / Friday, July 18, 2003 /
Notices
[[Page 42908]]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-7529-1]
RIN 2040-AD67
National Primary Drinking Water Regulations; Announcement of
Completion of EPA's Review of Existing Drinking Water Standards
AGENCY: Environmental Protection Agency.
ACTION: Notice.
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SUMMARY: The Safe Drinking Water Act (SDWA) requires the United States
Environmental Protection Agency (EPA) to conduct a periodic review of
existing National Primary Drinking Water Regulations (NPDWRs). EPA has
completed its review of 69 NPDWRs that were established prior to 1997,
including 68 chemical NPDWRs and the Total Coliform Rule (TCR). The
intended purpose of the review was to identify those NPDWRs for which
current health risk assessments, changes in technology, and/or other
factors, provide a health or technological basis to support a
regulatory revision that will maintain or improve public health
protection.
EPA published its protocol for the review of NPDWRs and its
preliminary revise/not revise decisions for the 69 NPDWRs in the April
17, 2002, edition of the Federal Register (67 FR 19030 (USEPA, 2002g))
in order to seek comment from the public. Today's action briefly
describes the major comments, other new information, and EPA's current
revise/not revise decisions for the 69 NPDWRs.
ADDRESSES: The official public docket for this action is located at EPA
West Building, Room B102, 1301 Constitution Avenue, NW., Washington,
DC.
FOR FURTHER INFORMATION CONTACT: Contact: Ken Rotert, (202) 564-5280,
e-mail: [email protected] for inquiries regarding the TCR. For all
other technical inquiries contact: Judy Lebowich, (202) 564-4884, e-
mail: [email protected], or Wynne Miller, (202) 564-4887, e-mail:
[email protected]. General information may also be obtained from the
EPA Safe Drinking Water Hotline. Callers within the United States may
reach the Hotline at (800) 426-4791. The Hotline is open Monday through
Friday, excluding Federal holidays, from 9 a.m. to 5:30 p.m. Eastern
Time.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. General Information
A. Does this Notice Apply to My Public Water System?
B. How Can I Get Copies of Related Information?
1. Docket
2. Electronic Access
II. Background
A. What Is the Statutory Requirement for the Six-Year Review?
B. What Has the Agency Done to Address the Statutory
Requirement?
III. EPA's Current Revise/Not Revise Decisions for the 69 Pre-1997
NPDWRs
IV. Summary of Major Comments and New Information and the Agency's
Response
A. What Did Commenters Say Regarding the Reasonableness and
Appropriateness of EPA's Six-Year Review Approach?
1. Overall Approach and Decision Criteria
2. Health Effects Technical Review
3. Analytical Methods Feasibility Technical Review
4. Review of Treatment Technologies and Related Issues
5. Review of Implementation-Related Issues
6. Review of Occurrence and Exposure
7. Consideration of Available Economic Information
B. What Comments or New Information Did EPA Receive on Chemical
Contaminant-Specific Issues?
1. Alachlor
2. Antimony
3. Atrazine
4. Beryllium
5. Carbofuran
6. Chromium
7. 1,1-Dichloroethylene
8. Dichloromethane
9. Di(2-ethylhexyl)adipate (DEHA)
10. Di(2-ethylhexyl)phthalate (DEHP)
11. Fluoride
12. Glyphosate
13. Lead and Copper
14. Lindane ([gamma]-hexachlorocyclohexane)
15. Simazine
C. What Comments Did EPA Receive Regarding the Review of
Implementation-Related Issues for Chemical NPDWRs?
D. What Comments Did EPA Receive on the Total Coliform Rule?
E. What Comments Did EPA Receive on Research Needs?
V. References
List of Tables
Table III-1: Current Revise/Not Revise Decisions for the 68 Chemical
NPDWRs and the TCR
Table IV-1: 1,1-Dichloroethylene Occurrence
Table IV-2: Lindane Occurrence
I. General Information
A. Does This Notice Apply to My Public Water System?
This action itself does not impose any requirements on anyone.
Instead, it notifies interested parties of the availability of EPA's
responses to comments received on EPA's Six-Year Review protocol and
the Agency's current revise/not revise decisions for 69 NPDWRs.
B. How Can I Get Copies of Related Information?
1. Docket
EPA has established an official public docket for this action under
Docket ID No. OW-2002-0012. The official public docket consists of the
documents specifically referenced in this action, any public comments
received, and other information related to this action. Although a part
of the official docket, the public docket does not include Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. The official public docket is the collection of
materials that is available for public viewing at the Water Docket in
the EPA Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution
Ave., NW., Washington, DC. The EPA Docket Center Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the Water Docket is (202)
566-2426.
2. Electronic Access
You may access this Federal Register document electronically
through the EPA Internet under the ``Federal Register'' listings at
http://www.epa.gov/fedrgstr/.
An electronic version of the public docket is available through
EPA's electronic public docket and comment system, EPA Dockets. You may
use EPA Dockets at http://www.epa.gov/edocket/ to view public comments,
access the index listing of the contents of the official public docket,
and access those documents in the public docket that are available
electronically. Although not all docket materials may be available
electronically, you may still access any of the publicly available
docket materials through the docket facility identified in section
I.B.1. Once in the system, select ``search,'' then key in the
appropriate docket identification number.
Abbreviations and Acronyms Used in This Action
BAT--best available technology
CBI--confidential business information
CCL--contaminant candidate list
CFR--Code of Federal Regulations
CMR--Chemical Monitoring Reform
DACT--diaminochlorotriazine
DEA--desethyl atrazine
DEHA--di(2-ethylhexyl)adipate
DEHP--di(2-ethylhexyl)phthalate
DIA--desisopropyl atrazine
EPA--United States Environmental Protection Agency
[[Page 42909]]
EPA/DC--EPA Docket Center
FQPA--Food Quality Protection Act
FR--Federal Register
IOC--inorganic chemical
IRED--interim reregistration eligibility decision
IRIS--Integrated Risk Information System
LCCA--Lead Contamination Control Act of 1988
LCR--Lead and Copper Rule
MCL--maximum contaminant level
MCLG--maximum contaminant level goal
MDL--method detection limit
mg/kg/day--milligram(s) per kilogram of body weight per day
mg/L--milligram(s) per liter
MYP--multi-year plan
NAS--National Academy of Sciences
NCOD--National Contaminant Occurrence Database
NDWAC--National Drinking Water Advisory Council
NPDWR--National Primary Drinking Water Regulation
NRC--National Research Council
NTP--National Toxicology Program
NTNCWS--non-transient non-community water system
Occurrence Methodology Document--Occurrence Estimation Methodology and
Occurrence Findings Report for the Six-Year Review of Existing National
Primary Drinking Water Regulations
Occurrence Summary Document--Occurrence Summary and Use Support
Document for the Six-Year Review of Existing National Primary Drinking
Water Regulations
OPP--Office of Pesticide Programs
OW--Office of Water
PE--performance evaluation
PHS--Public Health Service
PQL--practical quantitation level
Protocol Document--EPA Protocol for Review of Existing National Primary
Drinking Water Regulations
RED--reregistration eligibility decision
RfD--reference dose
ROS--regression on ordered statistics
RSC--relative source contribution
SAB--Science Advisory Board
SAP--Science Advisory Panel
SDWA--Safe Drinking Water Act
SOC--synthetic organic chemical
TCR--Total Coliform Rule
TMDLs--total maximum daily loads
Treatment Feasibility Document--Water Treatment Technology Feasibility
Support Document for Chemical Contaminants; In Support of EPA Six-Year
Review of National Primary Drinking Water Regulations
TT--treatment technique
VOC--volatile organic chemical
WQP--water quality parameter
WS--water supply
II. Background
A. What Is the Statutory Requirement for the Six-Year Review?
Under the Safe Drinking Water Act (SDWA), as amended in 1996, EPA
must periodically review existing National Primary Drinking Water
Regulations (NPDWRs) and, if appropriate, revise them. Section
1412(b)(9) of SDWA states:
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.
B. What Has the Agency Done To Address the Statutory Requirement?
The Agency developed a systematic process, or protocol, for the
review of existing NPDWRs in accordance with the SDWA requirements and
applied the protocol to the review of the NPDWRs for total coliforms
and 68 inorganic and organic chemicals published prior to the SDWA 1996
Amendments (i.e., pre-1997 NPDWRs). In the April 17, 2002, Federal
Register, EPA provided:
[sbull] A description of the review protocol;
[sbull] A detailed discussion of how the protocol was applied in
assessing each of the 69 pre-1997 NPDWRs;
[sbull] The preliminary results of each of the technical reviews,
and the preliminary decision for each NPDWR; and
[sbull] A request for the public to comment on any aspect of the
Agency's protocol and preliminary decisions.
Please refer to the April 17, 2002, Federal Register for the
detailed discussion of EPA's revise/not revise decisions for each of
the 69 NPDWRs. Today's action briefly summarizes the major public
comments, other new information, and EPA's current revise/not revise
decisions for the 69 NPDWRs. Today's action only discusses in detail
those decisions or rationales that were affected by public comments or
other new information that has become available since April 2002.
In June 2002, EPA consulted with the Science Advisory Board (SAB)
Drinking Water Committee and requested their review and comment on
whether the protocol EPA developed based on the National Drinking Water
Advisory Council (NDWAC) recommendations was consistently applied and
appropriately documented. The SAB provided verbal feedback regarding
the transparency and clarity of EPA's decision criteria for making its
revise/not revise decisions under the current review. EPA has revised
this protocol document to better explain how the decision criteria were
applied and will also take the SAB comments into consideration when
planning for the next review cycle.
III. EPA's Current Revise/Not Revise Decisions for the 69 Pre-1997
NPDWRs
EPA received comments from 44 commenters on its preliminary revise/
not revise decisions in the April 17, 2002, Federal Register. The
Agency responded to these comments in the ``Public Comment and Response
Summary for the Six-Year Review of National Primary Drinking Water
Regulations'' (USEPA, 2003e), which is available in the Water Docket in
the EPA Docket Center and at the EPA Dockets Web site http://www.epa.gov/epadocket/. Other technical support documents \1\ for the
decisions discussed in today's action are also available in the Water
Docket and at the EPA Dockets Web site http://www.epa.gov/epadocket/
and the Safewater Web site http://www.epa.gov/safewater/.
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\1\ These include: (1) EPA's overall protocol for the review of
NPDWRs (USEPA, 2003c); (2) health effects (USEPA, 2003f); (3)
analytical methods feasibility (USEPA, 2003a); (4) treatment
technology (USEPA, 2003g); (5) consideration of other regulatory
revisions (USEPA, 2003b); (6) occurrence and exposure (USEPA, 2003d;
USEPA, 2002f); (7) and economic considerations (USEPA, 2002c).
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Based on the Agency's preliminary review, as well as the public
comments received and other new information, EPA believes that it is
appropriate to revise the Total Coliform Rule (TCR). The Agency also
believes that it is not appropriate to revise the 68 chemical NPDWRs at
this time. However, for the reasons discussed in sections IV.B.7,
IV.B.13, and IV.B.14 of today's action, the Agency has modified the
basis of its not revise findings for 1,1-dichloroethylene, lead, and
lindane, respectively. Table III-1 reflects the Agency's current
revise/not revise decisions for the 69 NPDWRs. As indicated in Table
III-1, EPA's decision not to revise an NPDWR at this time is based on
one of the following reasons:
[sbull] Health risk assessment is in process: As of December 31,
2002, 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, or were not available in time for
consideration under the 1996-2002 review cycle, the Agency does not
believe it is appropriate to revise the NPDWR at this time. In these
cases, EPA will consider the results of the updated
[[Page 42910]]
health risk assessment during the 2002-2008 review cycle. If the
results of the health risk assessment indicate a compelling reason to
reconsider the maximum contaminant level goal (MCLG), EPA may decide to
accelerate the review schedule for that contaminant's NPDWR.
[sbull] 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.
[sbull] New information, but no revision appropriate at this time
because:
--Low priority: In EPA's judgment, any resulting revisions to the NPDWR
would not provide a meaningful opportunity for health risk reduction or
result in meaningful cost-savings to public water systems and their
customers. These revisions are a low priority activity for the Agency
and, thus, are not appropriate for revision at this time because of one
or more of the following considerations: competing workload priorities;
the administrative costs associated with rulemaking; and the burden on
States and the regulated community to implement any regulatory change
that resulted.
--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 time.
BILLING CODE 6560-50-P
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[GRAPHIC] [TIFF OMITTED] TN18JY03.070
BILLING CODE 6560-50-C
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IV. Summary of Major Comments and New Information and the Agency's
Response
This section summarizes the major public comments, including the
Agency's response, and other new information, and explains any
modifications to EPA's preliminary revise/not revise decisions. For a
more detailed summary of the comments and the Agency's response, please
refer to the document: ``Public Comment and Response Summary for the
Six-Year Review of National Primary Drinking Water Regulation'' (USEPA,
2003e).
A. What Did Commenters Say Regarding the Reasonableness and
Appropriateness of EPA's Six-Year Review Approach?
1. Overall Approach and Decision Criteria
a. Adequacy of the Review. Commenters generally agreed that EPA had
identified the appropriate key elements of the review. However, some
commenters stated that the Agency could have done more in some areas
(e.g., implementation) and a few commenters expressed the opinion that
the Agency's review process contains weaknesses, or was not applied
appropriately, because it did not identify any chemical NPDWRs for
revision at this time.
EPA Response: The Agency believes that its basic review protocol
and decision rationale are reasonable and appropriate. Even though
EPA's application of the protocol did not identify any chemical NPDWRs
for revision at this time, that is not a reason to reject or modify the
protocol. The review did result in the initiation of health risk
assessments for three contaminants and efforts to address data gaps/
research needs for several other contaminants. Health risk assessments
are underway for approximately half of the chemical contaminants
addressed in today's action. The Agency expects most of these
assessments to be completed within the next few years. When completed,
these assessments will support further analysis that may result in
different revise/not revise decisions as part of the ongoing Six-Year
Review process.
b. Criteria for Deciding that an MCLG/MCL Revision is Appropriate
and Definition of ``Significant'' and ``Negligible.'' While some
commenters agreed, others disagreed with the Agency's consideration of
estimated changes in occurrence levels and available economic
information whenever a health or technological basis exists to revise a
standard. For example, some commenters felt that EPA should revise the
MCLG and, as appropriate, the maximum contaminant level (MCL), whenever
a health basis exists, regardless of other considerations. A few
commenters criticized the Agency for not defining what it considers
``significant'' and ``negligible'' gains in public health protection
and/or cost-savings in terms of regulatory revision.
EPA Response: Section 1412(b)(9) of SDWA, as amended in 1996,
provides the Administrator with broad discretion to determine when a
revision to an NPDWR is appropriate. As a part of this determination,
the Agency believes it is reasonable to consider whether a potential
revision is likely to provide a meaningful opportunity for health risk
reduction. This criterion is consistent with the statutory provisions
governing the regulatory determination process under section
1412(b)(1)(A) for contaminants not currently regulated. EPA also
believes it is reasonable to consider the extent of potential cost-
savings for public water systems and their customers when determining
whether revisions that potentially would result in a relaxed standard
(i.e., where a health basis exists for a less stringent standard) or
streamlined implementation are appropriate. These considerations allow
the Administrator to better prioritize efforts that are most likely to
result in a meaningful opportunity for health risk reduction or cost-
savings to public water systems and their customers. Revisions that do
not satisfy at least one of these criteria are a low priority activity
for the Agency, and thus are not appropriate at this time because of
one or more of the following considerations:
[sbull] Competing workload priorities;
[sbull] The administrative costs associated with rulemaking; and
[sbull] The burden on States and the regulated community to
implement any regulatory change that resulted.
EPA believes that the determination of whether the impact of a
potential revision is ``significant'' or ``negligible'' is a matter of
judgment that depends on a number of variables, not all of which are
amenable to precise definition. However, EPA recognizes that the use of
``negligible/significant'' terminology may imply more precision and
quantitation in the determination than is possible. The Agency also
understands that the use of the term ``negligible'' may imply to some
that the Agency is belittling small gains in health risk reduction.
This is not the Agency's intent. Accordingly, in today's action, the
Agency has explained its rationale more clearly in terms of the
criteria noted in the previous paragraph.
c. Authority to Relax an Existing Standard and Deregulation of Low/
Non-Occurring Contaminants. Some commenters argued that the Agency
should never consider relaxing a standard because doing so, by
definition, would lessen the level of public health protection. Other
commenters encouraged the Agency to actively consider deregulating
contaminants that have low occurrence or do not appear to be occurring
in finished water or, at a minimum, to further reduce the frequency of
monitoring for these contaminants.
EPA Response: EPA disagrees with those commenters who oppose
relaxing a standard for any reason. The legislative history of the SDWA
Amendments of 1996 makes clear that Congress envisioned the possibility
that a relaxed standard might be appropriate under circumstances that
would not result in a lessening of the level of public health
protection. In its discussion of potential revisions to an existing
drinking water standard, Senate Report Number 104-169 (available
electronically at http://thomas.loc.gov/) states:
Amendments made by the bill require that any future standard
issued for a contaminant already regulated must maintain or provide
for greater protection of the health of persons. Generally, this
will preclude the promulgation of a revised standard for a
contaminant that is less stringent than the standard already in
place. However, there are circumstances under which a standard may
be relaxed. The maximum contaminant level goal for a contaminant is
set at a level at which there is no adverse effect on the health of
persons with an adequate margin of safety. New scientific
information may cause the MCLG to be revised and in some cases these
revisions may be to less stringent levels. This may lead to a
revision of the maximum contaminant level since it need be no more
stringent than the MCLG. New information may also allow for a
smaller margin of safety because it narrows the range of uncertainty
for estimates of health risks. Finally, some substances which have
been regulated as carcinogens for ingestion in drinking water may be
reclassified (as asbestos has been in the most recent revision) or
assigned a threshold for the effect based on new scientific
information. In each of these cases, EPA may issue a revised
standard for a contaminant that is less stringent than the one it
replaces.
(S. Rep.104-169, 104th Cong., 1st Sess. (1995) at 38)
However, because section 1412(b)(9) of SDWA requires that any
revision to an existing NPDWR maintain or improve the level of public
health protection, EPA believes that a clear, technically-based
demonstration
[[Page 42913]]
regarding the absence of potential risk is necessary to deregulate a
contaminant. EPA does not believe it is appropriate to deregulate any
currently regulated contaminant at this time because the Agency is not
able to make a determination, pursuant to section 1412(b)(9) of SDWA,
that there would be no lessening of public health protection if the
contaminant were deregulated. The Agency disagrees that evaluation of
finished water data is sufficient to consider deregulation of low or
non-occurring contaminants. The apparent low or non-occurrence of these
contaminants in finished water may be the result of effective treatment
processes in place rather than the lack of occurrence in source water.
EPA believes that the existing waiver provisions in the SDWA
regulations give States sufficient flexibility to reduce or potentially
eliminate monitoring of a chemical contaminant, where appropriate.
States that have primacy for the drinking water regulations are
responsible for their waiver programs and can grant waivers if a
particular pesticide or herbicide has not been previously used,
manufactured, stored, transported, or disposed in the area, a system's
source water is not susceptible to contamination from the chemical, or
the State has determined the system is not vulnerable. The State can
grant waivers for individual contaminants, a group of contaminants, or
issue an area-wide waiver (see 40 CFR 141.23 (b) and (c), and 141.24
(f) and (h)). In addition, States can adopt alternative monitoring
strategies as long as the approach is as stringent as the Federal
requirements (USEPA, 1997b).
2. Health Effects Technical Review
a. Contaminants Undergoing Health Risk Assessments. A few
commenters raised issues with respect to the 36 chemical contaminants
for which health risk assessments were underway when EPA published its
preliminary revise/not revise decisions in the April 17, 2002, Federal
Register. In particular, these commenters wanted to know the process
that EPA plans to follow to review each NPDWR once the risk assessment
is completed, including when that review would occur and when an
accelerated review would be appropriate.
EPA Response: Between April and August 2002, the Agency completed
health risk assessments for 2 of the 36 contaminants: 1,1-
dichloroethylene and lindane. The results of those assessments and the
impact on the Agency's revise/not revise decisions are discussed in
sections IV.B.7 and IV.B.14, respectively, of today's action. NPDWRs
for the remaining contaminants for which health risk assessments are in
process will be reviewed as a part of the 2002-2008 review cycle.
However, if in the Agency's judgment, a compelling reason exists to
revisit the ``not revise'' decision sooner, EPA may accelerate the
review cycle for that NPDWR. In reviewing these regulations, EPA
expects to apply an approach consistent with the protocol used for the
current review. That is, the Agency will consider the same key elements
and apply the same basic decision tree for making a revise/not revise
decision. The key elements of the review include health effects
technical review, technology review, other regulatory revisions review,
and, if appropriate, occurrence/exposure analyses and consideration of
available economic information (see 67 FR 19030 at 19038, April 17,
2002 (USEPA, 2002g)).
b. Other Issues Related to the Health Effects Technical Review. One
commenter stated that the Agency risk assessments underestimate risk
because absorption of chemicals through the skin, lung, and nose is not
``adequately'' taken into account. Another commenter encouraged the
Agency to evaluate the literature for potential reproductive and
developmental effects for chemicals with zero MCLGs since risk
management strategies, such as monitoring frequency or treatment
requirements, may be affected by such information.
EPA Response: EPA disagrees that the Agency underestimates risk
when deriving MCLGs. The Agency takes multiple routes of exposure into
account by including a relative source contribution (RSC) in its
calculation of an MCLG value. The RSC compares exposure from air, food,
and drinking water and uses the data in allocating a portion of the
total exposure to drinking water. When exposure data for the chemical
are not available, EPA assumes that the RSC from drinking water is 20
percent of the total exposure. This allows 80 percent of the total
exposure to come from sources other than drinking water, such as
exposure from food, inhalation, or dermal contact.
EPA recognizes the possibility that some chemicals with zero MCLGs
may also be of reproductive and/or developmental concern. EPA is
investigating these endpoints and their potential impact on monitoring
frequency or treatment requirements. However, the Agency does not
believe the analysis can be completed during the current review cycle
without significantly delaying the current revise/not revise decisions.
To the extent possible, EPA will consider the results of this analysis
and any additional information during subsequent Six-Year Reviews.
3. Analytical Methods Feasibility Technical Review
Commenters generally supported the Agency's approach of using
Performance Evaluation (PE) Water Supply (WS) data and the 10 times
method detection limit (MDL) multiplier to evaluate possible changes in
analytical feasibility for several of the contaminants under this Six-
Year Review. A few commenters agreed that the WS data are a valuable
source of information for evaluating interlaboratory performance and
for developing practical quantitation levels (PQLs). However, the same
commenters questioned whether the approach of using PE WS data will be
possible for future reviews since the Agency's laboratory certification
program that once collected this information has been externalized to
private providers. These commenters questioned whether the externalized
or privatized data would be sufficient for the determination and/or re-
evaluation of PQLs. In addition, at least one commenter suggested that
it may be appropriate (in the next Six-Year Review) to re-evaluate the
policy of basing the PQL on only EPA Regional and State laboratory
results, and recommended that the Agency include commercial and large
utility laboratory results. According to the commenter, these
laboratories (commercial and large utility) have demonstrated
``significant innovation in method development and improved
quantitation.''
EPA Response: EPA agrees that the WS studies have been a valuable
source of information for determining PQLs. At this time, the Agency
has not determined whether the privatized data will be sufficient for
the purposes mentioned by the commenter. In addition, the Agency has
not yet determined how best to gather data to determine and/or reassess
PQLs for future reviews. The Agency is in the process of evaluating
acceptable options. The policy for determining the most appropriate
methodology for calculating PQLs for drinking water contaminants is
outside the scope of the Six-Year Review.
4. Review of Treatment Technologies and Related Issues
Commenters suggested that, while EPA's review of existing NPDWRs
was generally consistent with the NDWAC recommendations to EPA (NDWAC,
2000), the Agency's review of treatment
[[Page 42914]]
technologies which support the regulations should be expanded.
Specifically, commenters recommended that EPA review all treatment
technique (TT) requirements and allow for changing or expanding these
TT requirements where new information warrants such a change.
EPA Response: EPA continues to believe its approach to reviewing TT
requirements is appropriate. The ``EPA Protocol for the Review of
Existing NPDWRs'' (Protocol Document) discusses when it is appropriate
for the Agency to consider revisions to TT-type regulations (see
sections II.C and III.B of the Protocol documents) (USEPA, 2002d;
USEPA, 2003c). The Agency discussed the review of the four chemical
treatment technique NPDWRs (i.e., acrylamide, copper, epichlorohydrin,
and lead) in both the draft and final ``Water Treatment Technology
Feasibility Support Document for Chemical Contaminants; In Support of
EPA Six-Year Review of National Primary Drinking Water Regulations''
(Treatment Feasibility Documents) (USEPA, 2002b; USEPA, 2003g). The
Agency has no specific information that provides a basis for revisions
to TT requirements at this time. However, EPA believes that research
data in a number of treatment-related areas may be useful in future
reviews of NPDWRs. The Agency is committed to working with stakeholders
to identify and prioritize treatment-related research needs, and to
work with EPA's research partners to address the highest priority
needs.
5. Review of Implementation-Related Issues
While several commenters felt overall that EPA's Six-Year Review
protocol was reasonable and appropriate, they encouraged EPA to
consider implementation-related modifications (i.e., ``other regulatory
revisions'') as a reason to revise a rule, even if there were no basis
to revise the MCLG and/or MCL/TT requirements.
EPA Response: Implementation-related issues are the primary reason
for the Agency's decision to revise the TCR at this time (67 FR 19030
at 19085, April 17, 2002 (USEPA, 2002g)), so it is clear that EPA
considered implemented-related issues in its review. The Protocol
Document (USEPA, 2002d; USEPA, 2003c) identifies the conditions under
which the Agency will consider implementation-related revisions. EPA
continues to believe these criteria are appropriate. During the current
review, none of the identified potential implementation-related
revisions pertaining to the chemical NPDWRs, in EPA's judgment, met the
stated criteria for reasons documented in EPA's final document,
``Consideration of Other Regulatory Revisions for Chemical Contaminants
in Support of the Six-Year Review of National Primary Drinking Water
Regulations'' (USEPA, 2003b).
6. Review of Occurrence and Exposure
a. Occurrence Database Concerns. A few commenters asked for
information regarding next steps for the National Contaminant
Occurrence Database (NCOD). Another commenter pointed out that States
have been willing to assist EPA by providing occurrence data beyond
what is required of them. However, the commenter raised concerns that
he/she felt EPA needs to address to facilitate further data sharing.
Some commenters expressed concern about the completeness and
representativeness of the 16-State data set used for the Six-Year
Review. One commenter suggested that the Agency should have issued an
Information Collection Request to obtain more complete data for the
Six-Year Review analysis.
EPA Response: The Agency is updating the NCOD to provide sample
data that have been quality checked and used in various EPA analyses.
This update to NCOD includes unregulated occurrence data collected
prior to 1999 as well as the latest Unregulated Contaminant Monitoring
Rule data (64 FR 50556, September 17, 1999 (USEPA, 1999b)) reported by
laboratories for public water systems required to report results. It
also includes the data used for the Six-Year Review of regulated
contaminants. EPA appreciates that some States are willing to share
their full compliance monitoring records with the Agency, even though
it is not required. The Agency and the States are continuing to work
together to establish a protocol for data sharing, including safeguards
to prevent misuse and misinterpretation of data.
The 16-State cross-section data set compiled for occurrence
analyses for the Six-Year Review is the largest compliance monitoring
data set for drinking water assembled by EPA to date. The design and
construction of the 16-State cross-section data set was based on the
fact that contaminant occurrence varies spatially (geographically) due
to differing patterns of population, land use, chemical use, geology,
hydrology, and climate. The detailed description of the ``pollution-
potential'' and geographic diversity considerations, and the derived
balanced cross-section of States (that was developed to be collectively
indicative of national occurrence) is included in the ``Occurrence
Estimation Methodology and Occurrence Findings Report for the Six-Year
Review of Existing National Primary Drinking Water Regulations''
(Occurrence Methodology Document) (USEPA, 2003d). EPA selected its 16-
State cross-section to be as representative as possible of national
contaminant occurrence. In EPA's judgment, these States provide a
reasonable cross-section of agricultural and industrial pollution
potential, as described in the Occurrence Methodology Document, and
also provide geographic coverage of the United States. Therefore, EPA
believes that the data assembled from these States is the most
representative data currently available of national contaminant
occurrence.
The Agency did receive occurrence data from States other than those
in its 16-State cross-section. However, many State data sets contained
incomplete records (e.g., no water type or population records
specified) or had other quality problems. Therefore, they were not
included in the analyzed data set.
b. Occurrence Analysis Methodology. One commenter noted that while
the occurrence estimation methodology has several strengths, it also
has a number of flaws. The commenter was concerned about the large
proportion of non-detected observations in the occurrence data, and the
difficulty of verifying the assumptions made by the Agency. The
commenter agreed that EPA's occurrence analysis may represent a
``decent'' estimate given the limitations of the data. The commenter
also noted that the occurrence estimation methodology is premised on
``subjective decisions or qualitative observations * * * rather than
documented, statistically-based quantitative ones'' and would like to
have seen alternate approaches used to provide confirmation of the
estimates. In addition, the commenter questioned why the Agency used
``modeled data sets to test the model rather than a standard
statistical strategy of basing the model on a portion of the data set
and using the remainder to test the model.''
One commenter stated that the Stage 2 analysis (Bayesian analysis)
was poorly described and that this conflicts with the transparency
requirements of the 1996 SDWA Amendments. In addition, the commenter
asked EPA to clarify how the occurrence data from other survey efforts,
which are summarized in ``Occurrence Summary and Use Support Document
for the Six-Year Review of Existing National Primary Drinking Water
Regulations''
[[Page 42915]]
(Occurrence Summary Document) (USEPA, 2002f), were used to inform the
modeling effort.
EPA Response: EPA's occurrence model development work was
significantly revised to reflect peer review comments prior to the
March 2002 Occurrence Methodology Document (USEPA, 2002e) and the April
17, 2002, Federal Register. The additional work involved the
development of a detailed simulation study to evaluate the Bayesian
model. EPA evaluated the performance of the Bayesian estimator and an
alternative occurrence estimation approach, the Regression on Ordered
Statistics (ROS) method, against synthetic data (i.e., data developed
with known national contaminant occurrence distributions). This
simulation study also enabled an explicit evaluation of the validity of
the assumption of a log-normal distribution of the data.
The simulation study was conducted using varying conditions of a
correctly and incorrectly specified model, and synthetic data sets
developed with high and low amounts of non-detected data. The study
findings indicated that the Bayesian estimator performed well at
estimating the distributions of contaminant concentration means
(especially in the upper tails), performed better than the alternate
approach (i.e., the ROS method), and accurately estimated the
uncertainty of the distributional estimates. The Agency believes that
this analysis supports the validity of EPA's analytical approach. The
Bayesian model was tested against the ROS approach because the ROS
method is an accepted drinking water contaminant occurrence estimation
approach and was used to estimate occurrence for the recent arsenic
rule. These findings were all included and described in the Six-Year
Review's Occurrence Methodology Document.
EPA has attempted to make its occurrence analysis as clear as
possible. In response to the concerns raised by the peer reviewers, a
less technical description of the occurrence estimation methodology,
aimed at the general reader, was added to the main body of the
document. A detailed description of the analysis, intended for readers
with technical expertise, including the complete computer code used for
model analysis, was incorporated into an appendix of the document. EPA
agrees that its estimation methodology is complex, but also believes
that it is as transparent as possible while still providing a
technically accurate description of the Agency's analysis. The use of
simple national occurrence (statistical) assessments is not possible at
this time because there is no national database with a complete
collection of regulated contaminant occurrence data. Thus, there is no
ideal basis for comparison of national occurrence studies (i.e., the
true system contaminant means and national distributions of contaminant
occurrence are not, and cannot, be known). The validation approach
suggested by the commenter (i.e., basing the model on a portion of the
data set and using the remainder to test the model) is intended for a
regression-type of model using observed system means to develop a model
for system-specific predictions. This approach is not possible for the
six-year occurrence assessments, since, to the best of EPA's knowledge,
data on the true individual system contaminant mean concentrations and
national distributions are not available.
Regarding the other survey studies included in the Occurrence
Summary Document, few, if any, provide the quantitative analytical
results and national, representative coverage that would enable direct
comparison to, or inclusion in, the Six-Year Review estimation analyses
conducted with the 16-State cross-section occurrence data.
c. Other Issues Related to the Occurrence Technical Review. One
commenter stated that the Agency's current approach to estimate
occurrence, employing a conservative methodology and making
conservative simplifying assumptions in the absence of definitive data,
was appropriate. On the other hand, the commenter argued that it was
not appropriate for the Agency to conduct as massive a data collection
and analysis project as was undertaken without clear quantitative
objectives for the analysis identified a priori. The commenter noted
that it was not apparent from either the April 17, 2002, Federal
Register or the Occurrence Methodology Document (USEPA, 2002e) that the
Agency undertook an effort to set performance objectives for the
occurrence estimation.
The commenter felt that the Occurrence Methodology Document does
not allow the reader to determine if the data are well apportioned
among the categories for which results are reported. They also noted
that they were unable to find indications in the support document that
such an analysis was undertaken in preparation for constructing the
Bayesian model. The commenter stated that the support document does not
include actual numeric counts or ranges of detected values and
suggested that it would be useful to have this information by
contaminant, State, system size category, and water type, as well as an
explicit count of non-detects by this same matrix.
EPA Response: There are several general approaches when undertaking
and designing studies that require large amounts of data. As the
commenter states, a priori data quality objectives are part of one
research approach where study objectives (including technical
statistical performance measures) are set, determinations are made on
how to meet those objectives, and then the study is designed and
implemented accordingly. This ideal was not practical for the national
occurrence study conducted for the Six-Year Review because EPA did not
have the resources to generate original data, and was thus dependent on
the data that could be obtained from the States. The approach taken by
the Six-Year Review was to gather a large amount of data that, in
aggregate, was expected to be indicative of national contaminant
occurrence, develop an occurrence estimation model that built upon what
has been learned from recent regulatory development work, and then
evaluate how good the resulting model estimates are.
As discussed in section IV.A.6.b of today's action, the true
national distributions of contaminant occurrence cannot be known. The
16-State national cross-section data set used for the Six-Year Review
is the largest compliance monitoring database for drinking water
compiled by EPA to date. The database represents approximately 37
percent of the total number of public water systems and 43 percent of
the total population served by public water systems in the United
States. External peer reviews assessed the approach for developing the
national cross-section and its ``representativeness'' separately under
the Chemical Monitoring Reform (CMR) project (in 1998/1999) (USEPA,
1999c) and the Six-Year Review project (USEPA, 2002e), and provided
generally favorable comments.
The data management and cross-section development have been
described in detail in the support documents for the CMR and the Six-
Year Review. Further tabulations of the data have been generated and
presented, as the commenter requested, in the final Occurrence
Methodology Document (USEPA, 2003d). This information includes the
numbers and percentages of analytical detections and non-detections for
each contaminant in each of the system size and source water type
categories. Generally, because of the large amount of data and the
manner in which the Bayesian model handles data, the distribution of
observations across the various categories does not significantly
affect EPA's estimates. The
[[Page 42916]]
number of analytical records differed by contaminant. EPA evaluated
27,648 to 93,062 analytical records for the individual inorganic
chemicals, 32,606 to 121,327 records for the synthetic organic
chemicals, and 123,229 to 201,235 records for the volatile organic
chemicals. Most importantly, the Stage 2 occurrence model also
quantifies the uncertainty of the estimates in the different categories
of system size and source water type. Hence, the statistical
significance of differences in occurrence between the categories can be
easily assessed. However, the Agency believes it is more appropriate to
consider the universe of potentially affected systems within the 16-
State cross-section, rather than individual system categories, when
making its revise/not revise decisions as part of the Six-Year Review
process.
7. Consideration of Available Economic Information
Some commenters stated that, while the Agency's review of NPDWRs
was generally consistent with NDWAC recommendations to EPA (NDWAC,
2000), it is not clear how the Agency took economic factors into
account.
EPA Response: An EPA memorandum, dated March 18, 2002, describes
the Agency's qualitative evaluation of economic factors (USEPA, 2002c).
This memorandum was cited in the April 17, 2002, Federal Register and
is available in the docket for the Six-Year Review (Docket No. OW-2002-
0012). It notes that detailed economic analyses were not deemed by the
Agency to be necessary to support its decisions of whether or not to
revise a particular NPDWR. Rather, a qualitative assessment, based on
the extent of occurrence of a contaminant at the MCL, as well as at
alternative levels, was undertaken to inform the Agency's judgment
about whether possible changes to an MCL offered a meaningful
opportunity for health risk reduction and/or cost-savings to public
water systems and their customers. EPA has conducted this assessment
for 15 of the chemical NPDWRs for which the Agency had determined that
a potential health or technological basis may exist for considering a
revision to the MCLG/MCL.\2\ EPA compared the estimated occurrence and
exposure values at the current MCL and at potentially revised
regulatory level(s). For 14 of these chemical NPDWRs, the Agency's
assessment showed that the differences were small. In EPA's judgment,
these differences are unlikely to provide a meaningful opportunity for
health risk reduction or cost-savings to public water systems and their
customers. After consideration of these factors, EPA decided that any
revision would be a low priority activity for the Agency, and, thus,
not appropriate to revise at this time because of: Competing workload
priorities; the administrative costs associated with rule making; and
the burden on States and the regulated community to implement any
regulatory change that resulted. In the case of dichloromethane, the
Agency did not have sufficient data to recalculate the PQL to support
any potential regulatory revision and thus placed it in the data gaps
category.\3\
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\2\ These 15 chemical NPDWRs are: Benzene; beryllium; chlordane;
1,2-dibromo-3-chloroproppane dichloromethane; 1,1-dichloroethylene;
1,2-dichloropropane; heptachlor; heptachlor, epoxide;
hexachlorobenzene; lindane; oxamyl; picloram; toxaphene; and 1,1,2-
trichloroethane.
\3\ The other three NPDWRs in the data gaps category, chromium,
fluorida, and lead, were placed there for reasons other than
occurrence and economic considerations. Chrominum is in the data
gaps category because of the studies being conducted by the National
Toxicology Program studies. Fluoride is in the data gaps category
pending a National Academy of Sciences update of the health risk
assessment and review of the RSC assumptions. Lead is in the data
gaps category based on consideration of public comments (see section
IV.B.13 of today's action).
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B. What Comments or New Information Did EPA Receive on Chemical
Contaminant-Specific Issues?
1. Alachlor
One commenter stated that the Office of Pesticide Programs (OPP)
found that the chloroacetanilide pesticides (acetochlor, alachlor, and
butachlor) should be considered as a group of chemicals having a common
mechanism of toxicity due to their ability to cause nasal turbinate
tumors. The commenter believes EPA therefore should adopt a strong
total chloroacetanilide pesticide standard that would strengthen the
current standards.
EPA Response: Butachlor and acetochlor do not presently have an
NPDWR and thus, are not included in the Six-Year Review. However,
acetochlor is included on the Contaminant Candidate List (CCL) and may
in the future be considered as a candidate for regulation. Alachlor is
a regulated drinking water contaminant and is included in the Six-Year
Review. It is currently undergoing a risk assessment and, therefore,
the Agency believes that revision of the NPDWR is not appropriate at
this time.
If the Agency decides to regulate either acetochlor or butachlor in
the future, EPA may consider regulating them as a group, including
alachlor, following a cumulative risk assessment process for pesticides
that have a common mechanism of toxicity. It would be premature to
propose a total chloroacetanilide pesticide standard until a cumulative
risk assessment is completed because this analysis could impact the
Agency's evaluation of specific members of this group, or the group as
a whole.
2. Antimony
a. Health Effects. A number of commenters have suggested that the
current MCLG and MCL of 0.006 milligrams per liter (mg/L) for antimony
need to be revised. Some of the reasons given were:
[sbull] The study used to derive the current MCLG (Schroeder et
al.,1970) is not consistent with current good laboratory practice
guidelines and there are several newer studies of antimony toxicity
that should be considered in deriving a new reference dose (RfD).
[sbull] Animals used in the Schroeder et al., 1970 study had a
viral infection. To compensate for this infection, adjustments were
made to the size of the animal groups in an attempt to salvage the
data.
[sbull] The antimony compound used in the Schroeder et al., 1970
study was potassium antimony tartrate, the most water soluble and toxic
form of antimony. Antimony found in drinking water is likely to be in
the form of less toxic trivalent and pentavalent antimony species.
Therefore, basing the MCLG on the most toxic species of antimony
(potassium antimony tartrate) is likely to overestimate the risk posed
by antimony in drinking water.
EPA Response: EPA agrees that the MCLG and MCL for antimony may
need to be re-evaluated. EPA is in the process of developing a new
health risk assessment for antimony, taking into consideration new
studies that have become available on the toxicity of antimony. EPA
expects to complete the health risk assessment for antimony in the
2003-2004 time frame (68 FR 5870, February 5, 2003 (USEPA, 2003h)). As
a result of the ongoing health risk assessment, a revision to the
antimony standard is not appropriate at this time, and antimony will be
re-evaluated as part of the next Six-Year Review process.
b. Treatment and Implementation Issues. Several commenters
questioned the appropriateness of the antimony MCL, and the
effectiveness of using the EPA-designated best available technologies
(BATs) to meet the antimony MCL. A few small systems in Utah have
levels of antimony in water at or above the MCL value of 0.006 mg/L.
These systems were granted
[[Page 42917]]
exemptions contingent upon testing and installation of treatment by
March 2004.
These systems are investigating treatment options for the removal
of antimony from their source water. Commenters submitted supporting
data documenting the results of their testing and cost analyses.
According to commenters, on-site testing indicated that the designated
BATs (i.e., reverse osmosis and coagulation/filtration) and most of the
other tested treatments were ineffective and/or prohibitively expensive
due to: raw water quality concerns; water conservation needs; current
costs for water production; and other concerns, such as waste water
management. However, commenters did identify treatment options that may
be feasible, but these may require further investigation prior to full
scale use.
EPA Response: As discussed in the April 17, 2002, Federal Register
and as noted in the previous response in section IV.B.2.a, EPA does not
believe it is appropriate to consider revisions to the NPDWR for
antimony at this time because of the ongoing health risk assessment (67
FR 19030 at 19051 (USEPA, 2002g)).
When EPA initially promulgated the antimony NPDWR in 1992, the
Agency estimated that 200 public water systems would be affected
(USEPA, 1992). EPA recognizes that implementation of this standard may
present challenges for a few localities. Although the use of the
designated BATs for antimony may not be appropriate in some cases, as
long as systems comply with the MCL, they are not limited to these
technologies.
EPA believes that the treatment data generated by the commenters
may be valuable and may provide insight into potential alternative
treatment technologies. The Agency has revised the document, ``Water
Treatment Technology Feasibility Support Document for Chemical
Contaminants; In support of EPA Six-Year Review of National Primary
Drinking Water Regulations'' (Treatment Feasibility Document) (USEPA,
2003g) to refer to these preliminary test data as they may be
applicable to the development of potential new treatment technologies
for the removal of antimony and other contaminants.
3. Atrazine
a. Health Effects. Several commenters addressed the EPA decision
not to consider revision of the MCL for atrazine at this time. Some of
these commenters stated that EPA should use the risk assessment,
released by OPP in May 2002, as a basis for reconsidering the atrazine
NPDWR. One of the commenters noted that the 2002 risk assessment is
based on reproductive and developmental endpoints which represents a
change from the toxicity endpoint that formed the basis of the current
MCLG. Two commenters stated that the MCL for atrazine should be revised
upward because of the results of the 2002 OPP risk assessment in which
the RfD increased and the cancer classification changed from ``possible
human carcinogen'' to ``not likely to be a human carcinogen.'' The
commenters stated that the change in the cancer assessment implies
elimination of the additional 10-fold risk management factor used in
1991 to derive the MCLG/MCL for atrazine. Another commenter stated that
atrazine should be regulated using a non-linear approach which
recognizes that there is a level at which no known health effects occur
and that these findings must be part of the new MCL.
Conversely, another commenter stated that there is substantial new
evidence from epidemiological and occupational studies that atrazine
poses a serious cancer risk, and that it is an endocrine disruptor at
low levels. The commenter believes EPA should adopt a revised atrazine
and total triazine standard lower than (i.e., more stringent than) the
current 0.003 mg/L standard for atrazine.
A commenter also urged the Agency to:
[sbull] Provide a definitive timetable for review of the standard;
[sbull] Outline a preliminary scope for its review of the standard;
and
[sbull] State the underlying premise for the scope of the review.
Other commenters stated that the existing NPDWR only regulates the
parent compound atrazine, and that a revised NPDWR should include the
chloro-metabolite degradants (i.e., diaminochlorotriazine (DACT),
desethyl atrazine (DEA), and desisopropyl atrazine (DIA)). These
commenters believe that inclusion of the chloro-metabolites would
strengthen compliance monitoring programs for public water systems
under SDWA and thereby strengthen public health protection. They stated
that a regulation for atrazine and the chloro-metabolites should be
developed and promulgated within the next 12 to 18 months. Another
commenter stated that since the Agency has found that atrazine,
simazine, propazine, and the degradants DACT, DEA, and DIA have a
common mechanism of toxicity, these should be regulated in a total
triazine regulation.
EPA Response: EPA does not believe it is appropriate to consider
revisions to the NPDWR for atrazine at this time because the revised
risk assessment has not been finalized. For purposes of the Six-Year
Review protocol, EPA considers a risk assessment final when an Interim
Reregistration Eligibility Decision (IRED), Reregistration Eligibility
Decision (RED), and/or IRIS assessments are complete.\4\ Even though an
IRED for atrazine was signed on January 31, 2003, an amended IRED is
scheduled to be released in October 2003 which will include a
Scientific Advisory Panel (SAP) peer review of new data related to
health effects. Based upon the outcome of the SAP review, the October
2003 IRED may include additional information that could impact a
revise/not revise decision. Therefore, EPA does not believe it is
appropriate to consider possible revisions to the NPDWR at this time.
---------------------------------------------------------------------------
\4\ The IRED is an intermediate decision for an individual
pesticide that does not take into account cumulative risk issues for
pesticides with a common mode of action. The RED does include
cumulative risk. If an IRIS assessment is also in process when the
IRED or RED is signed, EPA will make a case-by-case decision on
whether to wait for the IRIS assessment before considering possible
revisions to the NPDWR.
---------------------------------------------------------------------------
In reviewing the atrazine regulation, EPA will apply an approach
consistent with the protocol used for the current review. The Agency
will consider the same key elements (i.e., health effects review,
technology review, other regulatory revisions review, and, if
appropriate, occurrence/exposure analyses and consideration of
available economic information) and apply the same basic decision tree
for making a revise/not revise decision.
To address the issue of regulating the triazines as a group, the
Agency is evaluating the unregulated triazines as part of the CCL
process. When the risk assessment is completed for atrazine, the Agency
will consider whether or not there are compelling reasons for
considering a revision to the atrazine regulation or to wait until the
risk assessment for the triazines, which considers issues of cumulative
risk, is finalized. EPA will use the CCL regulatory determination
process in deciding whether the triazines should be regulated as a
group.
b. Costs of Treatment. Commenters stated that the costs associated
with not revising the MCL are great. These commenters are concerned
that State agencies will be required to develop total maximum daily
loads (TMDLs) based on 303(d) \5\ listings resulting from
[[Page 42918]]
an outdated MCL which creates a burden on State and local government,
its citizens, and diverts limited resources away from programs that
provide real benefits. Some commenters also stated that the treatment
costs to hundreds of community water systems are considerable. One
commenter also stated that these are real dollars that would otherwise
be available for emergency services, education, nutrition programs, and
other vital programs that are the responsibilities of local and State
agencies.
---------------------------------------------------------------------------
\5\ Section 303(d) of the Clean Water Act and the implementing
regulations (40 CFR 130.7) require States to develop TMDLs for
waters where required point and nonpoint source pollution controls
are not stringent enough to attain or maintain compliance with State
water quality standards after the application of technology-based
and other required controls. A TMDL establishes the maximum amount
of a pollutant that may be introduced into a waterbody while still
ensuring attainment and maintenance of water quality standards.
---------------------------------------------------------------------------
EPA Response: As stated in the previous response in section
IV.B.3.a, EPA does not believe it is appropriate to revise the NPDWR
for atrazine at this time because the risk assessment is not yet final.
If EPA decides to revise the NPDWR for atrazine, economic factors,
including feasibility and an assessment of costs and benefits, will be
taken into consideration for the drinking water program.
4. Beryllium
Two commenters believed that the current drinking water standard
for beryllium is more stringent than necessary for the protection of
public health and felt that EPA should adopt a higher value for the
beryllium standard. These commenters disagreed with EPA on the use of
an uncertainty factor of 300 in deriving the 1998 RfD. The commenters
stated the use of uncertainty factors of 3 for database uncertainty, 10
for extrapolating data from a dog study to humans, and 10 for
intraspecies variation is inappropriate. The commenters stated that EPA
has the authority to raise the current drinking water standards for
beryllium based on new information that allows for a smaller margin of
safety than the one used by EPA. The commenter felt that the current
standard for beryllium is ``lower than necessary to protect the public
from beryllium toxicity and results in clean-up standards that are
lower than naturally occurring level of beryllium in water sources and
soils.'' This commenter also expressed concern that the local
application of the Federal drinking water standard to private wells in
some cases caused undue concerns among users of those wells.
EPA Response: One of the purposes of the Six-Year Review is to
determine if the MCL of a chemical should be changed based on a revised
RfD or cancer classification. Analytical methods and treatment
technologies are considered, as well as occurrence in public water
systems. The RfD for beryllium was revised in 1998 based on extensive
Agency internal and external reviews, and is unlikely to be revised in
the absence of new data. The 1998 assessment also provided separate
cancer classification for inhalation and oral exposures (USEPA, 1998).
In the revised assessment, the carcinogenicity of beryllium by the
inhalation route was described as ``likely,'' while that by the oral
route of exposure ``cannot be determined.'' As discussed in the April
17, 2002, Federal Register, the Agency considered the occurrence of
beryllium at both potentially higher and lower regulatory levels. EPA
concluded that a revision to the NPDWR would not result in a meaningful
opportunity for health risk reduction or cost-savings to public water
systems and their customers. As a result, revision of this NPDWR is a
low priority action for the Agency and is not appropriate at this time.
The goal of drinking water standards is to protect public health.
Therefore, it does not matter whether the source of contamination is
naturally-occurring or man-made. While EPA appreciates the information
on private wells, the SDWA requirements do not apply to private wells
(i.e., wells that are not part of a ``public water system''). The costs
and benefits of a drinking water standard are assessed only with regard
to the impacts on public water systems and their customers.
5. Carbofuran
Some commenters mentioned that the Agency concluded that N-methyl
carbamates, including carbofuran, should be considered as a class
because they have a common mechanism of toxicity. Therefore, they
believe EPA should issue a stronger standard for total N-methyl
carbamates, including carbofuran, which would be more stringent than
the current carbofuran standard of 0.04 mg/L.
EPA Response: EPA is re-evaluating the toxicity of carbofuran.
However, a final assessment has not been issued by EPA. The Agency
considers N-methyl carbamate pesticides as a group of chemicals having
a common mechanism of toxicity due to their ability to inhibit
acetylcholinesterase. However, it is not appropriate to revise the
NPDWR for carbofuran at this time because the Agency has not yet
completed the final health risk assessment for carbofuran or the other
N-methyl carbamates.
6. Chromium
One commenter requested that EPA move quickly in making a revise/
not revise determination once the new data on chromium become available
from the National Toxicology Program (NTP) studies of the health
effects of chromium VI.
EPA Response: The NTP studies that the commenter refers to should
be available before the end of the next Six-Year Review cycle.
Meanwhile, EPA is continuing to follow the progress of NTP in
conducting subchronic and chronic studies of chromium VI.\6\ NTP made
the data from the subchronic portion of the study available to the
public in June 2002 (NTP, 2002). A peer review meeting was held at NTP
on July 24, 2002. EPA will examine the peer review report covering the
subchronic data once it becomes available. Once the subchronic and
chronic studies are completed, the health effects data will be
evaluated with regard to their impact on the present RfD and cancer
assessment, and integrated with the occurrence and analytical method
data before making a new revise/not revise decision.
---------------------------------------------------------------------------
\6\ Since NTP is posting its progress on its internet site
http://ntp-server.niehs.nih.gov/htdocs/Studies/HexChromium/hexchromiumpg.html, EPA and the public will be able to evaluate the
new data relative to the existing EPA assessment for chromium VI as
it is released.
---------------------------------------------------------------------------
7. 1,1-Dichloroethylene
In the April 17, 2002, Federal Register, the Agency preliminarily
placed 1,1-dichloroethylene in the no revision category because a
health risk assessment was pending at the time of publication. Since
the publication of the April 17, 2002, Federal Register, the Agency has
finalized the risk assessment for 1,1-dichloroethylene. The remaining
paragraphs in this section include a brief background discussion about
the original promulgation of the 1,1-dichloroethylene NPDWR, the
results of the appropriate six-year technical reviews and the Agency's
revise/not revise decision.
a. Background. EPA published the current NPDWR for 1,1-
dichloroethylene on July 8, 1987 (52 FR 25690 (USEPA, 1987)). The NPDWR
established an MCLG and an MCL of 0.007 mg/L. The Agency based the MCLG
on an RfD of 0.009 milligram per kilogram of body weight per day (mg/
kg/day) and a cancer classification of C, possible human carcinogen.
b. Technical Reviews. EPA updated the risk assessment for 1,1-
dichloroethylene on August 13, 2002 (USEPA, 2002i). The new risk
assessment established an RfD of 0.046 mg/kg/day, based on the same
toxicological study as that of the MCLG, but using an uncertainty
factor of 100
[[Page 42919]]
instead of 1,000, and using benchmark dose modeling for the dose-
response analysis. Under the 1986 cancer guidelines (51 FR 33992,
September 24, 1986 (USEPA, 1986)), 1,1-dichloroethylene was assigned to
Group C, possible human carcinogen. Under the draft revised
``Guidelines for Carcinogen Risk Assessment'' (USEPA, 1999a), the data
for 1,1-dichloroethylene were considered inadequate for an assessment
of human carcinogenic potential by the oral route.
Based on the change in RfD for 1,1-dichloroethylene, using a 20
percent RSC and a 10-fold risk management factor for possible
carcinogenicity, EPA used 0.03 mg/L as a level for evaluating the
occurrence data. Without the use of the 10-fold risk management factor,
EPA also used 0.3 mg/L as a level for evaluating the occurrence data.
Analytical or treatment feasibility do not pose any limitations for
the current MCL and would not be a limiting factor at the 0.03 mg/L or
the 0.3 mg/L level (USEPA, 2002a; USEPA, 2003g). The Agency's review of
possible ``other regulatory revisions'' did not identify any issues
that are specific to 1,1-dichloroethylene (USEPA, 2003b).
EPA evaluated the results of the occurrence and exposure analyses
for 1,1-dichloroethylene to determine whether possible changes to the
standard would be likely to result in a meaningful opportunity for
cost-savings to public water systems and their customers (USEPA,
2003d). Table IV-1 shows the results of the detailed occurrence and
exposure analysis based on the 16-State cross-section for the current
MCL (0.007 mg/L), and for two higher levels (0.03 mg/L and 0.3 mg/L).
Based on the detailed analysis, it appears that 1,1-dichloroethylene is
unlikely to occur at concentrations above 0.007 mg/L in the States used
for the cross-section.
BILLING CODE 6560-50-P
[[Page 42920]]
[GRAPHIC] [TIFF OMITTED] TN18JY03.071
BILLING CODE 6560-50-C
[[Page 42921]]
The results of the detailed occurrence and exposure analysis
indicate that less than 0.02 percent of the 19,101 systems sampled in
the 16-State cross-section, and less than 0.02 percent of the
population served by those 19,101 systems might be affected if EPA were
to consider levels as high as 0.03 mg/L to 0.3 mg/L. The current BATs
and small system compliance technology for 1,1-dichloroethylene have
other beneficial effects (e.g., reduction of other co-occurring
contaminants, or other common impurities) in addition to 1,1-
dichloroethylene removal. Therefore, if EPA were to consider any of
these higher levels, the Agency does not know how many of these public
water systems that are currently treating to comply with the current
MCL of 0.007 mg/L would be likely to discontinue treatment that is
already in place (USEPA, 2002c; USEPA, 2003g).
c. Current Decision. Although there are new health effects data
that might support calculation of a less stringent standard for 1,1-
dichloroethylene, EPA does not believe a revision to the NPDWR for 1,1-
dichloroethylene is appropriate at this time. In making this decision,
the Agency considered whether any potential revision to the 1,1-
dichloroethylene NPDWR is likely to provide a meaningful opportunity
for cost-savings to public water systems and their customers. After
consideration of this factor, EPA has decided that any revision to 1,1-
dichloroethylene would be a low priority activity for the Agency, and,
thus, is not appropriate to revise at this time because of:
[sbull] Competing workload priorities;
[sbull] The administrative costs associated with rulemaking; and
[sbull] The burden on States and the regulated community to
implement any regulatory change that resulted.
8. Dichloromethane
One commenter stated that it may be difficult to lower the PQL for
dichloromethane below the range of 0.001 to 0.002 mg/L since it is
required in a number of EPA methods and therefore is a common
laboratory contaminant. Because it is a common laboratory contaminant,
the commenter stated that using the MDL for 524.2 and 502.2 does not
constitute a reasonable basis for assuming that the PQL can be lower.
The commenter stated that none of the existing WS studies had spike
samples this low and, in addition, the occurrence data may have been
compromised due to laboratory contamination.
EPA Response: The basis for EPA indicating that a lower PQL ``may
exist'' was due to the fact that laboratories had greater than 95
percent laboratory passing rates using a +/-40 percent acceptance
window at ``known'' spike concentrations close to current MCL of 0.005
mg/L. If laboratory contamination due to dichloromethane were a
problem, such high passing rates at this value would not be expected.
The MDLs for 524.2 and 502.2 were only used with the 10 times MDL
multiplier to estimate what the lower value could be. However, EPA does
agree that, at this time, the Agency does not have sufficient data to
recalculate the PQL for dichloromethane and for this reason, the Agency
placed it in the data gap category.
Regarding the occurrence issue, EPA has no data to suggest that
high occurrence values were due to false positives from laboratory
contamination and the Agency is proceeding on the assumption that State
data are accurate unless there is information to the contrary. If
laboratory contamination due to dichloromethane does exist,
laboratories should be able to identify and discern a contamination
issue if they are running laboratory blanks.
9. Di(2-ethylhexyl)adipate (DEHA)
One commenter submitted detailed comments regarding di(2-
ethylhexyl)adipate (DEHA). The commenter believed that EPA should
consider removing the regulation for DEHA and provided the following
reasons:
[sbull] The regulation of DEHA in drinking water does not provide
any meaningful reduction in the health risk to humans because it is
unlikely to cause adverse effects to humans, including reproductive
effects, except at very high doses which cannot be attained in drinking
water, due to the low water solubility of DEHA.
[sbull] The weight of evidence indicates that the peroxisome
proliferation mechanism of DEHA rodent carcinogenicity is not relevant
to humans. Thus, the MCLG for DEHA should not include an additional 10-
fold risk management factor for possible carcinogenicity.
[sbull] The legislative history of the 1996 SDWA indicates that
Congress envisioned circumstances where relaxation of an MCL would
provide the same level of health protection as the existing regulation.
Accordingly, if DEHA cannot be deregulated, the commenter believes the
MCLG and MCL should be increased.
EPA Response: DEHA was regulated in 1992. Since that time, new
studies have become available on the toxicity of DEHA and its
metabolites. For this reason, EPA decided to initiate a new health risk
assessment of DEHA (67 FR 1212, January 9, 2002 (USEPA, 2002a)). The
assessment will include examination of the studies on which the current
NPDWR is based, as well as an evaluation of the data provided by this
commenter and new studies that have become available since DEHA was
regulated. This health risk assessment is planned for completion in the
2003-2004 time frame (68 FR 5870, February 5, 2003 (USEPA, 2003h)) and
is expected to include development of an RfD for non-cancer health
effects, as well as an assessment of potential carcinogenicity from
oral exposure. At this time, it is premature to predict the outcome of
the Agency's assessment. Thus, as discussed in section IV.A.2.a of
today's action, the Agency believes that revision to the NPDWR for DEHA
is not appropriate at this time. EPA will determine in the future if
revision of the MCLG/MCL is warranted. Any revision to the MCLG/MCL
will also take into consideration all the new information, including
the water solubility of DEHA under various environmental conditions.
As stated by the commenter, the legislative history of the 1996
SDWA Amendments supports EPA's interpretation that the Agency could
increase an MCLG and MCL as long as the relaxed standard does not
lessen the level of public health protection. However, EPA does not
believe, at the present time, that it can demonstrate that deregulating
DEHA would maintain the current level of public health protection (see
section IV.A.1.c of today's action).
10. Di(2-ethylhexyl)phthalate (DEHP)
The same commenter who submitted comments on DEHA also submitted
detailed comments regarding di(2-ethylhexyl)phthalate (DEHP). The
commenter felt that EPA should consider removing the regulation for
DEHP for a variety of reasons, including the following:
[sbull] The regulation of DEHP in drinking water does not provide
any meaningful reduction in the health risk to humans.
[sbull] The weight of the evidence indicates that the mode of
action through which DEHP causes cancer in rodents is not relevant to
humans and, thus, the MCLG for DEHP should not be zero. Any MCLG for
DEHP should be based on a threshold endpoint and not on cancer. The
commenter cited the February 2000 International Agency for Research on
Cancer reclassification of DEHP from Group 2B (possibly carcinogenic to
humans) to Group 3 (not classifiable as to its carcinogenicity to
humans) as justification for recommending that EPA also reconsider its
cancer classification.
[[Page 42922]]
[sbull] The solubility of DEHP in drinking water is well below any
concentrations that would pose a risk to humans.
[sbull] If DEHP were to be considered for regulation under the
statutory requirements of the 1996 SDWA, it would not be regulated.
[sbull] The legislative history of the 1996 SDWA indicates that
Congress envisioned circumstances where relaxation of an MCL would
provide the same level of health protection as the existing regulation.
Accordingly, the commenter believes consideration should be given to
increasing the MCLG for DEHP based on the new health effects data.
[sbull] Reproductive effects from DEHP as observed in rodents do
not appear to be relevant for primates and the doses that are
associated with effects in animals are well above those that would be
experienced for humans exposed through drinking water because of
solubility limitations. The commenter also highlighted the findings of
the NTP Center for the Evaluation of Risk to Human Reproduction that
there was ``minimal concern for reproductive or developmental toxicity
for the general population, based on estimates of total exposure to
DEHP.''
EPA Response: Revision of the NPDWR for DEHP is not appropriate at
this time because an Agency health risk assessment is currently in
process. The assessment is anticipated to be completed in the 2003-2004
time frame (68 FR 5870, February 5, 2003 (USEPA, 2003h)). Advances in
understanding differences between the primate and rodent response to
DEHP and the body of toxicological data that have become available in
the past decade motivated the Agency's re-examination of DEHP and will
be fully considered in the reassessment.
Once the Agency assessment is completed, EPA will consider the
findings and will determine if there is a compelling reason to review
the DEHP NPDWR prior to the next Six-Year Review cycle. As discussed in
sections IV.A.1.b and IV.A.2.a of today's action, ``revise'' versus
``not revise'' decisions under the Six-Year Review take into
consideration occurrence, advances in analytical methods, treatment
technologies, available economic information, and other factors.
As stated by the commenter, the legislative history of the 1996
SDWA Amendments supports EPA's interpretation that the Agency could
increase an MCLG and MCL as long as the relaxed standard does not
lessen the level of public health protection. However, EPA does not
believe, at the present time, that it can demonstrate that deregulating
DEHP would maintain the current level of public health protection (see
section IV.A.1.c of today's action).
11. Fluoride
EPA received three comments on the Agency's decision to place
fluoride in the data gap category while the National Academy of
Sciences (NAS) examines the toxicological and RSC data published over
the last decade. Two of the commenters supported EPA's decision. One of
these requested that the NAS concentrate its review on all of the data
on the toxicology of fluoride and not just data on the critical
skeletal effects. A third commenter requested that EPA not lower the
MCL for fluoride from 4 mg/L to 2 mg/L and supported the 1986 EPA
decision that dental fluorosis is a cosmetic effect rather than an
adverse health effect. The commenter stated that the Public Health
Service (PHS) recommended fluoridation level to be used at schools is 3
mg/L. The commenter also stated that if EPA were to lower the MCL, then
schools that are currently fluoridating might have a conflict with the
PHS recommendations and the EPA MCL.
EPA Response: The National Research Council (NRC) of the NAS has
agreed to review the toxicological data on fluoride that have been
published since it completed the 1993 study of ``Health Effects of
Ingested Fluoride'' (NRC, 1993), and to examine the data on relative
fluoride exposure from drinking water compared to fluoride exposure
from the diet and fluoride-containing dental products. Although the
Agency indicated in the April 17, 2002, Federal Register that new data
on bone effects were a reason for initiating the data review (because
bone effects were the basis of the present MCLG), the NAS review will
look at the new toxicological data for all endpoints. It is anticipated
that the NAS review will take about two years to complete. Because of
this pending review, revision of the NPDWR for fluoride is not
appropriate at this time.
It is therefore premature to make any judgment regarding the NAS
findings and whether or not they may lead to a consideration of a
change in the MCL. However, PHS recommendations for school fluoridation
programs are designed to provide the benefits of fluoridation without
increasing the risk for dental fluorosis. The PHS recommends school
water fluoridation only if:
[sbull] The school has its own source of water;
[sbull] The school is not connected to a community water system;
[sbull] More than 25 percent of students are not served by a public
water system that provides water at levels adequate to protect against
dental caries; and
[sbull] The students served are kindergarten age or greater.
12. Glyphosate
Two commenters made the statement that, despite continued use of
glyphosate in pesticide applications, available data and the Agency's
occurrence analysis, which includes a prediction of frequency of
occurrence at levels below detection, indicate that glyphosate is not
observed in compliance monitoring. One of these commenters stated that
the occurrence appeared to be rare (less than 0.1 percent) at
concentrations 1,000 times lower than the MCL. In addition, according
to the commenters, the cost of analyzing for glyphosate is expensive,
since it is a single analyte analysis. Accordingly, the commenters
wanted EPA to reconsider the glyphosate standard taking costs and
benefits into account. The commenters felt that the data may indicate
that a glyphosate standard is inappropriate and does not result in any
additional public health protection. Therefore, the commenters
recommended EPA pursue data gaps that the Agency would need to fill in
order to demonstrate that eliminating the glyphosate standard would not
lower public health protection.
EPA Response: EPA is conducting an Agency risk assessment for
glyphosate that will update the 1993 OPP assessment. As a part of this
process, EPA is considering all the data that have been published or
submitted to EPA since the completion of the RED in 1993 (USEPA, 1993).
Accordingly, revision of the glyphosate NPDWR is not appropriate at
this time due to the pending Agency assessment.
EPA recognizes that some utilities feel that the analysis of
glyphosate in drinking water is expensive and that this should be taken
into consideration with respect to cost and benefits. This will be
considered when EPA evaluates glyphosate in the next review cycle
(unless there is a compelling reason to evaluate glyphosate on an
accelerated schedule). For the reasons stated in section IV.A.1.c of
today's action, EPA does not believe it is appropriate to consider
deregulation of glyphosate at this time.
13. Lead and Copper
a. Research Needs. Three commenters acknowledged the Agency's
January 2000 revisions to the Lead and Copper Rule (LCR) but stated
that the Agency should continue to consider how to
[[Page 42923]]
make the LCR easier to implement. In particular, they recommended that
the following three LCR-related research areas be incorporated into
EPA's overall research strategy:
1. How well LCR monitoring results correlate to actual exposure and
the effectiveness of the rule in protecting public health.
2. Whether there is a correlation between water quality at indoor
and outdoor taps.
3. What effect the ban on lead in fixtures has had on lead levels
and whether changes need to be made based on this ban.
The commenters explained their rationale for recommending that the
Agency determine if a correlation could be established between indoor
and outdoor water quality. They stated that a major weakness of the LCR
is that sample integrity may be compromised by allowing customers to
collect water samples. If the Agency could establish such a
correlation, the LCR could be revised to allow water system operators
to collect samples from outdoor taps; thereby removing the need for
customer-collected sampling.
EPA Response: EPA recognizes that the LCR is a challenging rule
that requires difficult solutions to implement, but continues to
believe that the public health objective addressed by the rule is as
important and essential today as it was when the rule was first
promulgated. Since the Agency promulgated the revisions to the LCR in
January 2000 (65 FR 1950, January 12, 2000 (USEPA, 2000)), the Agency
has received no significant new information that would support a
revision. However, the Agency recognizes that more research would be
useful to obtain additional information that could be utilized to
address some of the issues associated with the implementation of this
rule. For this reason, EPA has revised its rationale for not revising
the NPDWR for lead and placed it in the data gaps category. Although
the Agency continues to believe that the NPDWR for copper belongs in
the risk assessment in process category at the present time, EPA will
also consider copper-related risk management and implementation issues
as a part of any LCR-related research plans. The Agency is committed to
working with stakeholders to support and coordinate identification and
prioritization of LCR-related research needs. Until this research is
completed, EPA believes it is premature to consider revisions to the
LCR; as a result, revision of the LCR is not appropriate at this time.
The Agency believes that understanding the possible correlation
between monitoring results and actual rates of exposure and public
health protection is a valid issue. However, EPA recognized during the
initial regulatory development of the LCR that a significant effort
would be necessary to provide a statistically valid number and
frequency of samples for an exposure assessment. The Agency thus
adopted an alternative approach which specified a monitoring scheme
that sought to ``* * * assure that systems are performing `optimal
corrosion control' in part by requiring systems to conduct
comprehensive tap sampling at homes specifically targeted for their
potential to contain elevated levels of lead and copper'' (56 FR 26460
at 26514, June 7, 1991 (USEPA, 1991b)). One issue in assessing exposure
reduction resulting from the LCR is a determination of an exposure
baseline. EPA does not have a lot of data against which to measure
changes in exposure that have occurred as a result of rule
implementation. For these reasons, EPA believes that there is still
insufficient information to change the basic monitoring approach
adopted in the original rule, but recognizes that additional research
may be useful.
Research on whether a correlation exists between the water quality
at indoor taps and water quality at outdoor taps is a very complex
issue. Several variables potentially affect whether a reliable
correlation exists between indoor and outdoor taps. These variables
include: standing time within the system; contact time with the
building plumbing; and the content of the interior plumbing. These
variables, coupled with the fact that lead levels from building-to-
building can be highly site-specific, make a correlation between indoor
and outdoor taps difficult to establish. EPA continues to believe that
focusing on the point of delivery to the customer most closely links
the data collected to the water quality consumed by the customer.
EPA recognizes the commenter's concerns regarding the integrity of
samples collected by drinking water customers. To date, however, the
Agency has not been able to identify an acceptable alternative to
monitoring at the consumer's tap that can produce results equivalent to
those obtained at the point of consumption in terms of ensuring
adequate public health protection.
Regarding the commenter's third recommendation, EPA will consider
this research need as part of the Agency's overall drinking water
research planning process.
b. Relaxing the Monitoring Requirements. Three commenters
recommended that water systems be allowed to conduct water quality
parameter (WQP) monitoring in lieu of continued lead and copper tap
monitoring. One of these commenters added that this should be allowed
once the system has demonstrated that it does not have a lead problem.
This commenter also stated that the new requirements to use lead-free
solder and plumbing fixtures should preclude problems with lead. Two
commenters noted the difficulty that water systems are having
maintaining their current sampling pool because homeowners no longer
want to participate in the LCR monitoring program. One of these
commenters recommended using WQP results to ensure corrosion control
treatment is being adequately maintained and to stop lead and copper
monitoring after three to five years. The commenter added that once the
system ceases lead and copper monitoring, it can use public education
to supplement continuing corrosion control, and can use coupons to
demonstrate that corrosion rates meet accepted standards.
EPA Response: While EPA is sensitive to the difficulties associated
with the monitoring requirements of the LCR, the Agency is also
concerned about the implications of reduced or discontinued monitoring.
Significant treatment changes or water chemistry disturbances (such as
new water sources, major pH/coagulation changes, disinfectant changes,
or seasonal water/treatment changes) can influence the effectiveness of
corrosion control, which in turn will require appropriate adjustments
of treatment. Current regulations require water systems to continue
monitoring lead and copper levels to assure that water quality changes
adversely affecting the presence of these contaminants in the drinking
water are detected and to assure that appropriate adjustments to
maintain optimal corrosion control are made. Proper process control,
including water quality and corrosion inhibitor residual concentration
monitoring in the distribution system, is the key to making any
corrosion control or other treatment work, and assure the continuation
of proper water quality. However, EPA recognizes that some changes
might be justified in the future based on new, scientifically valid,
information and/or research. EPA is considering aspects such as the
implications of simultaneous treatment modifications on water quality,
including lead and copper control, in its research planning. EPA is not
yet able to determine whether the outcome of such research will provide
a basis for modifications to the LCR treatment or monitoring
[[Page 42924]]
requirements. As stated in the response in section IV.B.13.a. of
today's action, EPA has placed the LCR in the data gaps category
pending the completion of future research.
c. Corrosion Control Treatment Strategy. Two commenters noted
concerns regarding the lead and copper corrosion control strategy. One
commenter indicated that the LCR should be revised to allow systems to
change corrosion control strategies. The commenter stated that
considerable development of the corrosion control market has occurred
since systems made their initial assessments and implemented corrosion
control programs. The commenter felt that currently, the ``LCR locks
utilities into a given control strategy,'' when in some instances
limited pilot work and ongoing WQP monitoring would allow a system to
re-assesses its treatment and implement an alternative corrosion
control inhibitor.
The second commenter indicated that the current corrosion control
strategies are marginally effective at preventing particulate lead and
copper from entering the water supply. The commenter recommended that
EPA consider methods for mitigating the release of insoluble components
from plumbing fixtures.
EPA Response: The Agency disagrees that the LCR locks utilities
into a given control strategy, but feels it is necessary to demonstrate
a sound basis for re-assessing and implementing an alternative
treatment strategy in the context of the existing regulation. EPA notes
that the current regulation provides some flexibility to both States
and water systems in the choice of a corrosion control strategy. For
example, in response to its own initiative, a request by a water system
or other interested party, a State may modify its determination of the
optimal corrosion control treatment, among those listed in the Federal
regulation, or may modify optimal WQPs if the State determines such
changes are necessary to ensure that the system continues to optimize
corrosion control treatment (40 CFR 141.82(h)).
The Agency believes that the existing requirements to notify the
State when changing a corrosion control strategy remain necessary and
appropriate. After they have optimized corrosion control, water systems
must notify the State of any treatment changes \7\ within 60 days of
the change (40 CFR 141.90(a)(3)). The Agency encourages water systems
to notify the State prior to making any changes thus allowing the
Primacy Agency to review the changes to reduce the potential for
detrimental side-effects. In the Agency's experience, changes in
treatment, such as (but not restricted to) replacement of high pH
treatment with corrosion inhibitor, changes in coagulant and
coagulation conditions, changes in disinfection, installation of
membrane processes, or introduction of chemically different waters into
the distribution system provide potential for detrimental side-effects.
Water treatment changes, therefore, should only be done with the
greatest care and pilot investigations. While changes to treatment can
be made under the existing regulation, systems should conduct
additional monitoring (e.g., of lead, copper, and WQPs) until the new
treatment is fully implemented and stabilized.
---------------------------------------------------------------------------
\7\ Treatment changes are categorized as changes to any water
quality treatment process, including (but not restricted to)
disenfection, disinfection by-product removal, and corrosion
control.
---------------------------------------------------------------------------
EPA also recognizes that the current LCR may limit flexibility to
some extent, particularly in the adoption of new or emerging
technologies. The original rule attempted to balance this concern with
the need to provide strong public health protection by ensuring that
only control strategies of proven effectiveness are adopted. The Agency
does not have an adequate basis to revise the treatment requirements at
this time but will continue to monitor new developments, including
emerging technology. The Agency may consider revisions to the LCR prior
to the end of the next Six-Year Review cycle if the Agency receives
new, scientifically-valid, information that provides a basis for
achieving significant improvement in public health protection or
significant cost-savings to utilities and their customers while
maintaining current public health protection.
EPA has always recognized that the release of insoluble particulate
material containing lead and copper can be an issue in some water
systems. While more research may be of interest to improve optimization
of corrosion control approaches with respect to this source, EPA
expects that evaluations and pilot studies by water systems should
include testing and consideration of the relative effectiveness of
different treatments towards particulate release in systems for which
it is important.
d. Lead Levels in School Drinking Water. One commenter was
concerned that the data on lead levels that was analyzed under the Six-
Year Review of NPDWR standards may not indicate actual lead
contamination of drinking water sources. As an example, the commenter
noted that even though Baltimore City is in compliance for lead levels,
\1/3\ of Baltimore schools are using alternative sources of drinking
water due to lead contamination. The commenter expressed concern that
since data obtained from schools, such as the data from Baltimore, was
not considered in the evaluation of lead contamination in drinking
water, the most vulnerable population may not be protected from
exposure to lead. The commenter stated that it is time for the Agency
to reassess how lead levels are evaluated.
EPA Response: The LCR is designed to address system-wide problems
with lead and copper contamination. The rule does not specifically
target particular structures, such as schools, but rather contains a
monitoring protocol designed to ensure that the overall levels of lead
and copper system-wide are minimized. Once optimal treatment is
implemented, any remaining problems with elevated lead levels in
schools may be due to plumbing, coolers, or other materials in the
building. These potential sources of lead in schools are of concern and
for this reason are explicitly addressed under the provisions of the
Lead Contamination Control Act of 1988 (LCCA) (sections 1461 to 1465 of
SDWA). The LCCA directed EPA to publish a guidance manual and testing
protocol to assist States and schools in identifying sources and
determining the extent of lead contamination in school drinking water
and, if necessary, in remedying such contamination. In January 1989,
the Agency published and distributed the guidance manual, ``Lead in
School's Drinking Water,'' to States and schools (USEPA, 1989). In
1994, the Agency updated and revised the guidance manual entitled
``Lead in Drinking Water in Schools and Non-residential Buildings''
(USEPA, 1994). A copy of this manual may be obtained from the Safewater
website http://www.epa.gov/safewater/consumer/leadinschools.html. In
addition, the LCCA imposed a ban on the manufacture and sale of water
coolers that are not lead free. The LCCA requirements are independent
of the NPDWRs and therefore are not addressed under the Six-Year Review
process. However, the Agency is continuing to work with schools and
States to address problems dealing with lead in school drinking water.
14. Lindane ([gamma]-hexachlorocyclohexane)
In the April 17, 2002, Federal Register, the Agency preliminarily
placed lindane in the no revision category because a health risk
assessment was pending at the time of publication. One commenter stated
that
[[Page 42925]]
the RED risk assessment for lindane, issued after publication of the
April 17, 2002, Federal Register, should be considered in the Agency's
review of the NPDWR and expressed concerns regarding the existing
regulation. The commenter stated that the current NPDWR is based on an
RfD developed in 1988 on the basis of adverse kidney effects and should
be revised (USEPA, 1988). The kidney effects were determined to occur
through a pathway that is not relevant to human health risk assessment.
The commenter stated that the new OPP toxicological assessment has
resulted in a significant change to the quantitative dose-response
assessment for lindane and that there are no data gaps or uncertainties
which would prevent a revision of the NPDWR for lindane at this time.
EPA Response: Since the publication of the April 17, 2002, Federal
Register and receipt of the comment regarding lindane, the Agency has
finalized the risk assessment for lindane and signed the RED on July
31, 2002. The remaining paragraphs in this section include a brief
background discussion about the original promulgation of the lindane
NPDWR, the results of the appropriate six-year technical reviews and
the Agency's revise/not revise decision.
a. Background. EPA published the current NPDWR for lindane on
January 30, 1991 (56 FR 3526 (USEPA, 1991a)). The NPDWR established an
MCLG and an MCL of 0.0002 mg/L. The Agency based the MCLG on an RfD of
0.0003 mg/kg/day and a cancer classification of C, possible human
carcinogen.
b. Technical Reviews. EPA updated the risk assessment on July 31,
2002 (USEPA, 2002h). The new risk assessment established an RfD of
0.0047 mg/kg/day. The Food Quality Protection Act (FQPA) of 1996
provides for an additional safety factor of up to 10-fold, if
necessary, in assessing the risks to infants and children to take into
account the potential for pre- and post-natal toxicity, and the
completeness of the toxicity and exposure databases. This is referred
to as the FQPA safety factor. The Agency concluded that an FQPA safety
factor of three was required for lindane since there is evidence for
increased susceptibility of the young demonstrated in a developmental
neurotoxicity and two-generation reproductive toxicity study in rats.
The rationale for using an FQPA safety factor of three is detailed in
the RED.
In accordance with the 1999 EPA Draft ``Guidelines for Carcinogen
Risk Assessment'' (USEPA, 1999a), the Agency classified lindane as
``suggestive evidence of carcinogenicity, but not sufficient to assess
human carcinogenic potential.'' Based on the RfD for lindane of 0.0047
mg/kg/day, the application of the additional FQPA safety factor of
three to this RfD, a 20 percent RSC, and a 10-fold risk management
factor of suggested evidence of carcinogenicity, EPA used 0.001 mg/L as
a level for evaluating the occurrence data.
Analytical or treatment feasibility do not pose any limitations for
the current MCL and would not be a limiting factor at the 0.001 mg/L
level (USEPA, 2003a; USEPA 2003g). The Agency's review of possible
``other regulatory revisions'' did not identify any issues that are
specific to lindane (USEPA, 2003b).
EPA evaluated the results of the occurrence and exposure analyses
for lindane to determine whether possible changes to the standard would
be likely to result in a meaningful opportunity for cost-savings to
public water systems and their customers (USEPA, 2003d). Table IV-2
shows the results of the detailed occurrence and exposure analysis
based on the 16-State cross-section for concentrations of 0.0002 mg/L
(the current MCL), and for 0.001 mg/L. Based on the detailed analysis,
it appears that lindane is unlikely to occur at concentrations above
0.0002 mg/L in the States used for the cross-section.
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The results of the detailed occurrence and exposure analysis
indicate that few, if any, of the 16,098 systems sampled in the 16-
State cross-section might be affected if EPA were to consider levels as
high as 0.001 mg/L. The current BATs and small system compliance
technology for lindane have other beneficial effects (e.g., reduction
of other co-occurring contaminants, or other common impurities) in
addition to lindane removal. Therefore, if EPA were to consider a
higher level, the Agency does not know how many of these public water
systems that are currently treating to comply with the current MCL of
0.0002 mg/L would be likely to discontinue any treatment that is
already in place (USEPA, 2002c; USEPA, 2003g).
c. Current Decision. Although there are new health effects data
that might support calculation of a less stringent standard for
lindane, EPA does not believe a revision to the NPDWR for lindane is
appropriate at this time. In making this decision, the Agency
considered whether any potential revision to the lindane NPDWR is
likely to provide a meaningful opportunity for cost-savings to public
water systems and their customers. After consideration of this factor,
EPA has decided that any revision to lindane would be a low priority
activity for the Agency, and, thus, is not appropriate to revise at
this time because of:
[sbull] Competing workload priorities;
[sbull] The administrative costs associated with rulemaking; and
[sbull] The burden on States and the regulated community to
implement any regulatory change that resulted.
15. Simazine
One commenter agreed that simazine should be addressed after the
risk assessment is completed in 2003 or 2004. The commenter requested
that the Office of Water (OW) work closely with the OPP on the risk
assessment at that time. The commenter also recommended that OW address
the revision of the existing simazine NPDWR before the next review
cycle year, scheduled for 2008. The commenter believes the extensive
mammalian toxicology database, submitted as part of the Triazine
Special Review, can be used in this process.
EPA Response: OW has been coordinating with OPP for the revision of
the atrazine and simazine risk assessments. Once the simazine risk
assessment is completed, EPA will determine whether a compelling reason
exists to consider review of the simazine NPDWR on an accelerated
schedule.
C. What Comments Did EPA Receive Regarding the Review of
Implementation-Related Issues for Chemical NPDWRs?
Several commenters recommended that EPA ensure consistent
application of rules by making rules more consistent with respect to
monitoring frequency, triggers for increased monitoring, criteria for
returning to routine monitoring, and criteria for reducing sample
requirements. In addition, commenters suggested that the Agency review
possible ways for reducing the reporting burden on States, which could
free up State resources currently used to implement rules.
One commenter was concerned about monitoring and reporting issues
in conjunction with CMR. The commenter felt that EPA should not miss an
opportunity to relieve some of the unnecessary confusion that the
monitoring requirements of Phase II and V have created. This confusion
includes issues such as, what a detection is and what the monitoring
requirements are for systems in States without a waiver program. EPA
was encouraged to provide this consistency as much as possible,
including using the standard monitoring framework to allow States and
water systems to more easily understand rule requirements and reduce
the need for States to update their data management systems.
One commenter said EPA should ensure consistent application of
rules by determining whether or not chronic contaminants should be
regulated at non-transient non-community water systems (NTNCWSs), and
review existing NPDWRs to ensure that rules are applied consistently.
Another commenter recommended that the compliance language for the
synthetic organic chemicals (SOCs) and volatile organic chemicals
(VOCs) in the Final Arsenic Rule (66 FR 6975, January 22, 2001 (USEPA,
2001)) be adopted for the inorganic chemicals (IOCs), and that systems
not be considered in violation of the MCL until it has completed one
year of quarterly samples.
EPA Response: The Agency agrees that consistency across regulations
is desirable to the extent that it does not jeopardize public health
protection or the environment.
As part of the Advanced Notice of Proposed Rulemaking for CMR (62
FR 36100, July 3, 1997 (USEPA, 1997a)), EPA considered some of the
issues raised by the commenters. However, during the comment period for
the CMR, stakeholders generally indicated that the existing monitoring
framework was sufficient. Most State commenters indicated that it would
be too burdensome to adopt CMR. As a result, the Agency decided to take
no further action on the CMR. However, the Agency established a
standardized monitoring framework which applies to all of the regulated
chemical and radiological contaminants (except lead and copper). The
new chemical and radiological rules that EPA has promulgated (e.g.,
arsenic and radionuclides) are coordinated with the standardized
monitoring framework. The Agency made special efforts to ensure that
the reduced monitoring periods are in line with the 3-year compliance
periods in the standardized monitoring framework.
To assist States with understanding rule requirements, the Agency
conducted a series of Phase II/V training in 2001. The training
provided information to help States make informed decisions about
reducing quarterly monitoring requirements. With respect to reduced
monitoring, States currently have the flexibility to reduce the
frequency of monitoring and/or to waive sampling requirements for any
given contaminant after minimum criteria are met to demonstrate that
the system is reliably and consistently below the MCL and/or not
vulnerable to contamination.
NTNCWSs are traditionally regulated for chronic contaminants.
However, through an alternative mechanism, the Agency is currently
evaluating risk and exposure as they pertain to NTNCWS monitoring
requirements. This review will not be completed in time for this Six-
Year Review process. Until all the issues have been identified and
specific options have been formulated, it will not be clear if a
revision to regulations is indicated.
EPA intends to consistently implement compliance determination
provisions for IOCs, SOCs, and VOCs for all NTNCWSs and community water
systems, as described in the preamble to the Final Arsenic Rule (66 FR
6975 at 6990, January 22, 2001 (USEPA, 2001)). The rule makes
compliance determinations based on a running annual average. The
clarifications to compliance determinations for SOCs, IOCs, and VOCs
are based on the average of the initial MCL exceedance and any
subsequent State-required confirmation samples. States have the
flexibility to require confirmation samples and more frequent
monitoring, in addition to required quarterly samples. The average of
the exceedance and confirmation sample constitutes the first quarterly
sample. Compliance with the MCL is based on the average of the first
quarterly sample and three
[[Page 42928]]
additional samples over a period of one year, unless any one quarterly
sample would cause the running annual average to exceed the MCL. Then
the system is out of compliance immediately.
D. What Comments Did EPA Receive on the Total Coliform Rule?
Several commenters addressed the TCR. Several commenters raised
several issues relating to monitoring. Some contended that routine
monitoring should be focused on critical locations in the distribution
system, rather than on the current requirement to monitor all parts of
the distribution system. They also urged EPA to allow the use of
dedicated sampling taps. Some commenters argued for allowing a finished
water storage reservoir as a routine monitoring site. Two commenters
urged EPA to focus on E. coli as the measure of water quality in the
distribution system, rather than on total coliforms. In addition to
routine monitoring, a few commenters addressed the topic of repeat
samples after a total coliform-positive sample. One commenter, for
example, urged EPA to eliminate the requirement to take upstream and
downstream repeat samples after a total coliform-positive sample.
Environmental groups urged EPA to strengthen the TCR and other rules
that protect against pathogens, and exhorted EPA not to ease the TCR
burden such that public health is compromised.
EPA Response: EPA's announcement in the April 17, 2002, Federal
Register was only intended to discuss the Agency's intent to begin the
process for revising the TCR. EPA will consider the commenters'
suggestions as part of the revision process. As stated in the April 17,
2002, Federal Register, the Agency plans to consider revisions to the
TCR with new requirements for ensuring the integrity of distribution
systems. The Agency remains committed to obtaining input from
stakeholders as part of the rule development process. EPA agrees with
the comment that public health should not be compromised, and will
consider only those revisions that will assure public health
protection.
E. What Comments Did EPA Receive on Research Needs?
Commenters found that EPA's information on potential research
resulting from the review of NPDWRs would be better represented by a
summary of research needs that were identified by the Agency.
Commenters felt that this summary is important to inform future
regulatory decisions. Commenters also suggested additional research
needs that had not been identified by EPA in its preliminary review.
EPA Response: EPA agrees that the identification of research needs
is an important component of the review of NPDWRs. Research findings
may support future reviews and/or revisions to NPDWRs.
The Agency is considering research needs that it identified as part
of the review as well as those suggested by commenters. EPA will
continue to identify areas where data are lacking. Dialogue with
industry and other groups, including those that sponsor or conduct
research on priority areas, would be beneficial to the drinking water
program. Collaboration in sponsoring studies can provide multiple
benefits.
There are two research needs associated with the Six-Year Review
that are being addressed through mechanisms external to EPA. The
National Research Council of the National Academy of Sciences is
conducting an assessment of recent data on fluoride health effects. In
addition, the National Toxicology Program is conducting a study on
chromium VI toxicity. Both of these research efforts are discussed in
the April 17, 2002, Federal Register announcement of EPA's preliminary
revise/not revise decisions. The current review identified several
general and specific areas of potential research related to treatment.
The treatment-related research areas are briefly discussed in the
Treatment Feasibility Document (USEPA, 2003g).
EPA is currently in the process of examining whether specific
research needs exist within each of the Six-Year Review areas of
regulatory consideration (i.e., health effects, analytical methods,
treatment, implementation, and occurrence/exposure). Some of the
research needs identified during the Six-Year Review effort will be
discussed in the context of the Multi-Year Plan (MYP) for drinking
water. The MYP describes the EPA Office of Research and Development's
fiscal year 2003 to 2010 research program to support the regulatory
development activities of the EPA Office of Water. EPA plans to make
this document available to the public in 2003.
V. References
National Drinking Water Advisory Council (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/guidfnl.pdf.
National Research Council (NRC). 1993. Health Effects of Ingested
Fluoride. National Academy Press, Washington, DC. August 1993.
Available on the Internet at: http://books.nap.edu/books/030904975X/html/R1.html.
National Toxicology Program (NTP). 2002. NTP study of the hexavalent
chromium compound sodium dichromate dihydrate. Available on the
Internet at: http://ntp-server.niehs.nih.gov/htdocs/Studies/HexChromium/hexchromiumpg.html.
Schroeder, H.A., Mitchener, M. and Nason, A.P. 1970. Zirconium,
niobium, antimony, vanadium and lead in rats: life term studies.
Journal of Nutrition. 100: 59-68.
Senate Report. 1995. Committee of Environment and Public Works, Safe
Drinking Water Act Amendments of 1995, S. Doc. No. 169, 104th Cong.,
1st Sess. 38 (1995).
USEPA. 1986. EPA Guidelines for Carcinogen Risk Assessment. Federal
Register. Vol. 51, No. 185. p. 33992, September 24, 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. 1988. Integrated Risk Information System, gamma-
Hexachlorocyclohexane. Available on the Internet at: http://www.epa.gov/iris/subst/0065.htm.
USEPA. 1989. Lead in School Drinking Water. EPA 570/9-89-001.
January 1989.
USEPA. 1991a. 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. 1991b. 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. 1992. Final Regulatory Impact Analysis National Primary
Drinking Water Regulations: Phase V Synthetic Organic and Inorganic
Chemicals. February 1992.
USEPA. 1993. Reregistration Eligibility Decision (RED)--Glyphosate.
EPA Report 738-R-93-014. Washington, DC: Office of Prevention,
Pesticides, and Toxic Substances. September 1993. Available on the
Internet at: http://www.epa.gov/oppsrrdl/REDs/old_reds/glyphosate.pdf.
USEPA. 1994. Lead in Drinking Water in Schools and Non-Residential
Buildings. EPA 812-B-94-002. Office of Water. April 1994.
USEPA. 1997a. National Primary Drinking Water Regulations--Advance
Notice of Proposed Rulemaking. Federal Register. Vol. 62, No. 156.
p. 36100, July 3, 1997.
USEPA. 1997b. Alternative Monitoring Guidelines. EPA 816-R-97-011.
August 1997. Available on the Internet at: http:/
[[Page 42929]]
/www.epa.gov/safewater/regs/pmrfin.html.
USEPA. 1998. IRIS, Beryllium and Compounds. Available on the
Internet at: http://www.epa.gov/iris/subst/0012.htm.
USEPA. 1999a. Guidelines for Carcinogen Risk Assessment. NCEA-F-0644
Review Draft. Environmental Protection Agency Risk Assessment Forum.
Washington, DC. July 1999.
USEPA. 1999b. Revisions to the Unregulated Contaminant Monitoring
Regulations for Public Water Systems; Final Rule. Federal Register.
Vol. 64, No. 180. p. 50556, September 17, 1999.
USEPA. 1999c. A Review of Contaminant Occurrence in Public Water
Systems. EPA 816-R-99-006. 78 pp. November 1999.
USEPA. 2000. National Primary Drinking Water Regulations for Lead
and Copper; Final Rule. Federal Register. Vol. 65, No. 8. p. 1950,
January 12, 2000.
USEPA. 2001. 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. Integrated Risk Information System (IRIS);
Announcement of 2002 Program; Request for Information; Notice.
Federal Register. Vol. 67, No. 6. p. 1212, January 9, 2002.
USEPA. 2002b. Water Treatment Technology Feasibility Support
Document for Chemical Contaminants; In support of EPA Six-Year
Review of National Primary Drinking Water Regulations. EPA 815-D-02-
001. Draft. February 2002.
USEPA. 2002c. An Evaluation of Available Economic Information in
Support of the Six-Year Review of Existing National Primary Drinking
Water Regulations. Memo from Marc Parrotta, Targeting and Analysis
Branch, Office of Ground Water and Drinking Water. March 2002.
USEPA. 2002d. EPA Protocol for Review of Existing National Primary
Drinking Water Regulations. EPA 815-D-02-004. Draft. March 2002.
USEPA. 2002e. Occurrence Estimation Methodology and Occurrence
Findings Report for the Six-Year Review of Existing National Primary
Drinking Water Regulations. EPA 815-D-02-005. Draft. March 2002.
USEPA. 2002f. Occurrence Summary and Use Support Document for the
Six-Year Review of Existing National Primary Drinking Water
Regulations. EPA 815-D-02-006. Draft. March 2002.
USEPA. 2002g. National Primary Drinking Water Regulations--
Announcement of the Results of EPA's Review of Existing Drinking
Water Standards and Request for Public Comment; Proposed Rule.
Federal Register. Vol. 67, No. 74. p. 19030, April 17, 2002.
USEPA. 2002h. Reregistration Eligibility Decision (RED)--Lindane.
EPA 738-R-02-012. Office of Prevention, Pesticides, and Toxic
Substances. July 2002. Available on the Internet at: http://www.epa.gov/oppsrrdl/REDs/lindane_red.pdf.
USEPA. 2002i. Integrated Risk Information System (IRIS), 1,1-
Dichloroethylene. August 2002. Available on the Internet at: http://www.epa.gov/iris/subst/0039.htm.
USEPA. 2003a. Analytical Feasibility Support Document for the Six-
Year Review of Existing National Primary Drinking Water Regulations
(Reassessment of Feasibility for Chemical Contaminants). EPA 815-R-
03-003. Final. March 2003.
USEPA. 2003b. Consideration of Other Regulatory Revisions for
Chemical Contaminants in Support of the Six-Year Review of National
Primary Drinking Water Regulations. EPA 815-R-03-005. Final. June
2003.
USEPA. 2003c. EPA Protocol for Review of Existing National Primary
Drinking Water Regulations. EPA 815-R-03-002. Final. June 2003.
USEPA. 2003d. Occurrence Estimation Methodology and Occurrence
Findings Report for the Six-Year Review of Existing National Primary
Drinking Water Regulations. EPA 815-R-03-006. Final. June 2003.
USEPA. 2003e. Public Comment and Response Summary for the Six-Year
Review of National Primary Drinking Water Regulations. EPA 815-R-03-
001. Final. June 2003.
USEPA. 2003f. Six-Year Review--Chemical Contaminants--Health Effects
Technical Support Document. EPA 822-R-03-008. Final. June 2003.
USEPA. 2003g. Water Treatment Technology Feasibility Support
Document for Chemical Contaminants; In Support of EPA Six-Year
Review of National Primary Drinking Water Regulations. EPA 815-R-03-
004. Final. June 2003.
USEPA. 2003h. Integrated Risk Information System (IRIS);
Announcement of 2003 Program; Request for Information and
Announcement of Workshop; Notice. Federal Register. Vol. 68, No. 24.
p. 5870, February 5, 2003.
Dated: July 11, 2003.
Linda J. Fisher,
Acting Administrator.
[FR Doc. 03-18152 Filed 7-17-03; 8:45 am]
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