,EPA 811-Z-94-004
Friday
July 29, 1994
Part II
X S.
Environmental
Protection Agency
40 CFR Parts 141 and 142
National Primary Drinking Water
Regulations; Disinfectants and
Disinfection Byproducts; Proposed Rule
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Parts 141 and 142
[WH-FRL-4998-2]
Drinking Water; National Primary
Drinking Water Regulations:
Disinfectants and Disinfection
Byproducts
AGENCY: Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
SUMMARY: In this document, EPA is
proposing maximum residual
disinfectant level goals (MRDLGs) for
chlorine, chloramines, and chlorine
dioxide; maximum contaminant level
goals (MCLGs) for four trihalomethanes
(chloroform, bromodichloromethane,
dibromochloromethane, and
bromoform), two haloacetic acids
(dichloroacetic acid and trichloroacetic
acid), chloral hydrate, bromate, and
chlorite; and National Primary Drinking
Water Regulations (NPDWRs) for three
disinfectants (chlorine, chloramines,
and chlorine dioxide), two groups of
organic disinfection byproducts (total
trihalomethanes (TTHMs)—a sum of the
four listed above, and haloacetic acids
(HAA5)—a sum of the two listed above
plus monochloroacetic acid and mono-
and dibromoacetic acids), and two
inorganic disinfection byproducts
(chlorite and bromate). The NPDWRs
consist of maximum residual
disinfectant levels or maximum
contaminant levels or treatment
techniques for these disinfectants and
their byproducts. The NPDWRs also
include proposed monitoring, reporting,
and public notification requirements for
these compounds. This notice proposes
the best available technology (BAT)
upon which the MRDLs and MCLs are
based and the BAT for purposes of
issuing variances.
DATES: Written comments must be
postmarked or hand-delivered by
December 29,1994. Comments received
after this date may not be considered.
Public hearings will be held at the
addresses indicated below under
"ADDRESSES" on August 29 (and 30, if
necessary) in Denver, CO and on
September 12 (and 13, if necessary) in
Washington, DC.
ADDRESSES: Send written comments on
the proposed rule to Disinfectant/
Disinfection By-Products Comment
Clerk, Drinking Water Docket (MC
4101), Environmental Protection
Agency, 401M Street, S.W.,
Washington, D.C. 20460. Commenters
are requested to submit three copies of
their comments and at least one copy of
any references cited in their written or
oral comments. A copy of the comments
and supporting documents are available
for review at the EPA, Drinking Water
Docket (4101), 401 M Street, S.W.,
Washington, DC 20460. For access to the
docket materials, call (202) 260-3027
between 9:00 a.m. and 3:30 p.m.
The Agency will hold public hearings
on the proposal at two different
locations indicated below:
1. Denver Federal Center, 6th and
Kipling Streets, Building 25, Lecture
Halls A and B (3d Street), Denver, CO
80225 on August 29 (and 30, if
necessary), 1994.
2. EPA Education Center Auditorium,
401 M Street SW., Washington, D.C.
20460, on September 12 (and 13, if
necessary), 1994.
The hearings will begin at 9:30 a.m.,
with registration at 9:00 a.m. The
Hearings will end at 4:00 p.m., unless
concluded earlier. Anyone planning to
attend the public hearings (especially
those who plan to make statements) may
register in advance by writing the D/
DBPR Public Hearing Officer, Office of
Ground Water and Drinking Water
(4603), USEPA, 401M Street, S.W.,
Washington, D.C. 20460; or by calling
Tina Mazzocchetti, (703) 931-4600.
Meeting dates are tentative and should
be confirmed by calling the Safe
Drinking Water Hotline prior to making
travel plans. Oral and written comments
may be submitted at the public hearing.
Persons who wish to make oral
presentations are encouraged to have
written copies (preferably three) of their
complete comments for inclusion in the
official record.
Copies of draft health criteria,
analytical methods, and regulatory
impact analysis documents are available
at some Regional Offices listed below
and for a fee from the National
Technical Information Service (NTIS),
U.S. Department of Commerce, 5285
Port Royal Road, Springfield, Virginia
22161. The toll-free number is (800)
336-4700 or local at (703) 487-4650.
FOR FURTHER INFORMATION CONTACT:
General information may be obtained
from the Safe Drinking Water Hotline,
telephone (800) 426-4791; Stig Regli,
Office of Ground Water and Drinking
Water (4603), U.S. Environmental
Protection Agency, 401M Street, SW.,
Washington, DC 20460, telephone (202)
260-7379; Tom Grubbs, Office of
Ground Water and Drinking Water
(4603), U.S. Environmental Protection
Agency, 401 M Street, SW., Washington,
DC 20460, telephone (202) 260-7270; or
one of the EPA Regional Office contacts
listed below.
SUPPLEMENTARY INFORMATION:
EPA Regional Offices
I. Robert Mendoza, Chief, Water Supply
Section, JFK Federal Bldg., Room 203,
Boston, MA 02203, (617) 565-3610
II. Robert Williams, Chief, Water Supply
Section, 26 Federal Plaza, Room 824, New
York, NY 10278, (212) 264-1800
III. Jeffrey Hass, Chief, Drinking Water
Section (3WM41), 841 Chestnut Building,
Philadelphia, PA 19107, (215) 597-9873
IV. Phillip Vorsatz, Chief, Water Supply
Section, 345 Courtland Street, Atlanta, GA
30365, (404) 347-2913
V. Charlene Denys, Chief, Water Supply
Section, 77 W. Jackson Blvd., Chicago, IL
60604, (312) 353-2650
VI. F. Warren Norris, Chief, Water Supply
Section, 1445 Ross Avenue, Dallas, TX
75202, (214) 655-7155
VII. Ralph Flournoy, Chief, Water Supply
Section, 726 Minnesota A.ve., Kansas City,
KS 66101, (913) 234-2815
VIII. Doris Sanders, Chief, Water Supply
Section, One Denver Place, 999 18th Street,
Suite 500, Denver, CO 80202-2405, (303)
293-1424
IX. Bill Thurston, Chief, Water Supply
Section, 75 Hawthorne Street, San
Francisco, CA 94105, (415) 744-1851
X. William Mullen, Chief, Water Supply
Section, 1200 Sixth Avenue, Seattle, WA
98101, (206) 442-1225.
Abbreviations used in this document.
AECL: Alternate enhanced coagulant level
AOC: Assimilable organic carbon
ASDWA: Association of State Drinking Water
Administrators
AWWA: American Water Works Association
AWWARF: AWWA Research Foundation
BAG: Biologically active carbon
BAF: Biologically active filtration
BAT: Best Available Technology
BCAA: Bromochloroacetic acid
BDOC: Biodegradable organic carbon
BTGA: Best Technology Generally Available
CI: Confidence interval
CWS: Community Water Sjrstem
DBF: Disinfection byproducts
D/DBP: Disinfectants and disinfection
byproducts
D/DBPR: Disinfectants and disinfection
byproducts rule
DBPP: Disinfection byproduct precursors
DBPRAM: DBF Regulatory Assessment model
DPD:N,N-diethyl-p-phenylenediamine
DWEL: Drinking Water Equivalent Level
EBCT: Empty bed contact time
EMSL: EPA Environmental Monitoring and
Support Laboratory (Cincinnati)
EPA: United States Environmental Protection
Agency
ESWTR: Enhanced Surface Water Treatment
Rule
FY: Fiscal year
GAG: Granular Activated Carbon
GWDR: Ground Water Disinfection Rule
GWSS: Ground Water Supply Survey
HAAS: Haloacetic acids (five)
HOBr: Hypobromous acid
1C: Ion chromotography
ICR: Information Collection Rule
IOC: Inorganic chemical
LOAEL: Lowest observed adverse effect level
LOQ: Limit of Quantitation
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38669
MCL: Maximum Contaminant Level
(expressed as mg/1,1,000 micrograms
(jig) = 1 milligram (mg))
MCLG: Maximum Contaminant Level Goal
MDL: Method Detection Limit
MF: Modifying factor
mg/dl: Milligrams per deciliter
mg/1: Milligrams per liter
MGD: Million Gallons per Day
MRDL: Maximum Residual Disinfectant
Level (as mg/1)
MRL: Minimum reporting level
MRDLG: Maximum Residual Disinfectant
Level Goal
NCI: National Cancer Institute
ND: Not detected
NIPDWR: National Interim Primary Drinking
Water Regulation
NOAEL: No observed adverse effect level
NOMS: National Organic Monitoring Survey
NORS: National Organics Reconnaissance
Survey for Halogenated Organics
NPDWR: National Primary Drinking Water
Regulation
NTNCWS: Nontransient noncommunity
water system
OBr: Hypobromite ion
OR: Odds ratio
PE: Performance evaluation
POE: Point-of-Entry Technologies
POU: Point-of-Use Technologies
ppb: Parts per billion
PQL: Practical Quantitation Level
PTA: Packed Tower Aeration
PWS: Public Water System
R1A: Regulatory Impact Analysis
RMCL: Recommended Maximum
Contaminant Level
RNDB: Regulations Negotiation Data Base
RSC: Relative Source Contribution
SDWA: Safe Drinking Water Act, or the
"Act," as amended in 1986
SM: Standard Method
SMCL: Secondary Maximum Contaminant
Level
SMR: Standardized mortality ratios
SOC: Synthetic Organic Chemical
SWTR: Surface Water Treatment Rule
THMFP: Trihalomethane formation potential
TOG: Total organic carbon
TTHM: Total trihalomethanes
TWG: Technologies Working Group
VOC: Volatile Synthetic Organic Chemical
WIDE: Water Industry Data Base
WS: Water Supply
Table of Contents
I. Summary of Today's Action
A. Applicability.
B. Proposed MRDLGs and MRDLs for
disinfectants
C. Proposed MCLGs and MCLs for organic
byproducts
D. Treatment technique for DBF precursors
E. Proposed Stage 1 MCLGs and MCLs for
inorganic byproducts .
F. Proposed BAT for disinfectants
G. Proposed BAT for organic byproducts
H. Proposed BAT for inorganic byproducts
I. Proposed Compliance Monitoring
Requirements
]. Analytical Methods
K. Laboratory Certification Criteria
L. Variances and Exemptions
M. State Primacy, Recordkeeping,
Reporting Requirements
N. System Reporting Requirements
O. D/DBP Stage 2 Rule requirements
P. Guidance
Q. Triennial Regulation Review
II. Statutory Authority
A. MCLGs, MCLs, and BAT
B. Variances and Exemptions
C. Primacy
D. Monitoring, Quality Control, and
Records
E. Public Water Systems
F. Public Notification
III. Overview of Existing Interim Standard for
TTHMs
IV. Overview of Preproposal Regulatory
Development
A. October 1989 Strawman Rule
B. June 1991 Status Report on D/DBP rule
development
C. Initiation of Regulatory Negotiation
Process
V. Establishing MCLGs
A. Background
B. Proposed MRDLGs and MCLGs
1. Chlorine, hypochloriteion and
hypochlorous acid
2. Chloramines
3. Epidemiology Studies of Chlorinated
and Chloraminanted Water
4. Chlorine dioxide, chlorite, and chlorate
5. Chloroform
6. Bromodichloromethane
7. Dibromochloromethane
8. Bromoform
9. Dichloroacetic acid
10. Trichloroacetic acid
11. Chloral hydrate
12. Bromate
VI. Occurrence of TTHMs, HAAS, and other
DBFs
A. Relationship of TTHMs, HAAS to
disinfection and source water quality
B. Chlorination Byproducts
C. Other Disinfection Byproducts
1. Ozonation Byproducts
2. Chlorine Dioxide Byproducts
3. Chloramination Byproducts
VII. General Basis for Criteria of Proposed
rule
A. Goals of regulatory negotiation
B. Concern for downside microbial risks
and unknown risks from DBFs of
different technologies
C. Ecological concerns
D. Watershed protection
E. Narrowing of regulatory options through
reg-neg process
VIII. Summary of the Proposed National
Primary Drinking Water Regulation for
Disinfectants and Disinfection
Byproducts
A. Schedule and coverage
B. Summary of DBF MCLs, BATs, and
monitoring and compliance requirments
C. Summary of disinfectant MRDLs, BATs,
and Monitoring and compliance
requirements '
D. Enhanced coagulation and enhanced
softening requirements
E. Requirement for systems to use qualified
operators
F. Basis for analytical method requirements
'G. Public Notice Requirements
H. Variances and Exemptions
I. Reporting and Record Keeping
requirements for PWSs
J. State Implementation Requirements
DC. Basis for Key Specific Criteria of
Proposed Rule
A. 80/60 TTHM/HAA5 MCLs, enhanced
coagulation requirements, and BAT
1. basis for umbrella concept vs. individual
MCLs
2. basis for level of stringency in MCLs,
BAT, and concurrent enhanced
coagulation requirements
3. basis for enhanced coagulation and
softening criteria
4. basis for GAG definitions
5. basis for monitoring requirements
B. Bromate MCL and BAT
C. Chlorite MCL and BAT
D. Chlorine MRDL and BAT
E. Chloramine MRDL and BAT
F. Chlorine dioxide MRDL and BAT
G. Basis for analytical method
requirements
H. Basis for compliance schedule and
applicability to different groups of
systems, timing with other regulations
I. Basis for qualified operator requirements
and monitoring plans
J. Basis for Stage 2 proposed MCLs
X. Laboratory Certification and Approval
A. PE-Sample Acceptance Limits for
Laboratory Certification
B. Approval Criteria for Disinfectants and
• Other Parameters
C. Other Laboratory Performance Criteria
XI. Variances and Exemptions
A. Variances
B. Exemptions
XII. State Implementation
A. Special primacy requirements
B. State recordkeepmg
C. State reporting
XIII. System Reporting and'Recordkeeping
Requirements
XIV. Public Notice Requirements
XV. Economic Analysis
A. Executive Order 12866
B. Predicted cost impacts on public water
systems
1. Compliance treatment cost forecasts
2. Compliance treatment forecasts
3. DBF exposure estimates
4. System level cost estimates
5. Effect on household costs
6. Monitoring and State implementation
costs, labor burden estimates
C. Concepts of cost analysis
D. Benefits
XVI. Other Requirements
A. Consultation with State, Local, and
Tribal Governments
B. Regulatory Flexibility Act
C. Paperwork Reduction Act
D. National Drinking Water Advisory
Council and Science Advisory Board
XVII. Request for Public Comment
XVIII. References and Public Docket
I. Summary of Today's Action
In 1992 EPA initiated a negotiated
rulemaking to develop a disinfectant/
disinfection byproduct rule. The Agency
decided to use the negotiated
rulemaking process because it believed
that the available occurrence, treatment,
and health effects data were inadequate
to address EPA's concerns about the
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tradeoff between risks from
disinfectants and disinfection
byproducts and microbial pathogen risk,
and wanted all stakeholders to
participate in the decision-making on
setting proposed standards. The
negotiators included State and local
health and regulatory agency staff and
elected officials, consumer groups,
environmental groups, and
representatives of public water systems.
The group met from November 1992
through June 1993.
Early in the process, the negotiators
agreed that large amounts of information
necessary to understand how to
optimize the use of disinfectants to
concurrently minimize microbial and
disinfectant/disinfection byproduct risk
were unavailable.
Therefore, the group agreed to
propose a disinfectant/disinfection
byproduct rule to extend coverage to all
community water systems that use
disinfectants, reduce the current total
trihalomethane (TTHM) maximum
contaminant level (MCL), regulate
additional disinfection byproducts, set
limits for the use of disinfectants, and
reduce the level of compounds that may
react with disinfectants to form
byproducts. These requirements were
based on available information. The
group further agreed that revisions to
the current Surface Water Treatment
Rule might be required at the same time
to ensure that microbial risk is not
increased as byproduct rules go into
effect. Finally, the group agreed that
additional information on health risk,
occurrence, treatment technologies, and
analytical methods needed to be
developed in order to better understand
the risk-risk tradeoff, whether further
control was needed, and how to
accomplish this overall risk reduction.
The outcome of the negotiation was
three rules: a Disinfectant/Disinfection
Byproduct rule (this notice), an
Enhanced Surface Water Treatment Rule
(also proposed today and appearing
separately in today's Federal Register),
and an Information Collection Rule
(proposed February 10,1994, 59 FR
6332). The Information Collection Rule
will provide information necessary to
determine whether the Enhanced
Surface Water Treatment Rule needs to
be promulgated and, if so, what
requirements it should set. The
Information Collection Rule will also
provide information on the need for,
and content of, long-term rules. The
schedule to produce these rules has also
been negotiated and is provided
elsewhere in this document. A summary
of today's rule follows.
A. Applicability. This action applies
to all community water systems and
nontransient noncommunity water'
systems that add a disinfectant during
any part of the treatment process
including addition of a residual
disinfectant. In addition, certain
provisions apply to transient
noncommunity water systems that use
chlorine dioxide.
B. Proposed MRDLGs and MRDLs for
disinfectants. EPA is proposing the
following maximum disinfectant
residual level goals and maximum
residual disinfectant levels.
Disinfectant Residual
(3) Chlorine dioxide ,
MRDLG (mg/l)
4 (as CI2)
4 (as CI2)
0.3 (as CIO2)
MRDL (mg/l)
4.0 (as CI2).
4.0 (as CI2).
0.8 (as CIO2).
C. Proposed MCLGs and MCLs for
organic byproducts. EPA is proposing
the following maximum contaminant
level goals and maximum contaminant
levels.
Total trihalomethanes
(TTHM)
Haloacetic acids (five)
(HAAS)
Chloroform
Bromodichloromethane
Dibromochloromethane
Bromoform
Dichloroacetic acid
Trichloroacetic acid
Chloral hvdrate
MCLG
(mg/l)
1N/A
2N/A
0
0
0.06
0
0
0.3
0.04
MCL
(mg/l)
0.080
.060
1N/A
1N/A
1N/A
1N/A
2N/A
2N/A
3N/A
systems that use surface water or ground
water under the direct influence of
surface water and use conventional
nitration treatment be required to
remove specified amounts of organic
materials (measured as total organic
carbon) that may react with
disinfectants to form disinfection
byproducts. Removal would be achieved
through a treatment technique
(enhanced coagulation or enhanced
softening) unless the system met certain
criteria.
E. Proposed Stage 1 MCLGs and MCLs
for inorganic by-products. EPA is
proposing the following maximum
contaminant level goals and maximum
contaminant levels.
1 Total trihalomethanes are the sum of the
concentrations of bromodichloromethane,
dibromochloromethane, bromoform, and chlo-
roform.
2 Haloacetic acids (five) are the sum of the
concentrations of mono-, di-, and
trichloroacetic acids and mono- and dibromo-
acetic acids.
3 EPA did not set an MCL for chloral hydrate
because the TTHM and HAAS MCLs and the
treatment technique (i.e., enhanced coagula-
tion) for disinfection byproduct precursor re-
moval will control for chloral hydrate. (See
Section IX.)
D. Treatment Technique for DBF
Precursors. EPA is proposing that water
Chlorite
Bromate
MCLG
(mg/l)
0.08
0
MCL
(mg/l)
1.0
0.010
F. Proposed BAT for disinfectants.
EPA is proposing the following best
available technologies for limiting
residual disinfectant concentrations in
the distribution system.
Chlorine residual—control of treatment
processes to reduce disinfectant
demand and control of disinfection
treatment processes to reduce
disinfectant levels
Chloramine residual—control of
treatment processes to reduce
disinfectant demand and control of
disinfection treatment processes to
reduce disinfectant levels
Chlorine dioxide residual—control of
treatment processes to reduce
disinfectant demand and control of
disinfection treatment processes to
reduce disinfectant levels.
G. Proposed BAT for organic
byproducts. EPA is proposing the
following best available technologies for
control of organic disinfection
byproducts in each stage of the rule.
1. Proposed Stage 1 BAT for organic
by-products. Total trihalomethanes—
enhanced coagulation or GAC10, with
chlorine as the primary and residual
disinfectant. Total haloacetic acids—
enhanced coagulation or GAC10, with
chlorine as the primary and residual
disinfectant.
2. Proposed Stage 2 BAT for organic
byproducts. Total trihalomethanes—
enhanced coagulation and GAG 10, or
GAC20; with chlorine as the primary
and residual disinfectant. Total
haloacetic acids—enhanced coagulation
and GAC10, or GAC20; with chlorine as
the primary and residual disinfectant.
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H. Proposed BAT for inorganic by-
products. EPA is proposing the
following best available technologies for
control of inorganic disinfection
byproducts.
Chlorite—control of treatment processes
to reduce disinfectant demand and
control of disinfection treatment
Erocesses to reduce disinfectant
svels.
Bromate—control of ozone treatment
process to reduce production of
bromate.
I. Proposed Compliance Monitoring
Requirements. Compliance monitoring
requirements are explained in Section
IX of the preamble and were developed
during the negotiated rulemaking. EPA
has developed routine and reduced
monitoring schemes that address the
health effects of each disinfectant or
contaminant in an individually
appropriate manner.
J. Analytical Methods. EPA is
proposing to withdraw one method for
measurement of chlorine residual and to
approve three new methods for
measurement of chlorine residuals. EPA
is proposing to approve one new
method for measurement of
trihalomethanes; two new methods for
measurement of haloacetic acids; one
new method for measurement of
bromate, chlorite, and bromide; and two
new methods for measurement of total
organic carbon.
K. Laboratory Certification Criteria.
Consistent with other drinking water
regulations, EPA is proposing that only
certified laboratories be allowed to
analyze samples for compliance with
the proposed MCLs and treatment
technique requirements. For
disinfectants and other specified
parameters in today's rule that the
Agency believes can be adequately
measured by other than certified
laboratories and for which there is a
good reason to allow analysis at other
locations (e.g., for samples which
normally deteriorate before reaching a
certified laboratory, especially when
taken at remote locations), EPA is
requiring that' such analyses be
conducted by a party acceptable to EPA
or the State.
L. Variances and Exemptions.
Variances and exemptions will be
permitted.
M. State Primacy, Recordkeeping,
Reporting Requirements. Requirements
for States to maintain primacy are listed
in Section XII of the preamble. In
addition to routine requirements, EPA
has included special primacy
requirements.
N. System Reporting Requirements.
System reporting requirements remain
consistent with requirements in
previous rules.
O. D/DBP Stage 2 Rule requirements.
EPA is proposing a total trihalomethane
MCL of 0.040 mg/1 and a haloacetic acid
(five) MCL of 0.030 mg/1, to apply only
to systems using surface water or
ground water under the direct influence
of surface water and serving at least
10,000 persons, as part of a plan to
develop new standards which
incorporates the results of additional
research conducted under the
Information Collection Rule (59 FR
6332).
P. Guidance. EPA is in the process of
developing guidance for both systems
and States for implementation of this
rule.
Q. Triennial Regulation Review.
Under the provisions of the Safe
Drinking Water Act (SDWA or the Act)
(Section 1412(b)(9)), the Agency is
required to review national primary
drinking water regulations at least once
every three years. As mentioned
previously, today's proposed rule
revises, updates, and (when
promulgated) supersedes the regulations
for total trihalomethanes, initially
published in 1979. Since that time,
there have been significant changes in
technology, treatment techniques, and
other regulatory controls that provide
for greater protection for health of
persons. As such, in proposing today's
rule, EPA has analyzed innovations and
changes in technology and treatment
techniques that have occurred since
promulgation of the initial TTHM
regulations. This analysis, contained
primarily in the cost and technology
document supporting this proposal,
supports amendment of the TTHM
regulation for the greater protection of
persons. EPA believes that the
innovations and changes in technology
and treatment techniques will result in
amendments to the TTHM regulations
that are feasible within the meaning of
SDWA Section 1412(b)(9).
n. Statutory Authority
Section 1412 of the Safe Drinking
Water Act, as amended in 1986
("SDWA" or "the Act"), requires EPA to
publish Maximum Contaminant Level
Goals (MCLGs) and promulgate National
Primary Drinking Water Regulations
(NPDWRs) for contaminants in drinking
water which may cause any adverse
effect on the health of persons and
which are known or anticipated to occur
in public water systems. Under Section
1401, the NPDWRs are to include
Maximum Contaminant Levels (MCLs)
and "criteria and procedures to assure a
supply of drinking water which
dependably complies" with such MCLs.
Under Section 1412(b)(7)(A), if it is not
economically or technically feasible to
ascertain the level of a contaminant in
drinking water, EPA may require the use
of a treatment technique instead of an
MCL.
Under Section 1412(b), EPA was to
establish MCLGs and promulgate
NPDWRs for 83 contaminants by June
19,1989. An additional 25
contaminants are to be regulated every
3 years. To meet this latter requirement,
EPA has developed a list of
contaminants (National Drinking Water
Priority List; 53 FR 1892) including
pesticides, organic and inorganic
elements or compounds, and
disinfectants and disinfection by-
products (D/DBP), plus the protozoan
Cryptosporidium. From this list, EPA is
to choose at least 25 contaminants for
regulation every three years. Today's
regulatory proposal represents part of
the first group of 25 chemicals to be
regulated. Both the general
contaminants (organics, inorganics, and
pesticides), and the D/DBPs were
considered for regulation. In today's
notice, EPA is proposing to regulate
certain disinfectants and disinfection
byproducts; Cryptosporidium is
proposed to be regulated in a separate
Notice today.
In October of 1990, EPA entered into
a consent order with Citizens Concerned
about Bull Run Inc. regarding a
timeframe for proposing the first group
of 25. The consent decree stipulated a
June 1993 date for proposal. That decree
was subsequently amended to establish
a proposal date of May 30,1994, for the
Disinfectants/Disinfection Byproducts
Rule and a proposal date of February 28,
1995, for the other contaminants that
comprise the required group of 25.
A. MCLGs, MCLs, and BAT
Under Section 1412 of the Act, EPA
is to establish MCLGs at the level at
which no known or anticipated adverse
effects on the health of persons occur
and which allow an adequate margin of
safety. MCLGs are nonenforceable
health goals based only on health effects
and exposure information.
MCLs are enforceable standards
which the Act directs EPA to set as
close to the MCLGs as feasible.
"Feasible" means feasible with the use
of the best technology, treatment
techniques, and other means which the
Administrator finds available (taking
cost into consideration) after
examination for efficacy under field
conditions and not solely under
laboratory conditions (SDWA.'section
1412(b)(5)). Also, the SDWA requires
the Agency to identify the best available
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technology (BAT) which is feasible for
meeting the MCL for each contaminant.
Also, in this proposal, EPA is
introducing several new terms—
"maximum residual disinfectant level
goals (MRDLGs)" and "maximum
residual disinfectant levels (MRDLs)"—
to reflect the fact that these substances
have beneficial disinfection properties.
As with MCLGs, EPA has established
MRDLGs at the level at which no known
or anticipated adverse effects on the
health of persons occur and which
allow an adequate margin of safety.
MRDLGs are nonenforceable health
goals based only on health effects and
exposure information and do not reflect
the benefit of the addition of the
chemical for control of waterborne
microbial contaminants.
MRDLs are enforceable standards,
analogous to MCLs, which recognize the
benefits of adding a disinfectant to
water on a continuous basis and in
addressing emergency situations such as
distribution system pipe breaks. As with
MCLs, EPA has set the MRDLs as close
to the MRDLGs as feasible. The Agency
has also identified the best available
technology (BAT) which is feasible for
meeting the MRDL for each disinfectant.
B. Variances and Exemptions
Section 1415 authorizes the State to
issue variances from NPDWRs (the term
"State" is used in this preamble to mean
the State agency with primary
enforcement responsibility for the
public water supply system program or
EPA if the State does not have primacy).
The State may issue a variance if it
determines that a system cannot comply
with an MCL despite application of the
best available technology (BAT). Under
Section 1415, EPA must propose and
promulgate its finding of the best
available technology, treatment
techniques, or other means available for
each contaminant, for purposes of
section 1415 variances, at the same time
that it proposes and promulgates a
maximum contaminant level for such
contaminant. EPA's finding of BAT,
treatment techniques, or other means for
purposes of issuing variances may vary
among systems, depending upon the
number of persons served by the system
or for other physical conditions related
to engineering feasibility and costs of
complying with MCLs, as considered
appropriate by EPA. The State may not
issue a variance to a system until it
determines that an unreasonable risk to
health (URTH) does not exist. When a
State grants a variance, it must at the
same time prescribe a schedule for (1)
compliance with the NPDWR and (2)
implementation of any additional
control measures.
Under Section 1416(a), the State may
exempt a public water system from any
MCL.or treatment technique
requirement if it finds that (1) due to
compelling factors (which may include
economic factors), the system is unable
to comply, (2) the system was in
operation on the effective date of the
MCL or treatment technique, or, for a
newer system, that no reasonable
alternative source of drinking water is
available to that system, and (3) the
exemption will not result in an
unreasonable risk to health. Under
section 1416(b), at the same time it
grants an exemption, the State is to
prescribe a compliance schedule and a
schedule for implementation of any
required interim control measures. The
final date for compliance may not
exceed three years after the initial date
of issuance unless the public water
system establishes that: (1) the system
cannot meet the standard without
capital improvements which cannot be
completed within the period of such
exemption; (2) the system has entered
into an agreement to obtain financial
assistance for necessary improvements;
or (3) the system has entered into an
enforceable agreement to become part of
a regional public water system. For
systems which serve 500 or fewer
service connections and which need
financial assistance to come into
compliance, the State may renew the
exemption for additional two-year
periods if the system is taking all
practicable steps to meet the above
requirements.
For exemptions resulting from a
NPDWR promulgated after June 19,
1986, the system's final compliance date
must be within 12 months of issuance
of the exemption. However, the State
may extend the final compliance date
for up to three years if the public water
system shows that capital improvements
to meet the MCL or treatment technique
requirement cannot be completed
within the exemption period and, if the
system needs financial assistance for the
improvements, it has an agreement to
obtain this assistance or the system has
an enforceable agreement to become
part of a regional public water system.
For systems that have 500 or fewer
service connections that need financial
assistance to comply with the MCLs, the
State may renew the exemption for
additional two-year periods if the
system is taking all practicable steps to
comply.
C. Primacy
As indicated above, States, territories,
and Indian Tribes may assume primary
enforcement responsibility (primacy) for
public water systems under Section
1413 of the SDWA. To date, 55 States
and territories have primacy. To assume
or retain primacy, States, territories, or
Indian Tribes need not adopt the
MCLGs but must adopt, among other
things, NPDWRs (i.e., MCLs,
monitoring, analytical, arid reporting
requirements) that are no less stringent
than those EPA promulgates.
D. Monitoring, Quality Control, and
Records
Under Section 1401(1)(D) of the Act,
NPDWRs are to contain "criteria and
procedures to assure a supply of
drinking water which dependably
complies with such maximum
contaminant levels; including quality
control and testing procedures to insure
compliance with such levels * * *."
E. Public Water Systems
Public water systems are defined in
section 1401 of the Act as those systems
which provide piped water for human
consumption and have at least 15
connections or regularly serve at least
25 people. By regulation EPA has
divided public water systems into
community, nontransient
noncommunity, and (transient)
noncommunity water systems.
Community water systems (CWSs) serve
at least 15 service connections used by
year-round residents or regularly serve
at least 25 year-round residents (40 CFR
141.2). Nontransient noncommunity
water systems (NTNCWSs) regularly
serve at least 25 of the same people over
six months of the year. Schools and
factories which serve water to 25 or
more of the same people for six or more
months of the year are examples of
NTNCWSs. Transient noncommunity
systems, by definition, are all other
public water systems. Transient
noncommunity systems may include,
for example, restaurants, gas stations,
campgrounds, and churches.
This rule would apply to all CWSs, all
NTNCWSs, and any transient
noncommunity water systems that use
chlorine dioxide as a disinfectant or
oxidant.
F. Public Notification
Section 1414(c) of the Act requires the
owner or operator of a public water
system which does not comply with an
applicable maximum contaminant level
or treatment technique, testing
procedure, or Section 1445(a)
(unregulated contaminant) monitoring
requirement to give notice to the
persons served by the system. Notice
must also be given if a variance or
exemption is in effect or the system fails
to comply with a compliance schedule
resulting from a variance or exemption.
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EPA's public notification regulations are
codified at 40 CFR Section 141.32.
Those regulations were amended by
EPA on October 28,1987 (52 FR 41534).
HI. Overview of Existing Interim
Standard for TTHMS
In 1974, researchers in The
Netherlands and the United States
clearly demonstrated that total
trihalomethanes (TTHMs) are formed as
a result of drinking water chlorination
(Rook, 1974; Bellar et al, 1974). EPA
subsequently conducted surveys
confirming widespread occurrence of
TTHMs in chlorinated water supplies
(Symons, 1975; USEPA, 1978). During
this time lexicological studies became
available which supported the
contention that chloroform, one of the
four trihalomethanes, is carcinogenic in
at least one strain of rat and one strain
of mouse (National Academy of
Sciences, 1977).
EPA then set an interim maximum
contaminant level (MCL) for the TTHMs
of 100 ug/1 as an annual average in
November 1979 (USEPA, 1979). This
standard was based on the need to
balance the requirement for continued
disinfection of water to reduce exposure
to pathogenic microorganisms while
simultaneously lowering exposure to
animal carcinogens like chloroform.
The interim TTHM standard only
applies to systems serving at least
10,000 people that add a disinfectant
(oxidant) to the drinking water during
any part of the treatment process. At
their discretion, States are allowed to
extend coverage to smaller size systems.
About 80 percent of the smallest
systems are served by groundwater
systems that are mostly low in THM
precursor content (USEPA, 1979).
The proportion of these small
groundwater systems that use chlorine
is less than that of large systems;
currently, less than half of these systems
disinfect. Also, the shorter hydraulic
detention and chlorine contact times in
the small system distribution systems
results in lower TTHM concentrations.
Therefore, drinking water systems
serving less than ten thousand people
are less likely to have high
concentrations of TTHMs.
Moreover, these small systems are
most likely to have greater risks of
significant microbiological
contamination, especially if they reduce
or eliminate chlorination. In 1979, the
majority of outbreaks attributable to
inadequate disinfection occurred in
small systems. Further, small systems
have limited or no access to the
financial resources and technical
expertise needed for TTHM control.
Therefore, EPA concluded that small
system resources would best be spent on
maintaining and improving
microbiological quality and safety. The
revised drinking water regulations now
under consideration will extend to these
small systems as required by the Safe
Drinking Water Act Amendments of
1986 (P.L. 99-339,1986). EPA will also
be considering disinfection as a
treatment technique requirement and
maximum contaminant levels (MCLs)
for the residual disinfectants. The
impacts these requirements will have on
small systems is an important
component of the regulation
development process.
Technology Basis for the Interim TTHM
Standard
When an MCL is established for
TTHMs or any other contaminant that
can be measured, EPA is not required to
specify any particular method for
achieving that standard. Instead, the
requirement for the interim regulations
was to set an MCL which could be
achieved using technology generally
available in 1974. Three general control
alternatives were available:
(1) use of a disinfectant (oxidant) that
does not generate (or produces less)
THMs in water;
(2) treatment to lower precursor
concentrations prior to chlorination;
and
(3) treatment to remove THMs after their
formation.
There are many possible choices
among these broad options and in some
cases a combination of approaches
might be necessary. The ultimate choice
was left up to the water supplier based
on its individual circumstances.
EPA's evaluation led to the following
conclusions concerning generally
available technologies for setting the
TTHM MCL:
(1) alternate oxidants like ozone,
chloramines, and chlorine dioxide are
available;
(2) precursor removal strategies like
changing the point of disinfection, off-
line raw water storage, and improved
coagulation are available; and,
(3) precursor removal using granular
activated carbon (GAG) as a
replacement for existing filter media
with a regeneration frequency of one
year is feasible as well as biologically
activated carbon (ozone plus GAG)
with a regeneration frequency of every
two years.
Three conditions concerning
modifications of disinfection processes
were also proposed by EPA:
(1) the total quantity of chlorine dioxide
added during the treatment process
should not exceed 1 mg/1;
(2) chloramines should not be utilized
as a primary disinfectant; and
(3) monitoring for heterotrophic plate
count bacteria (HPC) should be
conducted as determined by the State,
but at least every day for a minimum
of one month prior to and six months
subsequent to the modifications.
These recommendations concerning
disinfection, although useful, were
deleted from the final regulation to
allow States greater discretion. The
basis for the MCL became alternate
oxidants and precursor removal.
Technology Basis for Variances
Later, in 1983, EPA promulgated
regulations specifying best technology
generally available for obtaining
variances (USEPA, 1983). A variance is
granted by the State when a system has
installed the best technology generally
available as specified in the regulation
and still cannot meet the MCL. The best
technologies generally available for
variances to the TTHM MCL are:
(1) Use chloramines as an alternate or
supplemental disinfectant or oxidant.
(2) Use chlorine dioxide as an alternate
or supplemental disinfectant or
oxidant.
(3) Improve existing clarification for
THM precursor reduction.
(4) Move the point of chlorination to
reduce TTHM formation and, where
necessary, substituting for the use of
chlorine as a pre-oxidant chloramines,
chlorine dioxide, or potassium
permanganate.
(5) Use of powdered activated carbon for
THM precursor or TTHM reduction
seasonally or intermittently at dosages
not to exceed 10 mg/1 on an annual
average basis.
EPA also identified Group II
technologies, which are not "generally
available," but may be available to some
systems:
(1) Introduction of off-line water storage
for THM precursor reduction.
(2) Aeration for TTHM reduction, where
geographically and environmentally
appropriate.
(3) Introduction of clarification where
not currently practiced.
(4) Consideration of alternative sources
of raw water.
(5) Use of ozone as an alternate or
supplemental disinfectant or oxidant.
Note that GAG and BAG are not
mentioned as either Group I or Group II
technologies even though they were
discussed as technologies for standard
setting purposes (USEPA, 1979). EPA
concluded in its cost and technologies
document for the removal of
trihalomethanes from drinking water
that (USEPA, 1981):
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(1) GAG in the sand replacement mode
of operation is often inappropriate
due to the short performance life and
high frequency of regeneration
required to achieve substantial TTHM
or THM-formation potential
reduction;
(2) the finding took into consideration
costs, but primarily was made due to
the complexities of the modifications
to prior unit operations, i.e.,
disinfection, and in the logistics of the
carbon replacement;
(3) greater operating, maintenance, and
monitoring than for other treatments;
and
(4) on-site regeneration had only been
demonstrated at one U.S. site.
Thus, EPA decided to defer the
decision to include GAG and BAG as
best generally available technology for
granting variances under the Safe
Drinking Water Act Amendments of
1974.
EPA also did not list ozonation as
being "generally available" because:
(1) lack of experience in the U.S.;
(2) mixed results in experimental
studies; and
(3) most States require a residual in the
distribution system which is not
obtainable with ozone.
Thus, EPA decided to defer the
decision to include ozone as best
generally available technology for
granting variances under the Safe
Drinking Water Act Amendments of
1974.
Economic Impacts of the Interim
Standard
Currently, there are 2,700 community
water supply systems serving at least
10,000 people required to comply with
the interim TTHM regulation. In 1988,
a survey of large systems found that, on
average, the MCL of 0.10 mg/1 had
reduced the concentration of TTHMs by
40 to 50 percent (McGuire and
Meadows, 1988). Of these, 33 were in
violation of the standard in FY88
(average=115 ug/1, range=108-180 ug/1).
However, by FY92, only nine systems (a
decrease of 73 percent) violated the
requirements, for a total of 14 violations.
Seven of the nine violating systems and
12 of the 14 violations occurred in
systems serving 10,000 to 50,000
people. This indicates that even when
systems violate, they are able to return
to compliance after one or two
violations of the running annual
average.
In 1979, approximately 500 systems
were estimated to exceed 100 ug/1
TTHMs. Most of these were able to
come into compliance with minor
modifications of chlorination practices.
A smaller portion used alternate
oxidants like chlorine dioxide and
chloramines. No system installed ozone
or GAG to meet the interim TTHM
regulations. Compliance with the
interim TTHM standard involved
estimated capital expenditures of
between $31 million and $102 million
and yearly operating and maintenance
costs of between $8 million and $29
million for systems required to comply
with the TTHM MCL (i.e., community
water systems serving a population of at
least 10,000 people) (McGuire and
Meadows, 1988).
IV. Overview of Preproposal Regulatory
Development
A. October 1989 Strawman Rule
1. Purpose. EPA was required to
develop rules for additional
contaminants under the 1986
Amendments to the Act. In order to
solicit public comment in developing a
rule, EPA released a strawman rule
(preproposal draft) in October 1989. A
strawman was used because of the
complexity of the problem, the large
amount of (occasionally contradictory)
information, and the ability to reorient
the rule approach based on public
comment or new data. In this strawman,
EPA included a lead option of setting
MCLGs and MCLs for TTHMs,
haloacetic acids, chlorine, chloramines,
chlorine dioxide, chlorite, and chlorate.
The Agency also identified potential
add-on compounds: chloropicrin,
cyanogen chloride, hydrogen peroxide,
bromate, iodate, and formaldehyde.
Some of these compounds could also
conceivably be used as surrogate
monitoring compounds for the
compounds identified in Table IV-1
below.
ADDITIONAL CANDIDATE BYPRODUCT COMPOUNDS
Chlorination byproducts
Ozonation byproducts
—Individual THMs: chloroform, bromodichloromethane, dibromochloromethane, bromoform
—Individual haloacetic acids: mono-, di-, and trichloroacetic acids; mono- and dibromoacetic acids
—Individual haloacetonitriles: di- and trichloroacetonitrile; bromochloroacetonitrile, dibromoacetonitrile
—Haloketones: 1,1 di- and 1,1,1-trichloropropanone.
—Chlorophenols: 2-; 2,4-di; and 2,4,6-trichlorophenol
—Others: chloral hydrate, N- organochloroamines
—Aldehydes: acetaldehyde,
hexanal, heptanal.
—Organic acids.
—Ketones.
—Epoxides.
—Peroxides.
—Nitrosamines.
—N-oxy compounds.
—Quinones.
—Bromine substituted com-
pounds.
In addition, the strawman provided
that EPA would set treatment technique
requirements or provide guidance for
control of the following: MX, as a
surrogate for mutagenicity; total
oxidizing substances, as a surrogate for
organic peroxides and epoxides; and
assimilable organic carbon, as a
surrogate for microbiological quality of
oxidized waters. Monitoring parameters
based on the particular disinfection
process were also identified.
As BAT, EPA included precursor
removal (conventional treatment
modifications, GAG of up to 30 minute
duration and three months
regeneration), alternate oxidants (ozone
plus chloramines, chlorine dioxide with
chlorite removal plus chloramines), and
byproduct removal (aeration, GAG
adsorption, reducing agents, AOC
removal). Each of the options had
problems. GAG was not universally
applicable to all waters for either
precursor removal or DBF removal.
Membranes were not included as BAT
because of lack of full-scale experience.
As lead options, EPA included a
TTHM MCL of 25 or 50 ug/1 and other
MCLs based on feasibility analyses
similar to those that would be used to
develop the TTHM MCL.
2. Summary of Public Comments.
Several commentors expressed a desire
for EPA to look at coordination of
requirements with those for other
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regulations, including issues such as
requirements for maintenance of
distribution system disinfectant
residuals and system optimization for
multiple contaminants. Many
commentors were concerned about the
lack of health data and the
interpretation of existing data. Many
system operators were also concerned
about the effects of modifying their
treatment processes to meet DBF MCLs.
These concerns included lowered
microbiological protection, creation of
conditions that favored distribution
system microbiological growth (e.g., use
of ozone would create biodegradable
organics and use of chloramines would
create a nitrogen source), and creation of
other environmental problems when
changing treatment (e.g., residual
handling with precursor removal and
GAG regeneration). While commentors
expressed concern about use of alternate
disinfectants, several offered to provide
data and others recommended
epidemiological studies in systems with
long histories of alternative disinfectant
use.
B. June 1991 Status Report on D/DBP
Rule Development
TL. Purpose and transition from
Strawman Rule. EPA published a status
report on the development of D/DBPR in
June 1991 that was designed to indicate
the Agency's thinking on rule criteria.
The status report indicated that EPA
was considering extending coverage
under the rule to all nontransient
systems (instead of just those serving at
least 10,000 people, as under the 1979
TTHM rule) and proposing a shorter list
of compounds for regulation than were
included in the 1989 strawman. The
1991 list included disinfectants
(chlorine, chloramines, and chlorine
dioxide), THMs, haloacetic acids,
chloral hydrate, bromate, chlorite, and
chlorate). For both THMs and haloacetic
acids, three options were included:
MCLs for individual compounds, a
single MCL for the total, and a
combination of the two. Individual
MCLs were considered because health
risks for compounds differed, in some
cases significantly. The total MCL was
considered because of the precedent
established in the 1979 TTHM rule and
to act as a surrogate to limit other DBFs
for which the Agency lacked adequate
health effects and/or occurrence data.
The list of compounds was shorter
than that in the 1989 strawman for
several reasons. Several compounds
were deleted because they did not
appear to pose significant health effects
at levels present in drinking water (e.g.,
haloacetonitriles, chloropicrin). Others
were deleted because the health risks
were not expected to be adequately
characterized in time for rule proposal
(e.g., certain aldehydes and organic
peroxides), although it was noted that
these compounds might be regulated in
the future when more data became
available.
2. Major issues. In the status report,
EPA identified several major issues that
needed to be considered as the D/DBP
rule was developed. The first was that
of trade-offs with microbial and DBF
risks. The goal was to ensure that the
water remained microbiologically safe at
the level that disinfectant and DBF
MCLs were set. The discussion raised
questions regarding uncertainties in
defining microbial and DBF risks, levels
of risks that would be considered
acceptable and at what cost, and
defining practical (implementable)
criteria to demonstrate that an
achievable risk had been reached.
The second issue was the use of
alternate disinfectants to limit
chlorination byproducts. The Agency
recognized that while alternate
disinfection schemes (e.g., ozone and
chloramines) could greatly reduce
byproducts typical of chlorination, little
was known about the byproducts of the
alternate disinfectants and their
associated health risks. EPA did not
want to promulgate a standard that
encouraged the shift to alternate
disinfectants unless the associated risks
(including both those from byproducts
and differential microbial risks from a
change in disinfectants) were
adequately understood.
The third issue was integration with
the Surface Water Treatment Rule.
Although the rule only mandated 3-log
removal or inactivation of Giardia and
4-log of viruses, EPA guidance
recommended higher levels for poorer
quality source waters. EPA was
concerned that systems would reduce
microbial protection to levels nearer to
the regulatory requirements by reducing
disinfection and possibly greatly
increase microbial risks in an effort to
meet DBF MCLs. The Agency wanted to
ensure adequate microbial protection
while reducing risk from DBFs.
The last issue was the best available
technology. The BAT defined would
determine the levels at which MCLs
were set. For example, allowing
alternate disinfectants as BAT would
drive the chlorination byproduct MCLs
down, but could result in increased
exposure to (not well characterized)
alternate byproducts. EPA believed that
it therefore might be appropriate to
define chlorine and a precursor removal
technology as BAT.
To address these issues, EPA
suggested two possible regulatory
strategies. One was to define the MCL(s)
based on what was possible to achieve
using the most effective DBF precursor
removal strategy as BAT (e.g., GAG or
membrane filtration). While installing
such precursor removal technology
might minimize health concerns, the
costs would be substantial (without
finding out if other less costly
technologies, such as use of alternative
disinfectants, provided similar benefits).
Also, since systems are not required to
install BAT to meet MCLs, EPA believed
that many systems would attempt to
meet the MCLs by lower-cost alternative
disinfectants (ozone, chloramines,
chlorine dioxide). Since health effects
for alternative disinfectant byproducts
are not adequately characterized, risks
may not be reduced.
The second strategy was a two-phase
regulation, with the first phase designed
to address risks using lower cost options
during concurrent efforts to obtain more
data on treatment alternatives and ,
health effects of compounds not
currently adequately characterized. This
strategy would prevent major shifts into
use of new treatment technology until
the full consequences of such shifts
(both costs and benefits) are better
understood.
3. Suggested monitoring scenario. In
its fact sheet accompanying the status
report, EPA recommended that routine
TTHM and haloacetic acid monitoring
for systems serving at least 10,000
people have the same monitoring
requirements as were in the 1979 TTHM
rule. Smaller systems would have less
frequent monitoring requirements, but
would have compliance based on worst-
case samples. EPA included provisions
for reduced monitoring (compliance
based on worst-case samples or
surrogate monitoring), waiver criteria,
and requirements for disinfectant and
other DBF monitoring.
4. Summary of public comments. EPA
received comments on the status report
from numerous parties. Many
commentors agreed with EPA's
concerns with issues such as alternative
disinfectant DBFs and balancing
microbial and DBF risks. Several
commentors supported the two-phase
regulatory approach, but expressed
concern about timing. Others
recommended that DBF MCLs not be set
so low as to force many systems to
install expensive technology or decrease
microbial protection. Several
commentors were concerned with the
availability of both analytical methods
and certified laboratories for the low
levels that were being considered. One
commentor recommended that EPA
make it clear that MCLs set for '
disinfectants should allow temporary
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high levels to address distribution
system microbiological problems.
Finally, many commentors supported
allowing reduced monitoring wh
possible.
C. Initiation of the Regulatory
Negotiation Process
EPA became interested in pursuing a
negotiated rulemaking process for the
development of the D/DBP rule, in large
part, because no clear path for
addressing all the major issues
identified in the June 1991 Status
Report on D/DBP rule was apparent.
EPA's most significant concern was
developing regulations for DBFs while
also ensuring that adequate treatment be
maintained for controlling
microbiological concerns. A negotiated
rule process would help people
understand the complexities of the risk-
risk tradeoff issue and, hopefully, reach
a consensus on tho most appropriate
regulation to address concerns from
both DBFs and microorganisms.
It also appeared to EPA that the
criteria for initiating a negotiated rule
under the Negotiated Rulemaking Act of
1990 for establishing a negotiated
rulemaking could be met. These
include:
(1) there is a need for a rule,
(2) there are a limited number of
identifiable interests that will be
significantly affected by the rule,
(3) there is a reasonable likelihood
that a committee can be convened with
a balanced representation of persons
who—
(A) can adequately represent the
interests identified under paragraph (2);
and
(B) are willing to negotiate in good
faith to reach a consensus on the
proposed rule,
(4) there is a reasonable likelihood
that a committee will reach a consensus
on the proposed rule within a fixed
period of time,
(5) the negotiated rulemaking
procedure will not unreasonably delay
the notice of proposed rulemaking and
the issuance of a final rule,
(6) the Agency has adequate resources
and is willing to commit such resources,
including technical assistance, to the
committee, and
(7) the Agency, to the maximum
extent possible consistent with the legal
obligation's of the Agency, will use the
consensus of the committee with respect
to the proposed rule as the basis for the
rule proposed by the Agency for notice
and comment.
In 1992 EPA hired a contractor,
Resolve, which added a subcontractor,
Endispute, to assess the feasibility and
usefulness of convening a negotiated
rulemaking. Resolve and Endispute
conducted more than forty interviews
during the summer of 1992 with
representatives of State and local health
and regulatory agencies, water
suppliers, manufacturers of equipment
and supplies used in drinking water
treatment, and consumer and
environmental organizations. These
interviews revealed that:
(1) The entities interested in or
affected by the rulemaking were readily
identifiable and relatively few in
number.
(2) The rulemaking required
resolution of a limited number of
interdependent issues, about which
there appeared to be a sufficiently well-
developed factual base to permit
meaningful discussion. Further, there
appeared to be several ways to resolve
these issues, providing a potential basis
for productive joint problem-solving.
(3) The parties expressed some
common goals, along with an unusually
strong degree of good faith interest in
resolving the issue through negotiation.
(4) The Agency had adequate staff and
technical resources and was willing to
commit such resources to the negotiated
rulemaking.
Resolve and Endispute recommended
to EPA that the negotiated rulemaking
proceed. EPA concurred with this
recommendation.
However, it was also noted that
reaching consensus on the proposed
rule would be a challenge. The
interviews revealed that parties differed
in their perceptions about the nature
and magnitude of the risks associated
with DBFs, and many expressed strong
doubts about the adequacy of available
scientific and technical information.
Moreover, some parties stated that
marginal improvements in disinfection
technology were all that should be done
until the relative risks are better
understood, while others said that a
fundamentally new approach focusing
on precursor reduction should be
considered.
EPA published a notice of intent to
proceed with a negotiated rulemaking
on September 15,1992 (57 FRN 42533),
proposing 17 parties to be Negotiating
Committee members. In general, '
comments indicated very positive
support for the negotiated rulemaking.
As part of the convening process, an
organizational meeting was held
September 29-30,1993. Participants
discussed Negotiating Committee
composition and organizational
protocols. Between comments expressed
at the meeting and submitted in writing,
eleven additional parties—including
water suppliers not substantially
represented by the Committee's original
proposed membership, and chemical
and equipment suppliers—asked to be
added to the Committee. In addition,
participants discussed the need to
develop accurate scientific and
technical information.
On November 13,1992,, EPA
published a notice of establishment for
the Negotiating Committee (57 FRN
53866), and an 18th member was added
to the Negotiating Committee.
Based on comments received at the
organizational meeting, a Technical
Workshop was organized and conducted
on November 4-5,1992. Composed of
presentations and panel discussion by
23 of the Nation's leading experts on
drinking water treatment, the workshop
provided participants with
opportunities to familiarize themselves
with the technical elements in this
rulemaking and to explore the range of
scientific opinions about: (1) The nature
and magnitude of potential health
effects from exposure to DBFs and
microbial contaminants in drinking
water, (2) available information on the
cost and efficacy of precursor removal
and drinking water disinfection
technologies, and (3) EPA's efforts to
model and compare chemical and
microbial risks in drinking water.
Additional presentations were given
throughout the rulemaking process, as
new information became available and
more questions were raised by
participants.
At the first formal negotiating session,
on November 23-24,1992, participants
formed a technologies working group
(TWG) to develop reliable and
consistent information about the cost
and efficacy of drinking water treatment
technologies. This approach provided a
forum for participants to arrive at a
shared understanding of complex issues
in the rulemaking, setting a cooperative
tone for the rest of their discussions.
The working group, which continued to
meet throughout the rulemaking, also
provided a formal opportunity for input
from the chemical and equipment
suppliers who had not been named to
the Committee.
In addition, three experts were hired
through EPA's contract with Resolve to
provide ongoing scientific advice and
technical support to participants in the
Committee and on the technologies
working group, principally for members
without access to similar resources
within their own organizations.
Based on scientific data presented and
discussed through the November 23-24
meeting, participants agreed that some
type of DBF Rule was warranted.
The Committee developed and
reached agreement on criteria for a
"good" DBF Rule at the September 29-
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38677
30 and November 23-24 meetings. A
good rule is one which would be.
flexible and affordable and would
protect public health from chemical and
microbial risks. It was noted that
limiting some DBFs could encourage
changes in treatment that might increase
the formation of other DBFs, or
compromise protections against
microbial contaminants.
Next, Committee members and other
participants were invited to present
regulatory options as a starting point for
further discussion. Sixteen options were
introduced at the December 17-18
meeting, and discussed at the meeting
on January 13-14,1993. These were
merged into three consolidated options
at the January 13-14 meeting, and
discussion continued at the meeting on
February 9-10. At this point, areas of
disagreement included:
(1J Whether to regulate DBFs through
Maximum Contaminant Levels (MCLs)
or through a treatment technique (i.e.,
by exceeding DBF "action levels,"
systems would trigger additional steps
to minimize chemical and microbial
risks).
(2) Whether to minimize formation of
the DBFs about which relatively little is
known by establishing a regulatory limit
for their naturally occurring organic
precursors (e.g., Total Organic Carbon,
or TOG) in the water prior to the point
of disinfection.
(3) Whether to provide greater
protection against microbial
contaminants in drinking water, in
conjunction with new DBF limits, by
developing an enhanced Surface Water
Treatment Rule (ESWTR).
(4) Whether to develop a second
round of DBF controls along with the
first (assuring broad improvements in
drinking water quality), or to wait until
better scientific information becomes
available.
Concurrently, the TWG modelled
systems' potential compliance choices
under several regulatory scenarios, and
presented revised household and
national compliance cost estimates at
several meetings.
Using a "strawman" developed from
the consolidated options by EPA staff as
the starting point for negotiation, the
Committee worked out an "agreement in
principle" on the first round of DBF
controls at its February 24-25 meeting.
The "Stage 1" agreement set MCLs for
trihalomethanes and haloacetic acids—
two principal classes of chlorination by-
products—at levels the Committee
deemed protective of public health,
based on current information: 80 and 60
micrograms per liter, respectively. To
limit DBF precursors, the Committee
agreed to develop a series of "enhanced
coagulation" requirements, to vary
according to systems' influent water
quality and treatment plant
configurations. Members also agreed to
reconvene in several years to develop a
second stage of DBF regulations, when
the results of more health effects
research and water quality monitoring
are available. In addition, members
agreed that more expeditious changes to
the rules may be necessary if additional
information becomes available on short-
term or acute health effects of DBFs.
Members also agreed that, if data on
short-term or acute health effects
warrant earlier action, a meeting shall
be convened to review the results and
to develop recommendations.
A drafting group was named at the
February 24-25 meeting. Assisted by the
TWG, these members drafted an
"agreement in principle" for
presentation and discussion at the
March 18-19 meeting. Using "straw"
provisions from the facilitators, the
Committee devised a regulatory
"backstop" (i.e., Stage 2 MCLs of 0.040
mg/1 for TTHMs and 0.030 mg/1 for
HAAS for surface water systems serving
at least 10,000 people) at this meeting to
assure participants favoring further DBF
controls that other members would
return for the "Stage 2" negotiation. The
Committee also agreed to recommend
that EPA propose several ESWTR
options for comment, developed a
collaborative process to guide the health
effects research program, and agreed to
formulate short-term water quality and
technical data collection provisions
within an Information Collection Rule.
Based on the discussion to this point,
one member withdrew from the
Committee at the March 18-19 meeting.
The drafting group presented
regulatory language for the DBF Rule,
ESWTR, and ICR at each of the
Committee's last two meetings, held
May 12-13 and June 22-23,1993. These
texts provided a framework for further
discussion and resolution of remaining
issues, including: limits for residual
disinfectants and individual by-
products; public notification and
affordability provisions; and timing,
applicability, and conditions under
which systems might qualify for
exceptions from various requirements.
Committee members agreed to reserve
their rights t'o comment on the draft
preambles.
The drafting group continued working
through the summer of 1993, and
revisions to each of the rules and their
preambles were mailed to the
Committee for comment on July 8,1993,
September 8,1993, February 8,1994,
and May 12,1994. Each member had
signed die agreement by June 7,1994.
Unless otherwise noted, EPA has
adopted the recommendations of the
Negotiating Committee and its
Technologies Working Group and
reflects those recommendations in the
following preamble and proposed
regulations.
V. Establishing MCLGs
A. Background
1. MCLGs and MCLs Must Be Proposed
and Promulgated Simultaneously
Congress revised the Safe Drinking
Water Act in 1986 to require that
MCLGs and National Primary Drinking
Water Regulations (NPDWRs) be
proposed simultaneously and
promulgated simultaneously [SDWA
section 1412 (a)(3)]. Simultaneous
promulgation was intended to
streamline the development of drinking
water regulations.
2. How MCLGs Are Developed
MCLGs are set at concentration levels
at which no known or anticipated
adverse health effects occur, allowing
for an adequate margin of safety.
Establishment of an MCLG for each
specific contaminant depends on the
evidence of carcinogenicity from
drinking water exposure or an
assessment for adverse noncarcinogenic
health effects.
a. MCLG Three Category Approach.
EPA currently follows a three-category
approach in developing MCLGs for
drinking water contaminants (Table V-
TABLE v-1.— ERA'S THREE-CAT-
EGORY APPROACH FOR ESTABLISH-
ING MCLGs
Category
I
II
Evidence of
carcinogenicity
via drinking
water 1
Strong evi-
dence con-
sidering
weight of
evidence,
pharmacoki-
netics, po-
tency and
exposure.
Limited evi-
dence con-
sidering
weight of
evidence,
pharmacoki-
netics, po-
tency and
exposure.
MCLG ap-
proach
Zero
RfD approach
with added
safety mar-
gin of 1 to
10 or 10-s
to 10~6 can-
cer risk
range.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
TABLE V-1.—ERA'S THREE-CAT-
EGORY APPROACH FOR ESTABLISH-
ING MCLGs—Continued
Category
HI
Evidence of
carcinogenicity
via drinking
water1
Inadequate or
no animal
evidence.
MCLG ap-
proach
RfD approach.
Considering oral exposure data such as
drinking water, dietary and gavage studies.
Each chemical is evaluated for
evidence of carcinogenicity from
drinking water. For volatile
contaminants, inhalation data are also
considered. EPA takes into
consideration the overall weight of
evidence for carcinogenicity,
pharmacokinetics, potency and
exposure.
EPA's policy is to set MCLGs for
Category I contaminants at zero. The
MCLG for Category II contaminants is
calculated by using the Reference dose
(RfD) approach (described below) with
an added margin of safety to account for
possible cancer effects. If adequate data
are not available to calculate an RfD,
then the MCLG is based on a cancer risk
level of 10~5 to 10~6. MCLGs for
Category III contaminants are calculated
using the RfD approach.
Category I contaminants are those for
which EPA has determined that there is
strong evidence of carcinogenicity from
drinking water. The MCLG for Category
I contaminants is set at zero because it
is assumed, in the absence of other data,
that there is no threshold dose for
carcinogenicity. In the absence of route
specific (e.g., oral) data on the potential
cancer risk from drinking water,
chemicals classified as Group A or B
carcinogens (see section c below) are
generally placed in Category I.
Category II contaminants include
those contaminants for which EPA has
determined that there is limited
evidence of carcinogenicity from
drinking water, considering weight of
evidence, pharmacokinetics, potency,
and exposure. In the absence of route
specific data, chemicals classified in
Group C (see section c below) are
generally placed in Category II.
For Category II contaminants, one of
two options have traditionally been
used to set the MCLG. The first option
sets the MCLG based upon
noncarcinogenic endpoints of toxicity
(the RfD), then applies an additional
safety factor of 1 to 10 to the MCLG to
account for possible carcinogenicity. An
MCLG set by the option 1 approach is
compared with the cancer risk, if
quantified. The second option is to set
the MCLG based upon a theoretical
lifetime excess cancer risk level of 10~5
to 10 ~6 using a conservative
mathematical extrapolation model. EPA
generally uses the first option; however,
the second approach is used when valid
noncarcinogenic data are not available
to calculate an RfD and adequate
experimental data are available to
quantify the cancer risk.
Category III contaminants include
those contaminants for which there is
inadequate or no evidence of
carcinogenicity from drinking water. If
there is no additional information to
consider, contaminants classified in
Group D or E (see section c below) are
generally placed in Category HI. For
these contaminants, the MCLG is
established using the RfD approach.
b. Assessment of Noncancer Health
Effects. The risk assessment for
noncancer health effects can be
characterized by a Reference Dose (RfD).
The oral RfD (expressed in mg/kg/day)
is an estimate, with uncertainty
spanning perhaps an order of
magnitude, of a daily exposure to the
human population (including sensitive
subgroups) that is likely to be without
an appreciable risk of deleterious health
effects during a lifetime. The RfD is
derived from a no- or lowest-observed-
adverse-effect level (called a NOAEL or
LOAEL, respectively) that has been
identified from a subchronic or chronic
study of humans or animals. The
NOAEL or LOAEL is then divided by an
uncertainty factor(s) to derive the RfD.
Although the RfD is represented as a
point estimate, it is actually a range
since the RfD is a number with an
inherent uncertainty of an order of
magnitude.
Uncertainty factors are used to
estimate the comparable "no-effect"
level for a large heterogeneous human
population. The use of uncertainty
factors accounts for several data gaps
including intra- and inter-species
differences in response to toxicity, the
small number of animals tested
compared to the size of the population,
sensitive subpopulations and the
possibility of synergistic action between
chemicals (see 52 FR 25690 for further
discussion on the use of uncertainty
factors).
EPA has established certain
guidelines (shown below) to determine
how to apply uncertainty factors when
establishing an RfD (USEPA, 1986).
e Use a 1- to 10-fold factor when
extrapolating from valid experimental
results from studies in average healthy
humans. This factor is intended to
account for the variation in sensitivity
among the members of the human
population.
• Use an additional 10-fold factor
when extrapolating from valid results of
long-term studies on experimental
animals when results of studies of
human exposure are not available or are
inadequate. This factor is intended to
account for the uncertainty in
extrapolating animal data to the case of
humans.
• Use an additional 10-fold factor
when extrapolating from less than
chronic results on experimental animals
when there are no useful long-term
human data. This factor is intended to ,
account for the uncertainty in
extrapolating from less than chronic
NOAELs to chronic NOAELs.
• Use an additional 10-fold factor
when deriving an RfD from a LOAEL
instead of a NOAEL. This factor is
intended to account for the uncertainty
in extrapolating from LOAELs to
NOAELs.
• An additional uncertainty factor
may be used according to scientific
judgment when justified,
• Use professional judgment to
determine another uncertainty factor
(also called a modifying factor, MF) that
is greater than zero and less than or
equal to 10. The magnitude of the MF
depends upon the professional
assessment of scientific uncertainties of
the study and data base not explicitly
treated above, e.g., the completeness of
the overall data base and the number of
species tested. The default value for the
MF is 1.
To determine the MCLG, the RfD is
adjusted by the body weight of the
protected (or most sensitive) individual
(usually a 70 kg adult), average volume
of water consumed daily over a lifetime
(2 L/day for an adult) and exposure to
the contaminant from a drinking water
source (relative source contribution or
RSC);
Generally, EPA assumes that the RSC
from drinking water is 20 percent of the
total exposure, unless other exposure
data for the chemical are available [see
54 FR 22069 and 56 FR 3535]. When
adequate data are available and the data
indicate that drinking water exposure
contributes between 20 and 80 percent
of total exposure, EPA uses the actual
percentage to determine the MCLG, as is
indicated by equation (3), below. When
data indicate that contributions from
drinking water are between zero and 20
percent, or between 80 and 100 percent,
EPA utilizes a 20 percent floor and an
80 percent ceiling, respectively.
The calculations below express the
derivation of the MCLG based on
noncancer health effects:
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38679
_ (NOAELorLOAELin mg/kg/d) x body weight x RSC
: : — = mg/L (rounded to one significant figure)
uncertainty factor(s) x water consumption
c. Assessment of Carcinogenic Health
Effects. For chemicals suspected of
being carcinogenic to humans, the
assessment for non-threshold toxicants
consists of the weight of evidence of
carcinogenicity in humans, using
bioassays in animals and human
epidemiological studies as well as
information that provides indirect
evidence (i.e., mutagenicity and other
short-term test results). The objectives of
the assessment are to determine the
level or strength of evidence that the
substance is a carcinogen and to provide
an upperbound estimate of the possible
risk of human exposure to the substance
in drinking water. A summary of EPA's
general carcinogen classification scheme
is (USEPA, 1986):
Group A—Human carcinogen based
on sufficient evidence from
epidemiological or other human studies.
Group B—Probable human carcinogen
based on limited evidence of
carcinogenicity in humans (Group Bl)
or based on sufficient evidence in
animals with inadequate or no data in
humans (Group B2).
Group C—Possible human carcinogen
based on limited evidence of
carcinogenicity in animals in the
absence of human data.
Group D—Not classifiable based on
lack of data or inadequate evidence of
carcinogenicity from animal data.
Group E—No evidence of
carcinogenicity for humans (no
evidence for carcinogenicity in at least
two adequate animal tests in different
species or in. both epidemiological and
animal studies).
d. MRDLGs—appropriateness of a
new concept? As stated in section H.A
of this preamble, EPA is proposing a
new term, "maximum residual
disinfectant level goal" (MRDLG), in
lieu of MCLGs for all disinfectants
because disinfectants are intentionally
added to drinking water as a treatment
technique to kill disease-causing
microorganisms. The proposal of this
concept was agreed to through the
negotiated rulemaking process.
Certain members ofthe Negotiating
Committee were concerned that if
"MCLGs," which included the term
"contaminant," were set for
disinfectants, water treatment plant
operators might be reluctant to apply
disinfectant dosages above the MCLG
during short periods of time to control
for microbial risk, even though such
exposure to elevated disinfectant
concentration levels would pose little or
no risk. For example, NOAELs for
chlorine and chloramines are based
upon animal studies following long
term exposure to high levels of the
disinfectants in drinking water. Short-
term exposures at elevated levels would
not be a concern (see the following
discussion on health effects for chlorine
and chloramines). During emergency
situations such as distribution system
pipe breaks or significant fluctuations in
source water quality, systems will on
occasion need to apply short term
disinfectant residual concentrations of
chlorine or chloramines, well above the
regulatory goal, to protect from
waterborne disease.
The MRDLGs are developed in the
same way as MCLGs. EPA solicits
comment on the appropriateness of
adopting the term "MRDLG" in lieu of
MCLGs for disinfectants in the final
rule.
B. Proposed MRDLGs and MCLGs
The following includes a summary of
the health effects information available
for each disinfectant or by-product.
These summaries are taken from more
complete and comprehensive
descriptions ofthe data given in the
cited Health Criteria Documents that
have been developed for each of these
chemicals. These documents are
available in the water docket.
1. Chlorine, hypochlorite ion and
hypochlorous acid
The following assessment for both
chlorine and chloramines includes a
consideration of available animal data,
as well as epidemiology studies which
have been conducted on chlorinated or
chloraminated drinking water. The
epidemiology data are discussed in
section C of this preamble.
Chlorine (CAS # 7782r50-5)
hydrolyses in water to form
hypochlorite (CAS # as sodium salt
7790-92-3) and hypochlorous acid
(CAS # 7681-52-9). Because of their
oxidizing characteristic and solubility,
chlorine and hypochlorites are used in
water treatment to disinfect drinking
water, sewage and wastewater,
swimming pools, and other types of
water reservoirs. They are also used for
general sanitation and control of
bacterial odors in the food industry.
Chlorine is a highly reactive and
water soluble species. The fate,
transport, and distribution of chlorine in
natural waters is not well understood.
Much of the available information
Comes from the addition and oxidation
reactions with inorganic and organic
compounds known to occur in aqueous
solutions. Factors such as reactant
concentrations, pH, temperature,
salinity and sunlight influence these
reactions.
Occurrence and Human Exposure.
For the purpose of setting an MRDLG,
consideration is given to chlorine levels
resulting from disinfection of drinking
water. Chlorine exposures from
swimming pools and hot tubs are not
evaluated in determining the MRDLG.
Persons who swim frequently or use a
hot tub may have greater dermal and
possibly inhalation exposure to
chlorine.
Chlorine is added to drinking water as
chlorine gas (C12) or as calcium or
sodium hypochlorite. In drinking water,
the chlorine gas hydrolyses to
hypochlorous acid and hypochlorite ion
and can be measured as the free
chlorine residual. Maintenance of a
chlorine residual throughout the
distribution system is important for
minimizing bacterial growth and for
indicating (by the absence of a residual)
water quality problems in the
distribution system. Currently,
maximum chlorine dosage is limited by
taste and odor constraints and for
systems needing to comply with the
total trihalomethane (TTHM) standard
regularly. Additionally, for systems
using chlorination, the surface water
treatment rule (SWTR) requires a
minimum residual of 0.2 mg/L prior to
the entry point to the distribution
system, and the presence of a detectable
residual throughout the distribution
system.
Table V-2 presents occurrence
information available for chlorine in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," USEPA 1992a. The table lists
five surveys conducted by Federal, as
well as private agencies. Median
concentrations of chlorine in drinking
water appear to range from <1 to 2 mg/
Li.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
TABLE V-2.—SUMMARY OF OCCURRENCE DATA FOR CHLORINE
Occurrence of chlorine in drinking water
Survey (year) 1
EPA, 1992b2 (1987-
1991).
AWWARF (1987)
McGuire & Meadow,
1988.
EPA/AMWA/CDHS2
(1988-1989) Krasner
etal., 1989b.
WIDB (1989-1990)
AWWA Disinfection Sur-
vey (1991).
Location
Disinfection By-
products
Field Studies.
National Survey
35 Water Utili-
ties Nation-
wide.
228 SW Plants .
21 5 GW Plants
283 Utilities in
the U.S..
Sample information
(No. of samples)
Finished Water
At the Plant (71)
Distribution System (45)
Finished Water From:
Lakes
Flowing Streams
Ground Waters
Mixed-supplies
Samples from • Clean/veil Efflu-
ent, 4 Quarters (17).
Residual Chlorine Provided to
the Average Customer (sys-
tems >50,000 people).
Finished Water Entering Dis-
tribution System.
Concentration (mg/L)
Range
0.1-5.0
0.0-3.2
0.3-5.2
0-3.5
0-5
Mean
1.7
0.7
1.5
0.937
0.872
0.07-5.0
Median
1.4
0.5
1.0
0.8
0.325
1.1
Other
(Typical doses).
2.2 3
2.3 3
1.23
1.0s
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Typical dosage used by treatment plants.
SW: Surface Water.
GW: Ground Water.
AMWA: Association of Metropolitan Water Agencies.
AWWA: American Water Works Association.
AWWARF: American Water Works Association Research Foundation.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.
WIDB: Water Industry Data Base.
Exposure to chlorine residual varies
both between systems and within
systems. Chlorine residual within
systems will vary based on where
customers are located within the
distribution system and changes in the
system's disinfection needs over time.
Using residual concentrations from the
1989-1991 AWWA Disinfection Survey
and WIDB, exposure to chlorine due to
drinking water can be estimated using a
consumption rate of 2 liters per day.
Based on the estimated 25th percentile
and 75th percentile chlorine residuals
in the 1991 AWWA Disinfection Survey,
exposure was determined to range from
1.5 to 3.8 mg/day and the median would
be 2.2 mg/day. Using the WIDB data,
exposures to the average customer from
surface and ground water sources using
chlorination, respectively, were
determined to be 1.9 mg/day and 1.7
mg/day.
Little information is available
concerning the occurrence of chlorine in
food and indoor air in the United States.
The Food and Drug Administration
(FDA) does not analyze for chlorine in
foods. However, there are several uses of
chlorine in food production, such as the
disinfection of chicken in poultry plants
and the superchlorination of water at
soda and beer bottling plants (Borum,
1991). Therefore, the possibility exists
for dietary exposure to chlorine from its
use in food production. However,
monitoring data are not available to
characterize adequately the extent of
such potential exposures. Additionally,
preliminary discussions with FDA
suggest that there are no approved uses
for chlorine in most foods consumed in
the typical diet. Similarly, EPA's Office
of Air and Radiation is not currently
conducting any sampling studies for
chlorine in indoor air. Data on levels of
chlorine in ambient air are forthcoming.
Considering the limited number of
food groups that are believed to contain
chlorine and that no significant levels of
chlorine are expected in ambient or
indoor air, it is anticipated that drinking
water is the predominant source of
exposure to chlorine. Air and food are
believed to provide only small
contributions, although the magnitude
and frequency of these potential
exposures are issues currently under
review. EPA, therefore, is considering
setting an MRDLG for chlorine in
drinking water using an RSC value of
80%, the current exposure assessment
policy ceiling. EPA requests any
additional data on known
concentrations of chlorine in drinking
water, food and air.
Health Effects. The health effects
information for chlorine is summarized
from the draft Drinking Water Health
Criteria Document for Chlorine,
Hypochlorous Acid and Hyperchlorite
Ion (USEPA, 1994a). The studies cited
within this section are summarized in
the draft criteria document.
Chlorine and the hypochlorites are
very reactive and thus can react with the
constituents of saliva and possibly food
and gastric fluid to yield a variety of
reaction by-products (e.g.,
trihalomethanes). Thus, the health
effects associated with the
administration of high levels of chlorine
and/or the hypochlorites in various
animal studies may be due to these
reaction by-products and not the
disinfectant itself. Oxidizing species
such as chlorine and the hypochlorites
are probably short-lived in biological
systems due to both their reactivity and
the large number of organic compounds
found in vivo. Scully and White (1991)
noted that reactions of aqueous chlorine
with sulfur-containing arnino acids
appear to be so fast in saliva that all free
available chlorine is dissipated before
the water is swallowed.
Oral studies with radio labeled (i.e.,
36C1) hypochlorite and hypochlorous
acid indicate that, as measured by the
radiolabel, these compounds may be
well absorbed and distributed
throughout the body with, the highest
levels measured in plasma and bone
marrow. However, considering the
reactivity of the hypochlorites, these
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38681
results may only reflect the presence of
reaction by-products (e.g., chloride).
The major route of excretion appears to
be urine and then the feces.
Acute oral LDso values for calcium
and sodium hypochlorite have been
reported at 850 mg/kg in rats and 880
mg/kg in mice, respectively. Humans
have consumed hyperchlorinated water
for short periods of time at levels as
high as 50 mg/L (1.4 mg/kg) with no
apparent adverse effects.
Short-term oral studies in animals
have indicated decreases in blood-
glutathione levels, hemolysis and
biochemical changes in liver in rodents
following a gavage dose of hypochlorite
in water. No adverse effects on
reproduction (Druckery, 1968) or
development were observed in rats
administered chlorine in drinking water
at concentrations of 100 mg/L or less.
However, Meier et al. (1985) observed
an increase in sperm-head abnormalities
in mice receiving hypochlorite at 200
mg/L, but not at 100 mg/L or less.
No systemic effects were observed in
rodents following oral exposure to
chlorine as hypochlorite in distilled
water at levels up to 275 mg/L over a 2
year period (NTP, 1990).
Chlorinated water has been shown to
be mutagenic to bacterial strains and
mammalian cells. Investigations with
rodents to determine the potential
carcinogenicity of chlorine, or
chlorinated water have been negative. In
the most recent study, no apparent
carcinogenic potential was
demonstrated following oral exposure to
chlorine in distilled drinking water as
hypochlorite, at levels up to 275 mg/L
over a 2 year period (NTP, 1990).
However, NTP observed a marginal
increase in the incidence of
mononuclear cell leukemia in mid-dose
female F344 rats but not in male rats or
male and female mice (NTP, 1990).
Mononuclear cell leukemia has a high
spontaneous rate of occurrence in
female F344 rats. The levels reported in
the NTP study are within the historical
control range of incidence for the sex
and strain of rat. EPA believes that
mononuclear cell leukemia can not be
solely attributed to exposures to
chlorine in drinking water but rather
may reflect the high background rate of
mononuclear cell leukemia in the test
species.
EPA has classified chlorine in Group
D, not classifiable as to human
carcinogenicity (IRIS, 1993). This
classification stems from the findings of
the NTP (1990) study indicating
equivocal evidence in female rats
(increased mononuclear cell leukemia)
and no evidence in male rats or male
and female mice. The International
Agency for Research on Cancer (IARC,
1991) also evaluated chlorinated
drinking water and hypochlorite for
potential human carcinogenicity. IARC
determined that there was inadequate
evidence for carcinogenicity of
chlorinated drinking water and
hypochlorite salts in humans and
animals. (See section C for a description
of these studies.) IARC concluded that
chlorinated drinking water and
hypochlorite salts were not classifiable
as to their carcinogenicity to humans
and thus assigned these chemicals to
IARC Group 3. This category is similar
to EPA cancer classification Group D.
Based on the previous discussion,
EPA is proposing that chlorine,
hypochlorite and hypochlorous acid be
placed in Category III for the purpose of
setting an MRDLG. The study selected
for determining an RfD is the previously
mentioned 2 year rodent study that was
conducted by the National Toxicology
Program (NTP, 1990). In this study,
male and female F344 rats and B6C3F1
mice were given chlorine in distilled
drinking water at levels of 0, 70,140
and 275 mg/L for 2 years. Based on body
weight and water consumption values,
these concentrations correspond to
doses of approximately 0,4, 7 and 14
mg/kg/day for male rats; 0,4,8, and 14
mg/kg/day for female rats; 0, 7,14, and
24 mg/kg/day for male mice and 0, 8,14
and 24 mg/kg/day for female mice.
There was a dose related decrease in
water consumption for both rats and
mice, presumably due to taste aversion.
No effect on body weight or survival
were observed for any of the treated
animals. Using a NOAEL of 14 mg/kg/
d identified from female rats in the NTP
(1990) study an MRDLG of 4 mg/L,
based on lack of toxicity in a chronic
study is derived as follows.
100x2L/d
Where 14 mg/kg/d is the NOAEL for
female rats in the NTP study, and 100
is the uncertainty factor applied to
account for inter and intra-species
differences in accordance with EPA
guidelines when a NOAEL from a
chronic animal study is the basis for the
RfD. The MRDLG is based on a 70 kg
adult consuming an average of 2 liters
water per day over their lifetime. In
addition, an 80% RSC is assumed in the
absence of data to the contrary.
Public comments are requested on the
following issues: 1) placing chlorine in
Category HI for developing an MRDLG,
2) selection of the study and NOAEL as
the basis for the MRDLG, 3) the 80%
RSC, 4) the appropriateness of the UF of
100, 6) the cancer classification for
chlorine.
2. Chloramines
Inorganic chloramines (CAS Nos.
10599-90-3 and 10025-85-1 for mono-
and trichloramine, respectively) are
formed in waters undergoing
chlorination which contain ammonia.
Monochloramines, dichloramines and
trichloramines may be formed.
Monochloramine is the principal
chloramine formed in chlorinated
natural and wastewater at a neutral pH
and is much more persistent in the
environment.
Chloramine is used as a disinfectant
in drinking water to control taste and
odor problems, limit the formation of
chlorinated disinfection by-products,
and maintain a residual in the
distribution system for controlling
biofilm growth. At typical pHs of most
drinking waters, the predominant
chloramine specie is monochloramine.
For purposes of this regulation, only
monochloramine will be considered
since the other chloramines occur at
much lower concentrations in almost all
drinking waters. Monochloramine has
also been much more extensively
studied.
Monochloramine, the principal
chloramine formed in chlorinated
natural and wastewaters at neutral pH,
is relatively stable when discharged to
the environment. First-order decay rate
constants of 0.03 to 0.075 hr1 for
monochloramine in the laboratory, and
higher rate constants of 0.28 to 0.31 hr1
outdoors using chlorinated effluents,
have been reported. If discharged into
receiving waters containing bromide,
monochloramine will decompose faster,
probably through the formation of
NHBrCl and decomposition of the
dihalamine. The rate of
monochloramine disappearance is
primarily a function of pH and salinity.
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For example, at pH 7 and 25°C, the half-
life of monochloramine is 6 hr at 5 parts
per thousand (ppt) salinity and 0.75 hr
at 35 ppt salinity; at pH 8.5 and 25°C,
the half-life is 188 hr at 5 ppt salinity
and 25 hr at 35 ppt salinity.
Monochloramine is expected to
decompose in wastewater discharges
receiving waters via chlorine transfer to
organic nitrogen-containing compounds.
Occurrence and Human Exposure.
Chloramine occurs in drinking water
both as a by-product and intentionally
for disinfection. Chloramine is formed
during chlorination when source waters
contain ammonia. It is also used as a
primary or secondary disinfectant,
usually with chloramine being
generated on site by the addition of
ammonia to water following treatment
by chlorination. The use of chloramines
has been shown to reduce the formation
of certain by-products, notably
trihalomethanes, relative to the by-
products formed with chlorination •
alone. Chlorination by-product
formation can be minimized when the
ammonia is added prior to or in
combination with chlorine by reducing
the chlorine residual of the water being
treated. In most plants, however,
ammonia is added some time after the
addition of chlorine, to allow for more
effective disinfection since chlorine is a
much stronger disinfectant than
chloramines.
Table V-3 presents occurrence
information available for chloramine in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," USEPA, 1992a. Typical dosages
of chloramine used as a disinfectant in
drinking water treatment facilities range
from 1.5 to 2.7 mg/L. Median
concentrations of chloramine in
drinking water were found to range from
1.1 to 1.8 mg/L.
TABLE V-3.—-SUMMARY OF OCCURRENCE DATA FOR CHLORAMINES
Occurrence of chloramine in drinking water
Survey (year) 1
AWWARF (1987)
McGuire &
Meadow, 1988.
EPA/AMWA/
CDHS2 (1988-
1989) Krasner
etal., 1989b.
EPA, 1992b2
(1987-1991).
Location
National Survey ..
35 Water Utilities
Nationwide.
Disinfection By-
products Field
Studies.
Sample information
(No. of samples)
Finished Water From:
Lakes .'.
Flowing Streams
Samples from Clearwell Effluent, 4
Quarters (13).
At the Plant (11) ....
Distribution System (8)
Concentration (mg/L)
Range
0.9-5.5
1.2-3.6
0.1-3.3
Mean
2.3
2.1
1.4
Median
1.8
1.5
1.1
Other
Typical dosages:
1 .5 mg/L
2.7 mg/L
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
AMWA: Association of Metropolitan Water Agencies.
AWWARF: American Water Works Association Research Foundation.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.
Based on the residual concentrations
given above, a high and low estimate for
exposure to chloramine from drinking
water can be calculated using an
assumed consumption of 2 liters per
day. Using the target range of 1.5 to 2
mg/L, the exposure may range from 3 to
4 mg/day. Some systems may deviate
significantly from this range.
No information is available on the
occurrence of chloramine in food or air.
Currently > the Food and Drug
Administration (FDA) does not measure
for chloramine in foods since the
analytical methods have not been
developed. Preliminary discussions
with FDA suggest that there are not
approved uses for chloramine in foods
consumed in the typical diet. Similarly,
EPA's Office of Air and Radiation is not
sampling chloramines in air (Borum,
1991).
Based on the previous discussion,
EPA assumes that drinking water is the
predominant source of exposure to
chloramine. Air and food intakes are
believed to provide only small
contributions, although the magnitude
and frequency of these potential
exposures are issues currently under
review. EPA, therefore, is proposing to
establish an MRDLG for chloramine in
drinking water with an RSC value of
80%, the current exposure assessment
policy ceiling. EPA requests any
additional data on known
concentrations of chloramine in
drinking water, food and air.
Health Effects. The health effects
information in this section is
summarized from the draft Drinking
Water Health Criteria Document for
Chloramines (USEPA, 1994b). Studies
mentioned in this section are
summarized in the Criteria Document.
Short-term inhalation exposures to
high levels (500 ml of 5% household
ammonia mixed with 5% hypochlorite
bleach) of chloramines in humans result
in burning in the eyes and throat,
dyspnea, coughing, nausea and
vomiting. Inhalation of the chloramine
fumes resulted in pneumonitis but did „
not result in permanent pulmonary
damage.
Short-term exposures to chloramines
in drinking water, in which human
subjects were administered single
concentrations ranging between 1 and
24 mg/L (1, 8,18 or 24 mg/L), have not
resulted in any adverse effects in human
subjects. Following human exposure,
the subject's physical condition,
urinalysis, hematology, arid clinical
chemistry were evaluated. No adverse
clinical effects were noted in any of the
studies.
In another study, acute hemolytic
anemia, characterized by oxidation of
hemoglobin to methemoglobin and
denaturation of hemoglobin, was
reported in hemodialysis patients when
tap water disinfected with chloramines
was used for dialysis baths.
Chloramines were reported to produce
oxidant damage to red blood cells and
inhibit the metabolic pathway used by
red blood cells to prevent and repair
such damage. Many dialysis centers
have installed reverse osmosis units
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38683
coupled with charcoal filtration or the
addition of ascorbic acid to prevent
hemolytic anemia.
Animal studies indicate varying
sensitivity and conflicting results among
different animal species. Toxic effects
noted among rats are changes in blood
glutathione and methemoglobin. Both
monkeys and mice were unaffected
during short-term assays with doses up
to 200 mg/L chloramines. Based on
studies up to 6 weeks in length, rats
appear to be more sensitive to
monochloramine than mice and
monkeys.
Toxicokinetic studies of chloramines
indicate that the absorption of
chloramines is rapid, peaking within 8
hours of administration. In the rat,
chloramines are metabolized to chloride
ion and excreted mostly through the
urine with a small portion excreted
through the feces.
Longer-term oral studies (90 days or
longer) showed decreased body and
organ weights in rodents. Some effects
to the liver (weight changes,
hypertrophy, and chromatid pattern
changes) appear to be related to overall
body weight changes caused by
decreased water consumption due to the
unpalatibility of chloramines to the test
animals.
In addition, chloramine may induce
immunotoxicity in rats in the form of
increased prostaglandin Ez synthesis,
reduced antibody synthesis, and spleen
weight at levels as low as 9 to 19 mg/
L chloramines for 90 days. The
significance of these findings for risk
use in risk assessment is compromised
by the design flaws of the study (i.e.,
animals were exposed to two antigens)
and the lack of corroboration of these
findings by a follow-up study.
Two lifetime rodent studies involving
oral exposures to rats and mice via
drinking water have been considered by
EPA for the derivation of the MRDLG for
monochloramine. Both studies were
performed by the National Toxicology
Program (NTP, 1990) and involved 70
animals/sex/dose exposed to distilled
drinking water containing 0, 50,100 or
200 ppm chloramines.
The first NTP (1990) study was a 2-
year study in'mice to determine the
potential chronic toxicity or
carcinogenic activity of chloraminated
drinking water. B6C3F] mice were
administered chloramine at doses of 0,.
50,100 and 200 ppm in distilled
drinking water. These doses were
calculated based on a time-weighted
average to be 0, 5.0, 8.9 and 15.9 mg/
kg/day for male mice and 0,4.9,9.0 and
17.2 mg/kg/day for female mice. There
was a dose-related decrease in the
amount of water consumed by both
sexes; this decrease was noted during
the first week and continued throughout
the study. Dosed male and female mice
had similar food consumption as
controls except for females in the 200
ppm dose group that exhibited slightly-
lower consumption than controls.
Study results indicated that there was
a dose-related decrease in mean body
weights of dosed male and female mice
throughout the study. Mean body
weights of high-dose male mice were
10—22% lower than their control group
after week 37 and the body weights of
high-dose female mice were 10-35%
lower after week 8. However, the
survival of mice receiving
monochloramine in drinking water was
not significantly different than controls.
Clinical findings observed were not
attributed to the consumption of
chloraminated drinking water. Body
weight loss and systemic toxicity were
not considered related to the toxicity of
chloramine, but rather due to decreased
water consumption resulting from the
unpalatability of chloramines in
drinking water to the test animals.
Therefore, the highest dose tested, 17.2
mg/kg/day, is considered a NOAEL in
mice.
In the second study F344/N rats were
administered monochloramine for 2
years at doses of 0, 50,100 and 200 ppm
in distilled drinking water.-These doses
were calculated on the basis of a time-
weighted average to be 0, 2.1, 4.8 and
8.7 mg/kg/day for male rats and 0, 2.8,
5.3 and 9.5 mg/kg/day for female rats.
There was a dose-related decrease in the
amount of water consumed by both
sexes; this decrease was noted during
the first week and continued throughout
the study. Food consumption of treated
rats was the same as the controls with
males consuming more. In addition,
mean body weights of 200 ppm dosed
rats (both sexes) were lower than their
control groups. However, mean body
weights of rats receiving
monochloramine in drinking water (at
all levels) were within 10% of controls
until week 97 for females and week 101
for males. Though several clinical
changes were noted, no clinical changes
were attributable to chloraminated
drinking water. The survival of rats
receiving chloraminated drinking water
was not significantly different than
controls except that, for the 50 ppm
dose groups, survival was greater than
that of controls. Therefore, EPA
considers the highest dose tested, 9.5
mg/kg/day, as the NOAEL.
Based on two bacterial assays,
monochloramine appears to be weakly
mutagenic. One study examining the
reproductive effects and another which
examined developmental effects of
chloramines concluded that there are no
chemical-related effects due to
chloramines.
The NTP evaluation, using the results
of the two lifetime NTP bioassays,
concluded that chloramines exhibited
equivocal evidence of carcinogenic
activity of chloraminated drinking water
in female F344/N rats. This conclusion
results from an increase in mononuclear
cell leukemia. There was no evidence of
carcinogenic activity in male rats or
mice of either sex. The findings do not
establish a link between chloramine
exposure and carcinogenicity because of
the high historical background
occurrence of this type of cancer in test
animals. The incidence of mononuclear
cell leukemia in the female control
groups (16%) was substantially less
than the incidence reported in untreated
historical controls (25%). Incidence of
mononuclear cell leukemia in test
animals reached a high of 32% in the
high dose female rats. This study also
discovered incidence of renal tubular
cell neoplasms in two high-dose male
mice receiving chloraminated water.
Since this type of tumor is rarely seen
in historical controls, there is some
concern that these may be treatment
related. However, the overall evidence
regarding the potential carcinogenicity
of chloramines in drinking water can be
described as inconclusive since no long-
term study has linked any tumor
development to actual chloramination
exposure. On this basis, as well as
consideration of those studies described
in section C, EPA placed chloramine in
Group D: not classifiable based on
inadequate evidence of carcinogenicity.
EPA selected the lifetime study in rats
(NTP, 1990) as the basis for calculating
the MRDLG for chloramines. The
NOAEL for the rat (9.5 mg/kg/d) is
proposed because the rat was not tested
at the higher doses where mice were
tested (17.2 mg/kg/d). Rats appear to be
more sensitive considering observed
changes in biochemistry. Following a
Category III approach and using the rat
NOAEL of 9.5 mg/L from the NTP study,
an MRDLG of 4 mg/L (measured as total
chlorine), based on lack of toxic effects
in a chronic study can be derived for the
70-kg adult consuming 2 liters of water
per day applying an uncertainty factor
of 100, which is appropriate for use of
a NOAEL derived from an animal study
and assuming an RSC drinking water
contribution of 80 percent.
* Since chloramines, on a practical basis, will be
measured as total chlorine, it is necessary to present
the MRDLG in terms of a chlorine equivalent
concentration. Three mg/L chloramine is equivalent
to 4 mg Clz/liter, based on the molecular weights
ofCl2andNH2Cl.
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MRDLG =
_ (9.5 mg/kg/day)x70kgx0.8 =3
100x2L/day
EPA requests comments on the
proposed MRDLG for chloramines and
the RSC of 80%, the significance of the
findings of immunotoxicity for setting
the RfD instead of the NTP study, the
significance of the finding of
mononuclear cell leukemia in female
F344 rats, the significance of the finding
of tuhular cell neoplasms in high-dose
exposed mice, and whether the adjusted
MRDLG, which takes into account the
measurement of monochloramine as
total chlorine, is appropriate.
3mgNH2Cl/Lx
70.9 mgCl
2 _
51.48 mgNH2Cl
= 4 mg C12/L (rounded)
3. Epidemiology Studies of Chlorinated
and Chloraminated Water
Several studies have been conducted
to evaluate the association of
chlorination or chloramination with the
risk of cancer, cardiovascular disease or
adverse reproductive effects in humans.
A summary of some of these studies is
given below. This discussion reflects
EPA's assessment of these data and is
summarized from the draft Drinking
Water Criteria Documents for Chlorine
(USEPA, 1994a) and Chloramines
(USEPA, 1994b), respectively.
Introduction to Epidemiology Studies.
Two distinct types of epidemiology
studies have been conducted: ecologic
and analytical. These types of studies
differ markedly in what they reveal
about the association between water
quality and disease. In an ecological
epidemiology study, information is
available on exposure and disease for
groups of people rather than for
individuals, and therefore, the results
are difficult to interpret. What is
considered to be an important or
relevant group variable may not be
important for or may not pertain to
individuals within that group.
Theoretical and empirical analyses have
offered no consistent guidelines for the
interpretation of ecological associations,
and results from these studies are
appropriate only to suggest hypotheses
for further study by analytical
epidemiological methods (Piantiadosi et
al., 1988; Connor and Gillings, 1974).
Analytical epidemiology studies
provide an estimate of the magnitude of
risk and information which can be used
to evaluate causality. For each
individual in the study, information is
obtained about disease status and
exposure to various contaminants and
other characteristics. In several of the
studies reported here, individual
exposures to disinfected water or
specific disinfection by-products were
estimated using group exposure
information. All reported
epidemiological associations from
analytical studies require an evaluation
of random error (statistical significance)
and potential sources of systematic bias
(misclassification, selection,
observation, and confounding biases) so
that results can be interpreted properly.
It must be noted that random error or
chance can never be completely ruled
out as the explanation for an observed
association and that statistical
significance does not necessarily imply
biological significance. Regardless of
statistical significance, it is important to
consider potential biological
mechanisms. Random error does not
address the possibility of systematic
error or bias. Misclassification of
exposure and disease, selection bias,
and observation bias must be avoided;
confounding bias, on the other hand,
can be prevented both in study design
and during analysis if information is
obtained about possible confounders. It
is important to determine for each
specific epidemiology study the validity
of the association observed between
exposure and disease before considering
possible causality between exposure
and disease or inferring that the results
apply to a larger or target population.
Systematic bias can lead to spurious
associations; in some but not all
instances, the direction of the bias can
be determined. For example, a random
misclassification of exposure usually
biases a study toward not observing an
effect or observing a smaller risk than
may actually be present, but nonrandom
misclassification can result in either
higher or lower estimates of risk
depending upon the distribution of
misclassification.
In addition, because of the
observational nature of epidemiology,
the interpretation of epidemiology
studies requires a sufficient number of
well designed and well conducted
epidemiology studies, and must include
appropriate toxicological and biological
information. Judging causality from
epidemiology studies is based largely on
guidelines developed over the years,
including sequence of events, strength
of association (relative risk or odds
ratio), consistency of results under
different conditions of study, biological
plausibility, dose or exposure response
relationship, and specificity of effect.
The relative risk represents a basic
measure of an association between
exposure and disease. It is defined as
the rate of disease in the exposed
population divided by the rate of
disease in an unexposed population.
a. Cancer Studies. Since the early
1970's, numerous epiderniologic studies
have attempted to assess the association
between cancer and the long term
consumption of water from various
sources with and without disinfection
and of various chemical quality,
especially chlorinated surface waters
which supply the majority of the U.S.
population. Ecological, case control, and
cohort studies have been conducted.
Case control studies have included
incident and decedent cases; in some
studies information about various risk
factors has been collected through
interviews, but in others information
was obtained primarily from death
certificates.
i. Ecological Studies. The earliest
studies were analyses of group or
aggregate data available on drinking
water exposures and cancer. Usually the
variables selected for analyses were
readily available in published census,
vital statistics, or public records and
easily abstracted and assembled. These
analyses, referred to as ecological but
also called aggregate, geographical, or
correlational, were designed to
investigate cancer mortality rates,
usually on a county or State level. Areas
of different water quality, source, and
chlorination status were compared to
identify possible statistical associations
for further study. Drinking water
exposures were most often characterized
as simple dichotomous variables which
served as indicators of exposure to
differing source water quality, e.g., the
drinking water source for the county or
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38685
geographic area was categorized as a
surface or groundwater source. In some
instances exposure variables included
estimates of the proportion of the area's
or county's population that received
surface or groundwater and whether it
was chlorinated. Surface water was
assumed to be more contaminated with
synthetic organics than groundwater,
but no attempt was made to estimate
levels of contaminants.
In 1974 it was discovered that when
surface waters were disinfected with
chlorine, the chlorine reacted with pre-
existing organic materials in the water
to create a great number of chemical by-
products (Craun, 1988). The major
group of disinfection by-products (by
weight) was the trihalomethanes
(THMs) which included an animal
carcinogen, chloroform. Chlorinated
surface water was evaluated as an
exposure variable in several of the
ecological studies, and since almost all
surface waters are chlorinated, the
analyses usually compared cancer
mortality among populations receiving
chlorinated surface water with those
receiving unchlorinated groundwater.
Chlorinated water was assumed to
contain disinfection by-products, and at
higher levels than chlorinated
groundwaters. However, the quality of
surface and groundwater may also differ
for other contaminants, and this was not
considered. Any observed association
might be due to other water quality
differences among surface and
groundwaters (e.g., organic
contaminants from nonpoint and point
source discharges to surface waters from
industrial, urban, and agricultural
sources before pollution control
regulations).
In some ecological analyses, the
investigators attempted to study the
association between cancer mortality
and an estimate of group exposure to
levels of chlorinated by-products based
on THM or chloroform levels was
determined from a limited number of
water samples. The exposure
information used in ecological studies
was available in only broad geographic
units such as census tracts or counties
(Crump and Guess, 1982; Shy, 1985).
Although these exposure variables were
statistically associated with mortality
rates for all cancers combined and
several site-specific cancers, the
interpretation must necessarily be
cautious due to limitations of ecological
studies. In several of these studies,
aggregate or group information on
several covariates, e.g., occupation,
income, or population density, also was
included in the statistical analysis in an
attempt to adjust for potential
confounding factors. In one study the
statistical significance of the observed
associations between stomach and rectal
cancer mortality and group exposures to
current THM levels disappeared when
migration patterns and ethnic data were
included in the regression model
(Tuthill and Moore, 1980). A wide range
of cancer sites was found to be
statistically associated with estimates of
population group exposures based on
current levels of THM or chloroform
including gall bladder, esophagus,
kidney, breast, liver, pancreas, prostate,
stomach, bladder, colon, and rectum.
The most frequent associations observed
were for the last four sites; however,
these associations were not consistent
when viewed by gender, race, and
geographic region.
The ecologic design coupled with the
lack of specific exposure indicators in
these studies precludes the inference of
a causal relationship (Morgenstern,
1982). A subcommittee of the National
Academy of Sciences (NAS, 1980)
reviewed 12 of the ecological studies
and noted "Results of these studies
demonstrate the problems of
establishing relationships between
health statistics and environmental
variables, and lend emphasis to the
caution with which they should be
interpreted." The NAS further
commented that the ecological studies
in which the current THM exposures
were estimated were deemed to be more
informative than others and "suggest
that higher concentrations of THM in
drinking water may be associated with
an increased frequency of cancer of the
bladder. The results do not establish
causality, and the quantitative estimates
of increased or decreased risk are
extremely crude. The effects of certain
potentially important confounding
factors, such as cigarette smoking, have
not been determined." The studies are
useful, however, as an initial step for
identification of potential hazards and
they indicated the need for further
epidemiologic studies or analytic
studies of individuals with a specific
etiologic hypothesis.
ii. Cohort Studies. A cohort study (or
follow-up) study (the study can be
called either retrospective or
prospective) is one in which two or
more groups (referred to as 'cohorts') of
people-that differ according to the
extent of exposure to a potential cause
of disease are compared with respect to
incidence of the disease of interest in
each of the groups. The essential
element of this study type is that
incidence rates are calculable directly
for each study group (Rothman, 1986).
One advantage of this study type is the
ability to study multiple disease
endpoints. One disadvantage of this
study type is that a large study
population is needed to detect a
relatively small risk. In addition,
because of the latency period for
carcinogenicity, a long follow-up time
may be required for the study.
There exists one cancer drinking
water cohort study where individual
data were available for a well-defined,
fairly homogeneous area that allowed
disease rates to be computed by
presumed degree of exposure to by-
products of chlorination, although the
population was relatively small. Wilkins
and Comstock (1981) studied the
residents of Washington County,
Maryland and ascertained the source of
drinking water at home for each county
resident in a private census conducted
in 1963. In addition to water source,
information was collected on age,
marital status, education, smoking
history, number of years lived in the
household, and frequency of church
attendance. Death certificates and
cancer registry information was sought
for county residents whose date of death
or diagnosis occurred in the 12 year
period following the census. Sex and
site-specific cancer rates were
constructed for malignant neoplasms of
biliary passages and liver, kidney, and
bladder. Several additional causes of
death were analyzed as well for
comparison purposes. The population
was stratified into three separate
exposure subgroups: chlorinated surface
water, unchlorinated deep wells, and
small municipal systems with a mixture
of chlorinated and unchlorinated water,
each reflecting a different history of
exposure to by-products of chlorination.
The study group which included
individuals who obtained drinking
water from small municipal systems
were not included as a comparison with
the other drinking water cohorts
because of their exposure to both
chlorinated and unchlorinated water.
Both crude and adjusted incidence
rates for liver cancer in males and
females and for cancer of the liver
among males were essentially the same
for persons supplied with chlorinated
surface water at home (high THM
exposure) and for persons with deep
wells (low THM exposure). The
adjusted rates for bladder cancer
(RR=1.6; 95% CI=0.54,6.32) and cancer
of the liver (RR=1.8; 95% CI=0.64,6.79)
among females were highest among
persons using chlorinated surface water.
Given the low relative' risk and broad
confidence intervals, the authors
indicated that this finding could be
attributed to chance (Wilkins and
Comstock, 1981). Confounding bias may
also influence the interpretation of a
small relative risk. EPA considers that
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the results of this study are inconclusive
because the results are based on small
numbers of cases, hence, the reported
rates are statistically unstable and
subject to random variation.
iii. Case Control Studies. In a case
control study, persons with a given
disease (the cases) and persons without
the given disease (the controls) are
selected for study. The proportions of
cases and controls who have certain
background characteristics or who have
been exposed to possible risk factors are
then determined and compared.
Exposure odds ratios (ORs) are
determined. The odds of exposure
among cases is compared with that of
controls. For rare diseases, the ORs are
considered good estimates of relative
risk. These studies are sometimes called
case-referent or retrospective studies.
Because there are many variations of
this study design (e.g., how cases and
controls are selected, how information
on exposures, risk factors, and
confounding factors are obtained, and
who is interviewed), each case control
study should be evaluated individually
to determine if the specific study design
parameters introduce systematic bias
(Kelsy et al., 1986). As previously noted,
all epidemiology studies require careful
evaluation of systematic bias. For those
studies with major bias, the results are
generally considered inconclusive.
Those studies with minor bias may still
provide useful information.
Two types of studies were conducted:
(1) Decedent cases without interviewing
survivors for information about
residential histories and risk factors and
(2) incident cases with interviews.
Decedent Case-Control Studies.
Several case-control studies were
conducted to continue to investigate the
possibility that there was a causal
relationship between chlorinated
drinking water, including byproducts
such as THMs, and gastrointestinal or
urinary tract cancers. Most of these case-
control studies used deceased cases of
the specific cancers of interest, although
some continued their investigations in a
relatively nonspecific way by using both
total cancer mortality as well as several
of the site- specific cancers studied in
the ecologic studies (Crump and Guess,
1982; Shy, 1985). Controls were
noncancer deaths from the same
geographic area and in all but one study
matched for several potentially
confounding variables including age,
race, sex, and year of death. As in all
studies of this design (i.e., death
certificate studies with no available
interviews), control of confounding
factors was restricted to information that
is routinely recorded on death
certificates and no information was
obtained from next-of-kin interviews.
The exposure variables of interest at this
time included a comparison of surface
v ground water sources, or chlorinated
v nonchlorinated ground water sources.
The place of residence listed on the
death certificate was linked to public
records of water source and treatment
practices in order to classify the
drinking water exposure variable for a
particular case or control (Shy, 1985).
Similar to the earlier ecologic studies,
the Agency considers the results from
these studies to be inconsistent in their
findings. The calculated ORs, varied by
cancer site and sex, as well as in their
magnitude and statistical significance.
This variability was found for all the
cancer endpoints studied including
those of specific interest, i.e., bladder,
colo-rectal, and/or colon. These
endpoints were found to vary by
geographic region. For example, a
statistically significant increased
bladder cancer risk was observed in
North Carolina for males and females
combined (OR=1.54) and New York for
males (OR=2.02), but not for females; no
statistically significant risk was seen in
Louisiana, Wisconsin or Illinois.
Increased colon cancer risk was
observed in Wisconsin (OR=1.35) and
North Carolina (OR=1.30) for males, but
not females; no increased risk was seen
in Louisiana or Illinois. Increased rectal
cancer risk was observed in North
Carolina (OR=1.54) and Louisiana
(OR=1.68) for males and females
combined, in Illinois for females
(OR=1.35) but not males, and in New
York for males (OR=2.33) but not
females; no increased risk was seen in
Wisconsin. Although increased risk was
observed for cancer of the liver and
kidney (OR=2.76), esophagus (OR=2.39),
and pancreas (OR=2.23) among males in
New York, no increased risk for these
cancers was seen among females in New
York, Illinois, Wisconsin or Louisiana.
Although many of the ORs were
statistically significant, these decedent
case control studies with extremely
limited information on confounding
factors and potential exposures to
chlorinated water are of limited
usefulness in assessing whether cancer
is associated with chlorinated drinking
water, or judging the causality of such
as association. Although some of the
ORs were large enough to cause concern
about an exposure association, the
magnitude of the OR was such that the
association could be attributed to
incomplete control of confounding
factors and the ORs might represent
spurious elevations (Crump and Guess,
1982).
Although not subject to all the same
limitations as ecologic studies, decedent
case-control studies are considered
more limited by some epidemiologists
than others as a tool for causal inference
because of a high probability of
systematic bias associated with the use
of information obtained only from the
death certificate (e.g., inadequate or no
information on residential history, water
exposures, and major potential
confounders). The variability seen in
these five studies is likely a
combination of several factors,
including available sample size, choice
of causes of death included as controls,
regional variability in true composition
of the raw and treated drinking waters,
definition of exposure variables, a high
probability of exposure misclassification
from imputing a lifetime exposure to a
certain water source or treatment from
residence listed on the death certificate,
and uncontrolled confounding (e.g., diet
and smoking).
Given the limitations of decedent case
control studies without interviews, the
evidence from these studies are
considered insufficient to determine a
causal association between any or all
the components which exist in the
complex mixture created during the
chlorination of surface waters and any
site-specific cancer. The findings
provided a stimulus for a further refined
epidemiologic study using incident
cases of bladder and colon cancer and
appropriate controls who could be
interviewed for residential history and
numerous other covariates.
Case-Control Studies with Interviews.
At the time when these more recent
studies were planned, it was still
believed that THMs were the major by-
products of chlorinated drinking water
that should be investigated and studies
were designed and conducted in areas
where a THM difference might be
expected and somehow measurable.
Exposure assessment for individuals
remained problematic in the study
design. The best available means of
exposure measurement, however, was at
best a surrogate for the true exposure of
interest which is the actual level of
THMs or other by-products ingested
over a person's lifetime through
consumption of surface water
disinfected with chlorine. Only two
studies attempted to estimate long-term
exposure to THMs. Most studies used
residence at a location served by
chlorinated drinking water. In all except
one of the studies, comparisons of
exposure were between chlorinated
surface water and unchlorinated
groundwater. As previously discussed
in the section on ecological studies, the,
water quality for surface and ground
water differ for many other consituents.
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38687
Because it was known, that
disinfection of surface water using
chloramine produced very low levels of
THMs and other by-products compared
to the same water disinfected with
chlorine, a study was conducted in
Massachusetts to compare the patterns
of mortality in communities which used
these different disinfectants (Zierler et
al., 1986). Statewide mortality records
for 1969—1983 were analyzed using
standardized mortality ratios (SMRs)
and showed little variation by
community. However, mortality odds
ratios (MORs) comparing bladder cancer
deaths to all other deaths were
considered by the authors to indicate a
slight elevation for last residence in a
chlorinated community compared to a
chloraminated community (MOR=1.7;
95% CI=1.3, 2.2). The authors noted that
the results were preliminary and "crude
descriptions of the relationship under
study" (Zierler et al., 1986). The authors
further indicated that the results may
have been caused by unidentified or
uncontrolled confounding factors.
Bladder cancer deaths were
investigated further using a case-control
design with proxy interviews to
determine residential and smoking
histories (Zierler et al., 1988). The
association of bladder cancer was
assessed for individuals with lifetime
and usual exposure to chlorinated and
chloraminated water depending on the
number of years of residence at a
particular water source. Residence in a
community using chlorinated drinking
water was used as an index for exposure
to chlorinated by-products, while
residence in a community using
chloramine for disinfection was
considered an index for no exposure to
chlorinated by-products. An association
was observed between bladder cancer
and both lifetime (MOR=1.6; 95%
CIsl.2-2.1) and usual (MOR=1.4; 95%
CIsl.1-1.8) exposure to chlorinated
water. A subgroup of study participants
was noted to have lived their entire
lives in an area served with water
supplied by the Massachusetts Water
Resources Authority, disinfected with
either chlorine or chloramine (same
water source, different disinfectant,
lifetime exposure). Within this group
the bladder cancer mortality risk was
1.6 times higher (MOR=1.6; 95% CI=1.1,
2.4) when the water had been
disinfected with chlorine compared to
chloramine (Zierler et al., 1988).
In addition to analyses using a control
group which consisted of deaths from
cardiovascular disease, cerebrovascular
disease, chronic obstructive lung
disease, lung cancer, and lymphatic
cancer, a separate analysis was done
using only die lymphatic cancer
controls. This was considered necessary
by the authors because of the possibility
that some of the other deaths among
controls may also be related to the
exposure of interest. If true, then the
MOR estimate would be biased toward
the hypothesis of no increased risk.
When the analysis considered only
lymphatic cancer controls, the
magnitude of the association with
chlorinated water increased for lifetime
exposure (MOR=2.7; 95% CI=1.7-4.3),
usual exposure (MOR=2.0; 95% CI=1.4-
3.0), and lifetime exposure in the
previously mentioned subgroup
(MOR=3.5; 95% CI=1.8-6.7). Sources of
misclassification bias that may have
been present were considered to be
randomly distributed among the cases
and controls which implies that the
observed MOR would be an
underestimate of risk (Zierler et al.,
1988). It is also possible that
nondifferential misclassification of the
variables used to control confounding,
leading to residual confounding of the
summary estimates, could have caused
a systematic spurious elevation in the
MORs.
The largest study to date investigating
the relationship of chlorinated water
and bladder cancer incidence involved
an ancillary study to the National
Cancer Institute's (NCI) 10 area study of
bladder cancer and artificial sweeteners
(Cantor et al., 1985,1987,1990). The
original study conducted interviews
with 2,982 newly diagnosed bladder
cancer cases and 5,782 population
controls; lifetime information on source
and treatment of drinking water was
collected and analyzed for only a subset
of the original study population (1,244
cases and 2,550 controls). Subgroup
analyses of nonsmokers among
participants and those reporting
beverage intake necessarily involved
even smaller numbers. Duration of
exposure, measured by years of
residence at a chlorinated surface or
nonchlorinated ground water source
was presumed to be a surrogate for dose
of disinfectant by-products. Overall,
there was no association of duration of
exposure with bladder cancer risk
(Cantor et al., 1985,1987). In
nonsmokers who never smoked, a 2-fold
increased risk was reported for those
exposed for 60 or more years to
chlorinated surface water (n=46 cases,
77 controls) compared to unchlorinated
ground water (n=61 cases, 268 controls)
users (OR=2.3; 95% CI=1.3,4.2). These
data were further analyzed according to
beverage intake level, type of water
source and treatment (Cantor et al.,
1987,1990). It was observed that people
who reported drinking the most tap
water-based beverages from any source
(>1.96 liters/day) had a bladder cancer
risk about 40% higher (OR=1.43; 95%
CI=1.23-1.67, males and females
combined) than people who drank the
least. The association between water
ingestion and bladder cancer risk for
males was an OR=1.47; 95% CI=1.2-1.8,
and for females an OR=1.29; 95%
CI=0.9-1.8.
. Evaluation of bladder cancer risk by
both duration of exposure and amount
of water consumed showed that the risk
increased with higher water
consumption only among those who
drank chlorinated surface water for 40
or more years. Evaluation of risk by
smoking status revealed that most of the
duration effect was observed in
nonsmokers. Among nonsmokers who
consumed tap water in amounts above
the population median (>1.4 L/day), a
risk gradient was apparent only for
males. However, a higher risk was also
seen for nonsmoking females who
consumed less than the median level.
The increasingly smaller numbers of
cases and controls available for these
subgroup analyses produce statistically
unstable OR estimates making it
difficult to evaluate the trend results.
This is the first study of incident
bladder cancer cases that obtained and
analyzed fluid consumption patterns in
this way. The noted inconsistencies in
the reported data must be more
thoroughly explored and indicate a need
for replication before any causal
relationship can be assumed (Devesa et
al., 1990). An additional consideration
is a more refined exposure
measurement; many of the disinfection
by-products are volatile. Thus exposure
may occur through inhalation as well as
ingestion.
Two conflicting studies of colon
cancer and presumed THM exposure
have been reported. The first one (Cragle
et al., 1985) was a hospital based case
control study that included 200 incident
colon cancer cases from seven hospitals
and 407 hospital controls with no
history of cancer who were diagnosed
with diseases unrelated to colon cancer.
It should be noted that both colon and
rectal cancer cases were included as
cases in the study. Controls were
matched to cases on hospital and
admission date, as well as age, race, sex
and vital status. Residential histories
were linked with water source and
disinfectant information for the 25 years
prior to diagnosis. Logistic regression
analysis using qualitative data
groupings for the variables of interest
showed a strong interaction of age and
chlorination status (Table V-4). THM
levels were not estimated. Odds ratios
computed from the regression
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coefficients increased with age, and
within age groups. The ORs are higher
for a longer duration of exposure.
TABLE V-4.—COMPARISON OF OR's BY EXPOSURE DURATION AND AGE
Age (years)
OftOQ
71V-7Q
QftQQ
OR (95% Cl) 1-
15 years exposure
0.23
(0.11,0.49)
0.36
(0.2, 0.66)
0.57
(0.36, 0.88)
0.89
(0.83,1.12)
1.18
(0.94,1.47)
1.47
(1.16,1.84)
1.83
(1.32, 2.53)
OR(95%CI)>15
years exposure
0.48
(0.23, 1.01)
0.6
(0.33, 1.09)
0.75
(0.48, 1.18)
0.94
(0.69, 1.29)
1.38
(1.1,1.72)
2.15
(1.7,2.69)
3.36
(2.41,4.61)
From these data, it appears that risk
is increased only in those persons 60
years old and older with greater than 15
years of exposure to chlorinated water
and in those greater than 70 years of age,
regardless of exposure duration,
A second colon cancer study (Young
et al, 1987) conducted in Wisconsin
involved 366 incident colon cancer
cases, 785 controls diagnosed with other
cancers, and 654 population controls.
Extensive interviews were conducted
with all participants to obtain
information on past drinking water
sources, drinking water habits and a
number of potentially confounding
covariates. This information was
combined with data provided by water
companies to construct models to
predict historical levels of THMs to be
used as both cross-sectional and
cumulative exposure variables. Simpler
methods of denning exposure were also
used, (e.g., surface vs. ground,
chlorinated v. nonchlorinated), and all
methods looked at the data by period
specific exposure levels. The results did
not indicate any association between
THMs in Wisconsin drinking water and
colon cancer risk. Odds ratios for all
exposure variables were uniformly close
to 1.0 with few exceptions. It should be
noted, however, that in this study the
majority of the water supplies contained
less than 20 ug/1 of THMs. No excess
risk was observed at these levels, given
the limitations of this study design in
detecting a small risk.
The association of THM and colo-
rectal cancer was studied in New York
where the THM levels were higher than
those in the above Wisconsin study
(Lawrence et al., 1984). A total of 395
colon and rectal cancer deaths among
white female teachers in New York State
(excluding New York City) was
compared with an equal number of
deaths of teachers from causes of death
other than cancer. All deaths were
ascertained using the defined cohort of
the New York State Teachers Retirement
System. Cumulative chloroform
exposure was estimated by the
application of a statistical model to
operational records from water systems
that served the home and work
addresses of the study participants
during the 20 years prior to death. The
distribution of chloroform exposure was
not significantly different between cases
and controls. No effect of cumulative
chloroform exposure was observed in a
logistic analysis controlling for type,
population density, marital status, age,
and year of death. No excess risk was
associated with exposure to a surface
water source containing THMs
(OR=1.07; 90% CI=0.79,1.43). Although
the data were not presented in the
article, the authors reported that no
appreciable differences were seen when
the colon and rectal cases were analyzed
separately, compared to the combined
analyses reported above.
Although most all the studies
reviewed here have looked at colon,
colo-rectal or bladder cancer risk, one
recently published work investigated
the risk of pancreatic cancer in relation
to presumed exposure to chlorinated
drinking water. Ijsselmuiden et al.
(1992) conducted a population-based
case-control study in Washington
County, Maryland, using the same
population data that were originally
ascertained during a private population
census for an earlier cohort study
(Wilkins and Comstock, 1981). The
original cohort study did not find any
association between pancreatic cancer
and chlorinated drinking water
(OR=0.80, 95% CI=0.44-1.52).
This case-control study was
conducted to reexamine chlorinated
drinking water as a possible .
independent risk factor for pancreatic
cancer in this population. It is not
reported of any of the other endpoints
from the original study also were
reexamined, e.g., bladder, kidney, or
liver cancer. Cases were those residents
who were reported to the County cancer
registry with a first time pancreatic
cancer diagnosis during the period July,
1975 through December 1989, and who
had been included in the 1975 census
(n=101). Controls were randomly
selected by computer from the 1975
census population (n=206). Drinking
water source, as obtained during the
1975 census, was the exposure variable
used. In univariate analyses, municipal
water as a source of drinking water,
increasing age, and unemployment were
significantly associated with increased
risk of pancreatic cancer. Multivariable
analyses that controlled for confounding
variables indicated that the use of
municipal chlorinated water at home
was associated with a significant OR of
2.23 (95% CI=1.24-4.10). The OR
adjusted is 2.18 (95% CI==1.20-3.95);
only age and smoking were assessed as
potential confounders.
Interpretation of these findings is
hampered by several problems regarding
the assessment of exposure, including
the fact that information obtained in
1975 on type of water and other
variables is an exposure collected at one
point in time and may not reflect actual
exposure patterns prior to 1975. In
addition, there is no information on the
actual amounts of water consumed.
Additionally, different residential
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38689
criteria were used for the cases and
controls. The cases had to still be
residing in the County at the time'of
their cancer diagnosis to be included in
the study, but the controls may not have
been current residents. If controls
emigrated out of the county
differentially on the basis of exposure,
the ORs may be an over- or
underestimate of the risk depending on
emigration patterns. Finally, it can not
be ruled out that the exposure variable
used for this and other studies—
residence served by a particular water
source—is simply a surrogate for some
other unidentified factor associated with
nonrural living. The nonspecific
relationship of several different causes
of death and water source at home
observed in the earlier cohort study
(VVilkins and Comstock, 1981) lends
some support to this possibility. More
valid individual exposure information
over a long period of time for both
specific contaminants and the use of
chlorinated/unchlorinated water are
needed to assess the results of this and
other analytical epidemiology studies.
Morris et al. (1992) conducted a meta-
analysis, evaluating 12 studies and
pooling the relative risks from 10
epidemiological studies of cancer and a
presumed exposure to chlorinated water
and its byproducts. Meta-analysis refers
to the application of quantitative
methods to combine the published
results of a related body of literature
(Dickerson and Berlin, 1992). Morris et
al. (1992) reported a pooled relative risk
estimate of 1.21 (95% CI, 1.09-1.34) for
bladder cancer and 1.38 (95% CI, 1.01-
1.87) for rectal cancer (i.e., 9% of
bladder cancer cases and 15% of the
rectal cancer cases in the U.S. or
approximately 10,000 additional cases
of cancer per year could be attributed to
chlorinated water and its by-products).
Pooled relative risk estimates for ten
other site specific cancers including
colon, colo-rectal and pancreas were not
felt to be significantly elevated nor were
they statistically significant.
If the indications from this analysis
are true such that water chlorination
could result in as many as 10,000 cases
of cancer a year, then chlorination could
represent a significant cause of rectal
and bladder cancer in the U.S. However,
there was disagreement among the
negotiating parties over the
appropriateness of this meta-analysis.
Some believed that the use of the meta-
analysis may not be appropriate for
these data. Others disagreed, expressing
their view that the analysis was
statistically probative and otherwise
valuable. Meta-analysis has been used
successfully to combine the results of
small clinical trials and of some
epidemiology studies that have similar
experimental design and exposure
conditions. Application of meta-analysis
to the water chlorination data requires
careful consideration of exposure
variables and systematic bias in each of
the studies. Chlorinated drinking water
is a complex mixture of many
substances that vary geographically and
seasonally. There is even variability
within a geographic region. In addition,
the information on exposure and
potential confounding is much more
limited for the four decedent case
control studies used in the meta-
analysis. Their study design is
dissimilar to the other studies included,
resulting in concerns about their
inclusion in the meta-analysis. Study-
specific methodological problems,
systematic bias, and problems of
exposure definition and assessment
could not be corrected by this analysis
(Murphy, 1993). Thus, the overall
results of the Morris et al. analysis may
over- or underestimate the risk.
However, the estimate of risk in regard
to rectal cancer might be particularly
affected by the inclusion of these case
control studies. It should also be noted
that the results of the Morris et al.
analysis does not provide additional
information to establish causality.
The chlorinated drinking water
epidemiology studies have been
reviewed extensively by EPA, the
National Academy of Sciences, the
International Agency for Research on
Cancer (IARC), and the International
Society for Environmental
Epidemiology (ISEE). In 1987, the
National Academy of Sciences
Subcommittee on Disinfectants and
Disinfectant By-Products concluded that
there was a major health concern with
the chronic ingestion of low levels of
disinfection byproducts (NRC, 1987).
The Subcommittee commented that
some of the epidemiology studies
reported "increased rates of bladder
cancer associated with trends of levels
of certain contaminants in water
supplies. Interpretation of these studies
is hampered by a lack of control for
confounding variables (e.g., age, sex,
individual health, smoking history,
other exposures)." The Subcommittee
recommended that epidemiologists
continue to improve protocols and
conduct studies on drinking water and
bladder cancer where exposure data can
be obtained from individuals, rather
than through estimation from exposure
models.
EPA and IARC, along with other
individual scientists, have interpreted
the epidemiologic evidence as
inadequate. IARC concluded that "there
is inadequate evidence for
carcinogenicity of chlorinated drinking
water in humans."
The ISEE presented a full spectrum of
opinion regarding the epidemiology
data (Neutra and Ostro, 1992). The ISEE
reported a "general consensus that the
results of the recent EPA-sponsored
studies of cancer endpoints have
strengthened the evidence for linking
bladder cancer with long term exposure
to chlorinated drinking water. The
evidence for links with colon cancer are
not convincing. * * * Any risks, if real,
are low when compared to the risk of
infection from not disinfecting water."
In 1992, the International Life
Sciences Institute sponsored a
conference with the Pan American
Health Organization, EPA, Food and
Drug Administration, World Health
Organization, and the American Water
Works Association on the safety of
water disinfection. Although they do
not necessarily reflect the views of the
sponsoring organizations, conclusions
prepared by the conference's editor and
editorial board (Craun et al., 1993) noted
that "Adverse human health effects may
be associated with the chemical
disinfection of drinking water. However,
current scientific evidence is inadequate
to conclude that water chlorination
poses a significant risk to humans.
Uncertainties about the available
toxicologic evidence limit assessment of
human health risks associated with
chlorine, chloramine, chlorine dioxide,
and ozone disinfection. The
epidemiologic evidence for increased
cancer risks of chlorinated drinking
water is equivocal."
Some members of the reg-neg
committee felt that the epidemiology
data, taken in conjunction with the
results from toxicological studies,
provide an ample and sufficient basis to
conclude that the usual exposure to
disinfection by-products in drinking
water could result in an increased
cancer risk at levels encountered in
some public water supplies.
Because of the spectrum of
conclusions concerning these data, the
Agency is pursuing additional research
to reduce the uncertainties associated
with these data and better characterize
the potential of cancer risks associated
with the consumption of chlorinated
drinking water.
b. Serum Lipids/Cardiovascular
Disease. Laboratory studies on animals,
conducted in the early 1980's indicated
a possible link between consumption of
chlorinated drinking water and elevated
serum lipid profiles which are
indicators of cardiovascular disease
(USEPA 1994a). The animal work was
followed by a cross-sectional study in
humans (Zeighami et al., 1990) that
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included 1,520 adult residents, aged 40
to 70 years, in 46 Wisconsin
communities supplied with either
chlorinated or unchlorinated drinking
water of varying hardness. The study
was designed to determine whether
differences in calcium or magnesium
intake from water and food and
chlorination of drinking water affect
serum lipids.
The communities selected for study
had the following characteristics: (1)
They were small in population size
(300-4,000) and not suburbs of larger
communities; (2) they had not
undergone more than 20% change in
population between 1970 and 1980; (3)
they had been in existence for at least
50 years; and (4) all obtained water from
groundwater sources with no major
changes in water supply characteristics
since 1980 and did not artificially soften
water. The water for the communities
contained total hardness of either < 80
mg/1 CaCO3 (soft water) or > 200 mg/1
CaCO3 (hard water); 24 communities
used chlorine for disinfection and 22
communities did not disinfect. Eligible
residents were identified through state
driver's license tapes and contacted by
telephone; an age-sex stratified
sampling technique was used to choose
a single participant from each eligible
household. Only persons residing in the
community for at least the previous 10
years were included. A questionnaire
was administered to each participant to
obtain data on occupation, health
history, medications, dietary history
water use, water supply and other basic
demographic information. Water
samples were collected from a selected
subset of homes and analyzed for
chlorine residual, pH, calcium,
magnesium, lead, cadmium, and
sodium. Fasting blood specimens were
collected from each participant and
analyzed for total cholesterol,
triglycerides and high- and low-density
lipoprotein (HDL and LDL, respectively)
subfractions.
Among females, adjusted mean total
serum cholesterol levels were
statistically significantly higher in the
chlorinated communities compared to
the nonchlorinated communities (249
mg/dl and 238 mg/dl, respectively).
These changes are not considered
biologically significant as they reflect
background variation. Total serum
cholesterol levels were also higher for
males in chlorinated communities, on
the average, but the difference was
smaller and not statistically significant
(236 mg/dl vs. 232 mg/dl). LDL mean
values followed a similar pattern to that
for total cholesterol, higher in
chlorinated communities for females,
but not different for males. However, for
both sexes, HDL cholesterol levels are
nearly identical in chlorinated and
nonchlorinated communities and there
were no significant differences found in
the HDL/LDL ratios. The implications of
these findings for cardiovascular disease
risk are unclear at this time given the
inconsistencies in the data. The
possibility exists that the observed
association in females may have
resulted from some unknown or
undetermined variable in the
chlorinated communities.
The results from a second study,
designed to further explore the findings
among female participants in the
Wisconsin study (Zieghami et al., 1990),
were presented in 1992 (Riley et al.,
1992, manuscript submitted for
publication). Participants were 2,070
white females, aged 65 to 93 years who
were enrolled in the Study of
Osteoporotic Fractures (University of
Pittsburgh Center) and had completed
baseline questionnaires on various
demographic and. lifestyle factors. Total
serum cholesterol was determined for
all participants. Full lipid profiles (total
cholesterol, triglycerides, LDL, total
HDL, HDL-2, HDL-3, Apo-A-I, and
Apo-B) were available from fasting
blood samples for a subset of 821
women. Interviews conducted in 1990
ascertained residential histories and
type of water source used back to 1950
and all reported public water sources
were contacted for verification of
disinfectant practices. Private water
sources were presumed to be
nonchlorinated. A total of 1,896 women
reported current use of public,
chlorinated water, 201 reported current
use of nonchlorinated springs, cisterns,
or wells and 35 reported having mixed
sources of water. Most of the women
had been living in the same home with
the same water service for at least 30
years.
Overall, there were no meaningful
differences detected in any of the
measured serum lipid levels between
women currently exposed to
nonchlorinated water and those exposed
to chlorinated water (246 mg/dl vs. 247
mg/dl, respectively, for total
cholesterol). The data were also
stratified by age and person-years of
exposure to chlorinated water at home.
There was some suggestion that women
with no exposure to chlorine had lower
total cholesterol levels but this finding
was inconsistent and may represent
random fluctuation since there was no
trend noted with LDL cholesterol or
Ape—B, both of which are known to
correlate with total cholesterol. There
was also no association between
increasing duration of exposure to
chlorine and HDL cholesterol, Apo-A-
I, or triglycerides.
The only notable differences were that
women with chlorinated water reported
significantly more cigarette and alcohol
consumption than the women with
nonchlorinated drinking water (Riley et
al., 1992). This was evident in all age
groups and across strata of duration of
exposure. This finding lends support to
the possibility that the previously
reported association of chlorinated
drinking water and elevated total serum
cholesterol (Zeighami et al., 1990) may
have arisen due to incomplete control of
lifestyle factors which were
differentially distributed across
chlorination exposure groups.
c. Reproductive/Developmental
Outcomes. Several recently conducted
epidemiologic studies have examined
reproductive or developmental
endpoints and various components of
drinking water. Kramer et al. (1992) .
conducted a population-based case-
control study to determine whether
water supplies containing relatively
high levels of chloroform and other
THMs within the state of Iowa are
associated with low birthweight,
prematurity, or intrauterine growth .
retardation (IUGR). Iowa birth certificate
data from January, 1989 through June,
1990 served as the source of both cases
and controls. Definitions for cases and
controls were as follows: the low
birthweight group included 159 live
singleton infants weighing <2,500 grams
and 795 randomly selected control
infants weighing >2,500 grams from the
same population; the prematurity group
included 342 live singleton infants with
gestational ages of <37 weeks as
determined from the mother's reported
last menstrual period, arid 1,710
randomly selected control infants with
gestational ages >37 weeks; IUGR
analyses included 187 IUGR infants
(defined as weighing less than the 5th
percentile for a particular gestational
age based on California standards for
non-Hispanic whites) and 935 randomly
selected controls. Exposure status was
assigned to infants according to reported
maternal residence in a given
municipality at the time of birth. The
assigned THM levels came from a water
survey conducted in 1987 in the state of
Iowa so the exposure information came
from aggregate data. Odds ratios were
computed using multiple logistic
regression to control for measured , ,
confounders (including smoking, but
not alcohol consumption). The authors
reported an increased risk for IUGR
associated with residence in
communities where chloroform levels
exceeded 10 ug/1 (OR=1.8; 95% (3=1.1-
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38691
2.9). Prematurity was not associated
with chloroform exposure and the risk
for low birthweight was only slightly
increased (OR=1.3; 95% CI=0.8-2.2).
The authors considered the results of
this study to be preliminary.
Accordingly, they should be interpreted
with caution. They considered the major
limitations of the study to involve
assessment and classification of
individual exposure, the potential
misclassification due to residential
mobility and the fluctuation of THM
levels.
Aschengrau et al. (1993) conducted a
case-control study in Massachusetts to
determine the relationship between
community drinking water quality and
a wide range of adverse pregnancy
outcomes, including congenital
anomalies, stillbirths, and neonatal
deaths. The data were obtained during
a previous study of 14,130 pregnant
women who delivered infants at
Brigham and Women's Hospital in
Boston between 1977 and 1980.
Drinking water quality information
came from routine analyses of the metal
and chemical content of Massachusetts
public water. An attempt was made to
link each woman in the study to the
result of the water analyses conducted
in her town at the time of her
pregnancy. Information was also
obtained on drinking water source and
chlorination of surface water. Drinking
water samples from 155 towns were
linked to 2,348 pregnant women to
estimate exposure for the case-control
study.
A large number of exploratory
analyses were conducted with this data
set, which demonstrated both increases
and decreases in risk associated with
various water quality parameters. A
higher frequency of stillbirths was
correlated with chlorination and
detectable lead levels, cardiovascular
defects were associated with lead levels,
CNS defects with potassium levels, and
face, ear, and neck anomalies with
detectable silver levels. A decrease in
neonatal deaths was associated with
detectable fluoride levels.
The authors indicated that the
findings from this study, being non-
specific, must be considered as
Sreliminary given the problems and
mitations of the exposure assessment
and the lack of an a priori study
hypothesis. They indicated a need for
further research (Aschengrau et. al.
1993).
The New Jersey Department of Health
recently reported the results of a cross-
sectional study and a case-control study
evaluating the association of drinking
water contaminants with birth weight
and selected birth defects (Bove et al.
1992a and b). Four counties selected for
the study were included because they
had the highest levels of monitored
drinking water and they were served by
well defined public water systems
which used ground and surface water,
or a mixture of these sources. The
exposures evaluated total volatile
organic contaminants (VOCs) as well as
individual VOCs such as
trichloroethylene, tetrachloroethylene,
carbon tetrachloride, benzene and
THMs. The cross sectional study base
included 81,055 live single births and
599 single fetal deaths between January,
1985 and December, 1988; 593 mothers
were interviewed in the case control
study. Exposure scenarios to THMs
were stratified as follows: >20-40 ug/L,
>40-60 ug/L, >60-80 ug/L, and >80 ug/
Li.
In the cross sectional study, ORs with
exposure to THMs >80 ug/L were
elevated for low term birth weight
(OR=1.34; 95% 0=1.13-1.6; adjusted
OR=1.29; 95% CI=1.08-1.5), small for
gestational age (OR=1.22; 95% CI=1.12-
1.3; adjusted OR=1.14; 95% CI=1.04-
1.3), and prematurity (OR=1.09; 95%
CI=0.99-1.2; adjusted OR=1.04; 95%
CI=0.94-1.1). Among birth defects, the
ORs were elevated for all surveillance
malformations: OR=1.53; 95% CI=1.14-
2.1; central nervous system defects
OR=2.6; 95% CI=1.48^4.6; neural tube
defects: OR=2.98; 95% CI=1.25-7.1; and
cardiac defects: OR= 1.44; 95%
CI=0.97-2.1. In the case control study,
associations were found between THMs
>80 ug/L and neural tube defects
(OR=4.25; 95% CI=1.02-17.7) and
between THM levels >15 ug/L and
cardiac defects (OR=2.0; 95% CI= 0.94-
4.5). The authors note their findings
should be interpreted with caution
because of possible exposure
misclassification, unmeasured
confounding, and associations which
could be due to chance occurrences.
Although the case control study
included interviews of mothers for
information about residence and various
risk factors, the authors reported a
number of limitations in the
interpretation of the results from the
case control study, especially as a result
of selection bias. Evaluation of selection
bias indicated that the bias led to an
overestimate of the associations with
THM levels.
Some members of the Reg Neg
committee viewed that these studies
indicate the possibility of a reproductive
risk related to exposure to disinfectant
by-products. As a result of this concern,
EPA convened a panel of experts to
review the epidemiology studies
described above (USEPA, 1993a). The
panel concluded that the studies by
Bove et al. (1992a and b) were useful for
hypothesis generation and identification
of a number of areas for further research.
The panel further concluded that the
findings were limited by a number of
issues surrounding study design and
data analysis. Some of the limitations
included untested assumptions of
maternal exposure to chlorinated water,
limitations in the exposure assessment
for THMs and other disinfection by-
products, possibility for exposure
misclassification, confounding risk
factors and that some of these findings
may have been due to chance.
d. Request for Public Comments. EPA
requests comments on the significance
of the epidemiological studies with
chlorine and chloramines as indicators
of risk. EPA recognizes that there are
different interpretations of these
epidemiological studies and specifically
solicits comment on the rationale for
EPA's interpretations. EPA further
requests comments on the studies
suggesting a reproductive risk related to
disinfectant by-product exposure.
4. Chlorine Dioxide, Chlorite and
Chlorate
Chlorine dioxide is used as a
disinfectant in drinking water treatment
as well as an additive with chlorine to
control tastes and odors in water
treatment. It has also been used for
bleaching pulp and paper, flour and oils
and for cleaning and tanning of leather.
Chlorine dioxide is a strong oxidizer
that does not react with organics in the
water, as does chlorine, to produce by-
products such as the trihalomethanes.
Chlorine dioxide is fairly unstable and
rapidly dissociates into chlorite, and
chloride in water. Chlorate may also be
formed as a result of inefficient
generation or generation of chlorine
dioxide under very high or low pH
conditions. The dissociation of chlorine
dioxide into chlorite and chloride may
be reversible with some chlorite
converting back to chlorine dioxide if
free chlorine is available. Chlorite ion is
generally the primary product of
chlorine dioxide reduction. The
distribution of chlorite, chloride and
chlorate is influenced by pH and
sunlight. Chlorite, (as the sodium salt),
is used in the onsite production of
chlorine dioxide and as a bleaching
agent by itself, for pulp and paper,
textiles and straw. Chlorite is also used
to manufacture waxes, shellacs and
varnishes. Chlprate, as the sodium salt,
was once a registered herbicide to
defoliate cotton plants during harvest, to
tan leather and in the manufacture of
dyes, matches, explosives as well as
chlorite.
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Occurrence and Human Exposure.
Based on information from the Water
Industry Data Base (WIDE), it has heen
estimated that for large systems (serving
greater than 10,000 people),
approximately 10% of community
surface water systems serving 12.4
million people and 1% of community
ground water systems, serving 0.2
million people currently use chlorine
dioxide for disinfection in the United
States. It was assumed that none of the
smaller community systems (fewer than
10,000 people) use chlorine dioxide
(WIDB, 1990).
Table V-5 presents occurrence
information available for chlorine
dioxide, chlorate, and chlorite in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). Typical
dosages of chlorine dioxide used as a
disinfectant in drinking water treatment
facilities appear to range from 0.6 to 1.0
mg/L. For plants using chlorine dioxide,
median concentrations of chlorite and
chlorate were found to be 240 and 200
Hg/L, respectively. However, the data
base upon which these numbers are
based is very limited. A more extensive
discussion of chlorine dioxide and
chlorite occurrence is described in
section VI. of this preamble.
TABLE V-5:—SUMMARY OF OCCURRENCE DATA FOR CHLORINE DIOXIDE AND CHLORITE
Occurrence of Chlorine Dioxide, Chlorate, and Chlorite in Drinking Water
Survey (year) 1
AWWARF (1987)
McGuire & Meadow,
1988.
EPA, 1992b2 (1987-
1991).
Location
Disinfection
By-Prod-
ucts Field
Studies
Finished Water From:
Plants Using CIO2:
Chlorite at the Plant (4)
Chlorate at the Plant (4)
Plants Not Using CIO2:
Chlorate at the Plant (30)
Chlorate, Distr. System (4)
Concentration ftig/L)
Range
15-740
21-330
<1 0-660
<10-47
Mean
1.0 mg/L3
0.6 mg/L3
240
200
87
18
Median
110
220
16
13
Other
Positive
Detec-
tions
100%
100%
60%
75%
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Typical dosage used by treatment plants.
AWWARF American Water Works Association Research Foundation.
EPA Environmental Protection Agency.
No information is available on the
occurrence of chlorine dioxide, chlorate,
and chlorite in food or ambient air.
Currently, the Food and Drug
Administration (FDA) does not analyze
for these compounds in foods.
Preliminary discussions with FDA
suggest that there are not approved uses
for chlorine dioxide in foods consumed
in the typical diet. In addition, the EPA
Office of Air and Radiation does not
require monitoring for these compounds
in air. However, chlorine dioxide is
used as a sanitizer for air ducts (Borum,
1991).
EPA believes that drinking water is
the predominant source of exposure for
these compounds. Air and food
exposures are considered to provide
only small contributions to the total
chlorine dioxide, chlorate, and chlorite
exposures, although the magnitude and
frequency of these potential exposures
are issues currently under review.
Therefore, EPA is considering proposing
to regulate these compounds in drinking
water with an RSC value of 80 percent,
the current exposure assessment policy
ceiling. EPA requests any additional
data on known concentrations of
chlorine dioxide, chlorate and chlorite
in drinking water, food and air.
Health Effects. The following health
effects information is summarized from
the draft Drinking Water Health Criteria
Document for Chlorine Dioxide,
Chlorite and Chlorate (USEPA, 1994c).
Studies cited in this section are
summarized in the draft criteria
document.
As noted above, chlorine dioxide is
fairly unstable and rapidly dissociates
predominantly into chlorite and
chloride, and to a lesser extent, chlorate.
There is a ready interconversion among
chemical species in water (before
administration to animals) and in the
gut (after ingestion). Therefore, what
exists in water or the stomach is a
mixture of these chemical species and
possibly their reaction products with
the gastrointestinal contents. Thus, the
toxicity information on chlorite, the
predominant degradation product of
chlorine dioxide, may also be relevant
to characterizing chlorine dioxide
toxicity. In addition, studies conducted
with chlorine dioxide may be relevant
to characterizing the toxicity of chlorite.
As a result, the toxicity data for one
compound are considered applicable for
addressing toxicity data gaps for the
other.
The main health effects associated
with chlorine dioxide and its anionic
by-products include oxidative damage
to red blood cells, delayed
neurodevelopment and decreased
thyroxine hormone levels. Chlorine
dioxide, chlorite and chlorate are well
absorbed by the gastrointestinal tract
and excreted primarily in urine. Once
absorbed, 36Cl-radiolabeled chlorine
dioxide, chlorite and chlorate are
distributed throughout the body.
Lethality data for ingested chlorine
dioxide have not been located in the
available literature. A lethal
concentration for guinea pigs by
inhalation was reported at 150 ppm.
Oral LDso values for chlorite have been
reported at 100 to 140 mg/kg in rats. A
more recent study indicates that the oral
LDso may be closer to 200 mg/L. Limited
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38693
data suggest an oral LDso value between
500 to 1500 rag/kg for chlorate in dogs.
In subchronic and chronic studies,
animals given chlorine dioxide treated
water exhibited osmotic fragility of red
blood cells (1 mg/kg/d), decreased
thyroxine hormone levels (14 mg/kg/d),
possibly due to altered iodine
metabolism and hyperplasia of goblet
cells and inflammation of nasal tissues.
The nasal lesions are not considered
related to ingested chlorine dioxide.
However, it is not clear if the nasal
effects are due to off-gassing of chlorine
dioxide from the sipper tube of the
animal water bottles, or from dermal
contact while the animal drinks from
the sipper tube. In addition, the chlorine
dioxide treated group drank water at a
pH of 4.7 which may also have
contributed to the nasal tissue
inflammation. The concentration
associated with this effect (25 mg/L) is
considerably greater than what would
be found in drinking water.
Studies evaluating developmental or
reproductive effects have described
decreases in the number of implants and
live fetuses per dam in female rats given
chlorine dioxide in drinking water
before mating and during pregnancy.
Delayed neurodevelopment has been
reported in rat pups exposed perinatally
to chlorine dioxide (14 mg/kg/d) or
chlorite (3 mg/kg/d) treated water.
Delayed neurodevelopment was
assessed by decreased locomotor
activity and decreased brain
development.
Subchronic studies with chlorite
administered to rats via drinking water
resulted in transient anemia, decreased
red blood cell glutathione levels and
increased hydrogen peroxide formation
at doses greater than 5 mg/kg/d. Chlorite
administration orally to cats at a dose of
7 mg/kg/d produced 10 to 40 percent
methemoglobin formation within a
couple of hours following dosing.
Exposure to chlorite in drinking water
resulted in an increased turnover of red
blood cells in cats rather than oxidation
of hemoglobin.
Oral studies with chlorate also
demonstrate effects on hematological
parameters and formation of
methemoglobin, but at much higher
doses than chlorite (157-256 mg/kg/d).
No clear tumorigenic activity has been
observed in animals given oral doses of
chlorine dioxide, chlorite or chlorate.
Chlorine dioxide concentrates did not
increase the incidence of lung tumors in
mice nor was any initiating activity
observed in mouse skin or rat liver
bioassays. Lung and liver tumors were
increased in mice given sodium
chlorite; however, the incidence was
within the historical range for these
tumor types. Carcinogenic studies on
chlorate were not located in the
available literature. Chlorate has been
reported to be mutagenic in bacterial
and DrosopMa tests. EPA has classified
chlorine dioxide and chlorite in Group
D: not classifiable as to human
carcinogenicity. This classification is for
chemicals with inadequate evidence or
no data concerning carcinogenicity in
animals in the absence of human data. '
EPA has not classified chlorate with
respect to carcinogenicity.
There are a number of cases of
poisoning in humans who used chlorate
as an herbicide. Effects observed
following exposures to 11 to 3,400 mg/
kg include cyanosis, renal failure,
convulsions and death. The lowest
lethal dose reported in adults is
approximately 200 mg/kg. It is not clear
if this is the actual dose received or if
other components in the formulation
were contributors to the toxicity. In an
epidemiology study of a community
where chlorine dioxide was used as the
primary drinking water disinfectant for
12 weeks, no consistent changes were
observed in the clinical parameters
measured.
Three studies have been selected as
the basis for the RfD and MRDLG for
chlorine dioxide. These studies identify
a NOAEL of 3 mg/kg/d and a LOAEL of
approximately 10 mg/kg/d. A NOAEL of
3 mg/kg/d has been identified in an 8
week rat study by Orme et al. (1985). In
this study, chlorine dioxide was
administered to female rats via drinking
water at concentrations of 0, 2, 20 and
100 mg/L before mating, during
gestation and lactation until the pups
were 21 days old. Based on body weight
and water consumption data, these
concentrations correspond to doses of 1,
3 and 14 mg/kg/d. No effects were noted
in dams. Pups in the high dose group
(14 mg/kg/d) exhibited decreased
exploratory and locomotor activity and
a significant depression of thyroxine.
These effects were not observed at the
3 mg/kg/d dose level. In a second
experiment, pups were given 14 mg/kg/
d chlorine dioxide directly by gavage
during postnatal days 5 through 20. A
greater and more consistent delay in
neurobehavioral activity was observed
along with a greater depression in
thyroxine. Analysis of the DNA content
of cells in the cerebellum from animals
in the high dose drinking water group
(14 mg/kg/day) at postnatal day 21 and
the gavage group at day 11 indicated a
significant depression (Taylor and
Pfohl, 1985). Another study confirmed
14 mg/kg/d as a LOAEL based on
decreased brain cell proliferation in rats
exposed postnatally by gavage (Toth et
al., 1990).
The no-effect level of 3 mg/kg/day is
also supported by a monkey study
(Bercz et al., 1982), where animals were
given chlorine dioxide at concentrations
of 0, 30,100 or 200 mg/L in drinking
water following a rising dose protocol.
These concentrations correspond to
doses of 0, 3.5,9.5 and 11 mg/kg/d
based on animal body weight and water
consumption. Animals showed signs of
dehydration at the high dose; exposure
was discontinued at that dose (11 mg/
kg/d). A slight depression of thyroxine
was observed following exposure to 9.5
mg/kg/d. No effects were seen with 3.5
mg/kg/d, which is considered the
NOAEL.
MRDLG for Chlorine Dioxide. EPA is
proposing an MRDLG for chlorine
dioxide based on developmental
neurotoxicity following a Category HI
approach. Using a NOAEL of 3 mg/kg/
d and an uncertainty factor of 300, an
RfD of 0.01 mg/kg/d for chlorine dioxide
is calculated. An uncertainty factor of
300 is used to account for differences in
response to toxicity within the human
population and between humans and
animals. This factor also accounts for
lack of a two-generation reproductive
study. Availability of an acceptable two-
generation reproduction study would
likely reduce the total uncertainty factor
to 100. The Chlorine Dioxide panel of
the Chemical Manufacturers Association
is conducting a two-generation
reproductive study with chlorite to
address this data gap. EPA will review
the results of this study and determine
if any changes to the RfD for chlorine
dioxide are warranted.
After adjusting for an adult
consuming 2 L water per day, an RSC
of 80 percent is applied to calculate an
MRDLG of 0.3 mg/L. An RSC of 80% is
used since most chlorine dioxide
exposure is likely to come from a
drinking water source.
MRDLG = 3 mg/kg/d X 7° kg X °-8 = 0.3 mg/L (rounded)
300x2IVday
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The Drinking Water Committee of the
Science Advisory Board (SAB) agreed
with the use of the Orme et al. (1985)
study as the basis for the MRDLG and
suggested that an uncertainty factor of
100 be applied (USEPA, 1992c). They
also suggested that a child's body
weight of 10 kg and water consumption
of 1 L/d may be more appropriate for
setting the MRDLG than the adult
parameters, given the acute nature of the
toxic effect. EPA requests comments on
the SAB's suggestion.
EPA also requests comment on the
appropriateness of the 300-fold
uncertainty factor, the studies selected
as the basis for the RfD, and the 80%
relative source contribution.
MCLG for Chlorite. The
developmental rat study by Mobley et
al. (1990) has been selected to serve as
the basis for the RfD and MCLG for
chlorite. Other studies reported effects
at doses higher than the Mobley et al.
study. In this study, female Sprague-
Dawley rats (12/group) were given
drinking water containing 0, 20, or 40
mg/L chlorite (0, 3, or 6 mg chlorite ion/
kg/day) as the sodium salt beginning 10
days prior to breeding with untreated
males until the pups were sacrificed at
35 to 42 days postconception (a total
exposure of 9 weeks). Exploratory
activity was depressed in the pups
treated with 3 mg/kg/day chlorite on
postconception days 36-37 but not on
days 38—40. Pups from the high
exposure group also exhibited
depressed exploratory behavior during
days 36-39 postconception (p<0.05).
Exploratory activity was comparable
among the treated and control groups on
postconception days 39-41. No
significant differences in serum total
thyroxine or triiodothyronine were
observed between treated and control
pups. Free thyroxine was significantly
elevated in the 6 mg/kg/day pups. A
LOAEL of 3 mg/kg/day was determined
in this study based on the
neurobehavioral effect (depressed
exploratory behavior) in rats. This
endpoint is similar to that reported for
chlorine dioxide. •
EPA had considered using a study by
Heffernan et al. (1979) which described
dose-related decreases in red blood cell
glutathione levels from rats orally
exposed to chlorite in drinking water for
up to 90 days. The decreases in
glutathione were accompanied by
decreases in red blood cell
concentration, hemaglobin
concentration and packed red cell
volume. Taken together, these effects
were considered reflective of oxidative
stress resulting from the ingested
chlorite. In this study, a NOAEL of 1
mg/kg/d and LOAEL og 5 mg/kg/d were
identified.
The EPA Science Advisory Board had
cautiously agreed with the selection of
the Heffernan et al. (1979) study as the
basis for the RfD, but noted that the
endpoint would likely be controversial
since normal fluctuations occur with
glutatione levels. Thus this effect, alone,
may not necessarily be the result of
chlorite exposure. The EPA RfD
workgroup was unable to reach
consensus on decreased glutathione
levels as an appropriate endpoint to
base an RfD. They agreed with the
selection of the Mobley et al. (1990)
study since the endpoint,
developmental neurotoxicity,
represented the next critical effect and
was consistent with the toxicity
observed with chlorine dioxide.
Following a Category III approach,
EPA is proposing an MCLG of 0.08 for
chlorite. The MCLG is based on an RfD
of 0.003 determined from the LOAEL of
3 mg/kg/day from the Mobley et al.
study. This endpoint was selected since
it is similar to that reported for chlorine
dioxide. An uncertainty factor of 1,000
is used in the derivation of the RfD and
MCLG to account for use of a LOAEL
from an animal study.
After adjusting for an adult
consuming 2 L water per day, an RSC
of 80% is applied to calculate an MCLG
of 0.08 mg/L. An RSC of 80% was used
since most exposure to chlorite is likely
to come from drinking water.
3mg/kg/dayx70kgx0.8
l,OOOx2L/day
The Drinking Water Committee of the
EPA Science Advisory Board suggested
that EPA consider basing the MCLG on
the child body weight of 10 kg and
water consumption of 1 L/day instead of
the adult default values. EPA requests
comments on the SAB's suggestion
along with the study selected as the
basis for the MCLG, the uncertainty
factor and the RSC of 80%.
MCLG for Chlorate. Data are
considered inadequate to develop an
MCLG for chlorate at this time. A
NOAEL of 0.036 mg/kg/d (the only dose
tested) was identified in the Lubbers et
al. (1982) human clinical study
following a 12-week exposure to
chlorate in drinking water. NOAELs
identified from animal studies are
considerably higher (approximately 78
mg/kg/d). However, doses that are lethal
to humans (200 mg/kg/d) are only 2-fold
greater than this animal no-effect level.
No information is available to
characterize the potential human
toxicity between the doses of 0.036, the
only human NOAEL and 200 mg/kg/d,
the apparent human lethal dose. Thus,
EPA considers the data base too weak to
derive a separate MCLG for chlorate at
this time. The Agency will continue to
evaluate the animal data and any new
information that become available for
future consideration of an MCLG for
chlorate.
EPA requests comments on the
decision not to propose an MCLG for
chlorate at this time.
5. Chloroform
Chloroform [trichloromethane, CAS
No. 67-66-3] is a nonflammable,
colorless liquid with a sweet odor and
high vapor pressure (200 mm Hg at 25
°C). It is moderately soluble in water (8
gm/L at 20 °C) and soluble in organic
solvents (log octanol/water partition
coefficient of 1.97). Chloroform is used
primarily to manufacture fluorocarbon-
22 (chlorodifluoromethane) which in
turn is used for refrigerants and
fluoropolymer synthesis. A small
percentage of the manufactured
chloroform is used as an extraction
solvent for various products (e.g. resins,
gums). In the past, chloroform was used
in anesthesia and medicinal
preparations and as a grain fumigant
ingredient. Chloroform can be released
to the environment from direct
(manufacturing) and indirect
(processing/use) sources and chloroform
is a prevalent chlorination disinfection
by-product. Volatilization is the
principle mechanism for removal of
chloroform from lakes and rivers.
Chloroform bioconcentrates slightly in
aquatic organisms and adsorbs poorly to
sediments and soil. Chloroform can be
biodegraded in water and soil (half-life
of weeks to months) and ground water
(half-life of months to years), and photo-
oxidized in air (half-life of months).
Occurrence and Human Exposure.
The principle source of chloroform in
drinking water is the chemical
interaction of chlorine with commonly
present natural humic and fulvic
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38695
substances and other precursors
produced by either normal organic
decomposition or by the metabolism of
aquatic biota. Because humic and fulvic
material are generally found at much
higher concentrations in surface water
sources than in ground water sources,
surface water systems have higher
frequencies of occurrence and higher
concentrations of chloroform than
ground water systems. Several water
quality factors affect the formation of
chloroform including Total Organic
Carbon (TOG), pH, and temperature.
Different treatment practices can reduce
the formation of chloroform. These
include the use of precursor removal
technologies such as coagulation/
filtration, granular activated carbon
(GAG), and membrane filtration and the
use of chlorine dioxide, chloramination,
and ozonation.,
Table V-6 presents occurrence
information available for chloroform in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). The table lists
six surveys conducted by Federal and
private agencies. Median concentrations
of chloroform in drinking water appear
to range from 14 to 57 ug/L for surface
water supplies and <0.5 u,g/L for
ground-water supplies (many of which
do not disinfect). The lower bound
median concentration for chloroform in
surface water supplies is biased to the
low side because concentrations in this
survey were measured in the plant
effluent; the formation of chloroform
would be expected to increase in the
distribution in systems using chlorine as
their residual disinfectant.
TABLE V6.—SUMMARY OF OCCURRENCE DATA FOR CHLOROFORM
[Occurrence of Chloroform in Drinking Water]
Survey (year)
CWSS (1978) Brass
etal., 1981.
RWS (1978-1980)
Brass, 1981.
QWSS (1980-1981)
Westrick et al. 1983.
EPA, 1991 a2 (1984-
1991).
EPA, 1992b2 (1987-
1991).
EPA/AMWA/CDHS2
(1988-1989).
Krasner et al., 1989b .
Location
450 Water
Supply
Systems
>600 Rural
Systems
(>2,000
House-
holds)
945 GW Sys-
tems:
(466 Ran-
dom and
479
Nonrando-
m)
Unregulated
Contami-
nant Data
Base —
Treatment
Facilities
from 19
States
Disinfection
By-Prod-
ucts Field
Studies
35 Water Util-
ities Nation-
wide
Sample information (No. of samples)
Finished Water (1,100):
Surface Water
Ground Water
Drinking Water from:
Surface Water
Ground Water
Serving >1 0,000 (327)
Serving <1 0,000 (618)
Sampled at the Plant (5,806)
Finished Water:
At the Plant (73)
Distribution System (56)
Samples from Clearwell
Effluent for 4 Quarters
Concentration (ug/L
Rage
Max. 300
Max. 430
<0.2-240
<0.2-340
Max. 130
Mean
3 60
3<0.5
384
38.9
17
36
57
Median
57
<0.5
0.5
0
5
28
42
S9.6-15
14
Other
Positive
Detec-
tions:
"97%
"34%
Postive
Detec-
tion:
"82%
"17%
90th per-
centile:
17
7.8
Positive
Detec-
tions:
96%
98%
75% of
Data
was
Below
33 jigL.
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Mean of the positives.
4 Of systems sampled.
6 Range of medians for individual quarters.
AMWA Association of Metropolitan Agencies.
CDHS California Department of Health Services.
CWSS Community Water Supply Survey. •
GWSS Ground Water Supply Survey.
RWS Rural Water Survey.
EPA Environmental Protection Agency.
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Several studies have assessed
inhalation exposure to chloroform. The
major source of these data is from the
USEPA's Total Exposure Assessment
Methodology (TEAM) studies, which
measured chloroform exposure to
approximately 750 persons in eight
geographic areas from 1980 to 1987.
Personal exposure to chloroform from
air was measured over a 12-hour period
(excluding showers) for individuals in
three areas. The average exposures were
reported to range from 4 to 9 ug/m3 in
New Jersey and Baltimore, and about 0.5
to 4 ug/m3 in California cities (Wallace,
1992). In the 1987 Los Angeles TEAM
study, chloroform in indoor air was
measured in the living room and
kitchen of private residences. Observed
mean indoor concentrations ranged
from 0.9 to 1.5 ug/m3 (Pellizzari et al.,
1989 and Wallace et al., 1990 in
Wallace, 1992). For outdoor levels, the
12-hour average outdoor concentrations
measured in the California and New
Jersey TEAM studies ranged from 0.2 to
0.6 ug/m3 and 0.1 to 1.5 |ig/m3,
respectively (Pellizzari et al., 1989,
Wallace et al., 1990 and PEI et al., 1989
in Wallace, 1992).
Given the limited exposure data in
air, inhalation exposure can be
estimated using an inhalation rate of 20
m3/day. Resulting estimates for average
ambient air exposures range from 2 to
30 ug/d and 18-30 ug/d for average
indoor air exposures. However, based
on the personal air monitoring data, a
potentially higher average inhalation
exposure is indicated with a range of 10
to 180 ug/d.
Two studies analyzed some foods for
chloroform. In a pilot market basket
survey of four food groups at five sites,
measured chloroform levels were as
follows: dairy composite, 17 ppb (1 of
5 sites); meat composite, not detected;
oil and fat composite, trace amounts (1
of 5 sites); beverage composite, 6 to 32
ppb (4 of 5 sites) (Entz et al., 1982). In
a study of 15 table-ready food items,
chloroform was detected in 53% of the
foods tested: butter, 670 ppb; cheddar
cheese, 80 ppb; plain granola, 57 ppb;
peanut butter, 29 ppb; chocolate chip
cookies, 22 ppb; frozen fried chicken
dinner, 29 ppb; and high meat dinner,
17 ppb (Heikes, 1987).
Limited data are available to
characterize dietary exposure to
chloroform. Although some uses of
chlorine have been identified in the
food production/food processing area,
monitoring data are not adequate to
characterize the magnitude or frequency
of exposure to chloroform. Based on the
limited number of food groups that are
believed to contain chloroform and low
levels expected in ambient and indoor
air, EPA assumes that drinking water is
the predominant source of chloroform
intake. The characterization of potential
food and air exposures are issues
currently under review. EPA requests
any additional data on known
concentrations of chloroform in
drinking water, food, and air.
Health Effects. The health effects
information is summarized from the
draft Drinking Water Criteria Document
forTrihalomethanes (USEPA, 1994d).
Studies cited in this section are
summarized in the criteria document.
Chloroform has been shown to be
rapidly absorbed upon oral, inhalation
and peritoneal administration and
subsequently metabolized. The reported
mean human lethal dose, from clinical
observations of overdoses, was around
630 mg/kg. The LDso values in mice and
rats have been reported in the range of
908-1,400 mg/kg. Several reactive
metabolic intermediates (e.g. phosgene,
carbene, dichloromethyl radicals) can be
produced via oxidation (major pathway)
or reduction (minor pathway) by
microsomal preparations. Experimental
studies suggested that these active
metabolic intermediates are responsible
for the hepatic and renal toxicity and
possibly, carcinogenicity, of the parent
compound. Animal studies suggest that
the extent of chloroform metabolism
varies with species and sex. The
retention of chloroform in organs after
dosing was small. Due to the lipophilic
nature of the compound, the residual
concentration is in tissues with higher
fatty content. In humans, the majority of
the tested oral intake doses (0.1 to 1 gm)
were excreted through the lungs in the
form of a metabolite CCh or as the
unchanged compound. Urinary
excretion levels were below 1%.
Mammalian bioeffects following
exposure to chloroform include effects
on the central nervous system (CNS),
hepatotoxicity, nephrotoxicity,
reproductive toxicity and
carcinogenicity. Chloroform caused CNS
depression and affected liver and
kidney function in humans in both
accidental and long term occupational
exposure situations. In experimental
animals, chloroform caused changes in
kidney, thyroid, liver, and serum
enzyme levels. These responses are
discernible in mammals from exposure
to levels of chloroform ranging from 15
to 290 mg/kg; the intensity of response
was dependent upon the dose and the
duration of the exposure. Ataxia and
sedation were noted in mice receiving a
single dose of 500 mg/kg chloroform.
Short-term exposure to the low levels of
chloroform typically found in air, food,
and water are not known to manifest
acute toxic effects. The potential for
human effects from chronic lifetime
exposure is the basis for this regulation.
Developmental toxicity and
reproductive toxicity have been
investigated in animals. One
developmental study reported maternal
toxicity in rabbits administered
chloroform by the oral route. Decreased
weight gain and mild fatty changes in
liver were observed in dams receiving
50 mg/kg/day (LOAEL); the maternal
NOAEL was noted to be 35 mg/kg/day.
There was no evidence of
developmental effects.
The data from a 7.5-year oral study in
dogs conducted by Heywood et al.
(1979) were used to calculate the RfD.
EPA considers this study suitable for the
RfD derivation since it is a chronic
study and sensitive indices of
hepatotoxicity (serum enzyme levels,
liver histology) of sufficient numbers of
experimental animals were monitored.
In this study, chloroform was
administered to beagle dogs (16 per dose
group) in toothpaste base gelatin
capsules at dose levels of 15 or 30 mg/
kg/day 6 days/week for 7.5 years. A
LOAEL of 15 mg/kg/day was established
based on the observation of hepatic fatty
cysts in treated animals at both doses.
An RfD of 0.01 mg/kg/day has been
derived from this LOAEL by the
application of an uncertainty factor of
1,000, in accordance with EPA
guidelines.
The results of a number of assays to
determine the mutagenicity potential of
chloroform are inconclusive. Studies on
the in vitro genotoxicity of chloroform
reported negative results in bacteria
(Ames assays), negative results for gene
mutations and chromosomal aberrations
in mammalian cells, and mixed results
in yeasts. In vivo and in vitro DNA
damage tests indicate that chloroform
will bind to DNA. Gene mutation tests
in Drosophila were marginal, whereas
tests for chromosomal aberrations and
sperm abnormalities were mixed.
Several chronic animal studies
confirmed the carcinogenicity of
chloroform. Chloroform induced
hepatocellular carcinomas in mice when
administered by gavage in corn oil (NCI,
1976). Chloroform also induced renal
adenomas and adenocarcinomas in male
rats regardless of the carrier vehicle (oil
or drinking water) employed (NCI, 1976;
Roe et al., 1979; Jorgenson et al., 1985).
In the study by Jorgenson et al. (1985),
chloroform was administered in
drinking water to male Osborne-Mendel
rats and female B6C3Fi mice at doses of
0, 200, 400, 900 or 1,800 ppm (0,19, 38,
81 or 160 mg/kg/day in rats and 0, 34,
65,130 or 263 mg/kg/day in mice) for
2 years. Chloroform increased the
incidence of kidney tumors in male rats
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38697
in a dose-related manner. The combined
incidence of renal tubular cell
adenomas, renal tubular cell
adenocarcinomas, and nephroblastomas
in control, 200,400,900 and 1,800 ppm
groups were 5/301,6/313, 7/148, 3/48,
and 7/50, respectively. Jorgenson's
study reported no statistically
significant increase in the incidence of
hepatocellular carcinomas in the female
mice exposed to similar doses of
chloroform as reported in the 1976 NCI
study.
Since hepatic changes appeared to be
related to the corn oil vehicle, the
interaction of corn oil and chloroform
could account for the enhanced hepatic
toxicity and thus for the difference in
the NCI and Jorgenson studies. Because
the drinking water study did not
replicate hepatic tumors in female mice
and the potential role of corn oil in
enhancing toxicity, the National
Academy of Science Subcommittee on
the Health Effects of Disinfectants and
Disinfection By-Products (NAS, 1987)
recommended that male rat kidney
tumor data obtained from Jorgenson's
study be used to estimate the
carcinogenic potency of chloroform.
EPA agreed with the NAS
Subcommittee recommendation for
estimating risks of chloroform from
drinking water exposures.
Based on all kidney tumor data in
male Osborne-Mendel rats reported by
Jorgenson et al. (1985), EPA used a
linearized multistage model and derived
a carcinogenic potency factor for
chloroform of 6.1 x 10~3 (mg/kg/day)~'.
Assuming a daily consumption of two
liters of drinking water and an average
human body weight of 70 kg, the 95%
upper bound limit lifetime cancer risk
levels of 10-«, 10 ~5, and 10 ~4 are
associated with concentrations of
chloroform in drinking water of 6,60
and 600 ug/L, respectively.
In 1987 the Commission on Life
Sciences of the National Research
Council published Drinking Water and
Health (NAS, 1987). Volume 7,
Disinfectants and Disinfectant By-
Products, prepared by the Subcomittee
on Disinfectants and Disinfection By-
Products, discussed the available data
on chloroform, which are the same data
summarized above. The Subcommittee
concluded that "[njoting that
chloroform is the principal THM
produced by chlorination, the
subcommittee found [the 100 THM]
level to be unsupportable on the basis
of the risk values for chloroform
developed in this review," and that the
level should be reduced.
EPA has classified chloroform in
Group B2, probable human carcinogen,
based on sufficient evidence of
carcinogenicity in animals and
inadequate evidence in humans (IRIS,
1985). The International Agency for
Research on Cancer (IARC) has
classified chloroform as a Group 2B
carcinogen, agent possibly carcinogenic
to humans. (IARC, 1982).
According to EPA's three-category
approach for establishing MCLGs,
chloroform is placed in Category I since
there is sufficient evidence of
carcinogenicity via ingestion
considering weight of evidence,
potency, pharmacokinetics, and
exposure. Thus, EPA is proposing an
MCLG of zero for this contaminant. EPA
requests comment on the basis for the
proposed MCLG for chloroform.
6. Bromodichloromethane
Bromodichloromethane (BDCM; CAS
No. 75-27-4) is a nonflammable,
colorless liquid with a relatively high
vapor pressure (50 mmHg at 20°C).
BDCM is moderately soluble in water
(3.3 gm/L at 30°C) and soluble in
organic solvents (log octanol/water
partition coefficient of 1.88). Only a
small amount of BDCM is currently
produced commercially in the United
States. The chemical is used as an
intermediate for organic synthesis and
as a laboratory reagent. The principle
source of BDCM in drinking water is the
chemical interaction of chlorine with
the commonly present organic matter
and bromide ions. Degradation of BDCM
is not well studied, but probably
involves photooxidation. The estimated
atmospheric half-life of BDCM is two to
three months. Volatilization is the
principal mechanism for removal of
BDCM from rivers and streams (half-life
of hours to weeks). Limited studies
reported that BDCM adsorbed poorly to
sediments and soils. No study of
bioaccumulation of BDCM was located.
Based on the data of a few structurally
similar chemicals such as chloroform,
the bioconcentration potential of BDCM
in aquatic organisms is low.
Biodegradation of BDCM is limited
under aerobic conditions and extensive
(completion within days) under
anaerobic conditions.
Occurrence and Human Exposure.
BDCM, occurs in public water systems
that chlorinate water containing humic
and fulvic acids and bromine that can
enter source waters through natural and
anthropogenic means. Several water
quality factors affect the formation of
BDCM including Total Organic Carbon
(TOG), pH, bromide, and temperature.
Different treatment practices can reduce
the formation of BDCM. These include
the use of chlorine dioxide,
chloramination, and ozonation prior to
chloramination, as well as the use of
precursor removal technologies such as
coagulation/filtration, granular activated
carbon (GAG), and membrane filtration.
Table V-7 presents occurrence
information available for BDCM in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). The table lists
six surveys conducted by Federal and
private agencies. Median concentrations
of BD.CM in drinking water appear to
range from 6.6 to 15 ug/L for surface
water supplies and <0.5 ug/L for
ground-water supplies. The lower
bound median concentration for BDCM
in surface water supplies is biased to the
low side because concentrations in this
survey were measured in the plant
effluent; the formation of BDCM would
be expected to increase in the
distribution system when chlorine is
used as the residual disinfectant.
TABLE V-7: SUMMARY OF OCCURRENCE DATA FOR BROMODICHLOROMETHANE
Occurrence of Bromodichloromethane
Survey (Year) 1
CWSS (1978, Brass et
al., 1981.
Location
450 Systems ...
Sample Information
(No. of Samples)
Finished Water (1,1 00):
Surface Water
Ground Water
Concentration (ug/L)
Range
Mean
312
3 5.8
Median
6.8
<0.5
Other
Positive Detections:
94%4
33%"
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
TABLE V-7: SUMMARY OF OCCURRENCE DATA FOR BROMODICHLOROMETHANE—Continued
Occurrence of Bromodichloromethane
Survey (Year) 1
RWS (1978-1980)
Brass, 1981.
GWSS (1980-1 981)
Westricketal. 1983.
EPA, 1991a2 (1984-
1991).
EPA, 1992b2 (1987-
1989).
EPA/AMWA/CDHS2
(1988-1989) Krasner
etal., 1989b.
Location
>600 Rural
Systems
(>2,000
households).
945 GW Sys-
tems:
(466 Random
and 479
Nonrandom).
Unregulated
Contaminant
Data Base-
Treatment
Facilities from
19 States.
Disinfection By-
products
Field Studies.
35 Water Utili-
ties Nation-
wide. .
Sample Information
(No. of Samples)
Drinking Water from:
Surface Water
Ground water
Serving >1 0,000 (327)
Serving <1 0,000 (61 8)
Finished Water at Treatment
Plants (4,439).
Finished Water:
At the Plant (73)
Distribution System (56)
Samples from Clearwell Efflu-
ent for 4 Quarters.
Concentration (ng/L)
Range
Max. 110 ..
Max. 79 ....
<0.2-90 ....
<0.2-100 ..
Max. 82 ....
Mean
5.6
13
17
4.1 -105
Median
11
<0.5
0.4
0
3
11
15
6.6
Other
Positive Detections:
76%"
13%"
90Percentile
9.2
6.1
Positive Detections:
96%
98%
75% of Data was
Below 14 ng/L. ,
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Mean of the positives.
4 Of systems sampled.
5 Range of medians for individual quarters.
AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
CWSS: Community Water Supply Survey.
GWSS: Ground Water Supply Survey.
RWS: Rural Water Survey.
EPA: Environmental Protection Agency.
BDCM is usually found in air at low
concentrations. Based on information
obtained through a literature review,
Howard (1990) estimated the average
daily intake of BDCM from air using an
inhalation rate of 20 m3/day. Assuming
a range of 6.7 to 670 ng/m3, the average
exposure may be as low as 0.134 (ig/day
or as high as 13.4 ug/day.
BDCM is not a common contaminant
in food. In one market study of 39
different food items, BDCM was
detected in one dairy composite (1.2
ppb), butter (7 ppb), and two beverages
(0.3 and 0.6 ppb). Analysis of cola soft
drinks found BDCM in three samples
with reported concentrations of 2.3 ppb,
3.4 ppb, and 3.8 ppb (Entz et al., 1982
in Howard, 1990).
Limited data are available to
characterize food and air exposures to
BDCM. Although some uses of chlorine
have been identified in the food
production/food processing area,
monitoring data are inadequate to
characterize the magnitude and
frequency of potential BDCM exposures.
Based on the limited number of food
groups that are believed to contain
BDCM and that there are not significant
levels expected in ambient or indoor air,
EPA assumes that drinking water is the
predominant source of BDCM intake.
EPA requests any additional data on
known concentrations of BDCM in
drinking water, food, and air.
Health Effects. The health effects
information in this section is
summarized from the draft Drinking
Water Criteria Document for
Trihalomethanes (USEPA, 1994d).
Studies mentioned below are
summarized in the criteria document.
Studies indicated that gastrointestinal
absorption of BDCM is high in animals.
No studies were located regarding
BDCM in humans or animals following
inhalation or dermal exposure. By
analogy with the experimental data of a
structurally-related halomethane
chloroform, inhalation and dermal
absorption may be high for BDCM. The
reported LDso values in mice and rats
ranged from 450 to 969 mg/kg. Under
both in vivo and in vitro conditions,
several active metabolic intermediates
(e.g. dichlorocarbonyl, dichloromethyl
radicals) were produced via oxidation or
reduction by microsomal preparations.
Experimental studies suggested that
these active metabolic intermediates
may be responsible for hepatic and renal
toxicity and possibly, carcinogenicity of
the parent compound. Animal studies
suggest that the extent of BDCM
metabolism varies with species and sex.
The retention of BDCM in organs after.
dosing was small, even after repeated
doses. Urinary excretion levels were
below 3 percent.
Mammalian bioeffects following
exposure to BDCM include effects on
the central nervous system (decreased
operant response), hepatotoxicity,
nephrotoxicity, reproductive toxicity,
and carcinogenicity. In experimental
mice and rats, BDCM caused changes in
kidney, liver, serum enzyme levels, and
decreased body weight. These responses
were discernible in rodents from
exposure to levels of BDCM that ranged
from 6 to 300 mg/kg; the intensity of
response was dependent upon the dose
and the duration of the exposure. Ataxia
and sedation were observed in mice
receiving a single dose of 500 mg/kg
BDCM.
One study investigated developmental
and reproductive toxicity of BDCM in
rodents. Ruddick et al. (1983)
administered BDCM in com oil to
groups of pregnant rats by gavage at
doses of 0, 50,100 or 200 mg/kg/day on
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38699
days 6 to 15 of gestation. At 200 mg/kg/
day, BDCM significantly (p <0.05)
decreased maternal weight (25%) and
increased relative kidney weights. There
were no increases in the incidence of
fetotoxicity or external/visceral
malformations, but sternebral anomalies
were more prevalent at 100 and 200 mg/
kg than at 50 mg/kg. The sternebral
anomalies were not considered by the
authors to be evidence of a teratogenic
effect, but rather evidence of maternal
toxicity.
Data from a National Toxicology
Program (NTP) chronic oral study in
B6C3Fi mice (NTP, 1987) was used to
calculate the RfD. BDCM in corn oil was
given to mice by gavage 5 days/week for
102 weeks. Male mice (50/dose) were
administered doses of 0, 25 or 50 mg/
kg/day while female mice (50/dose)
received doses of 0, 75 or 150 me/kg/
day. Following treatment, mortality,
body weight and histopathology were
observed. Renal cytomegaly and fatty
metamorphosis of the liver was
observed in male mice >25 mg/kg/day).
Compound-related follicular cell
hyperplasia of the thyroid gland was
observed in both males and females.
The survival rate decreased in females
and decreases in mean body weights
were observed in both males and
females at high doses. Based on the
observed renal, liver and thyroid effects
in male mice, a LOAEL of 25 mg/kg/day
was identified. A RfD of 0.02 mg/kg/day
has been derived from the LOAEL of 25
mg/kg/day in mice by the application of
an uncertainty factor of 1,000, in
accordance with EPA guidelines for use
of a LOAEL derived from a chronic
animal study.
In vitro genotoxicity studies reported
mixed results in bacterial Salmonella
strains and yeasts. BDCM was not
mutagenic in mouse lymphoma cells
without metabolic activation, but
induced mutation with activation. An
increase in frequency of sister
chromatid exchange was reported in
cultured human lymphocytes, rat liver
cells, and mouse bone marrow cells (in
vivo), but not in Chinese hamster ovary
cells. Overall, more studies yielded
positive results and evidence of
mutagenicity for BDCM is considered
adequate.
Evidence of the carcinogenicity of
(1987) chronic animal study. In this
study BDCM in com oil" was
administered via gavage to groups of 50
rats (Fischer 344/N) of each sex at doses
of 0,50 or 100 mg/kg, 5 days/week, for
102 weeks (NTP, 1987). Male B6C3Ft'
mice (50/dose) were administered 0,25
or 50 mg/kg by the same route while
females received 0, 75 or 150 mg/kg/
day. BDCM caused statistically
significant increases in kidney tumors
in male mice, the liver in female mice,
and the kidney and large intestine in
male and female rats. In male mice, the
combined incidence of tubular cell
adenomas or adenocarcinomas of the
kidneys increased significantly in the
high-dose group (vehicle control, 1/46;
low-dose, 2/49; high-dose 9/50). The
combined incidences of hepatocellular
adenomas or carcinomas in vehicle
control, low-dose and high-dose female
mice groups were 3/50,18/48 and 29/
50, respectively.
In rats from the NTP study, the
combined incidences of tubular cell
adenomas or adenocarcinomas in
vehicle control, low-dose and high-dose
groups were 0/50,1/49 and 13/50 for
males and 0/50,1/50 and 15/50 for
females, respectively. Tumors of large
intestines were significantly increased
in a dose-dependent manner in male
rats, and only observed in high-dose
female rats. The combined incidences of
adenocarcinomas or adenomatous
polyps were 0/50,13/49, 45/50 for
males and 0/46, 0/50,12/47 for females,
respectively. The combined tumor
incidences of large intestine and kidney
were 0/50,13/49,46/50 for male rats
and 0/46,1/50, 24/48 for female rats,
respectively.
Using the linearized multistage
model, several cancer potency factors
for BDCM were derived based on the
observed cancer incidence of various
tumor types (large intestine, kidney, or
combined) in mice or rats reported in
the NTP bioassay. The resulting cancer
potency factors are in the range of 4.9
x 10~3 to 6.2 x 10~2 (mg/kg/day) -'. A
potency factor of 1.3 x 10 ~' (mg/kg/
day)-' was derived from the incidence
of hepatic tumors in female mice (IRIS,
1990). However, hepatic tumor data
should be interpreted with caution
because studies of an analog chloroform
indicated a possible role of the corn oil
vehicle in induction of these tumors.
Until future studies can provide a better
understanding of the corn oil effect on
hepatic carcinogenicity, EPA considers
carcinogenic risk quantification for
BDCM based on kidney or large
intestine tumor data to be more
appropriate. EPA is presently
conducting a cancer bioassay with
BDCM in drinking water for comparison
with the NTP study. EPA will evaluate
the results of this study when available
to determine if changes to the risk
assessment are warranted.
Following the Agency's Cancer Risk
Assessment Guidelines (USEPA, 1986),
when two or more significantly elevated
tumor sites or types are observed in the
same study, the slope factor of the
greatest sensitivity preferably should be
used for carcinogenic risk estimation.
Based on the potency factor of 6.2 x
10 ~2 (mg/kg/day)"1 derived from the
kidney tumor incidence in male mice,
the estimated concentrations of BDCM
in drinking water associated with excess
cancer risks of 10~4,10~s and 10~6 are
60, 6 and 0.6 |ig/L, respectively.
EPA has classified BDCM in Group
B2, probable human carcinogen, based
on sufficient evidence of carcinogenicity
in animals and inadequate evidence in
humans. The International Agency for
Research on Cancer (IARC) has recently
classified BDCM as a Group 2B
carcinogen, agent probably carcinogenic
to humans (IARC, 1991).
Following EPA's three-category
approach for establishing MCLGs,
BDCM is placed in Category I since
there is sufficient evidence for
carcinogenicity via ingestion
considering weight of evidence,
potency, pharmacokinetics, and
exposure. Thus, EPA is proposing an
MCLG of zero for this contaminant. EPA
requests comments on the basis of the
proposed MCLG for BDCM and the use
of tumor data of large intestine and
kidney, but not liver, in quantitative
estimation of carcinogenic risk of BDCM
from oral exposure.
7. Dibromochloromethane
bibromochloromethane (DBCM; CAS
No. 124-48-1) is a nonflammable,
colorless liquid with a relatively high
vapor pressure (76 mmHg at 20 °C).
DBCM is moderately soluble in water (4
gm/1 at 20 °C) and soluble in organic
solvents (log octanol/water partition
coefficient of 2.09). Currently DBCM is
not produced commercially in the
United States. The chemical has only
limited uses as a laboratory agent. The
principal source of DBCM in drinking
water is the chemical interaction of
chlorine with commonly present
organic matter and bromide ions.
Degradation of DBCM has not been well
studied, but probably involves
photooxidation. The estimated
atmospheric half-life of DBCM is one to
two months. Volatilization is the
principle mechanism for removal of
DBCM from rivers and streams (half-life
of hours to weeks). Several studies
reported that DBCM adsorbs poorly to
soil and sediments. No experimental
study was found regarding the
bioconcentration of DBCM. Based on the
data of a few structurally similar
chemicals, the bioconcentration
potential of DBCM in aquatic organisms
is assumed to be low. Biodegradation of
DBCM is limited under aerobic
conditions and more extensive under
anaerobic conditions.
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38700 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Occurrence and Human Exposure.
DBCM occurs in public water systems
that chlorinate water containing humic
and fulvic acids and bromine that can
enter source waters through natural and
anthropogenic means. Several water
quality factors can affect the formation
of DBCM, including Total Organic
Carbon (TOG), pH, bromide, and
temperature. Different treatment
practices can reduce the formation of
DBCM in drinking water. These include
the use of precursor removal
technologies such as coagulation/
filtration, granular activated carbon
(GAG), membrane filtration, and the use
of chlorine dioxide, chloramination, and
ozonation.
Table V-8 presents occurrence
information available for DBCM in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). The table lists
six surveys conducted by Federal and
private agencies. Median concentrations
of DBCM in drinking water appear to
range from 0.6 to 3.6 ug/L for surface
water supplies and <0.5 ug/L for
ground-water supplies. The lower
bound median concentration for DBCM
in surface water supplies is biased to the
low side because concentrations in this
survey were measured in the plant
effluent; the formation of DBCM would
be expected to increase in the
distribution in systems using chlorine as
their residual disinfectant.
TABLE V-8.—SUMMARY OF OCCURRENCE DATA FOR DIBROMOCHLOROMETHANE
Occurrence of dibromochloromethane in drinking water
Survey (year) 1
CWSS (1978) Brass et al.,
1981.
RWS (1978-1980) Brass,
1981.
GWSS (1980-1981)
Westrick et al. 1983.
EPA, 1991*2(1984-1991) •
EPA, 1992 b2 (1987-1 989) .
EPA/AMWA/CDHS2 (1988-
1989) Krasner et al.,
1989b.
Location
450 Systems
>600 Rural
Systems
(>2,000
house-
holds).
945 GW Sys-
tems: (466
Random
and 479
Nonran.
dom)
Unregulated
Contami-
nant Data
Base-
Treatment
Facilities
from 19
States.
Disinfection
By-Prod-
ucts Field
Studies.
35 Water Util-
ities Nation-
wide.
Sample information
(No. of samples)
Finished Water (1,100):
Surface Water
Ground Water
Drinking Water from:
Ground Water
Serving >1 0,000 (327).
Serving <1 0,000 (61 8)
Sampled at the Plant
(4,439).
Finished Water:
At the Plant (73)
In Distribution System
(56)
Samples from Clearwell Ef-
fluent for 4 Quarters.
Concentration (ug/L)
Range
Max. 59.
Max. 63 ....
<0.2-41.
<0.2-41
Max. 63 ....
Mean
35.0
36.6
38.5
39.9
3.0
4.9
6.6
Median
1.5
<0.5
0.8
<0.5
0.7
0
1.7
2.0
3.4
3.6
2.6-4.5 5
Other
Positive Detections:
67% 4
34%"
Positive Detections:
"56%
4 13%
90th Percentile:
9.2
5.6
Positive Detections:
92%
93%
75% of Data was Below
9.1 jig/L
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Mean of the positives.
4 Of systems sampled.
5 Range of medians for individual quarters.
AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
CWSS: Community Water Supply Survey.
GWSS: Ground Water Supply Survey.
RWS: Rural Water Survey.
EPA: Environmental Protection Agency.
No information is available
concerning the occurrence of DBCM in
food in the United States. The Food and
Drug Administration (FDA) does not
analyze for DBCM in foods. However,
there are several uses of chlorine in food
production, such as disinfection of
chicken in poultry plants and the
superchlorination of water at soda and
beer bottling plants (Borum, 1991).
Therefore, the possibility exists for
dietary exposure from the by-products
of chlorination in food products.
Based on information obtained
through a literature review, Howard
(1990) estimated the average daily
intake of DBCM from air using an
inhalation rate of 20m3/day. Assuming
a range of 8.25 to 425 ng/m3 the
exposure may be as low as 0.17 ug/day
or as high as 8.5ug/day.
Although some uses of chlorine have
been identified in the food production/
food processing area, monitoring data
are not available to adequately
characterize the magnitude or frequency
of potential exposure to DBCM.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38701
Additionally, preliminary discussions
with FDA suggest that there are not
approved uses for chlorine in most
foods consumed in the typical diet.
Based on the limited number of food
groups that are believed to contain
chlorinated chemicals and that there are
not significant levels expected in
ambient or indoor air, EPA assumes that
drinking water is the predominant
source of DBCM intake. Characterization
of food and air exposure are issues
currently under review. EPA, therefore,
is proposing to regulate DBCM in
drinking water with an RSC value at the
ceiling level of 80 percent. EPA requests
any additional data on known
concentration of DBCM in drinking
water, food, and air.
Health Effects. The health effects
information in this section is
summarized from the Drinking Water
Health Criteria Document for
Trihalomethanes (USEPA, 1994d).
Studies mentioned in this section are
summarized in the criteria document.
Studies indicated that gastrointestinal
absorption of DBCM is high in animals.
No studies were located regarding
DBCM in humans or animals following
inhalation or dermal exposure. Based on
the physical-chemical properties of
DBCM, and by analogy with the
structurally-related halomethanes such
as chloroform, it is expected that the
inhalation and dermal absorption could
be significant for DBCM.
The LDjo values in mice and rats
range from 800 to 1,200 mg/kg. Under
both in vivo and in vitro conditions,
several active metabolic intermediates
(e.g. dihalocarbonyl,
bromochloromethyl radicals) can be
produced via oxidation or reduction by
microsomal preparations.
Environmental studies suggest that
these active metabolic intermediates are
responsible for the hepatic and renal,
toxicity, and possibly carcinogenicity, of
the parent compound. Animal studies
suggest that the extent of DBCM
metabolism varies with species and sex.
The retention of DBCM in organs after
dosing was small and relatively higher
concentrations were found in stomach,
liver and kidneys. Urinary excretion
levels were below 2 percent.
Mammalian bioeffects following oral
exposure to DBCM include effects on
the central nervous system (decreased
operant response), hepatotoxicity,
nephrotoxicity, reproductive toxicity
and possible carcinogenicity. In
experimental mice and rats, DBCM
caused changes in kidney, liver, and
serum enzyme levels, and decreased
body weight. These responses are
discernible in mammals from exposure
to levels of DBCM ranging from 39 to
250 mg/kg; the intensity of response was
dependent upon the dose and the
duration of the exposure. Ataxia and
sedation were observed in mice
receiving a single dose of 500 mg/kg
DBCM.
Developmental and reproductive
toxicity of DBCM was investigated in
rodents. A multi-generation
reproductive study of mice treated with
)in drinking water showed maternal
toxicity (weight loss, liver pathological
changes) and fetal toxicity (decreased
pup weight & viability). The study
identified a NOAEL of 17 mg/kg/day
and a LOAEL of 171 mg/kg/day.
The National Toxicology Program
(NTP, 1985) evaluated the subchronic
and chronic toxicity of DBCM in F344/
N rats and B6C3Fi mice. In this study
corn oil is used as the gavage vehicle.
The chronic data indicated that doses of
40 and 50 mg/kg/day produced
histopathological lesions in the liver of
rats and mice, respectively. However,
the chronic studies did not identify a
reliable NOAEL. The subchronic study
identified both a LOAEL and a NOAEL
for hepatotoxicity, and was used to
calculate the RfD of 0.02 mg/kg/d.
In the NTP subchronic study, DBCM
in corn oil was administered to Fischer
344/N rats and B6C3Fi mice via gavage
at dose levels of 0,15, 30, 60,125 or 250
mg/kg/day, 5 days a week for 13 weeks.
Following treatment, survival, body
weight, clinical signs, histopathology
and gross pathology were evaluated.
Final body weights of rats that received
250 mg/kg/day were depressed 47% for
males and 25% for females. Kidney and
liver toxicity was observed in male and
female rats and male mice at 250 mg/kg/
day. A dose-dependent increase in
hepatic vacuolation was observed in
male rats. Based on this hepatic effect,
the NOAEL and LOAEL in rats were 30
and 60 mg/kg/day, respectively.
Several studies on the mutagenicity
potential of DBCM have reported
inconclusive results. Studies on the in
vitro genotoxicity of DBCM reported
mixed results in bacteria Salmonella
typhimurium strains and yeasts. DBCM
produced sister chromatid exchange
uncultured human lymphocytes and
Chinese hamster ovary cells (without
activation). An increased frequency of
sister chromatid exchange was observed
in mouse bone marrow cells from mice
dosed orally, but not via the
intraperitoneal route.
The carcinogenicity of DBCM was
reported in a NTP (1985) chronic animal
study. In this study DBCM in corn oil
was administered via gavage to groups
of male and female F344/N rats at doses
of 0, 40 or 80 mg/kg/day, 5 days/week
for 104 weeks; and groups of male and
female mice at 0, 50 or 100 mg/kg/day,
5 days/week for 105 weeks.
Administration of DBCM showed a
significant increase in the incidence of
hepatocellular adenomas in high-dose
female mice (vehicle control, 2/50; low
dose, 4/49; high dose, 11/50) and
combined incidence of hepatocellular
adenomas or carcinomas (6/50,10/49,
19/50). In high-dose male mice,
administration of DBCM showed a
significant increase in the incidence of
hepatocellular carcinomas (10/50, -, 19/
50); however, the combined incidence
of hepatocellular adenomas or
carcinomas was only marginally
increased (23/50, -, 27/50).
Administration of DBCM did not result
in increased incidence of tumors in
treated rats.
Using the linearized multistage
model, EPA derived a cancer potency
factor of 8.4 x 10-2 (mg/kg/day)-' (IRIS,
1990). The derivation was based on the
tumor incidence of the hepatocellular
adenomas or carcinomas in the female
mice reported in the 1985 NTP study.
Due to the possible role of the corn oil
vehicle in induction of hepatic tumors
as reported in studies on chloroform,
some uncertainty exists regarding the
relevance of this derived cancer potency
factor to exposure via drinking water.
However, the only tumor data currently
available on DBCM are for liver tumors
in mice. Until future studies can
provide additional data, EPA considers
this cancer potency factor valid for
potential carcinogenic risk
quantification for DBCM.
EPA has classified DBCM in Group C,
possible human carcinogen, based on
the limited evidence of carcinogenicity
in animals (only in one species) and
inadequate evidence of carcinogenicity
in humans. The International Agency
for Research on Cancer (IARC) has
classified DBCM as a Group 3'
carcinogen: agent not classifiable as to
its carcinogenicity to humans.
Using EPA's three-category approach
for establishing MCLG, DBCM is placed
in Category II since there is limited
evidence for carcinogenicity via
drinking water considering weight of
evidence, potency, pharmacokinetics,
and exposure. As a Category II chemical,
EPA proposes to follow the first option
and set the MCLG for DBCM on
noncarcinogenic endpoints (the RfD)
with the application of an additional
safety factor to account for possible
carcinogenicity. An RfD of 0.02 mg/kg/
day has been derived from the NOAEL
of 30 mg/kg/d, adjusted for dosing 5
days per week and divided by an
uncertainty factor of 1,000. This factor
is appropriate for use of a NOAEL
derived from a subchronic animal study.
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38702
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
EPA is proposing an MCLG of 0.06 possible carcinogenicity is used to
mg/L for DBCM based on liver toxicity calculate the MCLG along with an
and possible carcinogenicity. An assumed drinking water contribution of
additional safety factor of 10 for 80 percent of total exposure.
MCLG=;30mg/kg/dx5/7x70kx0.8=()06mg/L
1.000x2L/dxlO
EPA requests comments on the basis
for the proposed MCLG for DBCM, the
RSC of 80%, and the cancer
classification for DBCM.
8. Bromoform
Bromoform (tribromomethane, CAS
No. 75-25-2) is a nonflammable,
colorless liquid with a sweet odor and
a relatively high vapor pressure (5.6
mmHg at 25 °C). Bromoform is
moderately soluble in water (3.2 gm/L at
30 °C) and soluble in organic solvents
(log octanol/water partition coefficient
of 2.38). Bromoform is not currently
produced commercially in the United
States. The chemical has only limited
uses as a laboratory agent and as a fluid
for mineral ore separation. The
principle source of bromoform in
drinking water is the chemical
interaction of chlorine with commonly
present organic matter and bromide ion.
Degradation of bromoform is not well
studied, but probably involves
photooxidation. The estimated
atmospheric half-life of bromoform is
one to two months. Volatilization is the
principle mechanism for removal of
bromoform from rivers and streams
(half-life of hours to weeks). Studies
reported that bromoform adsorbs poorly
to sediments and soils. No experimental
studies were located regarding the
bioconcentration of bromoform. Based
on the data from a few structurally
similar chemicals, the potential for
bromoform to be bioconcentrated by
aquatic organisms is low.
Biodegradation of bromoform is limited
under aerobic conditions but more
extensive under anaerobic conditions.
Occurrence and Human Exposure.
Bromoform occurs in public water
systems that chlorinate water containing
humic and fulvic acids and bromine
that can enter source waters through
natural and anthropogenic means.
Several water quality factors affect the
formation of bromoform including Total
Organic Carbon (TOG), pH, and
temperature. Different treatment
practices can reduce the level of
bromoform. These include the use of
chloride dioxide, chloramination, and
ozonation prior to chloramination.
Table V-9 presents occurrence
information available for bromoform in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). The table lists
six surveys conducted by Federal and
private agencies. Median concentrations
of bromoform in drinking water appear
to range from <0.2 to 0.57 ug/L for
surface water supplies and <0.5 ug/L for
ground- water supplies. The lower
bound median concentration for
bromoform in surface water supplies is
biased to the low side because
concentrations in this survey were
measured in the plant effluent; the
formation of bromoform would be
expected to increase in the distribution
in systems using chlorine as their
residual disinfectant.
TABLE V-9.—SUMMARY OF OCCURRENCE DATA FOR BROMOFORM
Occurrence of bromoform in drinking water
Survey (year) 1
CWSS (1978) Brass et al.,
1981.
RWS (1978-1980) Brass,
1981.
GWSS (1980-1981)
Westrick et al. 1983.
EPA, 1991a2 (1984-1991) .
EPA, 199202(1987-1989) .
Location
450 Systems
>600 Rural
Systems
(>2,ooo
House-
holds).
945 GW Sys-
tems: (466
Random
and 479
Nonran-
dom).
Unregulated
Contami-
nant Data
Base —
Treatment
Facilities
from 19
States.
Disinfection
By-Prod-
ucts Field
Studies.
Sample information (No. of
samples)
Finished Water (1,1 00):
Surface Water
Ground Water
Drinking Water from:
Surface Water
Ground Water
Serving >1 0,000 (327).
Serving <10,000 (618)
Sampled at the Plants
(1,409).
Finished Water:
At the Plant (73)
In Distr. System (56) •
Concentration (ug/L)
Range
Max. 68.
Max. 110 ..
<0.2-6.7.
<0.2-10 ....
Mean
32.1
311
38.7
312
2.5
0.7
1.0
Median
<1.0
<0.5
<0.5
<0.5
0
0
1
<0.2
<0.2
Other
Positive Detections:
13%4
26%4
Positive Detections:
18%",
12%4
90th Percentile:
8.3
4.1
Positive Detections:
45%
48%
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38703
TABLE V-9.—SUMMARY OF OCCURRENCE DATA FOR BROMOFORM—Continued
Occurrence of bromoform in drinking water
Survey (year) 1
EPA/AMWA/CDHS2 (1988-
1989) Krasner et. al.,
1989b.
Location
35 Water Util-
ities Nation-
wide.
Sample information (No. of
samples)
Samples from Clean/veil Ef-
fluent for 4 Quarters.
Concentration (ng/L)
Range
Max. 72 ....
Mean
Median
0.33-0.885
0.57
Other
75% of Data was Below
2.8
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Mean of the positives.
4 Of systems sampled.
6 Range of medians for individual quarters.
AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
CWSS: Community Water Supply Survey.
GWSS: Ground Water Supply Survey.
RWS: Rural Water Survey.
EPA: Environmental Protection Agency. ,
No information is available
concerning the occurrence of
bromoform in food in the United States.
The Food and Drug Administration
(FDA) does not analyze for bromoform
in foods. However, there are several
uses of chlorine in food production,
such as disinfection of chicken in
poultry plants and the
superchlorination of water at soda and
beer bottling plants (Borum, 1991).
Therefore, the possibility exists for
dietary exposure from the by-products
of chlorination in food products.
Bromoform is usually found in
ambient air at low concentrations. One
study reported ambient air
concentrations from several urban
locations across the U.S. The overall
mean concentration of positive samples
was found to be 4.15 ng/m3 and the
maximum level was 71 ng/m3
(Brodzinsky and Singh, 1983 in USEPA,
1991b). Although the data are limited
for bromoform, an inhalation intake
could be estimated using the mean and
maximum values from the Brodzinsky
and Singh (1983) study, indicating a
possible range of 0.08 to 1.4 u,g/d.
Based on the limited number of food
groups that are believed to contain
bromoform and that significant levels
are not expected in ambient or indoor
air, EPA is assuming that drinking water
is the predominant source of bromoform
intake. Characterization of food and air
exposures are issues currently under
review. The EPA requests any
additional data on known
concentrations of bromoform in
drinking water, food, and air.
Health Effects. The health effects
information in this section is
summarized from the draft Drinking
Water Health Criteria Document for
Trihalomethanes (USEPA, 1994d) and
the draft Drinking Water Health
Advisory for Brominated
Trihalomethanes (USEPA, 1991b).
Studies mentioned in this section are
summarized in the criteria document or
health advisory.
Studies have indicated that
gastrointestinal absorption of
bromoform is high in humans and
animals. No studies were located
regarding bromoform in humans or
animals following inhalation or dermal
exposure. Based on the physical-
chemical properties of bromoform, and
by analogy with the structurally-related
halomethanes such as chloroform, it is
expected that both inhalation and
dermal absorption could be significant
for bromoform.
Bromoform was used as a sedative for
children with whooping cough. Based
on clinical observations of accidental
overdose cases, the estimated lethal
dose for a 10- to 20-kg child is about 300
mg/kg. The clinical signs in fatal cases
were central nervous system (CNS)
depression followed by respiratory
failure.
The LDso values in mice and rats have
been reported in the range of 1,147-
1550 mg/kg. Under both in vivo and in
vitro conditions, several active
metabolic intermediates (e.g.,
dibromocarbonyl, dibromomethyl
radicals) are produced via oxidation or
reduction by microsomal preparations.
Experimental studies suggested that
these active metabolic intermediates are
responsible for hepatic and renal
toxicity and possibly, carcinogenicity, of
the parent compound. Animal studies
suggest that the extent of bromoform
metabolism varies with species and sex.
The retention of bromoform in organs
after dosing was small; relatively higher
concentrations were found in tissues
with higher lipophilic content. Urinary
excretion levels were below 5 percent.
Mammalian bioeffects following
exposure to bromoform include effects
on the central nervous system (CNS),
hepatotoxicity, nephrotoxicity, and
carcinogenicity. Bromoform causes CNS
depression in humans. The reported
LOAEL which results in mild sedation
in humans is 54 mg/kg. In experimental
mice and rats, bromoform caused
changes in kidney, liver, serum enzyme
levels, decrease of body weight, and
decreased operant response. These
responses are discernible in mammals
from exposure to levels of bromoform
ranging from 50 to 250 mg/kg; the
intensity of response was dependent
upon the dose and the duration of the
exposure. Ataxia and sedation were
noted in mice receiving a single dose of
1,000 mg/kg bromoform or 600 .mg/kg
for 14 days.
Few studies have investigated
developmental and reproductive
toxicity of bromoform in rodents. A
developmental study in rats showed no
fetal variations in a group fed with 50
mg/kg/day. An increased incidence of
minor anomalies was noted at doses of
100 and 200 mg/kg/day. No maternal
toxicity in rats was observed. One
detailed reproductive toxicity study
reported no apparent effects on fertility
and reproduction when male and female
rats were administered bromoform via
gavage in corn oil at doses up to 200
mg/kg/day.
EPA used subchronic data from an
oral study (NTP, 1989) to calculate the
RfD. In this study, bromoform was
administered to rats in corn oil via
gavage at dose levels of 0,12,25, 50,
100 or 200 mg/kg/day 5 days a week for
13 weeks. Based on the observation of
hepatocellular vacuolization in treated
male rats, a NOAEL of 25 mg/kg/day
was established. An RfD of 0.02 mg/kg/
day has been derived from this NOAEL
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by the application of an uncertainty
factor of 1,000, in accordance with EPA
guidelines for use of a NOAEL from a
suhchronic study.
A number of studies investigated the
mutagenicity potential of bromoform.
Studies on the in vitro genotoxicity of
bromoform reported mixed results in
bacterial Salmonella typhimurium
strains. Bromoform produced mutations
in cultured mouse lymphoma cells and
sister chromatid exchange in human
lymphocytes. Under in vivo condition
bromoform induced sister chromatid
exchange, and chromosomal aberration
and micronucleus in mouse bone
marrow cells. Overall, most studies
yielded positive results and evidence of
mutagenicity for bromoform is
considered adequate.
The National Toxicology Program
(NTP, 1989) conducted a chronic animal
study to investigate the carcinogenicity
of bromoform. In this study bromoform
was administered in corn oil via gavage
to F344/N rats (50/sex/group) at doses of
0,100 or 200 mg/kg/day, 5 days/week
for 105 weeks. An evaluation of the
study results showed that adenomatous
polyps or adenocarcinoma (combined)
of the large intestine (colon or rectum)
were induced in three male rats (vehicle
control, 0/50; low dose, 0/50; high dose,
3/50) and in nine female rats (0/50,1/
50,8/50). The increase was considered
to be significant since these tumors are
rare in control animals. Neoplastic
lesions in the large intestine in female
rats reported in the NTP study were
used to estimate the carcinogenic
potency of bromoform. EPA derived a
cancer potency factor of 7.9 x 10 ~3 (mg/
kg/day)"' using the linearized
multistage model (IRIS, 1990).
Assuming a daily consumption of two
liters of drinking water and an average
human body weight of 70 kg, the 95%
upper bound limit lifetime cancer risks
of lO"6,10~s and 10~4 are associated
with concentrations of bromoform in
drinking water of 4,40 and 400 ug/L,
respectively.
EPA classified bromoform in Group
B2, probable human carcinogen, based
on the sufficient evidence of
carcinogenicity in animals and
inadequate evidence of carcinogenicity
in humans. The International Agency
for Research on Cancer (IARC) has
recently classified bromoform in Group
3: agent not classifiable as to its
carcinogenicity to humans (IARC, 1991).
IARC determined that there was limited
evidence of carcinogenicity in animals,
in contrast to EPA's judgment that there
is sufficient evidence in laboratory
animals. EPA requests comments on the
different viewpoints between IARC and
EPA regarding bromoform's
carcinogenic potential.
Using EPA's three-category approach
for establishing MCLG, bromoform is
placed in Category I since there is
sufficient evidence for carcinogenicity
from drinking water considering weight
of evidence, potency, pharmacokinetics,
and exposure. Thus, EPA is proposing
an MCLG of zero for this contaminant.
EPA requests comments on the basis for
the proposed MCLG for bromoform.
9. Dichloroacetic Acid
Chlorination of water containing
organic material (humic, fulvic acids)
results in the generation of many
organic compounds, including
dichloroacetic acid (DCA) (CAS. No. 79-
43-6), a nonvolatile compound.
Though DCA is generally a concern
due to its occurrence in chlorinated
drinking water, it is also used as a
chemical intermediate, and an
ingredient in pharmaceuticals and
medicine. Previously, DCA was used
experimentally to treat diabetes and
hypercholesterolemia in human
patients. In addition, DCA was used as
an agricultural fungicide and topical
astringent. It has also been extensively
investigated for potential therapeutic
use as a hypoglycemic, hypolactemic
and hypolipidemic agent.
Occurrence and Human Exposure.
DCA has been found to occur as a
disinfection by-product in public water
systems that chlorinate water containing
humic and fulvic acids.
Table V—10 presents occurrence
information available for DCA in
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). Median
concentrations of DCA in drinking water
were found to range from 6.4 to 17 ug/
L. The lower bound median
concentration for DCA in surface water
supplies is biased to the low side
because concentrations in this survey
were measured in the plant effluent; the
formation of DCA would be expected to
increase in the distribution system in
systems using chlorine as their residual
disinfectant.
TABLE V-10.—SUMMARY OF OCCURRENCE DATA FOR DICHLOROACETIC ACID
Occurence of dichloroacetic acid in drinking water
Survey (year) 1
EPA, 1992b2 (1987-
1989).
EPA/AMWA/CDHS2
(1988-1989) Krasner
et al., 1989b.
Location
Disinfection By-
products
Field Studies.
35 Water Utili-
ties Nation-
wide.
Sample information
(No. of samples)
Finished Water:
At the Plant (72)
In the Distr. System (56)
Samples from Clean/veil Effluent
for 4 Quarters.
Concentration (ug/L)
Range
<0.4-61
<0.4-75
<0.6-*6
Mean
18
21
Median
16
17
35.0-7.3
6.4
Other
Positive Detections:
93%
96%
75% of Data was
Below 12 ng/L DL
= 0.6 ug/L
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Range of medians for individual quarters.
AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.
Based on the above data, a range of
exposure to DCA from drinking water
can be calculated using a consumption
rate of 2 liters per day. The expected
median exposure from drinking water
would range from 13 to 34 u,g/day, using
these data sets.
No information is available
concerning the occurrence of DCA in
food and ambient or indoor air in the
United States. The Food and Drug
Administration (FDA) does not analyze
for DCA in foods. However, there are
several uses of chlorine in food
production, such as the disinfection of
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38705
chicken in poultry plants and the
superchlorination of water at soda and
heer bottling plants. Therefore, the
possibility exists for dietary exposure
from the by-products of chlorination in
food products. However, monitoring
data are not available to characterize
adequately the magnitude or frequency
of potential DCA exposure from diet.
Additionally, preliminary discussions
with FDA suggest that there are not
approved uses for chlorine in most
foods consumed in the typical diet.
Similarly, EPA's Office of Air and
Radiation is not currently sampling for
DCA in air (Borum, 1991). Little
exposure to DCA from air is expected
since DCA is nonvolatile.
Since only a limited number of food
groups are expected to contain
chlorinated chemicals and no
significant DCA levels are expected in
ambient or indoor air, EPA believes that
drinking water is the predominant
source of DCA intake. Characterization
of the potential exposures from food and
air are issues currently under review.
EPA requests any additional data on
known concentrations of DCA in
drinking water, food, and air.
Health Effects. The health effects
information in this section is
summarized from the draft Drinking
Water Health Criteria Document for
Chlorinated Acetic Acids, Alcohols,
Aldehydes and Ketones (USEPA,
1994e). Studies mentioned in this
section are summarized in the criteria
document.
Humans treated with DCA for 6 to 7
days at 43 to 57 mg/kg/day have
experienced mild sedation, reduced
blood glucose, reduced plasma lactate,
reduced plasma cholesterol levels, and
reduced triglyceride levels. At the same
time, the DCA treatment depressed uric
acid excretion, resulting in elevated
serum uric acid levels.
A longer term study in two young
men receiving 50 mg/kg for 5 weeks up
to 16 weeks, indicated that DCA
significantly reduces serum cholesterol
levels and blood glucose, and causes
peripheral neuropathy in the facial,
finger, leg and foot muscles.
Estimates of acute oral LDSO values
range from 2,800 to 4,500 mg/kg in rats
and up to 5,500 mg/kg in mice. Short-
term studies in dogs and rats indicate an
effect on intermediary metabolism, as
demonstrated by decreases in blood
lactate and pyruvate. Exposures to DCA
up to 3 months in dogs and rats result
in a variety of adverse effects including
effects to the neurological and
reproductive systems. These effects are
seen above 100 mg/kg/day in dogs and
rats.
Studies on the toxicokinetics of DCA
indicate that absorption is rapid and
that DCA is quickly distributed to the
liver and muscles in the rat. DCA is
metabolized to glyoxylate which in turn
is metabolized to oxalate. Although
there are few studies regarding the
excretion of DCA, studies in which rats,
dogs and humans received intravenous
injections of DCA indicated that the
half-life of DCA in human blood plasma
is much shorter than in rats or dogs.
Urinary excretion of DCA was negligible
after 8 hours. Total excretion of DCA
was less than 1% of total dose.
A drinking water study by Bull et al.
(1990) reported a dose-related increase
in hepatic effects in mice that received
DCA at 270 mg/kg/day for 37 weeks and
at 300 mg/kg/day for 52 weeks. Adverse
effects included enlarged livers, marked
cytomegaly with massive accumulation
of glycogen in hepatocyte and focal
necrosis. The NOAEL for this study was
137 mg/kg/day for 52 weeks.
DeAngeio et al. (1991) conducted a
drinking water study in which mice
received DCA at levels of 7.6, 77,410,
and 486 mg/kg/day for 60 or 75 weeks.
While this study was intended as an
assessment of carcinogenicity, other
systemic effects were measured. This
study concluded that levels at 77 mg/kg/
day and above caused an extreme
increase of relative liver weights and a
significant increase in neoplasia at
levels of 410 mg/kg/day and above. This
study indicates a NOAEL of 7.6 mg/kg/
day for noncancer liver effects.
Based on the available data, DCA does
not appear to be a potent mutagen.
Studies in bacteria have indicated that
DCA did not induce mutation or
activate repair activity. Two studies
have shown some potential for
mutagenicity but these results have not
been reproducible.
DCA appears to induce both
reproductive and developmental
toxicity. Damage and atrophy to sexual
organs has been reported in male rats
and dogs exposed to levels from 50 mg/
kg/day to 2000 mg/kg/day for up 3
months. Malformation of the
cardiovascular system has been
observed in rats exposed to 140 mg/kg/
day DCA from day 6 to 16 of pregnancy.
A 90-day dog study was selected to
determine the RfD for DCA (Cicmanec et
al., 1991). In this study, four month old
beagle dogs (5/sex/group) were
administered gelatin capsules
containing 0,12.5, 39.5, or 72 mg/kg
DCA/day for 90 days. Dogs were
observed for clinical signs of toxicity;
blood samples were collected for
hematology and serum chemistry
analysis. Clinical signs included
diarrhea and dyspnea in the mid and
high dose groups. Dyspnea was evident
at 45 days and became more severe with
continued exposure leading to general
depression and decreased activity by
day 90. Hindlimb paralysis was
observed in 3 dogs in the high dose
group. Other effects included
conjunctivitis, weight loss, reduced food
and water consumption, pneumonia,
decreased liver weights, and elevated
kidney weights in the dosed animals.
Histopathology revealed toxic effects in
liver, testis, and brain of the treated
dogs. A NOAEL was not identified in
this study. The lowest dose tested, 12.5
mg/kg/d, was considered a LOAEL. An
uncertainty factor of 3,000 was applied
in accordance with EPA guidelines to
account for use of a LOAEL from a less-
than-lifetime animal study in which
frank effects were noted as the critical
effect. The resulting RfD is 0.004 mg/kg/
d.
Several studies indicate that DCA is a
carcinogen in both mice and rats
exposed via drinking water lifetime
studies. These studies indicate that DCA
induces liver tumors. In one study with
male B6F3Fi mice, exposure to DCA at
0.5 g/L and 3.5 g/L for 104 weeks
resulted in tumor formation in exposed
animals at 75% (18/24) and 100% (24/
24) respectively. In female mice exposed
for 104 weeks to DCA at the same levels,
tumor prevalence was 20% and 100%,
respectively. In male rats exposed to
0.05, 0.5 or 5 g/L DCA for 104 weeks,
tumor prevalence increased to 22% in
the highest dose. No tumors were seen
at the lower doses. However, at 0.5 g/L,
there was an increase in the prevalence
of proliferation of liver lesions. Some of
these lesions are likely to progress into
malignant tumors.
EPA has classified DCA in Group B2:
probable human carcinogen, based on
positive carcinogenic findings in two
animal species exposed to DCA in
drinking water. A quantitative risk
estimate has not yet been determined for
DCA.
Following a Category I approach, EPA
is proposing an MCLG for DCA of zero
based on the strong evidence of
carcinogenicity via drinking water. EPA
requests comments on the basis for the
proposed MCLG for DCA in drinking
water and the cancer classification of
Group B2.
10. Trichloroacetic Acid.
Trichloroacetic acid (TCA; CAS No.
76-03-9) is also a major by-product of
chlorinated drinking water.
Chlorination of source waters
containing organic materials (humic,
fulvic acids) results in the generation of.
organic compounds such as TCA.
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TCA is also sold as a pre-emergence
herbicide. It is used in the laboratory to
precipitate proteins and as a reagent for
synthetic medicinal products. It is
applied medically as a peeling agent for
damaged skin, cervical dysplasia and
removal of tatoos.
Occurrence and Human Exposure.
TCA occurs in public water systems that
chlorinate water containing humic and
fulvic acids.
Table V-ll presents the most recent
and comprehensive occurrence
information available for TCA hi
drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). Median
concentrations of TCA acid in drinking
water were found to range from 5.5 to
15 jig/L. The lower bound median
concentration for TCA in surface water
supplies is biased to the low side
because concentrations in this survey
were measured in the plant effluent; the
formation of TCA would be expected to
increase in the distribution system in
systems using chlorine as their residual
disinfectant. Based on the available data
sets, and assuming a drinking water
consumption rate of 2 L/day, median
exposures from drinking water would
range from 11 to 30 p.g/day.
TABLE V-11 .—SUMMARY OF OCCURRENCE DATA FOR TRICHLOROACETIC ACID
Occurrence of trichloroacetic acid in drinking water
Survey (year) 1
EPA, 1992b2 (1987-
1989).
EPA/AMWA/CDHS2
(1988-1989) Krasner et
al., 1989D.
Location
Disinfection By-
products Field
Studies.
35 Water Utilities
Nationwide.
Sample information
(No. of samples)
Finished Water:
At the Plant (72)
Distribution System
(56)
Samples from Clearwell
Effluent for 4 Quarters.
Concentration ((ig/L)
Range
<0.4-54
<0.4-77
Mean
13
15
Median
11
15
4.0-5.8
5.5
Other
Positive Detections:
90%
91%
75% of Data was Below
15.3(ig/LDL = 0.6
1 Dates .indicate period of sample collection.
2 May not be representative of national occurrence.
3 Range of medians for individual quarters.
AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.
No information is available
concerning the occurrence of TCA in
food and ambient or indoor air in the
United States. The Food and Drug
Administration (FDA) does not analyze
for TCA in foods. However, there are
several uses of chlorine in food
production, such as the disinfection of
chicken in poultry plants and the
superchlorination of water at soda and
beer bottling plants. Therefore, the
possibility exists for dietary exposure
from the by-products of chlorination in
food products. Also, TCA has limited
use as a herbicide. However, monitoring
data are not available to characterize
adequately the magnitude or frequency
of potential TCA exposure from diet.
Similarly, EPA's Office of Air and
Radiation is not currently measuring for
TCA in air (Borum, 1991). The exposure
from air for TCA is probably not a large
source since TCA is nonvolatile.
Since only a limited number of food
groups are expected to contain
chlorinated chemicals and no
significant TCA levels are expected in
ambient or indoor air, EPA assumes that
drinking water is the predominant
source of TCA intake. Characterization
of potential exposures from food and air
are issues currently under review. EPA
is, therefore, proposing to regulate TCA
in drinking water with a relative source
contribution (RSC) value at the ceiling
level of 80 percent. EPA requests any
additional data on known
concentrations of TCA in drinking
water, food, and air.
Health Effects. The health effects
information in this section is
summarized from the Drinking Water
Health Criteria Document for
Chlorinated Acetic Acids, Alcohols,
Aldehydes and Ketones (USEPA,
1994e). Studies mentioned in this
section are summarized in the criteria
document.
Estimates of acute and LDso values for
TCA range from 3.3 to 5 g/kg in rats to
4.97 g/kg in mice. Short-term studies,
up to 30 days, in rats demonstrate few
effects other than decreased weight gain
after administration of 240-312 mg/kg/
day.
Few studies on toxicokinetics of TCA
were located; however, a human study
and a dog study show TCA to respond
pharmacokinetically similarly to DCA.
The response indicates a rapid
absorption, distribution to the liver and
excretion primarily through the urine.
The two studies indicate that TCA is
readily absorbed from all sections of the
intestine and that the urinary bladder
may be significant in the absorption of
TCA. TCA is also a major metabolite of
trichloroethylene.
Longer-term studies in animals
indicate that TCA affects the liver,
kidney and spleen by altering weights,
focal hepatocellular enlargement,
intracellular swelling, glycogen
accumulation, focal necrosis, an
accumulation of lipofuscin, and
ultimately tumor generation in mice.
In a study by Mather et al. (1990),
male rats received TCA in their drinking
water at 0,4.1, 36.5 or 355 mg/kg/day.
The high dose resulted in spleen weight
reduction and increased relative liver
and kidney weights. Hepatic
peroxisomal B-oxidation activity was
increased. Liver effects at the high dose
included focal hepatocellular
enlargement, intracellular swelling and
glycogen accumulation. The NOAEL for
this study was 36.5 mg/kg/day.
Parnell et al. (1988) exposed male rats
to TCA in their drinking water at 2.89,
29.6 or 277 mg/kg/day for up to one
year. No significant changes were
detected in body weight, organ weight
or histopathology over the study
duration. This study identified a
NOAEL as the highest dose tested, 277
BuH et ai. (1990) investigated the
effects of TCA on liver lesions and
tumor induction in male and female
B6C3Fi mice. Mice received TCA in
their drinking water at 0,1 or 2 g/L (164
or 329 mg/kg/day) for 37 or 52 weeks.
Dose-related increases in relative and
absolute liver weights were seen in
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38707
females and males exposed to 1 and 2
g/L for 52 weeks. Small increases in
liver cell size, accumulation of
lipofuscin and focal necrosis were also
seen. A LOAEL of 164 mg/kg/day (1 g/
L) was identified.
Several studies show that TCA can
produce developmental malformations
in fetal Long Evans rats, particularly in
the cardiovascular system. Teratogenic
effects were observed at the lowest dose
tested, 330 mg/kg/day.
With regard to mutagenicity tests,
TCA was negative in Ames mutagenicity
tests using Salmonella strain TA100, but
was positive for bone marrow
chromosomal aberrations and sperm
abnormalities in mice. It also induced
single-strand DNA breaks in rats and
mice exposed by gavage.
TCA has induced hepatocellular
carcinomas in two tests with B6C3Fi
mice, one of 52 weeks and another of
104 weeks. In the Bull et al. (1990)
study, a dose-related increase in the
incidence of hepatoproliferative lesions
was observed in male B6C3F] mice
exposed to 1 or 2 g/L for 52 weeks. An
increase in hepatocellular carcinomas
was observed in males at both dose
levels. Carcinomas were not found in
females.
DeAngelo et al. (1991) administered
mice and rats with TCA over their
lifetime. Male and female B6C3Fi mice
were exposed to 4.5 g/L TCA for 104
weeks. Male mice at 4.5 g/L TCA had a
tumor prevalence of 86.7%. Female
mice appeared to be less sensitive to
TCA than males: 60% prevalence over
a 104-week exposure to 4.5 g/L. At 104
weeks, 0.5 g/L TCA did not result in a
significant increase in tumors. In a
preliminary study of 60 weeks exposure
to 0.05, 0.5 and 5 g/L, no significant
additional increase in tumors was seen
at 0.05 g/L, but tumor prevalence was
37.9% and 55.2% at 0.5 and 5 g/L,
respectively.
F344 male rats administered TCA
over a lifetime at 0.05 to 5 g/L did not
produce a significant increase in
carcinqgenicity.
EPA has placed TCA in Group C:
possible human carcinogen. Group C is
for those chemicals which show limited
evidence of carcinogenicity in animals
in the absence of human data.
EPA is following a Category II
approach for setting an MCLG for TCA.
The developmental toxicity study by
Smith et al. (1989) has been selected to
serve as the basis for the RfD and MCLG.
In this developmental study, pregnant
Long-Evans rats (207dose) were
administered TCA at doses of 0,330,
800,1,200, or 1,800 mg/kg/d by gavage
during gestation days 6-15. Maternal
body weight was significantly reduced
at doses of 800 mg/kg/d and above.
Maternal spleen and kidney weights
were increased significantly in a dose-
dependent manner. Postimplantation
loss was noted in the three highest dose
groups with a significant decrease in the
number of live fetuses per litter
observed in the two highest dose
groups. Other fetal effects included
decreased fetal weight and crown-rump
length, and malformations of the
cardiovascular system, particularly the
heart. The lowest dose tested, 330 mg/
kg/d, was identified as a LOAEL. A
NOAEL was not identified from this
study.
An RfD of 0.1 mg/kg/day was derived
using the LOAEL of 330 mg/kg/d and an
uncertainty factor of 3,000 to account
for use of a LOAEL and lack of a 2
generation reproductive study.
Adjusting the RfD for a 70 kg adult
drinking 2 L water per day, possible
carcinogenicity and an RSC of 80%, an
MCLG of 0.3 mg/L can be determined.
A,™ /- (33° mg/kg/d) x 70 kg x 0.8
MCLG = - S-S—L - £ - =
3,OOOx2L/dxlO
(rounded)
EPA requests comments on the basis
for the MCLG and the cancer
classification for TCA.
11. Chloral Hydrate
Chlorination of water containing
organic materials (humic, fulvic acids)
results in the generation of organic
compounds such as
trichloroacetaldehyde monohydrate or
chloral hydrate (CH) (CAS No. 302-17-
0).
CH is used as a hypnotic or sedative
drug (i.e., knockout drops) in humans,
including neonates. CH is also used in
the manufacture of DDT.
Occurrence and Human Exposure. CH
has been found to occur as a
disinfection by-product in public water
systems that chlorinate water containing
humic and fulvic acids.
Table V—12 presents occurrence
information available for chloral hydrate
in drinking water. Descriptions of these
surveys and other data are detailed in
"Occurrence Assessment for
Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a). Median
concentrations of chloral hydrate in
drinking water were found to range from
2.1 to 4.4 ng/L.
TABLE V-12.—SUMMARY OF OCCURRENCE DATA FOR CHLORAL HYDRATE
Occurrence of chloral hydrate in drinking water
Survey (Year) 1
EPA, 1992b2 (1987-
1989).
EPA/AMWA/CDHS8
(1988-1 989) Krasneret
al., 1989b.
Location
Disinfection By-
products Field
Studies.
35 Water Utilities
Nationwide.
Sample information
(No. of samples)
Finished Water:
At the Plant (67)
Distribution System
(53)
Samples from Clearwell
Effluent for 4 Quarters.
Concentration (ng/L)
Range
<0.2-25
<0.2-30
Max. 22
Mean
5.0
7.8
Median
2.5
4.4
31. 7-3.0
2.1
Other
Positive Detections:
90%
91%
75% of Data was below
4.1 ng/L4
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
3 Range of medians for individual quarters.
'Detection limit was 0.02 jig/L in the first quarter and 0.1 ng/L thereafter.
AMWA: Association of Metropolitan Water Agencies.
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CDHS: California Department of Health Services.
EPA: Environmental protection Agency.
Based on the available data sets,
median exposures from CH due to
drinking water would range from 3.4 to
8.8 ug/day, based on the consumption of
2 liters per day.
•No information is available
concerning the occurrence of CH in food
and ambient or indoor air in the United
States. The Food and Drug
Administration (FDA) does not analyze
for CH in foods since the analytical
methods for such an evaluation have not
been developed (Borum, 1991).
CH has been used as a sedative of
hypnotic drug (see Health Effects
Section). There are several uses of
chlorine in food production, such as the
disinfection of chicken in poultry plants
and the superchlorination of water at
soda and beer bottling plants. Therefore,
the possibility exists for dietary
exposure from the by-products of
chlorination in food products. However,
monitoring data are not available to
adequately characterize the magnitude
or frequency of potential CH exposure
from the diet. Similarly, EPA's Office of
Air and Radiation is not currently
measuring for CH in air (Borum, 1991).
However, CH from indoor air may
contribute to exposure due to the
volatilization from tap water.
Since only a limited number of food
groups are expected to contain
chlorinated chemicals and no
significant levels are expected in
ambient or indoor air, EPA believes that
drinking water is the predominant
source of CH intake. Characterization of
potential food and air exposures are
issues currently under review. EPA is
therefore, proposing to regulate CH in
drinking water with an RSC value at the
ceiling level of 80 percent. EPA requests
any additional data on known
concentrations of CH in drinking water,
food, and air.
Health Effects. The health effects
information in this section is
summarized from the draft Drinking
Water Health Criteria Document for
Chlorinated Acetic Acids, Alcohols,
Aldehydes and Ketones (USEPA,
1994e). Studies mentioned in this
section are summarized in the criteria
document.
In its use as a sedative or hypnotic
drug in humans, a history of adverse
effects related to CH exposure have been
recorded. The acute and toxic dose to
humans is about 10 g (or 140 nag/kg),
causing severe respiratory depression
and hypertension. Adverse reactions
such as central nervous system
depression and gastrointestinal
disturbances are seen between 0.5 and
1.0 g CH. Cardiac arrhythmias are seen
when patients receive levels between 10
and 20 g (167-333 mg/kg). Chronic use
of CH may result in development of
tolerance, physical dependence, and
addiction.
Estimates of acute oral LDsos in mice
range from 1,265 to 1,400 mg/kg with
central nervous system depression and
inhibition of respiration being the cause
of death. Rats may be more sensitive
than mice with acute oral LDso values
ranging from 285 mg/kg in newborn to
500 mg/kg in adults.
Short-term studies in mice indicate
that the liver is the target of CH toxicity
with changes in liver weight as the
primary effect. NOAELs vary between
14 and 144 mg/kg/day.
Toxicokinetic studies of CH indicate
that absorption is rapid and complete in
dogs and humans. CH is metabolized to
trichloroacetic acid (TCA) and
trichloroethanol. CH is rapidly excreted
primarily through the urine as
trichloroethanol glucuronide and more
slowly as TCA.
Three 90-day studies in mice were
considered by EPA to derive the MCLG
for CH. Each used the same dose levels
(16 or 160 mg/kg/day) in mice. The first
study (Kallman et al., 1984) exposed
groups of 12 male mice to drinking
water containing CH at concentrations
of 70 and 700 mg/L for 90 days. These
concentrations correspond to doses of
15.7 and 160 mg/kg/day. No treatment-
related effects were observed for
mortality, body weight, physical
appearance, behavior, locomotor
activity, learning in repetitive tests of
coordination, response to painful
stimuli, strength, endurance or passive
avoidance learning. Both doses resulted
in a decrease of about 1° in mean body
temperature (p <0.05). The biological
significance of this hypothermic effect is
uncertain.
In the second study, Sanders et al.
(1982) supplied groups of 32 male and
female CD-I mice with CH in deionized
drinking water (70 or 700 mg/L, ,
corresponding to tune-weighted average
doses of approximately 16 mg/kg/day or
160 mg/kg/day, respectively). After 90
days, the liver appeared to be the tissue
most affected. Males appeared to be
more sensitive than females. In males,
there was a dose-related hepatomegaly
and microsome proliferation,
accompanied by small changes in serum
chemistry values for potassium,
cholesterol, and glutathione. Females
did not show hepatomegaly, but did
display changed hepatic microsomal
parameters. Based on hepatomegaly,
this study identifies a LOAEL of 16 mg/
kg/day for CH (the lowest dose tested).
In the third study, Kauffman et al.
(1982) studied the effect of CH on the
immune system. Groups of 13 to 18
male and female CD-I mice were
supplied with water containing 70 or
700 mg/L (corresponding to time-
weighted average doses of
approximately 16 or 160 mg/kg/day,
respectively) for 90 days. In males, no
effects were detected in either humoral
or cell-mediated immunity at either
dose level. In females, exposure to the
high dose (160 mg/kg/day) resulted in
decreased humoral immune function (p
<0.05), but no effects on cell-mediated
immunity were noted. Based on this
study, a NOAEL of 16 mg/kg/day and a
LOAEL of 160 mg/kg/day were
identified.
CH is weakly mutagenic in
Salmonella, yeast and molds. It has also
caused chromosomal aberration in yeast
and nondisjunction of chromosomes
during spermatogenesis.
One study has observed
neurobehavioral effects on mice pups
from female mice receiving CH at 205
mg/kg/day for three weeks prior to
breeding. Exposure of females
continued until pups were weaned at 21
days of age. Pups from the high dose
group (205 mg/kg/day) showed
impaired retention in passive avoidance
learning tasks. This result can be
construed as a developmental effect of
CH.
Two studies on the carcinogenicity of
CH indicate that CH produces mouse
liver tumors. In the earlier study,
Rijhsinghani et al. (1986), B6C3F] mice
given a single oral dose of CH at 5 or
10 mg/kg developed a significant
increase in liver tumors after 92 weeks.
In a later study, Daniel et al. (1992),
reported that male mice, receiving 166
mg/kg/day CH for 104 weeks, showed a
total liver tumor prevalence of 71
percent (17/24). Proliferative liver
lesions recognized and tabulated in this
study included hyperplastic nodules,
hepatocellular adenomas and
hepatocellular carcinomas. No other
studies were located on the
carcinogenicity of CH in other test
species.
Based on the limited evidence of
carcinogenicity in these two studies and
the extensive mutagenicity of CH, EPA
has classified CH in Group C: possible
human carcinogen. The concentrations
associated with a 10~4,10~s, and 10~6
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38709
excess cancer risk are 40 ng/L, 4 u.g/L 90-day study by Sanders et al. (1982) is
and 0.4 ug/L, respectively. . most appropriate to calculate the RfD
EPA is placing CH in Category H for an^i MCLG for CH because the liver
setting an MCLG based on liver toxicity effects observed in this study (i.e.,
and limited evidence of carcinogenicity change to hepatic microsomal
be more severe than the other studies
have indicated at similar dose levels.
From the mouse LOAEL of 16 mg/kg/
day and an uncertainty factor of 10,000
for use of a LOAEL from a less than
from drinking water. EPA believes the
parameters and hepatomegaly) appear to lifetime animal study, an MCLG of 0.04
mg/L is derived.
x ,™ ^ C16 mg/kg/d) x 70 kg x 0.8
MCLG = - & & 2 = 0.04 mg/L (rounded)
10,000 x 2 I/day xl
EPA is proposing to use an extra
safety factor of 1 instead of 10 to
account for possible carcinogenicity
since an uncertainty factor of 10,000 has
already been applied to the RfD. In
addition, the proposed MCLG equals the
10 ~* excess cancer risk. EPA requests
comment on the Category n approach
for setting an MCLG, the extra safety
factor of 1 instead of 10 for a Category
n contaminant, and whether the
endpoint of liver weight increase and
hepatomegaly is a LOAEL or NOAEL
given the lack of histopathology.
12. Bromate
Bromate (CAS #7789-38-0 as sodium
salt) is a white crystal that is very
soluble in water. Bromate may be
formed by the reaction of bromine with
sodium carbonate. Sodium bromate can
be used with sodium bromide to extract
gold from gold ores. Bromate is also
used to clean boilers and in the
oxidation of sulfur and vat dyes. It is
formed in water following disinfection
via ozonation of water containing
bromide ion. In laboratory studies, the
rate and extent of bromate formation
depends on the ozone concentration
used in disinfection, pH and contact
time.
Occurrence and Human Exposure.
Bromide and organobromine
compounds occur in raw waters from
both natural and anthropogenic sources.
Bromide can be oxidized to bromate or
hypobromous acid; however, in the
presence of excess ozone, bromate is the
principal product.
Table V-13 presents occurrence
information available for bromate in
drinking water. Descriptions of this data
are detailed in "Occurrence Assessment
for Disinfectants and Disinfection By-
Products (Phase 6a) in Public Drinking
Water," (USEPA, 1992a_J. Significant
bromate concentrations may occur in
ozonated water with bromide. More
recent occurrence data on bromate and
the influence of bromide concentration
and ozone on bromate formation is
discussed in Section VI of this
preamble.
TABLE V-13.—SUMMARY OF OCCURRENCE DATA FOR BROMATE
Occurrence of bromate in drinking water
Survey (year) 1
McGuire et al., 19902
EPA, 1992b* (1987-
1991).
Location
MWD Pilot Plant
Studies.
Disinfection By-
products Field
Studies.
Sample information (No.
of samples)
Ozonation: Hydrogen
Peroxide/Ozone.
Finished Water, Plants
Not Using Ozone (33).
Concentration (ng/L)
Range
Max. 60
Max. 90
<10
Mean
Median
Other
Detection
Limit of 5 ng/L
1 Dates indicate period of sample collection.
2 May not be representative of national occurrence.
EPA: Environmental Protection Agency.
Although bromate is used as a
maturing agent in malted beverages, as
a dough conditioner, and in
confectionery products (Borum, 1991),
monitoring data are not available to
adequately characterize the magnitude
or frequency of potential bromate
exposure from the diet. Currently, the
Food and Drug Administration does not
have available data for bromate in foods,
as bromate is not a part of their Total
Diet Study program. Similarly, EPA's
Office of Air and Radiation is not
currently measuring for bromate in air
(Borum 1991).
Since only a limited number of food
groups are expected to contain bromate
and no significant bromate levels are
expected in ambient or indoor air, EPA
believes that drinking water is the
predominant source of intake for
bromate, and contributions from air and
food would be small. Characterization of
potential exposures from food and air
are issues currently under review. EPA
requests any additional data on known
concentrations of bromate in drinking
water, food, and air.
Health 'Effects. The health effects
information in this section is
summarized from the Drinking Water
Health Quantification of Toxicological
Effects Document for Bromate (USEPA,
1993b). Studies mentioned in this
section are summarized in the criteria
document.
The noncancer effects of ingested
bromate have not been well studied.
Bromate is rapidly absorbed, in part
unchanged, from the gastrointestinal
tract following ingestion. It is
distributed throughout the body,
appearing in plasma and urine as
bromate and in other tissues as bromide.
Following exposure to bromate, bromide
concentrations were significantly
increased in kidney, pancreas, stomach,
small intestine, red blood cells and
plasma. Bromate is reduced in tissues
probably by glutathione or by other
sulfhydryl-containing compounds.
Excretion occurs via urine and to a
lesser extent feces.
Acute oral LDso values range from 222
to 360 mg bromate/kg for mice and 500
mg/kg for rats. Acute symptoms of
toxicity include decreased locomotion
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and ataxia, tachypnea, hypothermia,
hyperemia of the stomach mucosa,
kidney damage and lung congestion. In
subchronic drinking water studies,
decreased body weight gain and marked
kidney damage were observed in treated
rodents. These effects were observed at
the lowest doses tested (30 mg/kg/d).
Bromate was positive in a rat bone
marrow assay to determine
chromosomal aberrations. Positive
findings for bromate were also reported
in a mouse micronucleus assay. Bromate
has also been found to be carcinogenic
to rodents following long-term oral
administration. In these studies, an
increased incidence in kidney tumors
was reported for male and female rats.
Other tumors observed include thyroid
follicular cell tumor and peritoneal
mesothelioma. No carcinogenic effects
have been seen in mice. Dose and time
studies indicate that the minimum
exposure time to produce tumors in rats
is 13 weeks.
The available data are considered
insufficient to calculate an RfD. Only
one noncarcinogenic toxicity study
(Nakano et al., 1989) was located in the
literature. The study failed to provide
dose response data and did not identify
a NOAEL. Histopathological lesions in
kidney tubules that coincided with
decreased renal function were noted in
rats exposed to 30 mg bromate/kg/d. for
15 months. The available
carcinogenicity studies also do not
provide sufficient information on non-
cancer related effects to determine an
RfD.
In a cancer bioassay, Kurokawa et al.
(1986a) supplied groups of 50 male and
50 female F344 rats (4-6 weeks old)
with drinking water containing 0, 250 or
500 mg/L (the maximum tolerated dose)
of potassium bromate (KBrO3). The high
dose (500 mg/L) caused a marked
inhibition of weight gain in males, and
so at week 60 this dose was reduced to
400 mg/L. Exposure was continued
through week 110. The authors stated
the average doses for low dose and high
dose groups were 12.5 or 27.5 mg
KBrOs/kg/day in males (equivalent to
9.6 and 21.3 mg BrO3/kg/day) and 12.5
or 25.5 mg KBrO3 in females (equivalent
to 9.6 and 21.3 mg BrO3). The incidence
of renal tumors in the three groups
(control, low dose, high dose) was 6%,
60% and 88% in males and 0%, 56%
and 80% in females. The effects were
statistically significant (p <0.001) in all
exposed groups. The incidence of
peritoneal mesotheliomas in males at
three doses was 11% (control), 33%
(250 mg/L, p <0.05) AND 59% (500 mg/
L, p <0.001). The authors concluded
that KBrO3 was carcinogenic in rats of
both sexes.
In a subsequent study; Kurokawa et
al. (1986b) supplied F344 rats with
water containing KBrO3 at 0,154,30,
60,125,250 or 500 mg/L for 104 weeks.
The authors reported that these
exposures resulted in average doses of 0,
0.9,1.7, 3.3, 7.3,16.0 or 43.4 mg/kg/day
of KBrO3, equivalent to doses of 0,0.7,
1.3, 2.5, 5.6,12 or 33.4 mg/kg/day of
BrO3. The incidence of renal cell tumors
in these dose groups was 0%, 0%, 4%,
21% (p <0.05), 50% (p <0.001), 95% (p
<0.001) and 95% (p <0.001). Using the
linearized multistage model, estimates
of cancer risks were derived. Combining
incidence of renal adenomas and
adenocarcinomas in rats, and a daily
water consumption for an adult, lifetime
risks of 10 ~4,10s and 106 are associated
with bromate concentrations in water at
5,0.5 and 0.05 ug/L, respectively.
Equivalent concentrations in terms of
KBrOs, lifetime risks would be 7, 0.7
and 0.07 |ig/L, respectively.
The International Agency for Research
on Cancer placed bromate in Group 2B,
for agents that are probably carcinogenic
to humans. EPA has performed a cancer
weight of evidence evaluation, and has
placed bromate in Group B2: probable
human carcinogen since bromate has
been shown to produce several types of
tumors in both sexes of rats following
drinking water exposures. In addition,
positive mutagenicity studies which
have been reported include indications
of DNA interactions with bromate. As a
result of bromate formation following
disinfection, particularly with ozone,
there is a potential for considerable
exposure in drinking water. Thus, EPA
is proposing an MCLG based on
carcinogenicity and a Category I
approach. The resulting MCLG is zero.
EPA is also interested in examining
the mechanism of toxicity of bromate in
rats in terms of whether renal tumor
formation is due to direct action of
bromate or indirectly through formation
of specific adduct in kidney DNA of rats
treated with bromate.
EPA requests comment on the MCLG
of zero based on carcinogenic weight of
evidence and the mechanism of action
for carcinogenicity related to DNA
adduct.
VI. Occurrence of TTHMs, HAAS, and
other DBFs
A. Relationship of TTHMs, HAAS to
Disinfection and Source Water Quality
1. Primary and Residual Disinfectant
Use Patterns in U.S. and Relationship to
Formation of DBFs
A survey of 727 utilities nationwide
was conducted for the American Water
Works Association Research Foundation
(AWWARF) in 1987 to determine the
extent and cost of compliance with the
1979 maximum contaminant level
(MCL) for trihalomethanes (THMs) ->
(McGuire et al., 1988). The AWWARF
survey reflected more than 67 percent of
the population represented by water
utilities serving more than 10,000
customers. The survey found that
chlorine remained the most common
disinfectant among water utilities. At
the time of the survey, chlorine was
used by 85 percent of the flowing stream
and lake surface water systems and by
80 percent of the ground water systems.
The median chlorine dose for flowing
stream and lake systems was 2.2-2.3'
mg/L and for ground water systems it
was 1.2 mg/L. The range of chlorine
doses was 0.1 to >20 mg/L,
Chloramines were used by 25 percent
of the flowing stream systems and larger
lake systems, but by only 13 percent of
the smaller lake systems. Chloramines
were rarely used by ground water
systems reporting in the AWWARF
THM survey. Typical chloramine doses
for flowing stream systems was 2.7 mg/
L, compared with 1.5 mg/L for lake
systems. In addition, 10 percent of the
flowing stream systems and 5 percent of
the lake systems reported using chlorine
dioxide. The latter systems typically
served more than 25,000 customers. The
typical chlorine dioxide doses ranged
from 0.6 mg/L for the flowing stream
systems to 1.0 mg/L for the lake
systems. No ground water systems
reported using this disinfectant. At the
time of this survey, three utilities
reported using ozone.
The AWWA Disinfection Committee
also performed nationwide surveys on
disinfectant use in 1978 (AWWA
Disinfection Committee, 1983) and 1990
(AWWA Water Quality Division
Disinfection Committee, 1992),
principally among systems serving
>10,000 persons (<3 percent of the
surveyed systems served 10,000 persons
or fewer). Chlorine has historically been
applied early in the water treatment
process (precoagulation) in order to
utilize the benefit of chlorine as a
disinfectant and an oxidarit and to
control biological growths in basins. In
the 1978 survey, the vast majority (>85
percent) of those who relied on surface
waters prechlorinated (AWWA
Disinfection Committee, 1983). The
1990 survey found a significant •
reduction in the frequency of chlorine
addition prior to coagulation, along with
an increase in chlorine application after
sedimentation (AWWA Water Quality
Division Disinfection Committee, 1992).
The AWWARF THM survey had found
that 150 systems surveyed had changed
the point of disinfection to comply with
the 0.10-mg/L THM MCL (McGuire et
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38711
al., 1988). However, the 1990 AWWA
survey (AWWA Water Quality Division
Disinfection Committee, 1992) still
found that 35 percent of the utilities
reported chlorination before coagulation
or sedimentation. The range and median
chlorine doses in the 1990 AWWA
survey were similar to the AWWARF
THM survey.
In the 1990 AWWA survey,
disinfection modifications to reduce
THMs included (1) changes in
prechlorination practices (24 percent of
respondents moved the first point of
chlorination, 23 percent ceased
prechlorination, while 20 percent
decreased the prechlorination dose), (2)
implementation of ammonia addition
(19 percent added ammonia after some
free chlorine time, while nine percent
added ammonia before chlorination), (3)
or changed preoxidant (10 percent
switched to potassium permanganate,
five percent to chlorine dioxide, and 0.5
percent to ozone). A surprisingly large
percentage of utilities reported
operational problems with disinfection
modifications used for THM reduction
(e.g., 56 percent of utilities that
implemented postammoniation reported
such problems; as well as 44, 36, and 28
percent of those who moved the first
point of chlorination downstream,
ceased prechlorination, and decreased
the prechlorination dose, respectively).
Neither the exact nature of the problems
noted, nor their duration, were defined
in the survey. However, the Disinfection
Committee believed that many of the
reported problems were probably
transitional and were alleviated after
further experience.
The 1990 AWWA survey (Haas et al.,
1990) found that disinfection
modifications for THM minimization
differed between ground and surface
water utilities. For example, 13 percent
of surface water systems changed their
preoxidation practices, while this
option was rarely used by ground water
systems (which rarely preoxidize).
Sixteen and 25 percent of surface and
ground water utilities, respectively,
reported adding ammonia after some
free chlorine contact as their
modification strategy to reduce THMs.
Because 65 percent of the surveyed
ground waters had a THM formation
potential (THMFP) (a worst-case
measure of the possible THM
production rather than the amount
actually produced in the distribution
system) of <100 ug/1, most ground water
systems probably did not require
modifications to meet the 1979 TTHM
rule.
AWWA established a Water Industry
Data Base (WIDE) in 1990-91 (AWWA
Water Industry Data Base, 1991). The
WIDB contains information from about
500 utilities supplying water to more
than 50,000 people and over 800
utilities supplying between 10,000 and
50,000 people. The utilities in the WIDB
represent a combined population of 209
million people. In addition, a database
for the Disinfectants/Disinfection By-
Products (D/DBP) negotiated regulation
("reg neg" data base, RNDB) (JAMES M.
MONTGOMERY, CONSULTING
ENGINEERS, INC., 1992) was developed
for AWWA. The RNDB comprises data
on nationwide and regional DBF
studies, including data on individual
THMs and haloacetic acids (HAAs),
chloral hydrate, and bromate, performed
by EPA, water utilities, universities, and
engineering consultants, as well as total
THM (TTHM) data from the WIDB. The
non-WIDB part of the RNDB (i.e., those
studies on individual DBF occurrence
and control) includes 166 utilities
serving a combined population of about
72 million people. The majority of
systems in the non-WIDB data
occurrence part of the RNDB are also in
the WIDB. Thus, the former data base
represents a subset of the latter data
base, in which specialized DBF studies
were conducted. In addition, many of
these studies attempted to select
utilities that were representative of
source water quality, treatment plant
operations, disinfectant use, population
served, and geographical locations
throughout the United States (Krasner et
al., 1989). Furthermore, the RNDB
includes data on 48 utilities (serving a
combined population of 37 million
people) which have evaluated
alternative treatments to comply with
future DBF regulations.
Figure VI-1 shows a comparison of
disinfectant/oxidant uses reported in
the WIDB and the non-WIDB part of the
RNDB. In general, the current usage of
disinfectants/oxidants in both data
bases are comparable, which indicates
that the non-WIDB part of the RNDB is
representative of nationwide
disinfectant usage. Figure VI-2 shows
disinfectants evaluated under
alternative treatments in the RNDB.
While ozone is the most prevalent
alternative disinfectant under
investigation in the RNDB, this data
base is somewhat biased, as it does
include two AWWARF studies
involving ozonation. However, Figure
VI-2 does demonstrate that ozone is an
alternate disinfectant that is being
widely evaluated. While most systems
currently use chlorine only, the
percentage drops when the data are
population based. Figure VI-1 shows
that chloramine use is higher on a
population basis, probably due to its
usage by some of the larger utilities.
BILLING CODE 6560-50-P
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38712 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Figure VI-1
Comparison of Disinfectant Use Among Two Different Databases
100
80 -
1 60 -|
•8
40 -
20 -
69%
Non-Water Industry Database
# Utilities = 166
Water Industry Database
# Plants =1256
Chlorine Chloramines Ozone
Disinfectant
Chlorine
Dioxide
Potassium
Permanganate
100
80 -
i
60 -
I
Dri
40 -
20 -
59%
Non-Water Industry Database
Population = 72.5 M
Water Industry Database
Population = 209 M
21%
Chlorine Chloramines
Disinfectant
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38713
100
80 -
60 H
40 -
20 -
0
100
Figure VI-2
Alternative Disinfectants Under Evaluation
By The Drinking Water Industry1
(Population = 373 M)
81%
10%
8%
0%
I
80 -
60 -
40 -
20 -
0
Chlorine Chloramines Ozone
Disinfectant
(Utilities = 48)
85%
Chlorine
Dioxide
7%
8%
0%
Chlorine
Ozone
Disinfectant
1 Not a representation of changes expected to occur under this byproduct regulation.
Chlorine
Dioxide
0%
Potassium
Permanganate
0%
Potassium
Permanganate
BILLING CODE 6580-60-0
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2. National Occurrence of TOG
The total organic carbon (TOG) level
of a water is generally a good indication
of the amount of THM and other DBF
precursors present in a water (Singer et
al., 1989). In the WIDE, 157 utilities
provided TOG data. For the 100 surface
waters with TOG data, the range was
"not detected" (ND) to 30 mg/L. For
these waters, the 25th, 50th, and 75th
percentiles were 2.6,4.0, and 6.0 mg/L,
respectively. For the 57 ground waters
with TOG data, the range was ND to 15
mg/L. For these waters, the 25th, 50th,
and 75th percentiles were ND, 0.8, and
1.9 mg/L, respectively. Typically, most
ground waters are low in TOG.
However, there are some high-TOC
ground waters, especially in the
southeastern part of the United States
(EPA Region IV; see Figure VI-3 and
Table VI-1). For surface waters, the
. high-TOC waters also tend to be in the
southeastern part of the United States,
although there are some relatively high-
TOC waters in the south central (EPA
Region VI) and the mountain (EPA
Region VIII) states (see Figure VI-3 and
Table VI-2).
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38715
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TABLE VI-1 .—STATISTICS ON AVERAGE RAW GROUNDWATER TOTAL ORGANIC CARBON (MG/L) FOR UTILITIES IN THE
AWWA WATER INDUSTRY DATABASE
1
2
3
4
5
6
7
8
9
10
ALL
Number of utili-
ties with data
2
3
3
13
11
4
5
4
11
1
57
Number of utili-
ing data
48
72
96
163
182
82
53
46
118
37
897
ND
ND
ND
ND
ND
ND
071
ND
0.80
ND
1.38
1 91
15.00
4.00
1.87
1.40
200
1.00
0.80
15.00
25th
ND
0.63
ND
ND
Percentile
50th
2.74
2.19
1.45
ND
0.84
75th
8.50
1.92
0.30
1.88
TABLE VI-2.—STATISTICS ON AVERAGE RAW SURFACE WATER TOTAL ORGANIC CARBON (MG/L) FOR UTILITIES IN THE
AWWA WATER INDUSTRY DATABASE
1
2
3
4
5
6
7
8
9
10
ALL
Number of utili-
ties with data
6
10
20
11
14
10
2
7
16
4
100
Number of utili-
ing data
44
65
79
165
179
76
56
43
113
34
854
3.00
2.10
ND
1.60
ND
2.00
700
1.00
ND
1.25
ND
9.00
20.00
25.00
30.00
9.17
10.00
1000
14.00
5.90
3.30
30.00
25th
3.48
2.50
2.15
5.27
2.70
3.90
1.75
1.95
2.55
Percentile
50th
3.50
4.55
2.87
7.40
4.50
5.50
3.30
3.25
4.00
75th
4.50
5.00
4.80
12.60
5.90
6.90
8.50
3.88
5.95
For surface waters that filter but do
not soften, the median and 90th
percentile TOC levels are 3.7 and 7.5
mg/L, respectively (see Figure VI-4).
However, when the data are flow-
weighted (which would represent more
closely the distribution by population),
the median and 90th percentile values
drop to 2.7 and 5.1 mg/L, respectively
(see Figure VI-4). This is due, in part,
to a number of large facilities treating
water with TOC levels <4 mg/L. When
this same category of surface waters is
examined for choice of disinfectants
between chlorine and chloramines, the
latter group has a higher TOC
cumulative probability than the former
(see Figure VI-5). Switching from free
chlorine only to chloramination was one
of the options utilized by utilities with
high-TOC waters to comply with the
0.10 mg/L TTHMMCL.
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38717
Figure VI-4
50
20-
15-.
10-
6+ 1
0
0-1
Frequency Diitribution of Influent TOC
V.I.
Flow Weighted Frequency Diitribution of TOC
(surface water systems that filter but do not soften)
1990 WIDB Data: 111 systems
1-2
2-3
3-4
4-5 5-6 6-7
Influent TOC Concentration (mp/l)
[•FlowWeighted
7-8
Summary Statistics of lafluent TOC Distributions (1990 WIDE Data)
Win
Max
Median
Mean
Std.Dev.
80th Percwrtlle
0.01
25.0
3.7
4.5
3.2
7.5
FtowWatohted
0.01
25.0
2.7
3.4
2.1
5.1
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38718 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Figure VI-5
WTOB Cumulative Distribution of TOC
for Filtered Surface Water Systemi With No Softening
100% -i
QMt .
tynL .
JTVMt .
S. fXVL .
& «"*
O grftL .
4fMt •
30% •
9TML •
irwt .
nu.
/
f .
/.-•-
M »
X* ;'
J »
^S ;
| CWorinttion (n=65) Chtoramines (n=40) |
X
/ * * * *
..••*'
/
- *'*
» • " "
0 5 10 15 20 25
Concentration (mg/l)
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38719
As part of a ground water supply
survey (GWSS), TOG was measured at
the point of entry into the distribution
system (see Figure VI-6). Because most
groundwater systems do not have
precursor-removal technology as part of
their treatment, these treated-water TOC
levels provide a good indication of the
range of raw-water TOC levels in ground
waters. The median and 90th percentile
TOC levels of systems without softening
who chlorinate were 0.7 and 2.9 mg/L,
respectively. However, the median and
90th percentile TOC levels of systems
with softening who chlorinate were 1.7
and 6.8 mg/L, respectively.
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Figure VI-6
GWSS Cumulative Diitrlbotkm of TOC for Ground Water Syitemi Witt Softening
[."••Chlofltmion (n-58) |
ConcMrtnrtlon (mfl/l)
0.6-
0.6-
0.4
0.3
0.2
0.1
0.0
GWSS cnmulattve Dtatributton of TOC for Ground Water Syitemi Without Softening
|——Chfcxln«tlon(n-53e)|
6 8
Concwitratlon (mo/1)
10
12
14
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38721
In addition, the breakdown of treated-
water TOG levels of ground waters was
examined geographically (see Table VI-
3). As indicated above (see Table VI-l),
the southeastern part of the United
States (i.e., EPA Region 4) has
groundwaters with a relatively higher
level of TOG (see Tables VI-3A and VI-
3C). In addition, the mountain states
(i.e., EPA Region 8) also tended to have
a higher distribution of TOCs in the
ground waters tested (see Tables VI-3A
and VI-3C). Furthermore, these data are
also broken down into those that
chlorinate and those that do not (see
Table VI-3). Typically, ground waters
that are currently undisinfected tend to
be ones with lower TOG levels. Thus,
promulgation of the Ground Water
Disinfection Rule will probably tend to
have an impact on waters with a lower
precursor level than are currently
disinfecting.
TABLE VI-3A.—TOC VALUES FOR GWSS SYSTEMS THAT CHLORINATE
EPA region
1
2
3
4
5
6 ..
7
8
9
10
ALL
Number of
utilities with
data
19
59
62
185
90
46
103
26
39
25
654
Max value
4.3
4.6
4.2
14
8.9
8
7.8
11
11
3.3
14
Percentile
25th
0.4
0.3
0.3
0.8
0.7
0.6
0.8
0.6
<2
0.3
0.3
60th
0.5
0.5
0.5
0.7
1.1
1
0.8
1.9
0.2
0.9
0.7
75th
0.95
0.9
0.7
2.1
1.8
1.7
1.8
3.1
0.5
1.4
1.7
90th
2.3
1.5
1.2
5.3
2.6
2.4
3.7
6.6
1.2
2.2
3.3
TABLE VI-3B.—TOC VALUES FOR GWSS SYSTEMS THAT Do NOT CHLORINATE
EPA region
1
2
3
4
5
6
7
8
9
10
ALL
Number of
utilities with
data
27
14
28
34
41
26
18
14
49
40
291
Max value
3.6
0.8
5.3
3.2
18
5.6
2.9
5.9
3.4
5
18
Percentile
25th
0.3
<2
<2
0.3
0.7
0.2
0.6
0.3
<2
0.2
0.3
50th
0.5
0.3
0.3
0.5
1.3
0.6
0.9
0.4
0.3
0.4
0.5
75th
0.8
0.5
0.6
0.8
2.2
1.5
1.1
1.8
0.4
0.8
1.1
90th
1.3
0.6
1.5
1.7
3.4
2.9
2.2
2.7
0.9
2
2.2
TABLE VI-3C.—TOC VALUES FOR ALL GWSS SYSTEMS
EPA region
1
2
3
4
5
6
7
8
9
10
ALL
Number of
utilities with
data
46
73
90
219
131
72
121
40
88
65
945
Max value
4.3
4.6
5.3
14
18
8
7.8
11
11
5
18
Percentile
25th
0.3
0.3
0.3
0.3
0.7
0.4
0.4
0.3
<2
0.2
0.3
50th
0.5
0.5
0.4
0.7
1.2
0.9
0.9
1.8
0.2
0.5
0.6
75th
0.8
0.8
0.7
1.9
1.9
1.7
1.7
2.7
0.5
1.2
1.4
90th
1.6
1.3
1.2
4.8
3.2
2.4
3.2
5.9
1
2.2
2.9
3. National Occurrence of Bromide
Bromide is a concern in both
chlorinated and ozonated supplies. In
chlorinated supplies, while the organic
precursor level of a source water has an
impact on the amount of DBFs formed,
the bromide concentration has an
impact on the speciation as well as the
overall yield (Symons et al., 1993).
Typically, regardless of the organic
content in water, bromate can be formed
when waters containing sufficient levels
of bromide are ozonated (Krasner et al.,
Jan. 1993).
In a 35-utility nationwide DBF study,
bromide ranged from <0.01 to 3.0 mg/
L and the median bromide level was 0.1
mg/L (Krasner et al., 1989). Some
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utilities have bromide in their source
water due to saltwater intrusion (one
utility had as much as 0.4 to 0.8 mg/L
bromide due to this phenomenon)
(Krasner et al., 1989). However, some
non-coastal communities can have
moderate-to-high levels of bromide due
to connate waters (ancient seawater that
was trapped in sedimentary deposits at
the time of geological formation) or
industrial and oil-field brine discharges.
The highest bromide detected in the
latter study (2.8-3.0 mg/L) (Krasner et
al., 1989) was from a water in the
midsouthern part of the U.S.
Currently, a nationwide bromide
survey of 70 utilities has found bromide
levels ranging from <0.005 to >3.0 mg/
L (Amy et al., 1992-3). Some waters
have been sampled more than once (up
to three seasonal samples to date) in
order to determine the variability in
bromide occurrence. The average raw-
water bromide level per water, though,
provides an indication of the typical
occurrence of bromide in each water.
Table VI-4 provides some preliminary
insight into the geographical occurrence
of bromide. Ideally, more data per
region are needed; however, sufficient
data are available for general trends.
Regions 6 (which includes Texas) and 9
(which includes California) have the
highest occurrence of bromide. While
some California communities have
problems with saltwater intrusion, some
Texas communities may have bromide
from connate waters or oil-field brines.
However, most geographical regions
have at least one high-bromide water in
their area, except for the systems
surveyed in the Pacific Northwest (EPA
Region 10) and the northeast (EPA
Regions 1 and 2).
TABLE VI-4.—STATISTICS ON AVERAGE RAW-WATER BROMIDE (MG/L) FOR UTILITIES IN THE NATIONWIDE BROMIDE
SURVEY
EPA region
•j
2
3
4
5
6
7
8
9 ,
10
Number of
utilities
with data
8
4
8
7
6
7
6
7
11
6
Min value
0.005
0.023
0.005
0.010
0.012
0.014
0.042
0.006
0.008
<0.005
Max value
0.089
0.093
0.276
0.190
0.322
>3.00
0.206
0.368
0.429
0.015
Percentile :
25th
0.02
0.03
0.03
0.02
0.05
0.02
0.06
0.02
0.05
<0.005
50th
0.03
0.05
0.06
0.04
0.09
0.03
0.08
0.02
0.08
0.006
75th
0.05
0.08
0.07
0.05
0.12
0.25
0.09
0.06
0.33
0.009
90th
0.05
NA
0.08
0.05
0.14
0.37
0.10
0.09
0.36
0.012
NA=Not applicable; insufficient number of utilities to determine.
Figures VI—7, and VI-8 show the
cumulative probability distribution of
average raw-water bromide levels in
surface and ground waters, respectively,
in the nationwide bromide survey. In
surface waters in this survey, the
median, 75th, 90th, and 95th percentile
bromide level were 0.04, 0.08, 0.2, and
0.35 mg/L, respectively. In ground
waters in this survey, the median, 75th,
90th, and 95th percentile bromide level
were 0.06,0.1,0.25, and 0.35 mg/L,
respectively. Overall, ground waters
appear to have a somewhat higher
probability of bromide occurrence than
in surface waters. In the 35-utility DBF
study, one midwest utility pumped
ground water into a lake to augment a
low-lake level during a drought period.
Bromide rose from 0.19 to 0.68 mg/L
during this period of time.
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e
>;.
- 1 -8
Qnaaiad) £ffl!qeq
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38724
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
BILLING CODE 8MO-60-C
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B. Chlonnation Byproducts
1. TTHMs—Occurrence Studies
Prior to the promulgation of an MCL
of 0.10 mg/L TTHMs in 1979, EPA
performed two surveys to obtain
information on the occurrence of THMs
and other organic compounds: the
National Organics Reconnaissance
Survey (NORS) in 1975 (Symons et al.,
1975) and the National Organic
Monitoring Survey (NOMS) in 1976-77
(Brass et al., 1977 and The National
Organics Monitoring Survey, unpubl.).
NORS and NOMS were conducted
primarily to determine the extent of
THM occurrence in the United States.
These data were used, in part, in
determining the 1979 THM regulation.
Surveys in the 1980s were performed to
provide data for assessing a new MCL
for THMs, as well as to develop
regulations for other DBFs.
The AWWARF THM survey used data
from 1984-86, and these THM values
reflected the result of compliance with
the 1979 THM regulation. Mean TTHM
values were computed for each of the
utilities in the AWWARF THM survey;
these means, as well as data from the
NORS and NOMS surveys, are plotted
(see Figure VI-9) on a frequency
distribution curve. The AWWARF
survey's overall TTHM average was 42
Hg/L, which was a 40-50 percent
reduction in national THM
concentrations as compared to the
averages of the NORS and NOMS (all
phases) results. It is important to note
that the disinfection practices of some of
the utilities in the AWWARF survey
(such as the use of chloramines as a
primary disinfectant) were employed to
meet the 1979 TTHM MCL, and not to
meet the requirements of the recently
promulgated Surface Water Treatment
Rule (SWTR). Thus, THM and DBF
levels at some utilities would most
likely be different if their current
treatment practices required
modification in order to meet the new
disinfection requirements of the SWTR.
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1.000-1
500-
100-
80-
10-
NOMft-rtptlMM
AWWARF
uUIUywnny
I
—\
MM
T
10
T
T 1 1 T
SO TO
T
T
90
w
Pnetntm* UH Thm or Equd to Qhnn ConowiMtloa
f\g»n VI-9. Frequency distributions of national THM survey data (From: McGuire, MJ. & Meadow, R.G. AWWARF
Trihalomethane Survey, Jour. AWWA, 80:1:61 [Jan. 1988])
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38727
Median TTHM concentrations in the
AWWARF survey for the spring,
summer, fall, and winter seasons were
40,44, 36, and 30 ug/L, respectively.
THM levels were highest in the summer
and lowest in the winter, due primarily
to the faster formation rates in warmer
water temperatures. In the 35-utility
DBF study, the second highest THM
levels were in the fall (Krasner et al.,
1989). For many utilities in California
and the southern United States, fall can
be almost as warm as summer. However,
seasonal impacts may be due to changes
in the nature of naturally occurring
organics or bromide levels as well.
Compliance with the THM regulation is
based on a running annual average to
reflect these types of seasonal
variations.
Because the 1979 regulation did not
apply to systems that serve <10,000
people, the running annual average
TTHM distribution for small systems is
expected to be different. In the
AWWARF THM survey, TTHM data for
small systems from 12 states were
obtained (McGuire et al., 1988). While
the number of utilities (677) for which
TTHM data were received represents
only a small percentage of the total
number serving fewer than 10,000
customers (55,449), some important
observations can be made. The range of
TTHMs was from ND to 313 ug/L, with
a mean of 36 ug/L and a median of 18
ug/L (McGuire et al., 1988). The
cumulative probability distribution
differs significantly from the NORS and
NOMS data (see Figure VI-10). This
lack of agreement is probably due to
many of the small systems using ground
water sources, which are generally
much lower in THM precursors than
surface water sources. In addition, the
overall statistics of the AWWARF
survey (for 677 cities) were markedly
affected by the low TTHM results (range
of ND to 42 ug/L with a mean of 2 ug/
L) of the 204 systems sampled in
Wisconsin. Although McGuire does not
identify a reason for low TTHMs in
Wisconsin, EPA data indicate that over
90 percent of Wisconsin systems use
ground water (probably with low
precursor levels) as a primary source.
Since 30 percent of the systems in the
survey were from Wisconsin, this would
bias the results.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
1,000—1
800-
100-
50 -
10-
HORS
AWWARF tunny ol
utHDwMcvIng
t*mr Urn 10,000
10
• IIIO I I I
SO SO 70 MM
Pwowfeg* Uu Tim or Equal to Own ConowtMUon
9»J>
Figure Vl-10. Frequency distributions of National Organics Reconnaissance Survey, National Organics Monitoring Survey, and
AWWA Research Foundation data from surveys of smaller utilities (From: McGuire, MJ. & Meadow, R.G. AWWARF
Trihalomethane Survey, Jour. AWWA, 80:1:61 [Jan. 1988])
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38729
Since the AWWARF THM survey,
EPA measured DBF data in a number of
small systems. These data represent part
of the non-WIDB data in the RNDB.
Figure VI-11 compares the TTHM
frequency distribution for the WIDE
(large systems only) with that of the
non-WIDB data on both large and small
systems. For the small systems, there is
essentially a biomodal distribution of
TTHM levels: 50 percent of the small
systems have <10 ug/L TTHMs, while
the remaining utilities have TTHM
levels of 20 to 430 ng/L. Most likely,
many of the very low THM levels are
associated with treatment of low-TOC,
low-bromide ground waters. For
community water, non-purchased
systems serving <10,000 people, 4562
systems treat surface water, while 17941
disinfect ground water. For systems
serving >10,000 people, 1395" treat
surface water and 1117 disinfect ground
water. Thus, small systems are utilizing
ground water more than surface water.
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2
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iZ
CD
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if
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T/3n
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In the WIDB (which only includes
large systems), 482 utilities that treat
surface water or a mix of surface and
ground waters had TTHM median, 75th,
and 90th percentile values of 43,59, and
74 ng/L, respectively. In the WIDE, 277
utilities that treat ground water only had
TTHM median, 75th, and 90th
percentile values of 13,34, and 60 ng/
L, respectively. However, systems using
both types of source waters had TTHM
levels in the neighborhood of 100 ng/L.
Thus, while ground waters in general
tend to form less THMs than surface
waters, there are some ground waters
with sufficient precursor levels to form
significant amounts of THMs.
2. HAAs and Other Chlorination DBFs—
Occurrence Studies
a. Discovery of Additional
Chlorination By-Products. In 1985, EPA
determined chlorination DBFs at 10
operating utilities, using both target-
compound and broad-screen analyses
(Stevens et al., 1989). A total of 196
compounds that can be attributed to the
chlorination process were found in one
or more of the 10 utilities' finished
waters. Approximately half of the
compounds contained chlorine and
many were structurally identified;
however, 128 compounds were of
unknown chemical structure. The
compounds which were quantifiable
represented from 30 to 60 percent of the
total organic halide (TOX) of those
supplies. That study served to
significantly reduce the list of
compounds that EPA considered most
significant for further work.
b. Available Data on Chlorination By-
products. Taken as an example of
subsequent survey results where
quantifiable target-compound analyses
were used, Figure VI-12 shows the
occurrence of DBFs in the 35-utility
study (Metropolitan Water District of
So. Calif et al., 1989). The figure
presents an overview of the results of
four seasonal sampling quarters
combined. In addition, all sampling was
performed at treatment-plant clearwell
effluents. It is important to note that
these survey results do not reflect any
impacts of the SWTR under which a
substantial number of systems could be
expected to modify disinfection practice
to achieve compliance. On a weight
basis, THMs were the largest class of
DBFs detected in this study; the second
largest fraction was haloacetic acids
(HAAs). At the time of this study,
commercial standards were only
available for five of the nine theoretical
species: monochloro-, dichloro-,
trichloro-, monobromo-, and
dibromoacetic acid. The data indicate
that the median level of THMs (i.e., 36
Hg/L) was approximately twice that of
HAAs (i.e., 17 |ig/L). The third largest
fraction was the aldehydes (i.e.,
formaldehyde and acetaldehyde). These
two low-molecular-weight aldehydes
were initially discovered as by-products
of ozonation, but they also appear to be
by-products of chlorination. Every
target-compound DBF was detected at
some time in some utility's water during
the study; however, 2,4,6-
trichlorophenol was only detected at
low levels at a few utilities during the
first sampling quarter and was not
detected in subsequent samplings.
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£
a
04
g
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38733
The 35-utility DBF study assessed
systems using a range of disinfectants, a
number of which used chloramines as a
residual disinfectant. In a study (in
1987-89) by EPA, primarily chlorine-
only systems were evaluated at the plant
and in the distribution system (typically
a terminal location). The range of total
HAAs (THAAs) (a sum of the five
aforementioned species) at the plant
effluent was <1 to 86 ug/L (representing
73 samples), with a median value of 28
ug/L (Fair, 1992). In the distribution
system (56 samples collected), the range
and median THAAs were <1-136 and
35 ug/L, respectively.
In a six-utility DBP survey in North
Carolina (Grenier et al., 1992), the sum
of four measured HAAs—dibromoacetic ,
acid was not included in this study, as
these waters are all low in bromide—
ranged from 14 to 141 ug/L in the
distributed waters (with utility annual
averages of 51 to 97 ug/1). In this survey,
HAA concentrations consistently
exceeded the concentration of TTHMs
(which ranged from 13 to 114 ug/1, with
utility annual averages of 34 to 72
ug/1). The prevalence of the HAAs may
be due, in part, to chlorination of settled
and finished waters with pH levels of
5.9 to 7.8. Chlorination at lower pH
levels results in lower THM formation
but higher HAA concentrations (Stevens
et al., 1989).
Recently, a commercial standard for
bromochloroacetic acid (BCAA) has
become available. Studies to date
suggest that the other mixed
bromochloroacetic acids may be
unstable (Pourmoghaddas et al., 1992).
The RNDB includes the occurrence of
BCAA for 25 utilities. The median, 75th
and 90th percentile occurrence were 3,
5, and 8 ug/L, respectively. In the
chlorinated distribution system of a
water containing from 0.04 to 0.31 mg/
L bromide (i.e., an average- and a high-
bromide source water were being
treated), BCAA was present from 6 to 17
ug/L and accounted for 25 percent of the
concentration of the sum of the six
measured HAA species (D/DBP
Regulations Negotiation Data Base
(RNDB), 1992). Thus, most DBP studies
which measured only five of the HAA
species will have some level of
underestimation of total HAAs present,
although that should be a small error in
low bromide waters.
The RNDB includes HAA data,
including from the 35-utility, EPA, and
North Carolina DBP studies. When a
utility was sampled more than once in
time and space, a "quasi" running
annual average value was determined
(RNDB). Figure VI-13 shows the
cumulative probability occurrence of
THAAs (the four- to six-species sums)
for large and small systems. The median
THAA for either population group is 30
ug/L, although the small systems have
30 percent of the utilities with <7 ug/L
THAAs. The difference at the low
THAA levels was probably due to
treatment of low-precursor source
waters in small systems. The high end
of the THAA occurrence was not
significantly different, most likely due
to a lack of a HAA regulation and the
fact that pH of chlorination impacts
THM and HAA formation in opposite
ways. In the RNDB, 121 of the utilities
treated surface water or a ground water/
surface water mix. For those systems
treating some percentage of surface
water, the median, 75th, 90th percentile,
and maximum values were 28, 50, 73,
and 155 ug/L, respectively. In the
RNDB, 13 of the utilities treated ground
water only. For this limited ground
water data set, the median, 90th
percentile, and maximum values were 4,
13, and 37 ug/L, respectively.
BILLING CODE 6560-60-P
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38734
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38735
3. Modeling (DBPRAM) Formation
TTHMs, HAA5 and Extrapolation to
National Occurrence and Effects of
SWTR
As part of the D/DBP rulemaking
process, EPA developed regulatory
impact assessments of technologies that
will allow utilities to comply with
possible new disinfection and DBF
standards (Gelderloos et al., 1992). As
part of this process, a DBP Regulatory
Assessment Model (DBPRAM) was
developed. The DBPRAM included
predictive equations to estimate DBP
concentrations during water treatment
(Harringon et al., 1992). However,
because reliable equations for predicting
individual DBP formation in a wide
range of waters (e.g., those containing
high levels of bromide) were not
available, the regulatory impact
assessments emphasized TTHM (Amy et
al., 1987) and total HAAS formation.
Because BCAA was not commercially
available when HAAs were measured
during the development of the HAA
predictive equations, those equations
only included the formation of five
HAA species (Mallon et al., 1992).
However, for a low-bromide water, the
error from not including mixed
bromochloro HAA species was probably
low.
The DBPRAM predicted the removal
of TOG during alum coagulation,
granular activated carbon (GAG)
adsorption, and nanofiltration
(Harrington et al., 1992 and Harrington
et al., 1991). These equations were
developed based upon a number of
bench-, pilot-, and full-scale studies.
The removal of TOG during
precipitative softening, though, has not
been modeled to date. However, systems
that soften represent a small percentage
of the surface-water treatment plants
(about 10 percent). The DBPRAM also
predicted the alkalinity and pH changes
resulting from chemical addition
(Harrington et al., 1992), as well as the
decay of residual chlorine and
chloramines in the plant and
distribution system (Dharmarajah et al.,
1991).
In developing regulatory impact
assessments, the-first step was to
estimate the occurrence of relevant
source-water parameters (Letkiewicz et
al., 1992). TOG data from the WIDE and
bromide data from the nationwide
bromide survey formed the basis for
determining the DBP precursor levels
(Wade Miller Associates, 1992). Actual
water quality data were used to simulate
predicted occurrence values based upon
a statistical function such as a log-
normal distribution (Letkiewicz et al.,
1992 and Wade Miller Associates,
1992). In running the DBPRAM, the
production of DBPs was restricted to
surface-water plants that filtered but did
not soften. Surface waters typically have
higher disinfection criteria—and thus a
greater likelihood to produce more
DBPs—than ground waters (i.e., Giardia
in surface waters is more difficult to
inactivate than viruses in ground
waters). As mentioned before, an
equation to predict TOG removal during
softening was not available. However,
the surface water systems which were
modeled represented water treated and
distributed to approximately 103
million people (Letkiewicz et al., 1992).
Another mechanism was developed for
accounting for DBP occurrence in other
water systems (see below).
The second step in the regulatory
impact assessment was to prepare a
probability distribution of nationwide
THM and HAA occurrence if all surface
water plants that filter but do not soften
used a particular technology for DBP
control (i.e., enhanced coagulation,
GAG, nanofiltration, or alternative
disinfectants). Even though individual
utilities will consider a range of
technologies to meet disinfection and D/
DBP rules, the DBPRAM can only
predict the performance of one
technology at a time. Subsequently, a
decision-making process was employed
to examine the predicted compliance
choices that systems will make
(Gelderloos et al., 1992). As part of the
DBPRAM, compliance with the SWTR,
a potential enhanced SWTR, the total
coliform rule, and the lead-corrosion
rule were modeled. Thus, while
nationwide DBP studies typically
measured DBP occurrence prior to
implementation of these new microbial
and corrosion rules, the DBPRAM
allowed one to assess the impacts of
meeting a multitude of rules
simultaneously.
During the D/DBP negotiated
rulemaking, a Technology Workgroup
(TWG) of engineers and scientists was
formed. The TWG reviewed the
DBPRAM and regulatory impact
assessments, and provided input to
ensure that the predicted output was
consistent with real-world data. Prior
validation of the model in Southern
California (where bromide occurrence
was relatively high) indicated that the
central tendency was to underpredict
TTHMs by 20-30 percent (Harrington et
al., 1992). In addition, evaluation of the
, model in low-bromide North Carolina
waters also found that the model tended
to underpredict both THM and HAA
concentrations and resulted in absolute
median deviations of approximately 25-
30 percent (Grenier et al., 1992). Neither
Harrington nor Grenier were able to
identify reasons for the
underpredictions. Therefore, the TWG
adjusted the DBPRAM output to correct
for the underpredictions; the resultant
data were confirmed against full-scale
data from throughout the United States.
Prior validation of the alum
coagulation part of the model was
performed in several eastern states, as
well as in Southern California. The
overall central tendency was to
overpredict TOC removal by 5-10
percent. The TWG believed that utilities
would implement an overdesign factor
to ensure that precursor removal
technologies could consistently meet
water quality objectives. A 15 percent
overdesign factor for TOC removal
compensated for a typical
overprediction in TOC removal by alum.
For plants that do not filter or filter with
softening, case studies on a number of
systems through the nation were used to
assess compliance choices and
predicted water qualities. For ground
waters, data from the WIDE and GWSS
on TOC and THM levels were used in
developing regulatory impact analyses
(RIAs) for those systems.
With the revised DBPRAM output, the
proposed stage 1 D/DBP rule—i.e.,
MCLs of 80 ug/L TTHMs and 60 ug/L
THAAs, as well as a performance
criteria for DBP precursor removal—
would affect large systems that filter but
do not soften as follows: TTHMs would
drop on a median basis from 45 to 32
ug/L, while the 95th percentile would
drop from 104 to 58 ug/L; THAAs would
drop on a median basis from 27 to 20
ug/L, and the 95th percentile would
drop from 86 to 43 ug/L.
C. Other Disinfection Byproducts
1. Ozonation Byproducts
a. Identification of Ozonation
Byproducts. Ozone can convert organic
matter in water to aldehydes (e.g.,
formaldehyde) (Glaze et al., 1989) and
assimilable organic carbon (AOC) (Van
der Kooij et al., 1982). Recent research
optimized the aldehyde method in order
to quantitatively recover additional
carbonyls of interest (e.g., dialdehydes
such as glyoxal and aldo-ketones such
as methyl-glyoxal (Sclimenti et al.,
1990)). AOC is the fraction of organic
carbon that can be metabolized by
microorganisms; it also represents a
potential for biological regrowth in
distribution systems. Polyfunctional
ozone DBPs such as ketoacids have been
detected at higher levels than the low-
molecular-weight aldehydes and have
been shown to correlate well with AOC
(Xie et al., 1992). Using resin columns
to accumulate organics from ozonated
waters, Glaze and co-workers detected
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38736 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
aldehydes, carboxylic acids, aliphatic
and alicyclic ketones, and hydrocarbons
(Glaze et al., August 1989). Ozone is
known to produce other organic
oxygenated DBFs, such as peroxides and
epoxides (Glaze et al, 1989). Analytical
methods for low-level detection are
currently not available for epoxides, but
progress in detecting peroxides
(inorganic and organic) has recently
been made (Weinberg et al., 1991). As
with chlorine, occurrence data for ozone
DBFs are limited to compounds that can
be detected by current methods.
Although most ozone by-products are
oxygenated species, the presence of
bromide will result in the formation of
brominated DBFs (Haag et al., 1983 and
Dore et al., 1988). When bromide is
present in a source water, it may be
oxidized by ozone to hypobromous acid
(HOBr). At common drinking-water pH
levels, HOBr is in equilibrium with the
hypobromite ion, OBr-. Once
produced, HOBr can react with organic
THM/DBP precursors to form
bromoform and other brominated
organic by-products (Dore et al., 1988
and Glaze et al., Jan. 1993). OBr~ (but
not HOBr) can be oxidized by ozone to
bromate (BrO3~) (Krasner et al., Jan
1993 and Haag et al., 1983). Krasner and
colleagues found that ozonation of
bromide-containing waters can form a
number of brominated organic DBFs
that are analogous to chlorinated DBFs
(e.g., bromoform, dibromoacetic acid,
tribromonitromethane [bromopicrin],
and cyanogen bromide) (Krasner et al.,
1990 and Krasner et al., 1991).
Similarly, Glaze and co-workers studied
the formation of bromo-organic DBFs
formed during ozone (e.g., bromoform;
dibromoacetonitrile; mono-, di-, and
tribromoacetic acid; and
monobromoacetone) (Glaze et al., Jan.
1993). However, only a fraction of the
dissolved organic bromide was found as
targeted brominated organic DBFs
(Glaze et al., Jan. 1993). As with
chlorination, not all of the halogenated
DBFs can be accounted for with existing
analytical methodologies. However,
researchers are continuing to try to
uncover new DBFs all the time, such as
the bromine-substituted analogues of
chloral hydrate (trichloroacetaldehyde)
formed during chlorination and/or
ozonation (Xie et al., 1993, in press).
b. National Occurrence—Trends—i.
Ozone use in U.S., pre vs. post SWTR.
While ozone technology in drinking-
water treatment has been in use for
more than 80 years in Europe,
applications in the United States (U.S.)
have been much more limited. However,
the use of this disinfectant/oxidant is
growing rapidly in the U.S. as utilities
are working to meet the requirements of
the SWTR, anticipation of a D/DBP
Rule, regulations for volatile and
synthetic organic chemicals, and for
taste-and-odor control (Ferguson et al.,
1991 and Tate, 1991). Virtually every
surface water system use of ozone was
intended to accomplish multiple water
quality objectives, such as disinfection,
DBF control, taste and odor, or any
combination of these (Tate, 1991).
Ground water plants in Florida have
used ozone for controlling DBFs, color,
and odor (Tate, 1991).
The first U.S. ozone plant was on-line
in 1978. The number increased to 18 by
June 1990 (Tate, 1991). A recent survey
has identified an additional 11 facilities
under construction, as well as at least 37
U.S. ozone pilot-plant studies underway
(Rice, Aug.-Sept. 1992). As part of the
D/DBP negotiated regulation, the TWG
has evaluated compliance choices for
meeting stage 1 and possible stage 2
criteria. For example, the TWG
predicted that six percent of surface
water systems will use ozone/
chloramines in addition to enhanced
coagulation to achieve compliance with
Stage 1 requirements. Depending on the
role of precursor-removal criteria in a
stage 2 Rule, it is predicted that from 8
to 27 percent of large surface-water
systems would use ozone/chloramines
as part of the treatment process. The
current and projected ozone usage is
based on an existing SWTR and the
anticipation of a DBF Rule, both of
which have led to the choice of ozone,
a powerful disinfectant that typically
produces limited DBFs.
ii. AWWARF bromide/bromate survey
and studies. In order to comply with
new and more stringent regulations,
alternative treatments are being studied.
A 2-year study of ozone treatment at 10
North American utilities was conducted
at pilot and full scale (Glaze et al., 1993
in press). For four of the six surveyed
utilities where the bromide level was
£0.06 mg/L, bromate was not detected
with minimum reporting level (MRL)
values of 5-10 ug/L at the ozone dosages
investigated (Krasner et al., Jan. 1993).
For the other two low-bromide utilities,
bromate at 5-8 ug/L was detected
inconsistently over time and space. For
three of the four tested waters in which
the ambient bromide level was 0.18-
0.33 mg/L, bromate was typically
detected at levels of 9-18 ug/L. No
bromate was detected at one utility
where the very high level of TOG (i.e.,
26 mg/L) may have produced an ozone
demand that overwhelmed the
production of bromate. In another study,
using a special, labor-intensive
concentration method at an EPA
research facility, bromate was detected
in seven of the nine ozonated waters
tested at an MRL of 0.4 ug/L or higher
(Sorrell et al., 1992). In one instance,
bromate was detected in the source
water at this MRL value.
Utilizing these data, as well as that of
other EPA and AWWARF investigators
(Krasner et al., Jan 1993, Amy et al.,
1992-93, Sorrell et al., 1992, Hautman,
1992, and Miltner, Jan. 1993). The
nationwide distribution of bromate
occurrence if all surface water plants
switched to ozone for predisinfection
was estimated (Krasner et al., 1993). It
was estimated that the 20th, median,
and 80th percentile for bromate
occurrence in surface waters using
ozone for predisinfection might be 0.5-
0.8,1-2, and 3-5 ug/L, respectively.
The 90th to 95th percentile
occurrence of bromate could be in the
range of 5 to 20 ug/L (Krasner et al.,
1993). However, the proposed
regulation for bromate would result in
either (1) some utilities choosing not to
employ ozonation or (2) other utilities
operating the ozonation process in a
manner which would reduce bromate
formation. For example, demonstration-
scale tests of the ozonation of a surface
water containing bromide at
approximately the 90th to 95th
percentile level of occurrence (i.e., 0.17
to 0.49 mg/L) at an ambient pH of 8
produced from <3 to 25 ug/L bromate,
depending on the amount of ozone
added (Gramith et al., 1993). In the
latter tests, Giardia inactivations from
ozonation of from 0.5 to 3 logs were
achieved. When the pH of ozonation
was reduced to about 6, bromate
formation in this water was consistently
below 10 ug/L and often below 5 ug/L.
In addition, Giardia inactivations of up
to 4 logs were achieved at this pH.
c. Potential DBFs not regulated at this
time.—i. Aldehydes, ketones, peroxides,
and formation of precursors for other
DBFs—national occurrence. Miltner and
co-workers ozonated a surface water
with 1.4 mg/L TOG at various ozone
doses up to an ozone-to-TOC ratio of
2.8:1 mg/mg (Miltner et al., Nov. 1992).
They found that the formation of the
three most-prevalent aldehydes
(formaldehyde, glyoxal, and methyl-
glyoxal) continued to increase as the
ozone dose increased, arid that these
three aldehydes had not reached
maximum yields before the highest
ozone-to-TOC ratio was tested.
Weinberg and colleagues studied the
formation of aldehydes at 10 North
American utilities at pilot- and full-
scale plants (Weinberg et al., 1993). The
interquartile range (i.e., 25th to 75th
percentile occurrence) of formaldehyde
was 11 to 20 ug/L, while the sum of
aldehydes tested had an interquartile
range of 23 to 47 ug/L. The utility with
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38737
the highest TOG in the 10-utility study
(8.1 mg/L in the ozonator influent)
represented a maximum outlier in
aldehyde production (i.e., about 70 ug/
L formaldehyde and up to 150 ug/L of
summed aldehydes). The minimum
outlier was the summer testing of a low-
TOC water (1.0 mg/L) which received an
applied ozone dose of 1.0 mg/L. When
the occurrence data were normalized to
TOG level, the interquartile ranges were
3.9 to 8.4 ug formaldehyde per mg TOG
and 9 to 20 ug of summed aldehydes per
mg TOG. This normalization brought the
water with the highest TOC into the
interquartile range. When the aldehyde
formation was further normalized for
the ozone dose, the interquartile ranges
per unit TOC and per ozone dose were
1.2 to 4.2 ug formaldehyde/(mg * mg/L)
and 2.9 to 11 ug summed aldehydes/(mg
* mg/L). With this latter normalization,
the high-TOC water dropped to almost
the minimum outlier. Because the ozone
demand of the latter water exceeded the
dose, it is possible that more aldehydes
could have been produced with a higher
dose. These limited data suggest that
either TOC or ozone dose can be the
limiting factor in aldehyde production
(i.e., for the low-TOC water in the
summer testing and the high-TOC water,
respectively).
While ozonation can produce
significant levels of aldehydes, the
presence of these ozone by-products in
the distribution system are highly
dependent on whether the filters
downstream of ozone are operated
biologically (i.e., no secondary
disinfectant is applied before the filters),
as well as the choice of filter media and
filtration rate (or more exactly, the
empty bed contact time [EBCT] in the
filter media) (Miltner et al., Nov. 1992,
Weinberg et al., 1993, and Krasner et al.,
May 1993).
Using a bioreactor, many aldehydes
can be quantitatively removed (Miltner
et al., Nov. 1992). In pilot- and full-scale
studies, formaldehyde tended to be the
most biodegradable of the aldehydes
tested, while the glyoxals, in some
instances, were somewhat recalcitrant
(Weinberg et al., 1993, and Krasner et
al., May 1993). These aldehydes
(including the glyoxals) were typically
best removed at utilities in which
granular activated carbon (GAG)
contactors or filters were employed,
even when the GAG was removing little
or no TOC (Weinberg et al., 1993, and
Krasner et al., May 1993). When
anthracite coal/sand filters were used
without a secondary disinfectant before
filtration, these aldehydes could be
removed to varying degrees with the
best results at low filtration rates (or
high EBCTs) (Weinberg et al., 1993, and
Krasner et al., May 1993). Because part
of the proposed D/DBP Rule sets criteria
for biological filtration following
ozonation of raw water, it is anticipated
that the occurrence of aldehydes, while
not directly regulated, can be minimized
in the finished'Water.
Other oxygenated organic ozone by-
products (e.g., ketoacids (Xie et al.,
1992) and organic peroxides (Weinberg
et al., 1991) can also be reduced during
biological filtration. The use of
biological treatment for drinking water
treatment in the United States is
currently very limited, while in Europe
such processes are more common.
However, research into the
incorporation of biological filtration in
the United States is now being
extensively studied and its
implementation is becoming more
common (Weinberg et al., 1993). In
addition, some ozone by-products are
relatively unstable (e.g., peroxides and
epoxides) and may not persist in the
finished water. Furthermore, because
hydrogen peroxide can reduce chlorine
to chloride ions (Connick, 1947), the
addition of free chlorine should destroy
a peroxide residual (Weinberg et al.,
1991). Finally, because GAG can reduce
oxidant residuals, GAG downstream of
ozone should be able to destroy
hydrogen peroxide.
While ozone can partially destroy the
precursors of some THMs and HAAs
(Miltner et al., 1992), it can increase the
formation potential of other DBFs (e.g.,
chloropicrin (Miltner et al., Nov. 1992
and Hoigne et al., 1988) and chloral
hydrate (Mcknight et al., 1992)).
However, Miltner and co-workers found
that ozonation followed by biotreatment
reduced chloropicrin formation
potential (Miltner et al., 1992).
McKnight and Reckhow found that if
acetaldehyde—an ozone by-product—
undergoes an initial chlorine
substitution, then the reaction should
rapidly proceed to form the
trichlorinated product chloral hydrate
(Mcknight et al., 1992). Because
acetaldehyde can be reduced during
biological filtration (Miltner et al., Nov.
1992 and Weinberg et al., May 1993),
this should minimize subsequent
formation during postchlorination.
Jacangelo and colleagues found that
when biological filtration was not
practiced, preozonation increased
chloral hydrate formation in
postchlorinated waters (Jacangelo et al.,
1989). However, these researchers also
observed that chloral hydrate
production for systems using
preozonation/postchloramination was
lower than that for systems using
chlorination only (Jacangelo et al.,
1989). To avoid by-products of
secondary disinfection, more research
into the relative merits of biological
filtration and/or postchloramination for
systems using preozonation must be
pursued.
d. Concerns with AOCin high TOC
source waters. Typically a high-TOC
water will have a high oxidant demand.
Thus, ozonating a high-TOC water has
the potential to form a higher level of
ozone by-products, such as aldehydes
(see Section VI.C.l.c. above). In
addition, there are concerns that more
AOC can be formed in such a water.
Amy and colleagues found that
biodegradable organic carbon (BDOC)
correlated well (r2=0.92) with the TOC
level of ozonated waters (Amy et al.,
1992). On the average, 28 percent of the
TOC was present as BDOC after
ozonation (typical ozone dose of 1:1 mg
ozone/mg TOC). However, the
correlation between BDOC and AOC for
the six waters studied was poor,
suggesting that individual source waters
may have a unique relationship between
these constituents.
While there is a concern over forming
AOC, BDOC, aldehydes, etc., during
ozonation, current research is
examining the ability of the treatment
plant to remove significant portions of
the biodegradable organic matter (e.g.,
through biological filtration). A question
remains as to what level AOC needs to
be reduced to minimize biological
regrowth.
e. Removal of by-products. Ozonated
waters may require GAG treatment or
other biological processes for removal of
aldehydes, AOC, other DBFs. There are
concerns that switching to ozone may
increase the availability of AOC and
potentially increase bacterial
populations in distribution systems, hi
addition, some ozone by-products (e.g.,
certain aldehydes and organic
peroxides) may be regulated at a future
date when more data become available
(USEPA, 1991).
During the 35-utility DBF study
performed in 1988-1989, two utilities
switched to ozonation as the primary
disinfectant (Metropolitan Water
District of So. Calif et al., 1989 and
Jacangelo et al., 1989). Both utilities
applied a secondary disinfectant
(chlorine or chloramines) before the
filtration step. At both plants, ozonation
produced formaldehyde and
acetaldehyde (aldehydes for which ,
analytical methodology was being used),
the levels of which were undiminished
in passing through the filters and
distribution system. Subsequently, a
North American study of 10 utilities
that used ozonation at a pilot- and/or
full-scale in 1990-1991 (Glaze et al.,
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38738 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
1993, in press; and Weinberg et al.,
1993) indicated the following:
• Aldehydes and aldo-ketones—
especially formaldehyde, glyoxal, and
methyl-glyoxal—were ubiquitous ozone
DBFs, formed in all the surveyed
utilities.
• These compounds were removed to
varying extents by filters which were
allowed to operate in a biological mode
(i,e., secondary disinfection was
postponed until after filtration).
• In studies where formaldehyde and
acetaldehyde were efficiently removed,
glyoxals were sometimes removed to a
lesser extent.
• These aldehydes were typically best
removed at utilities in which GAG
contactors or filters were employed,
even when the GAG was removing little
or no TOG.
• However, GAG filters in this survey
were almost always operated at lower
filtration rates (1.0 to 5.0 gpm/sf),
whereas anthracite coal filters were
typically operated at higher filtration
rates (3.8 to 13.5 gpm/sf).
• In addition, secondary disinfection,
which was sometimes applied before
the anthracite filters, was never applied
before the GAG filters in this survey.
Because surveys provide a "snapshot"
of treatment practices in use, other
investigators have performed studies to
better assess individual parameters that
impact the efficacy of biological
filtration. Merlet and co-workers (Merlet
et al., 1991) evaluated biological
activated carbon (BAG) for the reduction
in BDOC produced by ozonation. As the
EBCT of the BAG was varied up to 25
min, BDOC removal increased up to a
point, at which its efficacy plateaued
out. LeChevallier and colleagues
(LeChevallier et al., 1992) also observed
that increased EBCTs increased AOC
removal; however, AOC levels of <100
|ig/L could be achieved with a 5- to 10-
min EBCT. In addition, the latter
researchers found that the application of
free chlorine to GAG filters did not
inhibit AOC removal, whereas the
application of chloramines showed a
slight inhibitory effect. Furthermore,
LeChevallier arid colleagues found that
GAG filter media supported larger
bacterial populations and provided
better removal of AOC than
conventional filter media (LeChevallier
et al., 1992).
Miltner and co-workers (Miltner et al.,
1992) found that biological activity was
established within approximately one
week, as evidenced by 90-percent
removal of certain aldehydes. However,
approximately 80 days of Filter use were
required before half of the AOC could be
removed. Price and colleagues (Price et
al., 1992) found that dual-media filters
(anthracite coal/sand) performed as well
as GAG after time, especially as the
water temperature went up. The latter
researchers also observed that GAG/
sand filters operating at 1, 3, and 5 gpm/
sf provided similar removals of AOC.
Reckhow and co-workers (Reckhow et
al., 1992) found that GAC/sand filters
removed less AOC and aldehydes when
backwashed with chlorinated water. As
the filtration rate increased, filters
backwashed with chlorinated water
achieved lower removals, whereas
filters backwashed with non-chlorinated
waters were less impacted by filtration
rate.
Clearly, many researchers are
investigating means of optimizing the
removal of AOC, BDOC, and aldehydes
produced by ozonation through
biologically active filtration. Because
many plants that are switching to
ozonation are retrofitting existing
treatment plants, it is desirable to
achieve biological filtration with the
same filters used for turbidity removal.
In pilot-plant testing of ozonation at
Metropolitan Water District of Southern
California (Metropolitan Water District
of So. Calif, et al., 1991), dual-media
(anthracite/sand) filters operating at 3
gpm/sf were evaluated, as these were
representative of the operation at some
of Metropolitan's full-scale facilities.
When secondary disinfection was
delayed until after filtration, these filters
were able to remove AOC,
formaldehyde, and acetaldehyde
(Paszko-Kolva et al., 1992 and
Metropolitan Water District of So. Calif.
et al., 1991). However, when the
aldehyde analysis was expanded to
include glyoxals at the end of the
project, limited testing indicated that
glyoxals were not well removed by these
filters (Metropolitan Water District of
So. Calif, et al., 1991). In addition, there
were concerns that because some of
Metropolitan's facilities operate with
higher filtration rates (up to 9 gpm/sf),
this could impact the biological
filtration process.
A new pilot-plant study was initiated
to evaluate biological filtration for the
removal of AOC and aldehydes,
including the glyoxals . Analyzing for a
wide range of aldehydes (i.e.,
monoaldehydes, such as formaldehyde;
the dialdehyde glyoxal; and the aldo-
ketone methyl-glyoxal) allowed for a
more thorough investigation into the
efficacy of biological filtration. Not only
may these individual carbonyls pose
different health concerns (USEPA, June
1991), but they also have the potential
to represent organic matter which is
relatively biodegradable (i.e.,
formaldehyde) and which is potentially
somewhat recalcitrant to biological
filtration (i.e., the glyoxals).
The latter pilot testing indicated that
biological activity was established
sooner on slow-filtration-rate filters
with a 4.2-min EBCT, but the high-
filtration-rate filters with 2.1- and 1.4- :
min EBCTs eventually were able to
achieve comparable capabilities for the
removal of AOC and most aldehydes
(Krasner et al., May 1993 and Paszko-
Kolva et al., 1992). However, even 111
days of operation did not allow the
anthracite coal filter operating with a
1.4-min EBCT an opportunity to
demonstrate consistently high removal
(80 percent) of the glyoxals. The latter
filter, though, did remove significant
amounts of AOC and formaldehyde.
Glyoxals were well removed on the
anthracite filter operated at a low
filtration rate (with a 4.2-min EBCT) or
the GAG filters operated at either low or
high filtration rates (with 4.2- and 1.4-
min EBCTs, respectively). Note that
these filters were able to remove
aldehydes and AOC efficiently at
relatively short EBCTs and that the
higher EBCTs associated with GAG
contactors were not required.
Use of a biological filter can produce
a more biologically stable water and can
minimize the presence of aldehydes and
other ozone by-products (e.g., ketoacids
(Xie et al., 1992) and peroxides
(Weinberg et al., 1991)) of potential
health and regulatory concern. As the
studies to date demonstrate, the
appropriate choice of media and
filtration rate can ensure that AOC and
specific organic ozone by-products can
be significantly reduced in
concentration.
2. Chlorine Dioxide Byproducts
Chlorine dioxide is used as an
alternative disinfectant to chlorine to
treat drinking water for THM control,
taste-and-odor control, oxidation of iron
and manganese, and oxidant-enhanced
coagulation-sedimentation (Aieta et al.,
1986). In 1977,103 facilities in the U.S.
were using or had used chlorine dioxide
(Symons et al., 1979). Currently, 500 to
900 municipalities in the U.S. use
chlorine dioxide, although some use •
was only seasonal (Private
communication with Chemical
Manufacturers' Association, 1993). In
Europe, several thousand utilities have
used chlorine dioxide, mostly to
maintain a disinfectant residual in the
distribution system (Aieta et al., 1986).
Chlorine-free chlorine dioxide does
not react with natural organic matter
such as humic and fulvic acids to form
THMs (Symons et al., 1981). Studies
show that the TOX formed with
chlorine dioxide is from 1 to 25 percent
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38739
of the TOX formed with chlorine under
the same reaction conditions (Aieta et
al., 1986 and Symons et al., 1981).
Before the introduction of high-yield
chlorine dioxide systems that were
capable of producing nearly chlorine-
free chlorine dioxide solutions,
significant amounts of chlorine could be
present in the chlorine dioxide
solutions used in water treatment.
Chlorine dioxide has been used
effectively by many utilities in order to
comply with the 1979 THM Rule (Aieta
et al., 1986 and Lykins et al., 1986).
However, when chlorine dioxide is
used, the inorganic by-products chlorite
and chlorate are produced. During water
treatment, approximately 50-70 percent
of the chlorine dioxide reacted will
immediately appear as chlorite and the
remainder as chlorate (Aieta et al.,
1984). The residual chlorite continues to
degrade in the water distribution system
in reactions with oxidizable material in
the finished water or in the distribution
system. In a study of five U.S. utilities
employing chlorine dioxide, median
chlorite and chlorate concentrations in
the distribution systems tested typically
ranged from 0.4 to 0.8 mg/L and
between 0.1 to 0.2 mg/L, respectively
(Gallagher et al., 1993, in press). For the
latter systems, the 75th percentiles for
chlorite concentrations ranged from 0.4
to 1.4 mg/L.
Data for up to 17 utilities in EPA
Region 6 who employ chlorine dioxide
were obtained (Personal
communication, Novatek 1993). In
many instances, data for chlorite
occurrence on a monthly basis were
available. As an example, for June 1992
chlorite ranged from 0.4 to 1.2 mg/L,
while in January 1993 chlorite was at
values of 0.2 to 0.8 mg/L. The higher
values in June may have been due, in
part, to the need for more chlorine
dioxide in warmer months to meet the
oxidant demand of the water. When the
data are examined quarterly (e.g.,
quarter 1 is January through March),
Figure VI-14 shows that the highest
occurrence for chlorite in the systems
sampled in EPA Region 6 was during
the spring and summer seasons.
BILLING CODE S560-60-P
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38741
a. Potential chlorine dioxide DBFs not
regulated at this time. This proposed
regulation will not include an MCLG or
MCL for chlorate. Insufficient data exist
at this time to develop an MCLG for
chlorate (Orme-Zavaleta, 1992). If
chlorate is regulated in the future,
systems which use hypochlorination
will also need to monitor for this by-
product (Bolyard et al., August 1992).
Limited testing shows that chlorine
dioxide can form low concentrations of
aldehydes (Weinberg et al., 1993).
However, studies also demonstrate that
chlorine can produce aldehydes
(Krasner et al., August 1989 and
Jacangelo et al., 1989).
3. Chloramination Byproducts
a. Cyanogen chloride. Typically,
chloramines do not react to form
significant levels of THMs and other
chlorinated DBFs. Because
monochloramine (the predominant form
of chloramines in most drinking-water
applications) is a much less potent
oxidant or chlorinating agent than
chlorine, the by-products of
monochloramine reactions with organic
substances are much less extensively
oxidized or chlorinated (Scully, 1990).
Nevertheless, chloramines appear to
chlorinate natural organic matter
sufficient to produce low levels of TOX.
During the 35-utility DBF study, 14 of
the 35 utilities surveyed were utilizing
chloramines (Krasner et al., 1989). Ten
of these had free-chlorine contact time
prior to ammonia addition, and the
remaining four added chlorine and
ammonia concurrently. The median
value of cyanogen chloride in utilities
that used only free chlorine was 0.4 ug/
L. Utilities that pre-chlorinated and
postammoniated had a cyanogen
chloride median of 2.2 ug/L. The 95-
percent confidence intervals around the
medians indicated that these two
disinfection schemes were statistically
different with regard to the cyanogen
chloride levels detected in the clearwell
effluents. Krasner and co-workers found
that a number of parameters affect the
formation of cyanogen chloride during
chloramination (Krasner et al., 1991).
b. Potential other chloramination
DBFs not regulated at this time. Studies
have demonstrated the formation of
organochloramines by the use of
inorganic chloramines in the
disinfection of water (Scully, 1982).
Recently, an analytical method has been
developed to distinguish organic
chloramines from the inorganic species
(Jersy et al., 1991). Monochloramine has
been shown to react with aldehydes to '
yield nitriles (Le Cloirec et al., 1985).
The presence of cyanogen chloride and
low concentrations of TOX in
chloraminated waters indicate a need to
further identify chloramine by-products.
VII. General Basis for Criteria of
Proposed Rule
A. Goals of Regulatory Negotiation
In the Federal Register "Notice of
Intent to Form an Advisory Cbmmitee to
Negotiate the Disinfection Byproducts
Rule and Announcement of Public
Meeting" (USEPA, 1992), EPA
identified key issues to be addressed
and resolved during the conduct of the
negotiation. They were:
—What disinfectants and disinfection
byproducts present the greatest risks,
and how should they be grouped for
Xlation?
ch categories of public water
suppliers should be regulated?
—Should the regulation establish
Maximum Contaminant Levels or be
technology driven?
—How effective are advanced
technologies and alternative
disinfectants in the removal of
disinfectants, disinfection byproducts,
and microbial risks?
—How should disinfectants,
disinfection byproducts, and
microbial risks be compared, given
differences in the type and certainty
of their effects?
—What levels of disinfectant,
disinfection byproduct, and microbial
risks are acceptable, and at what cost?
—How should the achievement of
acceptable levels of risks be defined?
—How might risk-risk models be used,
if at all, in the development of
Maximum Contaminant levels within
the current regulatory schedule?
—How should the needs of sensitive
populations be taken into account in
the rule?
—How should Best Available
Technology be defined for the
removal of disinfectants and
disinfection byproducts?
—Should a comprehensive disinfectant/
disinfection byproduct regulation be
issued in 1995, or should the control
of certain disinfectants/disinfection
byproducts be deferred until research
confirms the safety of alternative
treatment methods?
—How should affordability be factored
into judgements regarding feasibility
of treatment techniques?
—How should monitoring requirements
be defined?
—How can the rule be drafted to be
most easily understood by both State
regulators and small system
operators?
In addition to the issues identified in
the Federal Register that needed to be
resolved, potential negotiating
committee members identified the
following additional issues (RESOLVE,
1992a):
—How can the rule be drafted to be
most easily accepted and
understandable by the general public?
—Is there a need for further regulation
of DBFs?
—How should the rule account for
differences in size of a system (i.e.,
number of people served) or a
system's water source?
—How should the rule account for
differences in type of disinfection
technology and quality of source
water?
—How should the rule account for the
particular characteristics of some
water distribution systems that
complicate efforts to minimize DBF
formation?
—How should the rule account for the
cross-media environmental impacts
and ecological risks associated with
DBF control technologies?
—Will the DBF rule be compatible with
other EPA regulations (e.g.,
groundwater, lead, surface water)?
Will current exposure and occurrence
data change with implementation of
other rules? Are EPA's models good
enough to predict the effects of other
regulations on the occurrence of
various DBFs in drinking water?
—To what extent are watershed
protection and maintenance of source
water quality useful strategies to
achieve risk reduction?
—How should analytic methods be
defined? Should DBF content be
monitored at the treatment plant,
within the distribution system, or at
. the tap?
—How much has already been achieved
by the THM rule? How can this be
taken into account in the assumptions
for this rule?
—What types of research on DBF effects
and controls are presently being or
should be conducted in the future?
—What-are the assumptions that
underlie EPA's description of
acceptable risk from exposure to
microbes and DBFs in drinking water?
Is there a safe level for human
exposure to DBFs? How certain are
EPA's models? Should EPA's cancer
risk assessment policies be reopened
in this forum?
—How can the rule be most easily
implemented?
B. Concerns for Downside Microbial
Risks and Unknown Risks From DBFs of
Different Technologies
This rule is intended to limit
concentrations of disinfectants and their
byproducts in public water systems.
However, there is the possibility that
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 7 Proposed Rules
reducing the level of disinfection
without adequately addressing
microbial risk may result in increasing
microbial exposure. The Negotiating
Committee wanted to ensure that
drinking water utilities can effectively
provide treatment that controls hoth
disinfectants and their byproducts and
microbial contaminants. The
Negotiating Committee believes it
accomplished this goal by developing
an additional proposed rule (Enhanced
Surface Water Treatment Rule, proposed
elsewhere in today's Federal Register)
to control the level of microbial risk.
If disinfection is decreased to reduce
byproduct formation, there is the
possibility that risk from pathogenic
organisms could increase. This
relationship is not well understood,
particularly as it applies to the many
different source waters and the various
disinfectants that may be used. To better
understand and characterize this risk-
risk relationship, EPA proposed an
Information Collection Rule [59 FR
6332] to gather needed information.
In addition to concerns about
increasing microbial risk, the
Negotiating Committee had concerns
about large numbers of systems
switching from chlorine to an
alternative disinfectant (e.g., ozone,
chlorine dioxide, chloramines) whose
disinfection efficacy and byproducts
(both occurrence and health effects) are
not as well understood as those of
chlorine. Chlorine has been studied far
more than the alternative disinfectants;
this additional study may account for
some or all of the differences in known
health risks. Chlorine has proved to be
an effective disinfectant under a wide
range of conditions. For conditions
where chlorine was not adequate as a
disinfectant (e.g., high TTHM formation
potential or high pH), systems have
changed to other disinfectants.
However, the Committee does not want
to force large numbers of additional
systems to switch disinfectants before
more information is available, since
research has indicated that health risks
from alternative disinfectants may be
significant (e.g., bromate formation from
ozonation).
C. Ecological Concerns
In addition to concerns about risk-risk
tradeoffs and risks from alternative
disinfectants, the Technologies Working
Group (TWG) identified ecological risks
that could result from a change in
technology. These concerns included:
—Moving the point of chlorination may
result in problems with zebra mussel
infestation in the intake pipe.
—Increasing addition of coagulants may
result in increased sludge production
and attendant disposal problems.
—Changing to ozone may require large
amounts of additional energy
(electricity) for ozone generation.
—Adding GAG makes construction of
on- or off-site GAG regeneration
facilities necessary.
—Adding membranes may require large
amounts of additional energy
(electricity) for pressure, may cause
problems in disposing of brine in
some areas, and may not be feasible
in water-short areas.
D. Watershed Protection
One issue that the Negotiating
Committee considered throughout the
negotiation process was the relationship
and role of watershed protection to
these proposed regulations. The
Committee desired to promote
watershed protection and to provide
incentives to establish new watershed
protection programs and to improve
existing ones. These desires were
prompted by the benefits that watershed
protection provides not only for
disinfectant byproduct control, but for a
wide range of potential drinking water
contaminants and related water supply
and environmental issues.
Watershed protection reduces
microbial contamination in water
sources, and hence the amount of
disinfectant needed to reduce microbial
risk to a specified level in a finished
water supply. It also reduces the level
of turbidity, pesticides, volatile organic
compounds, and other synthetic organic
drinking water contaminants found in
some water sources. Precursor (material
that reacts with disinfectants to form
disinfection byproducts) levels can be
lowered, which may lower the levels of
DBPs formed. Watershed protection
results in economic benefits for water
supply systems by minimizing reservoir
sedimentation and eutrophication and
reducing water treatment operation and
maintenance costs. Moreover, adequate
watershed protection in many cases will
reduce overall organic matter (TOG) in
source water and therefore reduce DBP
formation. Watershed protection also
provides other environmental benefits
through improvements in fisheries and
ecosystem protection.
The types of watershed programs that
the Committee wished to encourage are
those that consider agricultural controls,
silvicultural controls, urban non-point
controls, point discharge controls, and
land use protections which are tailored
to the environmental and human
characteristics of the individual
watershed. These characteristics include
the hydrology and geology of the
watershed, the nature of human sources
of contaminants, and the legal, financial
and political constraints surrounding
entities which have control of aspects of
the watershed.
The Committee considered options for
providing incentives for watershed
protection programs directly within
these proposed regulations through such
things as reduced monitoring or reduced
requirements based on the existence of
a watershed program. However, unlike
other potential contaminants whose
introduction can be directly prevented
by watershed protection, disinfectant
byproducts do not directly enter the
water source, but are formed in the
water treatment process.
Because of general agreement that
watershed protection had qualitative
benefits, the Committee agreed that
watershed protection was desirable and
included several indirect incentives for
watershed protection within these
proposed regulations. The TOG levels
which trigger enhanced coagulation
requirements under the proposed
Disinfectant Byproducts Rule and which
trigger pilot studies under the proposed
Information Collection Rule are those
that are typically achieved in water
supplies with protected watersheds.
Systems which meet the source water
criteria for unfiltered systems under the
Surface Water Treatment Rule do not
have to conduct virus monitoring under
the proposed Information Collection
Rule [59 FR 6332], whether the system
is filtered or unfiltered. These systems
are likely to have watershed protection
Erograms. The proposed Enhanced
urface Water Treatment Rule
(proposed elsewhere in today's FR)
contains proposed options which
require less water treatment for water
sources with lower levels of .microbial ,
contamination. Such sources can
achieve those levels through watershed
protection programs. The Negotiating
Committee believes that these indirect
incentives will result in enhancements
to watershed protection efforts in many
systems.
E. Narrowing of Regulatory Options
Through Reg-Neg Process
The Negotiating Committee
considered a wide range of regulatory
options during the development
process. The initial approach was to
come up with several straw regulation
outlines. These could generally be
classified as being either (1) MCL
regulations (in which compliance would
be determined by meeting MCLs for
specified disinfectants and DBPs) or (2)
treatment technique regulations (in
which compliance would be determined
by meeting specified treatment
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38743
parameters or surrogate compound
maximum levels).
The Negotiating Committee
considered two categories of MCL
options. The first was MCLs for groups
of related DBFs, such as TTHMs and
HAAS. Advantages of this approach
included regulatory simplicity, •
avoidance of tinkering with disinfection
operations to address minor
exceedances of MCLs of individual
DBFs, and the complex, not-well-
understood production relationships
among related DBFs. MCLs for
individual compounds were also
considered. Some members of the
Negotiating Committee felt that
individual MCLs approach best met the
intent of the SDWA by regulating
specific, measurable chemicals.
The Negotiating Committee also
considered treatment technique options.
The first would have required systems
to reduce the levels of DBF precursors
(DBPP)—compounds that react with
disinfectants to form DBFs, such as total
organic carbon—to less than some
specified level before adding any
disinfectant. This approach may be
inappropriate for two reasons. First,
systems have different levels and types
of precursors; using a surrogate such as
TOG as a trigger may result in
tremendous variation in DBF levels
from system to system due to the
disinfectant used, composition and
reactivity of the DBPP, and presence of
other DBPPs such as bromide. Also,
many systems must add a disinfectant
as an oxidant immediately at the source
water intake to control water quality
problems (e.g., zebra mussels, iron).
The second treatment technique
option was enhanced coagulation,
which is the addition of higher levels of
coagulant than required to meet
turbidity limits for the purpose of
removing higher levels of DBPPs.
However, enhanced coagulation is
practical only in systems that operate
conventional filtration treatment.
Systems using other filtration
technologies (e.g., direct filtration, slow
sand filtration)-or that do not filter (such
as most ground water systems) cannot
operate enhanced coagulation without
addition of conventional filtration
treatment. Also, some systems have
water that cannot be effectively treated
by enhanced coagulation.
A final option considered was a "risk
bubble". Under this option, systems
would be required to keep the sum of
estimated risks from levels of specified
DBFs under a certain risk level.
However, this option was quickly
dropped because of many problems,
including failure to account for
potential synergisms and antagonisms
between DBFs, data gaps, and the
evolving nature of risk assessment.
VIII. Summary of the Proposed
National Primary Drinking Water
Regulation for Disinfectants and
Disinfection Byproducts
The Disinfectants'and Disinfection
Byproducts Rule (D/DBPR) proposal
addresses a number of complex and
interrelated drinking water issues. EPA
must balance the health risks from
microbial organisms (such as Giardia,
Cryptosporydium, bacteria, and viruses)
against risks from compounds formed
during water disinfection. Most of the
DBFs that have been measured in
drinking water are byproducts from the
use of chlorine. While there is some
occurrence information on even these
DBFs, the extent of exposure for systems
that have not reported DBF levels can
only be estimated using available
information on TOG levels and the
available models. A subset of DBFs has
been studied to determine whether long-
term exposure to them presents a risk to
public health. The current lack of data
on certain relatively unstudied DBFs
and on the effectiveness of certain
treatment techniques has made
regulatory decisions more difficult.
Water treatment facilities and their
customers potentially face significant
changes to treatment operations in
response to the proposed regulations
and will have to pay more for water
treatment. For these reasons, EPA is
proposing the D/DBPR in two stages.
The two-stage process allows the best
use of information available during the
regulatory development.
The Stage 1 D/DBPR, which will be
proposed, promulgated, and
implemented concurrently with the
Interim Enhanced Surface Water
Treatment Rule, will:
—Lower the maximum contaminant
level (MCL) for total trihalomethanes
(the only DBFs currently regulated);
—Add new disinfectants and DBFs for
regulation; and
—Extend regulations to include all
system sizes.
For the Stage 2 D/DBPR, EPA will
collect data on parameters that
influence DBF formation and
occurrence of DBFs in drinking water
through an Information Collection Rule
for large community water systems (59
FR 6332). Based on this information and
new data generated through research,
EPA will reevaluate the Stage 2
regulations and repropose, as
appropriate, depending on criteria
agreed on in a second regulatory
negotiation (or similar rule development
process). In addition, Stage 2 D/DBPR
MCLs for TTHMs and HAAS are being
proposed in this Federal Register
notice.
A. Schedule and Coverage
The requirements of this rule will
apply to community water systems
(CWSs) and nbntransient
noncommunny water systems
(NTNCWSs) that treat their water with
a chemical disinfectant for either
primary or residual treatment. In
addition, MRDL and monitoring
requirements for chlorine dioxide will
also apply to transient noncommunity
water systems because of the short-term
health effects from high levels of
chlorine dioxide (see section V. for a
detailed discussion of health effects).
The effective dates for compliance
with these requirements will be
staggered based on system size and raw
water source. The schedule is
summarized in Table VIII-1. Members
of the Negotiating Commitee reserved
the right to comment on the timetable
for promulgation of the final rule and on
the compliance dates of the rule.
—Subpart H systems (systems that use
surface water or ground water under
the direct influence of surface water,
in whole or in part) serving 10,000 or
more persons must comply with the
Stage 1 requirements beginning 18
months from promulgation.
—Subpart H systems serving fewer than
10,000 persons must comply with the
Stage 1 requirements beginning 42
months from promulgation.
—A CWS or NTNCWS using only
ground water not under the direct
influence of surface water serving
10,000 or more persons must comply
with the Stage 1 requirements
beginning 42 months from
promulgation.
—A CWS or NTNCWS using only
ground water not under the direct
influence of surface water serving
fewer than 10,000 persons must
comply with the Stage 1 requirements
beginning 60 months from
promulgation.
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TABLE Vlli-1 .—COMPLIANCE DATE OF STAGE 1 REGULATIONS FOR CWSs OR NTNCWSs
Raw water source
Surface
Surface
Ground
Ground
..,
Number of
people
served
>1 0,000
<1 0,000
>1 0,000
<1 0.000
Following promul-
gation, regulations
become effective
after
18 Months.
42 Months.
42 Months.
60 Months.
In this proposal, EPA has not
specified how monitoring and
compliance requirements should be
split among wholesalers and retailers of
water. The Agency believes that
§ 141.29 (consecutive systems) provides
the State adequate flexibility and
authority to address individual
situations. EPA solicits comment on
whether any specific federal regulatory
requirements are necessary to handle
such situations. If so, what are they?
B. Summary of DBF MCLs, BATs, and
Monitoring and Compliance
Requirements
EPA is proposing to amend Subpart G,
Maximum Contaminant Levels, by
adding § 141.64, Maximum
Contaminant Levels for Disinfection
Byproducts. Section 141.64 lists the
proposed MCLs for total •
trihalomethanes (TTHMs—i.e., the sum
of the concentrations of chloroform,
bromodichloromethane,
dibromochloromethane, and
bromoform), haloacetic acids (five)
(HAAS—i.e., the sum of the
concentrations of mono-, di-, and
trichloroacetic acids and mono- and
dibromoacetic acids), bromate, and
chlorite. Routine monitoring
requirements for all DBFs arid residual
disinfectants are summarized in Table
VIII-2. Reduced monitoring
requirements for all DBFs and residual
disinfectants are summarized in Table
VIII—3. Members of the Negotiating
Committee reserved the right to
comment on the question of whether
compliance monitoring is defined as an
average of several samples across the
distribution system and over time or
whether it will be based upon
monitoring at points of maximum
residence time. See Section IX of this
notice for further discussion and EPA's
solicitation of comments on this issue.
TABLE VIII-2.—ROUTINE MONITORING REQUIREMENTS7
Requirement (ref-
erence)
TOG (141 133(bK3)) ...
TTHMs
(141.133(b)(1)(i)).
THAAs
(141.133(b)(1)(i)).
Bromate4
(141.133(b)(1)(iii)).
Chlorite5
(141.133(b)(1)(ii)).
Chlorine
(141.133(b)(2)(i)).
Chlorine dioxide5
(141.133(b)(2)(ii)).
Chloramines
(141.133(b)(2)(i)).
Location for sampling
Paired samples3 —
Only required for
plants with conven-
tional filtration
treatment.
25% in dist sys at
max res time, 75%
at dist sys rep-
resentative loca-
tions.
25% in dist sys at
max res time, 75%
at dist sys rep-
resentative loca-
tions.
Dist sys entrance
point.
1 near first cust 1 in
dist sys middle, 1
at max res time.
Same points as coli-
form in TCP.
Entrance to dist sys ..
Same points as coli-
form in TOR.
Large surface sys-
tems 1
1 paired sample/
month/ plant3.
4/plant/ quarter
4/plant/ quarter
1/month/trt plant
using O3.
3/month
Same times as coli-
form in TOR.
Daiiy/trt plant using
CIO2.
Same times as coli-
form in TOR.
Small surface sys-
tems1
1 paired sample/
month/plant3.
1 /plant/quarter6 at
maximum resi-
dence time if pop.
<500, then 1 /plant/
yr".
1 /plant/quarter6 at
maximum resi-
dence time if pop.
<500, then 1/planV
yr8.
1/month/trt plant
using 03.
3/month
Same times as coli-
form in TCR.
Daily/trt plant using
CIO2.
Same times as coli-
form in TCR.
Large ground water
systems2
NA
1 /plant/quarter6 at
maximum resi-
dence time.
1/plant/quarter6 at
maximum resi-
dence time.
1/month/trt plant
using 03.
3/month
Same times as coli-
form in TCR.
Daily/trt plant using
CIO2.
Same times as coli-
form in TCR.
Small ground water
systems2
NA.
1/plant/year6-8 at
maximum resi-
dence time during
warmest month.
1 /plant/year s'8 at
maximum resi-
dence time during
warmest month.
1/month/trt plant
using 03.
3/month.
Same times as coli-
form in TCR.
Daily/trt plant using
CIC>2.
Same times as coli-
form in TCR.
1 Large surface (Subpart H) systems serve 10,000 or more persons. Small surface (Subpart H) systems serving fewer than 10,000 persons.
2 Large systems using ground water not under the direct influence of surface water serve 10,000 or more persons. Small systems using
ground water not under the direct influence of surface water serve fewer than 10,000 persons.
3 Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1) source water TOC prior to any treat-
ment and 2) treated TOC before continuous disinfection (except that systems using ozone followed by biological filtration may sample after bio-
logical filtration) at the same time; these two samples are called paired samples.
4 Only required for systems using ozone for oxidation or disinfection.
6 Only required for systems using chlorine dioxide for oxidation or disinfection. Additional chlorine dioxide monitoring requirements apply if any
chlorine dioxide sample exceeds the MRDL.
6 Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment plant for determining the minimum
number of samples.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38745
7 Samples must be taken during representative operating conditions. Provisions for reduced monitoring shown elsewhere.
8 If the annual monitoring result exceeds the MCL, the system must increase monitoring frequency to 1/plant/quarter. Compliance determina-
tions will be based on the running annual average of quarterly monitoring results.
TABLE VIII-3.—REDUCED MONITORING REQUIREMENTS2
Requirement (reference)
Location for reduced sampling
Reduced monitoring frequency and prerequisites1
TOG (141.133(c)(3))
TTHMs and THAAs (141.133(c)(1))
Paired samples3
In dist sys at point with max res
time.
Bromate4 (141.133(c)(1))
Dist sys entrance point.
Chlorite5 (141.133(c)(1))
Chlorine, chlorine dioxide5,
chloramines (141.133(c)(2)).
NA
NA.
Subpart H systems-reduced to 1 paired sample/plant/quarter if 1) avg
TOG <2.0mg/l for 2 years or 2) avg TOC <1.0mg/l for 1 year.
Monitoring cannot be reduced if source water TOC >4.0mg/l.
Subpart H systems serving 10,000 or more-reduced to 1/plant/qtr if
1) system has completed at least 1 yr of routine monitoring and 2)
both TTHM and THAA running annual averages are no more than
40 ng/l and 30 ng/l, respectively.
Subpart H systems serving < 10,000 and ground water systems6
serving 10,000 or more-reduced to 1/plant/yr if 1) system has com-
pleted at least 1 yr of routine monitoring and 2) both TTHM and
THAA running annual averages are no more than 40 ng/l and 30
ng/l, respectively. Samples must be taken during month of warm-
est water temperature. Subpart H systems serving <500 may not
reduce monitoring to less than 1/plant/yr.
Groundwater systems6 serving <10,000-reduced to 1/plant/3yr if 1)
system has completed at least 2 yr of routine monitoring and both
TTHM and THAA running annual averages are no more than 40
ng/l and 30 ng/l, respectively or 2) system has completed at least
1 yr of routine monitoring and both TTHM and THAA annual sam-
ples are no more than 20 (ig/l and 15 ng/l, respectively. Samples
must be taken during month of warmest water temperature.
1/qtr/trt plant using O3, if system demonstrates 1) avg raw water bro-
mide <0.05 mg/l (based on annual avg of monthly samples).
Monitoring may not be reduced.
Monitoring may not be reduced.
1 Requirements for cancellation of reduced monitoring are found in the regulation.
2 Samples must be taken during representative operating conditions. Provisions for routine monitoring shown elsewhere.
3 Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1) source water TOC prior to any treat-
ment and 2) treated TOC before continuous disinfection (except that systems using ozone followed by biological filtration may sample after bio-
logical filtration) at the same time; these two samples are called paired samples.
4 Only required for systems using ozone for oxidation or disinfection.
6 Only required for systems using chlorine dioxide for oxidation or disinfection.
8 Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment plant for determining the minimum
number of samples.
1. Maximum Contaminant Levels for
Total Trihalomethanes and Total
Haloacetic Acids
The formation rate of DBFs is affected
by type and amount of disinfectant
used, water temperature, pH, amount
and type of precursor material in the
water, and the length of time that water
remains in the treatment and
distribution systems. For this reason,
the proposed rule specifies the point in
the distribution system (and in some
cases, the time) where samples must be
taken.
In this action today, EPA proposes to
lower the MCL for TTHMs from 0.10
mg/l to 0.080 mg/l. In addition, EPA
proposes to set the Stage 1 MCL for
HAAS at 0.060 mg/l. EPA believes that
by meeting MCLs for TTHMs and
HAAS, water suppliers will also control
the formation of other DBFs not
currently regulated that may also
adversely affect human health.
a. Subpart H Systems Serving 10,000
or More People.
Routine Monitoring: CWSs and
NTNCWSs using surface water (or
ground water under direct influence of
surface water) (Subpart H systems) that
"treat their water with a chemical
disinfectant and serve 10,000 or more
people must routinely take four water
samples each quarter for both TTHMs
and HAAS for each treatment plant in
the system. At least 25 percent of the
samples must be taken at the point of
maximum residence time in the
distribution system. The remaining
samples must be taken at representative
points in the distribution system. This
monitoring frequency is the same as the
frequency required under the current
TTHM rule (§ 141.30).
Reduced Monitoring: To qualify for
reduced monitoring, systems must meet
certain prerequisites (see Figure VHI-1).
Systems eligible for reduced monitoring
may reduce the monitoring frequency
for TTHMs and HAAS to one sample per
quarter. Systems on a reduced
monitoring schedule may remain on
that reduced schedule as long as the
average of all samples taken in the year
is no more than 75 percent of each MCL.
Systems that do not meet these levels
revert to routine monitoring.
Compliance Determination: A public
water system (PWS) is in compliance
with the MCL when the running annual
average of quarterly averages of all
samples, computed quarterly, is less
than or equal to the MCL. If the running
annual average computed for any
quarter exceeds the MCL, the system is
out of compliance.
FIGURE VIII-1.—ELIGIBILITY FOR RE-
DUCED MONITORING: ALL SYSTEMS
SERVING 10,000 OR MORE PEOPLE
AND SURFACE WATER SYSTEMS
SERVING 500 OR MORE PEOPLE
All systems serving 10,000 or more people,
and surface water systems serving 500 or
more people, may reduce monitoring of
TTHMs and HAAS if they meet all of the
following conditions:
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38746 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
FIGURE Vlll-1.—ELIGIBILITY FOR RE-
DUCED MONITORING: ALL SYSTEMS
SERVING 10,000 OR MORE PEOPLE
AND SURFACE WATER SYSTEMS
SERVING 500 OR MORE PEOPLE—
Continued
—The annual average for TTHMs is no
more than 0.040 mg/l.
—The annual average for HAAS is no
more than 0.030 mg/l.
—At least one year of routine monitoring
has been completed.
—Annual average source water Total Or-
ganic Carbon (TOC) level is no more
than 4.0 mg/l prior to treatment.
b. Ground Water Systems Serving
10,000 or More People.
Routine Monitoring: CWSs and
NTNCWSs using only ground water
sources not under the direct influence of
surface water that treat their water with
a chemical disinfectant and serve 10,000
or more people are required to take one
water sample each quarter for each
treatment plant in the system. Samples
must be taken at points that represent
the maximum residence time in the
distribution system. For purposes of this
regulation, multiple wells drawing raw
water from a single aquifer may, with
State approval, be considered one plant
for determining the minimum number
of samples. Systems may take additional
samples if they desire. If additional
samples are taken, at least 25 percent of
the total number of samples must be
taken at the point of maximum
residence time in the distribution
system. The remaining samples must be
taken at representative points in the
distribution system.
Reduced Monitoring: To qualify for
reduced monitoring, systems must meet
certain prerequisites (see Figure VIII-1).
Systems eligible for reduced monitoring
may reduce the monitoring frequency to
one sample per treatment plant per year.
Systems that are on a reduced
monitoring schedule may remain on
that reduced schedule as long as the
average of all samples taken in the year
is no more than 75 percent of the MCLs.
Systems that do not meet these levels
must revert to routine monitoring.
Compliance Determination: A PWS is
in compliance with the MCL when the
running annual average of quarterly
averages of all samples, computed
quarterly, is less than or equal to the
MCL. If the running annual average for
any quarter exceeds the MCL, the
system is out of compliance.
c. Subpart H Systems Serving 500 to
9,999 People.
Routine Monitoring: Systems are
required to take one water sample each
quarter for each treatment plant in the
system. All samples must be taken at the
point of maximum residence time in the
distribution system.
Reduced Monitoring: To qualify for
reduced monitoring, systems must meet
certain prerequisites.(see Figure VIII-1).
Systems eligible for reduced monitoring
may reduce the monitoring frequency
for TTHMs and HAAS to one sample per
year per treatment plant. Systems that
are on a reduced monitoring schedule
may remain on that reduced schedule as
long as the average of all samples taken
in the year is no more than 75 percent
of the MCLs. Systems that do not meet
these levels must revert to routine
monitoring.
Compliance Determination: A PWS is
in compliance with the MCL when the
running annual average of quarterly
averages of all samples, computed
quarterly, is less than or equal to the
MCL. If the average for any quarter
exceeds the MCL, the system is out of
compliance.
d. Subpart H Systems Serving Fewer,
than 500 People.
Routine Monitoring: Subpart H
systems serving fewer than 500 people
are required to take one sample per year
for each treatment plant in the system.
The sample must be taken at the point
of maximum residence time in the
distribution system during the month of
warmest water temperature. If the
annual sample exceeds the MCL, the
system must increase monitoring to one
sample per treatment plant per quarter,
taken at the point of maximum
residence time in the distribution
system.
Reduced Monitoring: These systems
may not reduce monitoring. Systems on
increased monitoring may return to
routine monitoring if the annual average
of quarterly samples is no more than 75
percent of the TTHM and HAA5 MCLs.
Compliance Determination: A PWS is
in compliance when the annual sample
(or average of annual samples, if
additional sampling is conducted) is
less than or eqUal to the MCL. If the
annual sample exceeds the MCL, the
system must increase monitoring to one
sample per treatment plant per quarter.
If the running annual average of the
quarterly samples then exceeds the
MCL, the system is out of compliance.
e. Ground Water Systems Serving
Fewer than 10,000 People. ,
Routine Monitoring: GWSs and
NTNCWSs using only ground water
sources not under the direct influence of
surface water that treat their water with
a chemical disinfectant and serve fewer
than 10,000 people are required to
sample once per year for each treatment
plant in the system. The sample must be
taken at the point of maximum
residence time in the distribution
system during the month of warmest
water temperature. If the sample (or the
average of all annual samples, when
more than the one required sample is
taken) exceeds the MCL, the system
must increase monitoring to one sample
per treatment plant per quarter.
Reduced Monitoring: To qualify for
reduced monitoring, systems must meet
certain prerequisites (see Figure VIII-2).
Systems eligible for reduced monitoring
may reduce the monitoring frequency
for TTHMs and HAAS to one sample per
three-year monitoring cycle. Systems on
a reduced monitoring schedule may
remain on that reduced schedule as long
as the average of all samples taken in
the year is no more than 75 percent of
the MCLs. Systems that do not meet
these levels must resume routine
monitoring. Systems on increased
monitoring may return to routine
monitoring if the annual average of
quarterly samples is no more than 75
percent of the TTHM and HAAS MCLs.
FIGURE VIII-2.—ELIGIBILITY FOR RE-
DUCED MONITORING: GROUND
WATER SYSTEMS SERVING FEWER
THAN 10,000 PEOPLE
Systems using ground water not under the
direct influence of surface water that serve
fewer than 10,000 people rnay reduce
monitoring for TTHMs and HAAS if they
meet either of the following conditions:
1. The average of two consecutive annual
samples for TTHMs is no more than
0.040 mg/l, the average of two consecu-
tive annual samples for HAAS is no
more than 0.030 mg/l, at least two years
of routine monitoring has been com-
pleted, and the annual average source
water Total Organic Carbon (TOC) level
is no more than 4.0 mg/l prior to treat-
ment.
2. The annual sample for TTHMs is no
more than 0.020 mg/l, the annual sam-
ple for HAAS is no more than 0.015 mg/
I, at least one year of routine monitoring
has been completed, and the annual av-
erage source water Total Organic Car-
bon (TOC) level is no more than 4.6 mg/
I prior to treatment.
Compliance Determination: A PWS is
in compliance when the annual sample
(or average of annual samples) is less
than or equal to the MCL.
f. Best Available Technology.
EPA has identified the best
technology available for achieving
compliance with the MCLs for both
TTHMs and HAAS as enhanced
coagulation or treatment with granular
activated carbon with a ten minute
empty bed contact time and 180 day
reactivation frequency (GAC10), with
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38747
chlorine as the primary and residual
disinfectant. Enhanced coagulation
means the addition of excess coagulant
for improved removal of disinfection
byproduct precursors by conventional
filtration treatment.
2. Maximum Contaminant Level for
Bromate
Bromate is one of the principal
byproducts of ozonation in bromide-
containing source waters. The proposed
MCL for bromate is 0.010 mg/1.
Routine Monitoring: CWSs and
NTNCWSs using ozone, for disinfection
or oxidation, are required to take at least
one sample per month for each
treatment plant in the system using
ozone. The sample must be taken at the
entrance to the distribution system
when the ozonation system is operating
under normal conditions.
Reduced Monitoring: If a system's
monthly measurements for one yea?
indicate that the average raw water
bromide concentration is less than 0.05
mg/1, the system may reduce the
monitoring frequency to once per
quarter.
Compliance Determination: A PWS is
in compliance if the running annual
average of samples, computed quarterly,
is less than or equal to the MCL.
Best Available Technology: EPA has
identified the best technology available
for achieving compliance with the MCL
for bromate as control of ozone
treatment process to reduce production
of bromate.
3. Maximum Contaminant Level for
Chlorite
Chlorite is an inorganic DBF formed
when drinking water is treated with
chlorine dioxide. The proposed MCL for
chlorite is 1.0 mg/1.
Routine Monitoring: CWSs and
NTNCWSs using chlorine dioxide for
disinfection or oxidation are required to
take three samples each month in the
distribution system. One sample must
be taken at each of the following
locations: as close as possible to the first
customer, in a location representative of
average residence time, and as close as
possible to the end of the distribution
system (reflecting maximum residence
time in the distribution system).
Reduced monitoring: Systems
required to monitor for chlorite may not
reduce monitoring.
Compliance Determination: A PWS is
in compliance if the monthly average of
samples is less than or equal to the
MCL.
Best Available Technology: EPA has '
identified as the best means available
for achieving compliance with the
chlorite MCL as control of treatment
processes to reduce disinfectant
demand, and control of disinfection
treatment processes to reduce
disinfectant levels.
C. Summary of Disinfectant MRDLs,
BATs, and Monitoring and Compliance
Requirements
Disinfectants are added during water
treatment to control waterborne
microbial contaminants. Some residual
disinfectants will remain in water after
treatment. MRDLs protect public health
by setting limits on the level of residual
disinfectants in drinking water. MRDLs
are similar in concept to MCLs—MCLs
set limits on contaminants and MRDLs
set limits on residual disinfectants.
MRDLs, like MCLs, are enforceable.
1. MRDL for Chlorine
Chlorine is a widely used and highly
effective water disinfectant. The
proposed MRDL for chlorine is
4.0 mg/1.
Routine Monitoring: As a minimum,
CWSs and NTNCWSs must measure the
residual disinfectant level at the same
points in the distribution system and at
the same time as total colifprms, as
specified in § 141.21. Subpart H systems
may use the results of residual
disinfectant concentration sampling
done under the SWTR (§ 141.74(b)(6) for
unfiltered systems, § 141.74(c)(3) for
systems that filter) in lieu of taking
separate samples.
Reduced monitoring: Monitoring for
chlorine may not be reduced.
Compliance Determination: A PWS is
in compliance with the MRDL when the
running annual average of monthly
averages of all samples, computed
quarterly, is less than or equal to the
MRDL. Notwithstanding the MRDL,
operators may increase residual chlorine
levels in the distribution system to a
level and for a time necessary to protect
public health to address specific
microbiological contamination problems
(e.g., including distribution line breaks,
storm runoff events, source water
contamination, or cross-connections).
Best Available Technology: EPA has
identified the best means available for
achieving compliance with the MRDL
for chlorine as control of treatment
processes to reduce disinfectant
demand, and control of disinfection
treatment processes to reduce
disinfectant levels.
2. MRDL for Chloramines
Chloramines are formed when
ammonia is added during chlorination.
The proposed MRDL for chloramines is
4.0 mg/1 (as total chlorine).
Routine Monitoring: As a minimum,
CWSs and NTNCWSs must measure the
residual disinfectant level at the same
points in the distribution system and at
the same time as total coliforms, as
specified in § 141.21. Subpart H systems
may use the results of residual
disinfectant concentration sampling
done under the SWTR (§ 141.74(b)(6) for
unfiltered systems, § 141.74(c)(3) for
systems that filter) in lieu of taking
separate samples.
Reduced monitoring: Monitoring for
chloramines may not be reduced.
Compliance Determination: A PWS is
in compliance with the MRDL when the
running annual average of monthly
averages of all samples, computed
quarterly, is less than or equal to the
MRDL. Notwithstanding the MRDL,
operators may increase residual
chloramine levels in the distribution
system to a level and for a time
necessary to protect public health to
address specific microbiological
contamination problems (e.g., including
distribution line breaks, storm runoff
events, source water contamination, or
cross-connections).
Compliance Determination: A PWS is
in compliance with the MRDL when the
running annual average of samples,
computed quarterly, is less than or
equal to the MRDL. EPA recognizes that
it may be appropriate to increase
residual disinfectant levels in the
distribution system of chloramines
significantly above the MRDL for short
periods of time to address specific
microbiological contamination problems
(e.g., distribution line breaks, storm
runoff events, source water
contamination, or cross-connections).
Best Available Technology: EPA
identifies the best means available for
achieving compliance with the MRDL
for chloramines as control of treatment
processes to reduce disinfectant
demand, and control of disinfection
treatment processes to reduce
disinfectant levels.
3. MRDL for Chlorine Dioxide
Chlorine dioxide is used primarily for
the oxidation of taste and odor-causing
organic compounds in water. It can also
be used for the oxidation of reduced
iron and manganese and color, and is
also a powerful disinfectant and
algicide. Chlorine dioxide reacts with
impurities in water very rapidly, and is
dissipated very quickly. EPA is
proposing an MRDL of 0.80 mg/1 for
chlorine dioxide.
Routine Monitoring: CWSs and
noncommunity systems must monitor
for chlorine dioxide only if chlorine
dioxide is used by the system for
disinfection or oxidation. If monitoring
is required, systems must take daily
samples at the entrance to the
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38748 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
distribution system. If the MRDL is
exceeded, the system must go to
increased monitoring.
Increased Monitoring: If any daily
sample taken at the entrance to the
distribution system exceeds the MRDL,
the system is required to take three
additional samples in the distribution
system on the next day. Samples must
be taken at the following locations.
• Systems using chlorine as a residual
disinfectant and operating booster
chlorination stations after the first
customer. These systems must take
three samples in the distribution
system: One as close as possible to the
first customer, one in a location
representative of average residence time,
and one as close as possible to the end
of the distribution system (reflecting
maximum residence time in the
distribution system).
• Systems using chlorine dioxide or
chloramines as a residual disinfectant or
chlorine as a residual disinfectant and
not operating booster chlorination
stations after the first customer. These
systems must take three samples in the
distribution system as close as possible
to the first customer at intervals of not
less than six hours.
Reduced monitoring: Monitoring for
chlorine dioxide may not be reduced.
Compliance Determination: Acute
violations. If any daily sample taken at
the entrance to the distribution system
exceeds the MRDL and if, on the
following day, any sample taken in the
distribution system exceeds the MRDL,
the system will be in acute violation of
the MRDL and must take immediate
corrective action to lower the
occurrence of chlorine dioxide below
the MRDL and issue the required acute
public notification. Failure to monitor
in the distribution system on the day
following an exceedance of the chlorine
dioxide MRDL shall also be considered
an acute MRDL violation.
Nonacute violations. If any two
consecutive daily samples taken at the
entrance to the distribution system
exceed the MRDL, but none of the
samples taken in the distribution system
exceed the MRDL, the system will be in
nonacute violation of the MRDL and
must take immediate corrective action
to lower the occurrence of chlorine
dioxide below the MRDL. Failure to
monitor at the entrance to the
distribution system on the day following
an exceedance of the chlorine dioxide
MRDL shall also be considered a
nonacute MRDL violation.
Important note. Unlike chlorine and
chloramines, the MRDL for chlorine
dioxide may not be exceeded for short
periods of time to address specific
microbiological contamination
problems.
Monitoring for CT credit: Subpart H
systems required to operate enhanced
coagulation or enhanced softening may
receive credit for compliance with CT
requirements in Subpart H if the
following monitoring is completed and
the required operational standards are
met.
—For each chlorine dioxide generator,
the system must demonstrate that the
generator is achieving at least 95
percent yield and producing no more
than five percent free chlorine by
testing a minimum of once per week.
—On any day that a generator fails to
achieve at least 95 percent yield, and
on subsequent days until at least 95
percent yield is achieved, and/or any
day that the generator produces more
than five percent free chlorine and on
subsequent days until no more than
five percent free chlorine is produced,
the system may not receive credit for
compliance with CT requirements.
—On any day that a generator achieves
at least 90 percent, but less than 95
percent, yield, and/or any day that a
generator produces more than five
percent, but less than 10 percent, free
chlorine, the system may take
immediate corrective action to
achieve a minimum of 95 percent
yield and no more than five percent
free chlorine. If subsequent testing
conducted on the same day
demonstrates at least 95 percent yield
and no more than five percent free
chlorine, the system may receive
credit for compliance with CT
requirements on that day. If the
generator continues to fail tb
demonstrate at least 95 percent yield
and/or continues to produce more
than five percent free chlorine, the
system may not receive credit for
compliance with CT requirements on
that day.
—Measurements must be made at least
every seven days. If, in the interim,
the system changes generator
conditions (e.g., change in chlorine
dose, change conditions to match
changing plant flow rate), it shall
remeasure for chlorine dioxide yield
and free chlorine.
To calculate compliance with
§ 141.133(b)(2)(ii)(C) in order to receive
credit for CT compliance, Method 4500-
C1O2 E (Standard Methods for the
Examination of Water and Wastewater,
18th Ed. 1992) must be used to
determine concentrations of chlorine
dioxide, chlorine, and related species in
the generator effluent. Calculations are
performed as demonstrated below.
1. Perform titration on generator
sample aliquots as required by Method
4500-C1O2 E. Record the titration
readings for A through E below, the
normality (N) of the titrant used, and the
sample dilution.
—A (ml titrant/ml sample) for titration
of chlorine and one-fifth of ClOa.
—B (ml titrant/ml sample) for titration
of four-fifths of C1O2 and of chlorite.
—C (ml titrant/ml sample) for titration
of nonvolatilized chlorine.
—D (ml titrant/ml sample) for titration
of chlorite.
—E (ml titrant/ml sample) for titration
of chlorine, ClOa, chlorate, and
chlorite.
—N (normality of the titrant used in
equivalents per liter).
2. Determine chlorine dioxide
generator performance (yield). The
calculations in a. through c. below must
be corrected for the sample dilution.
a. Calculate chlorine dioxide
concentration.
[C1O2 (mg/l)]=13490x5/4x(B-D)xN
b. Calculate chlorite concentration.
[C1O2 (mg/1)] = 16863 x D x N
c. Calculate chlorate concentration.
[C103 (mg/1)] = 13909 x [E - (A+B)] x N
d. Calculate yield (in %).
%Yield =
[C1O2 (mg/1 )]x 100
[C102 (mg/l)]+[C102 (mg/1)]+ (67.5 /83.5)[C1O3 (mg/l)]
3. Determine excess chlorine. This
calculation must be corrected for sample
dilution.
a. Calculate chlorine concentration.
[C12 (mg/1)] = {A - [(B-D)/4]> x N
X35453
b. Using the concentrations of
chlorine dioxide, chlorite, and chlorate
calculated above (2.a.-c.), calculate
excess chlorine.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38749
Excess chlorine (in %) =
[C1O2 (mg/l)]xlOO
|[C102 (mg/l)]+[C102
L
83.5
70.9
2x67.5
4. Determine whether CT credit can
be taken.
a. If % Yield £ 95% and % Excess
Chlorine S 5%, CT credit may be taken.
b. If % Yield i 90% but < 95%, and/
or % Excess chlorine > 5% but < 10%,
the system may take immediate
corrective action and then remeasure.
CT credit may be taken if a subsequent
measurement performed on the same
day shows a yield 5 95% and % Excess
Chlorine £ 5%.
c. If % Yield < 90% or excess chlorine
> 10%, the system may not take CT
credit for that day and for any
subsequent days until a subsequent
measurement shows a yield > 95% and
% Excess Chlorine 5 5%.
Best Available Technology: EPA
identifies the best means available for
achieving compliance with the MRDL
for chlorine dioxide as control of
treatment processes to reduce
disinfectant demand, and control of
disinfection treatment processes to
reduce disinfectant levels.
D. Enhanced Coagulation and Enhanced
Softening Requirements
In addition to meeting MCLs and
MRDLs, some water suppliers must also
meet treatment requirements to control
the organic material (disinfection
byproduct precursors (DBPPs)) in the
raw water that combines with
disinfectant residuals to form DBFs.
Subpart H systems using conventional
treatment are required to control for
DBPPs (measured as total organic
carbon (TOG)) by using enhanced
coagulation or enhanced softening. A
system must remove a certain
percentage of TOC (based on raw water
quality) prior to the point of continuous
disinfection. Systems using ozone
followed by biologically active filtration
or chlorine dioxide which meets
specific criteria would be required to
meet the TOC removal requirements
Srior to addition of a residual
isinfectant. Systems able to reduce
TOC by a specified percentage level
have met the DBPP treatment technique
requirement. If the system does not meet
the percent reduction, it must determine
its alternative minimum TOC removal
level, which is further explained in
Section IX. The State approves the
alternative minimum TOC removal
possible for the system on the basis of
the relationship between coagulant dose
and TOC in the system.
1. Applicability'
Subpart H systems using conventional
treatment must use enhanced
coagulation or enhanced softening to
remove TOC unless they meet one of the
criteria in a. through d. below. Systems
using chlorine dioxide that achieve a 95
percent yield of chlorine dioxide and
have no more than five percent excess
chlorine would be required to meet the
TOC removal requirements prior to the
addition of another residual
disinfectant.
a. The system's treated water TOC
level, prior to the point of continuous
disinfection, is less than 2.0 mg/1.
b. The system's source water TOC
level, prior to any treatment, is less than
4.0 mg/1; the alkalinity is greater than 60
mg/1; and not later than the effective
dates for compliance for the system,
either the TTHM annual average is no
more than 0.040 mg/1 and the THAA
annual average is no more than 0.030
mg/1, or the system has made a clear and
irrevocable financial commitment not
later than the effective date for
compliance for Stage 1 to technologies
that will limit the levels of TTHMs and
THAAs to no more than 0.040 mg/1 and
0.030 mg/1, respectively. Systems must
submit evidence of the clear and
irrevocable financial commitment, in
addition to a schedule containing
milestones and periodic progress reports
for installation and operation of
appropriate technologies, to the State for
approval not later than the effective date
for compliance for Stage 1. These
technologies must be installed and
operating not later than the effective
date for Stage 2.
c. The system's TTHM annual average
is no more than 0.040 mg/1 and the
THAA annual average is no more than
0.030 mg/1 and the system uses only
chlorine for disinfection.
d. Systems practicing softening and
removing at least 10 mg/1 of magnesium
hardness (as CaCOs), except those that
use ion exchange, are not subject to
performance criteria for the removal of
TOC.
2. Enhanced Coagulation Performance
Requirements
Systems Not Practicing Softening.
Systems that use either (1) ozone
followed by biological filtration or (2)
chlorine dioxide and meet the
performance requirements for CT credit
must reduce TOC by the amount
specified in Table VIH-4 before the
addition of a residual disinfectant. All
other systems must reduce the
percentage of TOC in the raw water by
the amount specified in Table Vin-4
prior to continuous disinfection, unless
the State approves a system's request for
an alternative minimum TOC removal
level.
Required TOC reductions for Subpart
H systems, indicated in Table VIII—4, are
based upon the specified source water
parameters.
Systems Practicing Softening. Systems
that use either (1) ozone followed by
biological filtration or (2) chlorine
dioxide and meet the performance
requirements for CT credit must reduce
TOC by the amount specified in the far-
right column of Table Vin-4 (Source
Water Alkalinity >120 mg/1) for the
specified source water TOC before the
addition of a residual disinfectant. All
other systems practicing softening are
required to meet the percent reductions
in the far-right column of Table VHI-4
(Source Water Alkalinity >120 mg/1) for
the specified source water TOC prior to
continuous disinfection, unless the
State approves a system's request for an
alternative minimum TOC removal
level. Systems removing more than 10
mg/1 of magnesium hardness (as CaCos)
are considered to be practicing
enhanced softening, and are not subject
to performance criteria for the removal
of TOC (see paragraph D.l.(d) above).
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38750
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
TABLE Vlll-4.—REQUIRED REMOVAL OF TOG BY ENHANCED COAGULATION FOR SUBPART H SYSTEMS USING
CONVENTIONAL TREATMENT 1
[In percent]
Source water total organic carbon (mg/l)
>20-40
>40-80
>8.0
Source water alkalinity (mg/l)
0-60
40.0
45.0
50.0
>60-120
30.0
35.0
40.0
>120Z
20.0
25.0
30.0
1 Systems meeting at least one of the conditions in §141.135(a)(1)(i)-(iv) are not required to operate with enhanced coagulation.
2 Systems practicing softening must meet the TOG removal requirements in this column.
3. Alternative Performance Criteria
a. Non-softening systems. Non-
softening Subpart H conventional
treatment systems that cannot achieve
the TOG removals required above due to
unique water quality parameters or
operating conditions must apply to the
State for alternative performance
criteria. The system's application to the
State must include, as a minimum,
results of bench- or pilot-scale testing
for alternate performance criteria.
Alternative TOG removal criteria may be
determined as follows:
(1) bench- or pilot-scale testing used
to determine alternative TOG removal
criteria must be based on quarterly
measurements and must be conducted
at pH levels no greater than those
indicated in Table VIH-5, dependent on
the alkalinity of the water,
(2) the alternative TOG removal
criteria will be no less than the percent
removal determined by the alternative
enhanced coagulation level (AECL),
where an incremental addition of 10
mg/l of alum (or an equivalent amount
of ferric salt) results in a TOG removal
of 0.3 mg/l (determined as a slope),
(3) once approved by the State, this
new requirement (alternative TOG
removal criteria) supersedes the
minimum TOG removal required in
Table VIII-4 and remains effective until
the.State approves a new value/and
(4) if the TOG removal is consistently
less than 0.3 mg/lof TOC per 10 mg/l
of incremental alum dose at all dosages
of alum, the water is deemed to contain
TOG not amenable to enhanced
coagulation and the system may then
apply to the State for a waiver of
enhanced coagulation requirements.
TABLE VIII-5.—ALTERNATE ENHANCED
COAGULATION LEVEL MAXIMUM PH
Alkalinity
(mg/l as CaCO3)
0-60
60-120
>1 20-240 '.
>240
Maximum
pH
5.5
6.3
7.0
7.5
The system may then operate at any
coagulant dose or pH necessary to
achieve the minimum TOG removal
determined under the testing. For
example, a system may choose to use
lower levels of alum and depress the pH
further instead of adding higher levels
of alum at the higher pH.
b. Softening systems. During the
negotiation, tie Committee was not able
to develop alternative performance
criteria for Subpart H softening systems.
In Section IX of this Notice, EPA solicits
comments on what these criteria should
include.
4. Compliance Determinations
Compliance for systems required to.
operate with enhanced coagulation or
'enhanced softening is based on a
running annual average, computed
quarterly, of normalized monthly TOG
percent reductions. A system is in
compliance if the normalized running
annual average is at least 1.00. For
Subpart H systems using conventional
treatment but not required to operate
enhanced coagulation or enhanced
softening, compliance with the DBPP
treatment technique is based on
continuing to meet the avoidance
criteria in paragraph 1 above. Example
VIII-1 below shows how to determine
compliance with the enhanced
coagulation (or enhanced softening)
requirements for systems that do not
require alternative TOG removal
requirements.
Example VHI-1
The system conducts the required
monitoring for 12 months. Complete data are
included only for the most recent quarter of
monitoring.
(1) Using the procedure explained in
§ 141.135(b), the system determines the
percent TOC removal, which is equal to:
(1 - (treated water TOC/source water TOO)
xlOO
(2) Determine the required monthly TOC
percent removal (from either the table in
§ 141.135(a)(2)(i) or from § 141.135(a)(3).
Note that seasonal water quality variations
may require systems to determine required
TOC removals from both sections (i.e., both
Step 1 and Step 2 levels) during any one
year.
(3) Divide 1) by 2).
(4) Add together the results of 3) for the
last 12 months and divide by 12.
(5) If 4) <1.00, the system is not in
compliance.
In the report below, the system is in
compliance with the TOC removal
requirements.
Month
/\prj|
May
JU|y
Seotember
Treated
TOC(mg/l)
a.
Source
TOC(mg/l)
b.
(1-a./b.)x
100
c.
Source
water alka-
linity
Reqd. TOC
removal {%)
d.
c./d.
e.
1.10
0.94
1.03
1.07
0.98
1.24
1.10
1.07
1.02
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38751
Month
October
November
December
Last 12 mos
Treated
TOC(mg/l)
a.
4.6
40
44
N/A
Source
TOC(mg/l)
b.
82
6 1
62
N/A
(1 -a./b.) x
100
c.
44
34
29
N/A
Source
water alka-
linity
70
75
85
N/A
Reqd. TOG
removal (%)
d.
40
35
35
N/A
c./d:
e.
1 10
098
083
JV;
72.4&-(=f.)
f712-1.04 (-g.)
If g £ 1.00, the system is in compliance.
EPA solicits comment on how the
following situations should be handled
in compliance determinations.
—when the monthly source water TOG
is less than 2.0 mg/1 and enhanced
coagulation is not required.
—when seasonal variations cause the
system to determine that TOG is not
amenable to any level of enhanced
coagulation and the system would be
eligible for a waiver of enhanced
coagulation requirements.
EPA believes that assigning a value of
1.00 for these months is a reasonable
approach.
5. CT Credit.
Systems required to operate with
enhanced coagulation or enhanced
softening may not take credit for
compliance with CT requirements prior
to sedimentation unless they meet one
of the following criteria:
a. Systems may include CT credit
during periods when the water
temperature is below 5°C and the TTHM
and HAAS quarterly averages are no
greater than 40 ug/1 and 30 ug/1,
respectively.
b. Systems receiving disinfected water
from a separate entity as their source
water shall be allowed to include credit
for this disinfectant in determining
compliance with the CT requirements. If
the TTHM and HAAS quarterly averages
are no greater than 40 ug/1 and 30 ug/
1, respectively, systems may use the
measured "C" (residual disinfectant
concentration) and the actual contact
time (as TIO). If the TTHM and HAAS
quarterly averages are greater than 40
ug/1 and 30 ug/1, respectively, systems
must use a "C" (residual disinfectant
concentration) of 0.2 mg/1 or the
measured value, whichever is lower;
and the actual contact time (as TIO). This
credit shall be allowed from the
disinfection feed point, through a closed
conduit only, and ending at the delivery
point to the treatment plant.
c. Systems using chlorine dioxide as •
an oxidant or disinfectant may include
CT credit for its use prior to enhanced
coagulation or enhanced softening if the
following standards are met: the
chlorine dioxide generator must
generate chlorine dioxide on-site at a
minimum 95 percent yield from sodium
chlorite; and the generated chlorine
dioxide feed stream applied from the
chlorine dioxide generator must contain
less than five percent (by weight)
chlorine, measured as the weight ratio
of chlorine to chlorine dioxide, chlorite,
and chlorate in such feed stream.
Compliance with these standards must
be demonstrated by monitoring.
E. Requirement for Systems to Use
Qualified Operators
Under the proposed rule, each PWS
must be operated by qualified personnel
who meet the requirements specified by
the State. This proposed requirement is
similar to the requirement in the Surface
Water Treatment Rule. States must
develop operator qualifications if they
do not already have them and they must
require that systems be operated by
personnel who meet these
qualifications. In addition, the State
must maintain a register of qualified
operators. The appropriate criteria for
determining if an operator is qualified
depend upon the type and size of the
system.
F. Analytical Method Requirements
Disinfection By-Products. Disinfection
by-products must be measured by the
methods listed in Table VIII-6:
TABLE VIII-6.—PROPOSED METHODS
FOR DISINFECTION BY-PRODUCTS
Contaminant
Trihalomethanes (4) .
Haloacetic Acids (5) .
Bromate, Chlorite
Methods
1 502.2, 2 524.2, 3 551.
2 552. 1,4 6233 B.
5 300.0.
3 EPA Method 551 is in the manual "Meth-
ods for the Determination of Organic Com-
pounds in Drinking Water—Supplement I",
EPA/600/4-90/020, July 1990, NTIS PB91-
146027.
"Standard Method 6233 B is in "Standard
Methods for the Examination of Water and
Wastewater," 18th Edition, American Public
Health Association, American Water Works
Association, and Water Environment Federa-
tion, 1992.
5 EPA Method 300.0 is in the manual "Meth-
ods for the Determination of Inorganic Sub-
stances in Environmental Samples", EPA/600/
R/93/100, August 1993, with revisions. See
Section IX for revisions.
All measurements listed in this
section must be conducted by a
laboratory certified by EPA or the State.
To receive certification, the laboratory
must:
(1) Use the promulgated method(s).
(2) On an annual basis, successfully
analyze appropriate performance
evaluation (PE) samples provided by
EPA or the State.
Disinfectant Residuals. The three
disinfectant residuals are measured and
reported as follows: chlorine as free or
total chlorine; chloramines as combined
or total chlorine; and chlorine dioxide
as chlorine dioxide. Residual
disinfectant concentrations must be
measured by the methods listed in Table
VIII-7.
TABLE VIII-7.—PROPOSED METHODS
FOR DISINFECTANTS
1 EPA Method 502.2 is in the manual "Meth-
ods for the Determination of Organic Com-
pounds in Drinking Water", EPA/600/4-88/
039, July 1991, NTIS publication PB91-
231480.
2 EPA Methods 524.2 and 552.1 are in the
manual "Methods for the Determination of Or-
ganic Compounds in Drinking Water—Supple-
ment II", EPA/600/R-92/129, August 1992,
NTIS PB92-207703.
Disinfectant measure-
ment
Chlorine as free or
total residual chlo-
rine, chloramines
as combined or
total residual chlo-
rine.
Chlorine as free resid-
ual chlorine.
Chlorine or
Chloramines as
total residual chlo-
rine.
Proposed methods1
4500-CI D Ampero-
metric Titration.
4500-CI F DPD
Ferrous Titrimetric.
4500-CI G DPD
Colorimetric.
4500-CI H
Syringaldazine
(FACTS).
4500-CI E Low-
Level Ampero-
metric.
4500-CI I
lodometric Elec-
trode.
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38752 Federal Register / Vol. 59, No. 145 /Friday, July 29, 1994 / Proposed Rules
TABLE VI11-7.—PROPOSED METHODS
FOR DISINFECTANTS—Continued
Disinfectant measure-
ment
Chlorine Dioxide as
residual chlorine di-
oxide.
Proposed methods1
4500-CIO2 C Am-
perometric Titra-
tion.
4500-CIO2D DPD.
4500-CIO2 E Am-
perometric Titra-
tion.
1 Proposed methods are in "Standard Meth-
ods for the Examination of Water and
Wastewater," 18th Edition, American Public
Health Association, American Water Works
Association, and Water Environment Federa-
tion, 1992.
Residual disinfectant concentrations
for chlorine and chloramines may also
be measured by using DPD colorimetric
test kits if their use is approved by the
State. Measurement for disinfectant
residual concentration must be
conducted by a party approved by the
State.
Other Parameters—Total Organic
Carbon, Alkalinity and Bromide. Other
parameters that are monitored to meet
treatment technique requirements must
be measured using the methods listed in
Table VIII-8.
TABLE VIII-8.—PROPOSED ANALYT-
ICAL METHODS FOR OTHER PARAM-
ETERS
Parameter
Total Organic Carbon
Alkalinity
Bromide
Method
5310 C Persulfate-
Ultraviolet Oxida-
tion1
531OD Wet Oxida-
tion1
2320 B1, 310.1z, D-
1067-88B
Titrimetric3
1-1030-85
Electrometric4
300.0 Ion Chroma-
tography5
1 Standard Methods 2320 B, 5310 B and
5310 C are in Standard Methods for the Ex-
amination of Water and Wastewater, 18th Edi-
tion, American Public Health Association,
American Water Works Association, and
Water Environment Federation, 1992.
2 EPA Method 310.1 is in the manual "Meth-
ods for Chemical Analysis of Water and
Wastes", EPA/600/4-79-020, March 1983,
NTIS PB84-128677.
3 Method D-1067-88B is in the "Annual
Book of ASTM Standards", Vol. 11.01, Amer-
ican Society for Testing and Materials, 1993.
4 Method 1-1030-85 is in Techniques of
Water Resources Investigations of the U.S.
Geological Survey, Book 5, Chapter A-1, 3rd
ed., U.S. Government Printing Office, 1989.
5 EPA Method 300.0 is in the manual "Meth-
ods for the Determination of Inorganic Sub-
stances in Environmental Samples", EPA/600/
R/93/100—Draft, June 1993.
Measurement for these parameters
must be conducted by a party approved
by the State.
G. Public Notice Requirements
Standard provisions for public notice
apply to this rule. These provisions are
explained in Section XTV of this
preamble. There is only one acute
violation, which occurs when the
chlorine dioxide MRDL is exceeded in
the distribution system (or if the system
fails to take the required samples in the
distribution system).
H. Variances and Exemptions
Standard provisions for variances and
exemptions apply to this rule. These
provisions are explained in Section XI
of this preamble.
/. Reporting and Recordkeeping
Requirements for PWSs
Reporting: EPA has proposed
reporting requirements designed to
document compliance with the
treatment and monitoring requirements
described above. These requirements are
specified in § 141.134(b) of the proposed
rule. Systems required to sample
quarterly or more frequently must report
monitoring information to the State
within 10 days after the end of each
quarter in which samples were
collected. Systems required to sample
less frequently than quarterly must
report monitoring information to the
State within 10 days after the end of
each required monitoring period in
which samples were collected.
Recordkeeping: There are no
additional recordkeeping requirements
for systems.
/. State Implementation Requirements
Records Kept by States: EPA is
proposing to add several requirements
to § 142.14, Records Kept by States.
These include records of the currently
applicable or most recent State
determinations, including supporting
information and an explanation of the
technical basis for each decision.
—Records of systems that are installing
GAG or membrane technology.
—Records of systems that are required,
by the State, to meet alternative TOG
performance criteria (alternate
enhanced coagulation level).
—Records of Subpart H systems using
conventional treatment meeting any
of the enhanced coagulation or
enhanced softening exemption
criteria.
—Register of qualified operators.
—Records of systems with multiple
wells considered to be one treatment
plant.
Reports by States: EPA is proposing to
add several requirements to § 142.15,
Reports by States. These requirements
include:
—Reports of systems that must meet
alternative minimum TOG removal
levels.
—Reports of extensions granted for
compliance with MCLs in § 141.64
and the date by which compliance
must be achieved.
—A list of systems require d to monitor
for various disinfectants and
disinfection byproducts.
—A list of all systems using multiple
ground water wells which draw from
the same aquifer and are considered a
single source for monitoring purposes.
Special Primacy Requirements: EPA is
proposing to add several requirements
to § 142.16, Special Primacy
Requirements. These requirements
include how the State will:
—Determine the interim treatment
requirements for those systems
electing to install GAG or membrane
filtration.
—Qualify operators of community and
nontransient-noncommunity public
water systems subject to this
regulation.
—Approve alternative TOG minimum
removal levels.
—Approve parties to conduct pH,
alkalinity, temperature and residual
disinfectant concentration
measurements.
—Approve DPD colorimetric test kits for
free and total chlorine measurements.
—Define the criteria to use to determine
if multiple wells are being drawn
from a single aquifer and therefore be
considered a single source for
compliance with monitoring
requirements.
IX. Basis for Key Specific Criteria of
Proposed Rule
A. 80/60 TTHM/HAA5 MCLs, Enhanced
Coagulation Requirements, and BAT
I. Basis for Umbrella Concept vs.
Individual MCLs
The proposed rule would establish
limits for two DBP class sums (i.e.,
TTHMs and the sum of five HAA
species [HAA5J) rather than individual
DBFs. In performing the regulatory
impact analysis (RIA), TTHM and HAAS
data were generated that were believed
to represent occurrence data with
conventional drinking water treatment
as well as that achievable with the use
of advanced technologies. However,
individual DBFs could not be reliably
predicted over the range of TOG and
bromide levels that are found in surface
waters before and after treatment.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38753
In addition to the inability to
characterize individual DBF formation,
the Negotiating Committee was
concerned that individual DBFs cannot
all be controlled simultaneously
without adverse impacts. While
precursor removal processes (i.e.,
coagulation, precipitative softening,
GAG, and nanofiltration) can remove
TOG, they do not remove bromide
(except for nanofiltration to a limited
extent).. Such processes are best for
controlling the formation of chloroform
and least effective for controlling the
formation of bromoform (Summers et
al., 1993). Amy and colleagues found
that increasing the bromide-to-TOC ratio
(e.g., by reducing TOG with a precursor-
removal technology) yielded a higher
percentage of brominated THM species
(Amy et al., 1991). Symons and
colleagues speculated that this
phenomenon is due to the following: (1)
after treatment to lower TOG, a water
may be "precursor-limited"; (2) THM
formation kinetics favor bromine
incorporation; (3) thus bromine
consumes most of the active precursor
sites, leaving few for chlorine
substitution (Symons et al., 1993).
In an enhanced coagulation study of
16 waters nationwide, the median
reduction in TTHMs was 50 percent
(JAMES M. MONTGOMERY,
CONSULTING ENGINEERS, INC., 1991
and Means et al., 1993). Because this
technology removed TOG but not
bromide, chloroform levels were well
reduced (median of 65 percent), while
bromodichloromethane values were not
as well reduced (for 15 of the waters the
median reduction was 28 percent; this
THM level, though, went up six percent
in the sixteenth water). For the more
brominated species
(dibromochloromethane and
bromoform), the THM levels decreased
in some waters and increased in others.
Again, the increase in formation of these
brominated THMs was attributed to the
change in bromide-to-TOC ratio and/or
competition between bromine and
chlorine for precursors. For the raw
waters in this study (median TOG of 4.3
mg/L and bromide of 0.09 mg/L),
chlorination (at 20 °C for 16 hr) yielded
median values of 77 ug/L chloroform, 17
ug/L bromodichloromethane, 6 ug/L
dibromochloromethane, 0.2 ug/L
bromoform, and 124 ug/L TTHMs. For
the coagulated/settled waters,
chlorination yielded median values of
26 ug/L chloroform, 12 ug/L
bromodichloromethane, 6 ug/L
dibromochloromethane, 0.3 ug/L
bromoform, and 56 ug/L TTHMs. These
data demonstrate that enhanced
coagulation can reduce TTHMs, with
varying impacts on individual species.
While not all chemical species were
significantly reduced, the overall
theoretical cancer risk from THMs is
lower. This may also apply to HAAS
and other byproducts.
In the aforementioned coagulation
study, the median raw- and settled-
water DCAA levels were 28 and 14 ug/
L, respectively (JAMES M.
MONTGOMERY, CONSULTING
ENGINEERS, INC., 1991 and Means et
al., 1993). For the waters tested, the
median reduction in DCAA was 61
percent, which was comparable to the
reduction in chloroform. For
dibromoacetic acid (DBAA), the median
raw- and settled-water levels were 1.2
and 1.6 ug/L, respectively (JAMES M.
MONTGOMERY, CONSULTING
ENGINEERS, INC., 1991). For the three
waters in this study with very high
bromide levels, DBAA was reduced
from a range of 16 to 52 ug/L in the
chlorinated raw waters to a range of 11
to 30 ug/L in the chlorinated
coagulated/ settled waters.
These types of data indicate that
while it is feasible for systems utilizing
enhanced coagulation to reduce TTHM
and HAAS levels, it is not possible to
reduce all of the individual THMs and
HAAs to the same extent. Using
precursor control technologies, which
can remove TOG but not bromide, there
is a feasible limit on being able to
minimize the formation of each
individual THM or HAA. Alternatively,
using alternative disinfectants (e.g.,
ozone/chloramines), one can
significantly reduce the formation of all
THMs and HAAs. However, as
discussed in Section VI.C., there are
concerns with the byproducts of
alternative disinfectants.
Utilizing the DBF class sums, though,
the Technologies Working Group (TWG)
was able to evaluate the benefits of
enhanced coagulation with the
DBPRAM. For surface waters that filter
but do not soften, using conventional
filtration treatment and chlorine, it was
determined that the median, 75th, and
90th percentile TTHMs are 46, 68, and
90 ug/L, respectively. With enhanced
coagulation for all surface water systems
that filter but do not soften, it was
predicted that median, 75th, and 90th
percentile TTHMs would drop to 29, 41,
and 58 ug/L, respectively. Similarly,
using conventional treatment and
chlorine, it was determined that the
median, 75th, and 90th percentile
HAAS levels are 28, 47, and 65 ug/L,
respectively. With enhanced
coagulation, it was predicted that
median, 75th and 90th percentile HAAS
levels would drop to 17, 26, and 37 ug/
L, respectively.
In order to comply with MCLs of 80
ug/L TTHMs and 60 ug/L HAAS, the
TWG assumed that a utility would
design the treatment process to achieve
levels less than 80 percent of the MCL
values (i.e., 64 ug/L TTHMs and 48 ug/
L HAAS) as an operating margin of
safety. Such TTHM and HAAS levels
should be attainable for approximately
90 percent of the systems when using
enhanced coagulation with chlorine,
based upon the predicted 90th
percentile levels above. Similarly,
GAC10 with chlorine was predicted to
result in comparable levels of TTHMs
and HAAS. Note, though, that for some
waters the HAA levels may exceed the
THM- concentrations (Grenier et al.,
1992) and that compliance with both
sets of DBF classes may require
additional treatment changes. For
example, the DBPRAM predicted that
for these surface-water systems using
enhanced coagulation, the maximum
TTHM would be 80 ug/L while the
maximum HAAS level would be 81 ug/
L.
Enhanced coagulation can be used to
remove the precursors for other DBFs as
well as those associated with THMs and
HAAs. Reckhow and Singer
demonstrated that the formation
potential (a measure of precursor levels)
of THMs, di-, and trichloroacetic acid,
dichloroacetonitrile, 1,1,1-
trichloropropanone, and TOX could all
be reduced with enhanced coagulation
(Reckhow et al., 1990). Thus, enhanced
coagulation can be used to control other
DBFs as well, even though they are not
part of this proposed D/DBP Rule.
In a full-scale evaluation of enhanced
coagulation performed during the 35-
utility DBF study, the alum dose was
raised from 10 to 40 mg/L (Metropolitan
Water District of So. Calif, et al, 1989).
Removal of TOG (raw water TOG of 3
mg/L—a low-alkalinity water) through
coagulation and settling increased from
25 to 50 percent. Chlorination (at 25 °C
for 24 hr) of settled/filtered water during
the low-alum-dose test yielded 86 ug/L
TTHMs, 50 jig/L HAAS, and 9.4 ug/L
chloral hydrate. Chlorination of settled/
filtered water during the high-alum-dose
test yielded 55 ug/L TTHMs, 29 ug/L
HAAS, and 6.0 ug/L chloral hydrate. By
enhancing the coagulation process at
this utility, the levels of TTHMs, HAAS,
and chloral hydrate were all reduced
(compared to the low-alum-dose test) by
36-42 percent. In the 35-utility study,
the overall correlation between the
occurrence of chloral hydrate and
chloroform in the treatment plant
effluents of all the systems was good
(correlation coefficient of 0.85)
(Metropolitan Water District of So. Calif.
et al., 1989). Chloral hydrate has been
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38754 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
postulated to form as an intermediate in
the conversion of ethanol to chloroform
(Beibar et al., 1973). By removing THM
and HAA precursors during enhanced
coagulation, chloral hydrate should be
controlled as well.
2. Basis for Level of Stringency in MCLs,
BAT, and Concurrent Enhanced
Coagulation Requirements
The Safe Drinking Water Act directs
EPA to set the MCL as close to the
MCLG as is technically and
economically feasible to achieve and to
specify in the rule such best available
technology (BAT). Systems unable to
meet the MCL after application of BAT
can get a variance (see Section XI for a
discussion of variances). Systems that
obtain a variance must meet a schedule
approved by the State for coming into
compliance. Systems are not required to
use BAT in order to comply with the
MCL but can use other technologies as
long as they meet all drinking water
standards and are approved by the State.
For chemicals classified as B2
carcinogens, EPA must set standards as
close to zero (the MCLG) as is
technically and economically feasible to
achieve by the BAT. EPA has classified
three THMs (chloroform,
bromodichloromethane, and
bromoform) and one of the HAAs
(dichloroacetic acid) as probable human
carcinogens (i.e., B2 carcinogens) based
on evidence of carcinogenicity in
animals. EPA is also concerned with the
potential risks of chlorination
byproducts other than THMs or HAAs,
indicated in part by the presence of
THMs and HAAs. A TTHM MCL and
HAA MCL would limit exposure from
different THMs and HAAs as well as
other chlorinated DBFs.
EPA is proposing a combined limit for
only five of the HAAs (HAAS)—
monochloroacetic acid, dichloroacetic
acid, trichloroacetic acid,
monobromoacetic acid, and
dibromoacetic acid—because currently
available data enable EPA to predict
only their combined occurrence.
How BAT is defined determines the
level at which MCLs are set for TTHMs
and HAAS. Per agreement with the
Negotiating Committee, EPA is
proposing either enhanced coagulation
or shallow bed GAG (GAC10) with
chlorine as the primary and residual
disinfectant. The TWG considered
GAC10 as roughly equivalent to
enhanced coagulation in removing
organic precursors to DBFs. The
Negotiating Committee considered it
appropriate to define chlorination for
primary and residual disinfection
within the BAT definition because 1)
chlorine is an effective disinfectant for
inactivating most microbial pathogens
originating in the source water and for
limiting contamination in the
distribution system, and 2) health risks
from DBFs from use of alternate
disinfectants are not as yet as well
characterized as they are for DBFs of
chlorination. However, as noted above,
alternate disinfectants (such as ozone)
may be used to achieve D/DBPR
compliance.
As discussed previously, based on
model predictions by the DBPRAM,
most systems in the U.S. would be able
to achieve a TTHM level of 80 ng/1 or
an HAAS level of 60 (ig/1 if they were
to apply the proposed BATs. The
Negotiating Committee agreed to
propose the MCLs accordingly.
Alternative BATs and corresponding
MCLs were considered but not included
for the reasons discussed below.
Including a more effective precursor
removal technology such as GAC20 or
membrane filtration in the BAT would
result in significantly lower MCLs.
Setting such MCLs would probably
result in much greater use of alternative
disinfectants, such as ozone and
chloramines because these technologies
would be significantly less expensive
than the BAT for achieving the MCL.
While much greater use of such
technology may be appropriate, some
members of the Negotiating Committee
did not consider this increased use
desirable, at least until more was known
concerning health risk associated with
DBFs formed from use of alternative
disinfectants. For the same reasons,
alternative disinfectants were not
included in the BAT definition(s).
Setting the MCLs for TTHMs and
HAAS at 80 and 60 ng/1, respectively,
should lead to substantially lower
TTHM and HAA levels than those being
achieved under the existing TTHM
MCL. The TWG estimated that, for
surface water systems serving over
10,000 people that do not soften, the
median concentration for TTHMs and
HAAS would drop from about 46 jig/1 to
31 jig/1 and 28 ng/1 to 20 (ig/1,
respectively, as a result of such
regulations. As part of today's proposal,
EPA is also proposing that all systems
using surface water sources which use
sedimentation and filtration must
operate with either enhanced
coagulation or enhanced softening
unless they meet certain water quality
conditions (discussed in the following
section of the preamble). This
requirement was set in conjunction with
the MCLs for TTHMs and HAAS for the
following reasons:
(1) A substantial amount of precursors
to disinfection DBFs could be removed
at low cost and within a short period of
time, regardless of which disinfectants
were used. Thus, any health effects
associated with DBFs that might
otherwise be formed would be reduced
quickly and at low costs.
(2) Reducing precursors would lead to
lower TTHM and HAAS levels and
thereby diminish the incentive for many
systems to shift toward use of
alternative disinfectants in order to
comply with the new MCLs, thereby ,
limiting concerns from any potential
associated health risks.
(3) Enhanced coagulation and
enhanced softening will also
significantly reduce disinfectant
demand, thereby allowing utilities to
use less disinfectant while still
maintaining a residual in the
distribution system. Maintaining a
residual is important for identifying
when contamination occurs into the
distribution system (indicated by the
absence of a residual) and for limiting
bacterial growth.
While lowering DBF precursors and
disinfectant demand can provide
obvious benefits, there are also
associated potential downside risks.
Since water treatment plant operators
often apply disinfectant dosages in
order to maintain a residual in the
distribution system, if the disinfectant
demand is lowered, lower disinfectant
dosages could inadvertently lead to
lower levels of inactivation of pathogens
originating in the source water and
increased microbial risk. To prevent
such risks, compensating treatment
must be provided where appropriate.
EPA is therefore concurrently proposing
possible amendments to the SWTR to
address such concerns in today's
Federal Register.
Another concern with precursor
removal is that.in waters with high
bromide concentrations, it is possible
(as previously discussed) to increase the
concentrations of certain brominated
DBFs even though the group
concentrations of the TTHMs and HAAS
may decrease. Since the health risks .
associated with many of the brominated
DBFs are currently unknown, it remains
unclear whether the benefits of lowering
the concentrations of chlorinated DBFs
, outweigh the possible downside risks of
increasing certain brominated DBFs.
Nevertheless, since only a small
percentage of systems may experience
increased concentrations of certain
brominated DBFs from enhanced
coagulation, the Negotiating Committee
reached a consensus that setting a
national requirement for precursor
removal by enhanced coagulation or
enhanced softening would be
appropriate.
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38755
The Committee could not reach
consensus on whether to require
systems to use technologies such as
GAC20 or membrane technology in
conjunction with setting lower MCLs, as
was done for enhanced coagulation with
the proposed Stage 1 MCLs. Some
members did not consider it appropriate
without a better understanding of the
impacts of such a requirement.
Installation and use of GAC20 or
membrane technology involve greater
costs and time to begin implementing
than enhanced coagulation. Some
Committee members believed that,
depending on source water quality, use
of alternative disinfectants may be
significantly more cost-effective for
reducing health risks from DBF levels
than GAC20 or membrane technology.
Also, these members believed that use
of alternative disinfectants instead of
GAC20 or membranes may pose fewer
ecological impacts. However, other
members believed that GAC20 or
membranes would substantially
improve water quality and should be
required. The Committee did not reach
consensus.
If GAC20 or membrane technology
were required under Stage 1, bench- and
pilot-scale studies would need to be
conducted prior to design and
installation. Such studies would
probably require at least several years to
complete for most systems. Under the
ICR (59 FR 6332), large systems with
high TOC levels will be required to
conduct bench- or pilot-scale studies to
evaluate the treatment effectiveness of
GAG or membrane technology. These
studies will enable systems to design
and install GAG or membrane
technologies, if required by the Stage 2
D/DBPR, in a shorter time than
otherwise would be possible under the
Stage 2 rule. Bench- or pilot-scale
studies initiated under the ICR will in
part simulate the same initial actions
that many utilities will take in the
future and reduce the time needed to
come into compliance if GAC20 or
membrane technology are required.
3. Basis for enhanced coagulation and
softening criteria
a. Enhanced coagulation. Removal of
organic carbon in conventional drinking
water treatment by the addition of alum
or iron salts has been demonstrated by
laboratory research, pilot-scale,
demonstration plant, and full-scale
studies. Until recently, there have been
limited data available on the removal of
organic carbon (measured as TOC) using
natural organic carbon matrices. Much •
of the developmental work for the
removal of TOC by coagulation and
sedimentation has been done in the
laboratory using synthetic mixtures of
humic materials. Researchers have
demonstrated that natural TOC exhibits
a wide range of responses to treatment
with high doses of alum and iron salts.
A key indication of the ability of TOC
to be removed by coagulation is the
molecular weight distribution of the
organic carbon. A large proportion of
high molecular weight organic carbon is
much easier to remove than an organic
carbon that is predominantly low
molecular weight material.
Unfortunately, the procedure to
determine TOC molecular weight
distribution is cumbersome, is only
being used in research applications, and
is not generally available in water
treatment plants or to consulting firms.
Even though TOC removal has been
practiced for some time at conventional,
full-scale plants, there has not been a
standard method to evaluate the
potential for a water treatment plant to
remove TOC during the coagulation/
sedimentation process. As a result of the
work of the TWG of the Negotiating
Committee, a number of alternatives for
defining enhanced coagulation have
been evaluated. The term optimized
coagulation was not used to describe the
process of incremental removal of TOC
by coagulants to avoid confusion with
optimized coagulation for particle
removal practiced by many water
utilities.
The majority of the data for removal
of TOC in drinking water treatment has
been developed with the use of
aluminum sulfate (A1SO4 • 14H2O). Iron
salts are also effective for removing TOC
and equivalent dosages for iron salts
were developed on the basis of TOC
removal by alum. Research has
demonstrated that polyaluminum
chloride and cationic polymers are not
effective for removing the same degree
of TOC as either alum or iron salts.
Cationic polymers (as well as anionic
and nonionic polymers) have been
proven to be valuable in creating
settlable floe when high dosages of alum
or iron salts are used. Specific organic
polymers have been shown to remove
color in water treatment applications,
but significant TOC removal by organic
polymers has not been demonstrated on
a widespread basis. Other coagulation
process arrangements that result in the
required removals for enhanced
coagulation are acceptable. For example,
sludge blanket clarifiers with or without
powdered activated carbon have been
shown to remove significant levels of
TOC.
The TWG attempted to define what
percent TOC removals could be
achieved by most systems treating
surface water and using coagulation/
sedimentation processes using elevated,
but not unreasonable, amounts of
coagulant dose. The intent was to define
enhanced coagulation in such a manner
that (a) significant TOC reductions
would be achieved and (b) the criteria
could easily be enforced with minimal
State transactional costs. A TOC-based
performance standard was therefore
desirable. It was not considered
appropriate to base a performance
standard on what all systems would be
expected to be able to achieve since
some waters are especially difficult to
treat. Under such a standard many
systems with easier to treat waters might
not be motivated to reduce their TOC to
the extent that was reasonably
achievable. On the other hand, setting a
standard based on what many systems
would not be able to readily achieve
would introduce large transactional
costs to States enforcing the rule. To
address these concerns the TWG
developed a two-step standard for
enhanced coagulation. The first step
includes performance criteria which, if
achieved, would define compliance.
The second step would allow systems
that have difficult to treat waters to
demonstrate to the State, through a
specific protocol, alternative
performance criteria for achieving
compliance.
The TWG examined case histories of
TOC removal with alum and developed
the 4X3 matrix shown below (Table IX-
1) as the initial step for defining
enhanced coagulation. The TWG
members and other experts consulted
during this process attempted to specify
criteria by which about 90 percent of the
water utilities employing conventional
treatment and required to operate
enhanced coagulation would be able to
meet the TOC removal percentages
listed, without unreasonable addition of
alum. While limited empirical data were
used to develop these criteria, the 90
percent compliance objective with the
step 1 criteria is not statistically based.
Establishing criteria at the anticipated
90 percent level, versus (for example) a
50 percent level with more stringent
percent TOC removal requirements, was
expected to result in much lower
transactional costs to the State (because
fewer evaluations of experimental data
to establish alternative criteria would be
required) without significantly higher
TOC levels in treated waters nationally.
Systems not practicing conventional
treatment were excluded from enhanced
coagulation requirements because they
were generally expected to (a) have
higher quality source waters with lower
TOC levels than waters treated by
conventional water treatment plants,
and (b) not have treatment that could be
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
expected to achieve significant TOG
reduction (e.g., most ground water
supplies, direct filtration, diatomaceous
earth filtration, and slow sand
filtration).
TABLE IX-1 .—REQUIRED REMOVAL OF TOG BY ENHANCED COAGULATION FOR SUBPART H SYSTEMS USING
CONVENTIONAL TREATMENT 2
[In percent]
Source Water Total Organic Carbon (mg/l)
~*n n_A n
-id no n
>8.0
Source Water Alkalinity(mg/l)
0-60
40.0
45.0
50.0
>60-120
30.0
35.0
40.0
>1201
20.0
25.0
30.0
1 Systems practicing softening must meet the TOG removal requirements in this column.
2 Systems meeting at least one of the conditions in § 141.135{a)(1)(i)-(iv) are not required to operate with enhanced coagulation.
The percent removals required as part
of the initial compliance determination
were developed in recognition of the
general trends in TOG coagulation
research that removals of TOG were
more difficult the higher the alkalinity
(due to the difficulty of reaching the
optimum coagulation pH for TOG,
usually between 5.5 and 6.5). It is also
fairly well established that TOG removal
by coagulation is generally easier the
higher the initial TOG in the water.
More information on the practice of
removing TOG in a wide variety of
source waters would have been helpful
for developing the proposed criteria.
EPA solicits comment on whether the
TOG percent removal levels in Table
IX-1 indicated above are representative
of what 90 percent could be expected to
achieve with elevated, but not
unreasonable, coagulant addition.
About 10 percent of the utilities
required to operate enhanced
coagulation are not expected to achieve
the percent removals in Table IX-1. The
purpose of the second step in the
definition of enhanced coagulation is to
determine the point of diminishing
returns for the addition of coagulant for
TOG removal.
Some waters contain TOG composed
mostly of highly mineralized organic
carbon with most of the molecular
weight fraction in the low range. It is
known that this kind of TOG can be very
difficult to remove. It is not the intent
of this rule to require the addition of
very high concentrations of coagulants
with little removal of TOG. Therefore,
the second step in the definition of
enhanced coagulation allows utilities to
avoid such a situation. It requires the
evaluation of incremental addition of
coagulant in a bench- or pilot-scale test
and measurement of the amount of TOG
removed by 10 mg/L increments of
coagulant. Per recommendation of the
TWG, EPA is proposing that the point
of diminishing returns for coagulant
addition be defined as the alternate
enhanced coagulation level (AECL) at
0.3 mg/L of TOG removed per 10 mg/L
of alum added or equivalent addition of
iron coagulant, and that the percent
TOG removal achieved at this point be
defined, if approved by the State, as the
alternative minimum TOG removal level
(to that indicated in Table IX-1) that
could be met for demonstrating
compliance.
TABLE IX-1 a.—COAGULANT DOSE
EQUIVALENTS
[mg/n
Coagulant
Aluminum sulfate* 14H2O
Ferric chloride ; .....
Ferric sulfate* 9H20
Dose
10
9.1
5.5
9.5
The guidance manual contains a
bench-scale method for demonstrating
alternative performance criteria under
step 2 of the enhanced coagulation
definition (EPA, 1994). The method
described therein is patterned after the
ASTM D 2035-80 method for "Standard
Practice for Coagulation-Flocculation Jar
Test of Water."
The bench-/pilot-scale procedure for
determining alternative percent TOG
removal requirements does not require
the use of a laboratory filtration step.
Experience has shown that most TOG is
removed during coagulation/
sedimentation. Also, not requiring
laboratory filtration eliminates a point
of possible contamination. TOG is
known to leach from some
commercially available filters. Not
specifying laboratory filtration also
avoids the issue of requiring a particular
type of filter for the bench-scale studies.
During the development of this
proposed rule, no consensus could be
reached on the use of membrane filters
with various pore diameters versus glass
fiber filters.
If a utility wishes to include the TOG
removal in the filtration process as part
of compliance with enhanced
coagulation, under step 2, filtration
would then have to be part of the bench-
/pilot-scale study. Using filtration in the
treatment plant as part of compliance
with enhanced coagulation TOG
removal would also require that
continuous disinfection for CT credit
would not be allowed until after the
filters.
EPA solicits comment on whether
filtration should be required as part of
the bench-/pilot-scale procedure for
determination of Step 2 enhanced
coagulation. If so, what type of filter
should be specified for bench-scale
studies?
Figure IX-1 shows three examples of
the types of curves anticipated to result
from a step 2 analysis and. are based on
actual data collected during the TWG
evaluation. Curve A represents a water
containing a TOG highly susceptible to
removal by coagulation/sedimentation.
Step 2 is met at an alum dosage of 40
mg/L. Note that due to its low alkalinity
(<60 mg/L), the percent removal of TOG
at this point (57%) is actually more than
is required under step 1 (45%). In this
case, the utility is only required to
remove TOG to the level specified in
step 1,45%, although removal of higher
levels of easily removed TOG is
encouraged.
BILLING CODE 6560-60-P
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- 8
— o
BltUNQ CODE 65«0-eO-C
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Curve B is probably more typical of
waters that fall into the step 2
evaluation (alkalinity >60-120). Note
that the slope of 0.3/10 is located at a
dosage of 25 mg/L of alum and results
in a TOG removal of 26%. The method
used to determine the actual slopes of
portions of Curve B was to draw it on
graph paper and count squares. Curve
fitting programs with instantaneous
slope determinations may be available
to improve the precision of this task. If
the specified TOC removal in Table IX-
1 had been followed, 31 mg/L of alum
would have been added to achieve the
required 30% removal. Curve C shows
a water with a TOC that is not amenable
to removal by coagulation. A slope of
0.3/10 is never reached.
Once a TOC percent removal is
established at the slope of 0.3/10, a
utility may operate its water treatment
plant with any combination of acid and
coagulant to achieve that percent TOC
removal. Utilities may find that the
least-cost approach to achieving a
specific TOC percent removal may be
with both sulfuric acid and a metal salt
coagulant. Other utilities may wish to
avoid the concerns with handling
sulfuric acid and use alum or ferric salts
to depress pH and produce a metal
hydroxide precipitate.
EPA solicits comment on whether a
slope of 0.3 mg/L of TOC removed per
10 mg/L of alum added should be
considered representative of the point of
diminishing returns for coagulant
addition under Step 2. EPA also solicits
comment on how the slope should be
determined (e.g., point-to point, curve-
fitting). If the slope varies above and
below 0.3/10, where should the Step 2
alternate TOC removal requirement be
set—at the first point below 0.3/10? At
some other point?
The requirement to add alum at 10
mg/L increments until the "maximum
pH" is reached was developed to ensure
that enough alum was added to
adequately test if TOC removal was
feasible and to add it in small enough
increments to notice significant changes
in the slope of the coagulant dose-TOC
removal curve. The maximum pH varies
depending on the alkalinity due to the
difficulty in changing pH at the higher
alkalinities. Because alum coagulation
of natural organic material is most
effective at a pH level between 5.5 and
6.5, large amounts of acid would be
required for high alkalinity waters to
achieve this optimal pH, followed by
large amounts of base to raise the pH of
the water up to 8.0 before distributing
to ensure compliance with the lead/
copper rule.
It is well demonstrated that the
concentrations and characteristics of
TOC in source waters will change over
time. In some source waters, the rate of
change could be rapid (such as during
storm events). Other source waters have
a generally consistent TOC
concentration and characteristic due to
storage of source water in reservoirs.
EPA proposes that, under guidance, the
bench- or pilot-scale evaluation of
enhanced coagulation be performed on
at least a quarterly basis, for one year,
to reflect seasonal changes in source
water quality. Currently, the proposed •
rule does not specify the frequency at
which the bench- or pilot-scale
evaluation should be conducted because
such frequency of testing may not be
warranted for all waters.
EPA solicits comment on how often
bench- or pilot-scale studies should be
performed to determine compliance
under step 2. Should such frequency
and duration of testing be included in
the rule or left to guidance (i.e., allow
the State to define what testing would
be needed on a case by case basis for
each system)? Is quarterly monitoring
appropriate for all systems? What is the
best method to present the testing data
to the primacy agency that reflects
changing influent water quality
conditions and also keeps transactional
costs to a minimum? How should
compliance be determined if the system
is not initially meeting the percent TOC
reduction requirements because of a
difficulty to treat waters and a desire to
demonstrate alternative performance
criteria?
b. Enhanced softening. In general,
there is much less data on the removal
of TOC during the softening process
when compared to conventional
treatment. Based on the data available to
the TWG, the definition of enhanced
softening is (a) the percent TOC
removals indicated for high alkalinity
waters (> 120 mg/1) in Table IX-1, or (b)
the achievement of 10 mg/L magnesium
removal during the softening process.
There are limited data on the use of
ferrous salts at the high pH levels of
softening, but not enough to specify in
this rule.
The calcium carbonate precipitate
typically created during softening is
relatively dense and completely unlike
the amorphous aluminum and ferric
hydroxide precipitates created in
conventional coagulation processes. It is
the amorphous or gelatinous nature of
the aluminum and ferric hydroxides
with their high surface areas that give
them their ability to absorb and remove
TOC. Softening is carried out at a wide
range of pH levels, generally between
9.5 and 11.0. Above a pH of about 10.5,
magnesium precipitates as magnesium
hydroxide (which has very similar
characteristics to alum and ferric
precipitates). The TWG determined that
if a softening process could not achieve
the percent TOC removals shown in
Table IX-1 under the alkalinity column
of >120 mg/L and it was practicing
magnesium precipitation, there was
little more that could be done to
enhance TOC removal. It is anticipated
that the vast majority of softening
utilities will be able to comply with
these enhanced softening requirements.
Not enough data were available to the
TWG to determine whether alternative
enhanced coagulation criteria needed to
be defined and, if so, what they should
be.
EPA solicits comment on whether
data are available on the use of ferrous
salts in the softening process which can
help define a step 2 for enhanced
softening. For softening plants, is
enhanced softening properly defined by
the percent removals in Table IX-1 or
by 10 mg/L removal of magnesium
hardness reported as CaCO3? Is there a
step 2 definition? Can ferrous salts be
used at softening pH levels to further
enhance TOC removals?
c. Preoxidation credit. Except for the
conditions described below,
disinfection credit for the purpose of
complying with the ESWTR is not
allowed prior to enhanced coagulation.
The reason for these limitations is the
production of higher levels of DBPs
when disinfectants are used prior to the
precursor removal step.
A number of water treatment plants
add oxidants to the influent to the
treatment plant to control a variety of
water quality problems. The regulation
allows the continuous addition of
oxidants to control these problems. The
limitation on disinfection credit prior to
enhanced coagulation, except for the
conditions described below, is expected
to keep the addition of disinfectants to
the minimum necessary to control the
water quality problems that can be
controlled by oxidation.
EPA solicits comments on whether
preoxidation is necessary in water
treatment to control water quality
problems such as iron, manganese,
sulfides, zebra mussels, Asiatic clams,
taste and odor. Will allowing
preoxidation before precursor removal
by enhanced coagulation generate
excessive DBF levels?
Ozone. Disinfection credit for ozone is
allowed prior to enhanced coagulation if
it is followed by biologically active
filtration (BAF) because many of the
organic DBPs formed by ozone are
generally removed by a biological
process. In order to maintain a filter in
a biologically active mode, virtually no
chlorine, chlorine dioxide, or
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38759
chloramines con be added to the filter
influent.
EPA solicits comments on whether
biologically active filtration following
ozonation is sufficient to remove most
byproducts believed to result from
ozonation. What parameters, if any,
should be measured in and/or out of the
filter to demonstrate a biologically
active filter, or alternatively, that ozone
byproducts are adequately being
removed? For example, would it be
sufficient to demonstrate greater than 90
percent removal of formaldehyde to
establish that a filter is biologically
active and that predisinfection credit
could therefore be given?
Chlorine dioxide. Due to the wide
variation in the application of chlorine
dioxide generation technology, it is
common for water treatment plants to
apply chlorine dioxide along with an
excess of free chlorine. Technologies do
exist to produce high purity chlorine
dioxide, but these technologies are not
universally used. EPA is proposing to
allow disinfection credit for chlorine
dioxide prior to enhanced coagulation
in the same manner as for ozone and
BAF if the system can demonstrate the
generation of high purity chlorine
dioxide.
Under the proposal, a system using
chlorine dioxide could get disinfection
credit if the following standards are met:
the chlorine dioxide generator must
generate chlorine dioxide on-site at a
minimum 95 percent conversion
efficiency (yield) from sodium chlorite;
and the generated chlorine dioxide feed
stream applied from the chlorine
dioxide generator must contain less than
five percent (by weight) free chlorine
residual, measured as the weight ratio of
free residual chlorine (i.e.,
hypochlorous acid) to chlorine dioxide
in such feed stream. Compliance with
these standards must be demonstrated
on an ongoing basis for each generator
in use. By meeting these standards,
chlorite and chlorate (chlorine dioxide
generation byproducts) will be limited
and free residual chlorine will not be
available to react with the organic
precursors prior to TOC removal and the
potential for halogenated organic DBF
production is limited.
EPA solicits comments on whether
disinfection credit should be allowed
for chlorine dioxide used prior to
enhanced coagulation if virtually no
halogenated organic DBFs are formed.
Should some other limit, in addition to
or in lieu of that proposed, be set (e.g.,
5 ug/L TTHMs) on DBFs formed by high
purity chlorine dioxide to ensure
sufficient control for the production of
excessive halogenated organic DBFs if
disinfection credit were to be allowed
with chlorine dioxide prior to enhanced
coagulation?
Disinfection credit during cold water
months. It is well established that
temperature plays a critical role in the
production of DBFs and that DBF
concentrations are the lowest in winter
months. The cold water temperature
months are also the most difficult time
for utilities to meet CT requirements,
because longer contact times with a
disinfectant are needed to overcome the
poorer inactivation efficiencies.
Figure IX-2 plots the required CT
values for inactivation of Giardia cysts
for free chlorine at various pH and log
inactivation levels. The family of curves
clearly indicates a significant change in
slope below a temperature of 5° C
indicating that it is much more difficult
to achieve a log inactivation of Giardia
cysts in water below this temperature.
BILLING CODE 6560-60-P
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Figure IX-2
CT Values - laactivatton of Giardia Cysts by
Free Chlorine (Residual = 0.6 mg/L)
o
10 15
Temperature *C
20
KEY
pH-7.«,Lof lMcttatkn
BLLING CODE 6560-60-C
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38761
appropriateness of this provision or
alternative means for addressing this
NSERT FIGURE IX-2 HERE.
EPA is proposing that systems be
allowed to add a disinfectant before
enhanced coagulation when water
temperatures are less than or equal to
5°C. In order to ensure that excessive
DBFs are not produced by this special
case and to more cost effectively balance
chemical and microbial risks, exercise
of this provision would only be allowed
if the TTHM and HAAS winter quarterly
averages in the distribution system
served by the treatment plant are less
than 40 and 30 ug/1, respectively.
EPA solicits comment on the
3
issue.
d. Basis for Avoiding Enhanced
Coagulation or Enhanced Softening
Requirements. The purpose of the
treatment technique for control of
disinfection byproduct precursors
(DBPPs) is to remove one of the factors
which result in the production of DBFs
upon subsequent disinfection. Criteria
have been established which allow
systems to forgo the requirement to
implement enhanced coagulation for
control of DBPPs. These criteria were
generally established to either recognize
low potential of certain waters to
produce DBFs or to account for types of
water which contain TOG that is
difficult to remove by enhanced
coagulation. Implementation of
enhanced coagulation in difficult to
treat waters generally costs much more
than the average case used to develop
the national costs for this rule, and may
introduce other water quality problems.
TOC <2.0 mg/L. If a water contains
less than 2.0 mg/L TOG before
continuous disinfection, it does not
have to implement enhanced
coagulation. This level is calculated
each quarter as a running annual
average, based on monthly (or quarterly,
if the system has qualified for reduced
monitoring) treated water (i.e., prior to
continuous disinfection) TOC
measurements. The basis for this
criterion is related to the purpose of the
enhanced coagulation requirement
(which is to reduce the presence of
organic matter when chlorine or other
disinfectants are added to the water). A
TOC of less than 2.0 mg/L would be
expected, in general, to produce TTHM
and HAAS levels upon chlorination that
are less than 40 and 30 ug/L,
respectively. This criterion would apply
to high quality source waters and to
systems with water treatment plants
which have installed a precursor
removal process other than enhanced
coagulation prior to continuous
disinfection. High quality surface waters
with TOC levels less than 2.0 mg/L
account for less than 20 percent of the
total number of utilities using surface
water in the U.S.
Systems with other installed
precursor removal technologies include
a water treatment plant with granular
activated carbon in a post-filter adsorber
configuration, e.g., Cincinnati, Ohio. As
long as the TOC is less than 2.0 mg/L
before continuous disinfection, it is not
important which precursor removal
technology is employed.
40/30/<4/>60. It is harder to remove
organic matter by enhanced coagulation
in waters with alkalinities greater than
60 mg/L as CaCO3 and TOC levels less
than 4.0 mg/L. To compensate for this
phenomenon, systems with these water
quality characteristics are permitted to
apply alternate disinfectants before any
precursor removal step and, if the
TTHM and HAAS levels produced are
less than 40 and 30 ug/L, respectively,
the utility would not have to implement
enhanced coagulation. Source water
TOC, source water alkalinity and TTHM
and HAAS levels are calculated each
quarter as running annual averages,
based on monthly measurements.
In addition to allowing systems that
already meet these criteria to avoid
enhanced coagulation, the Committee
also agreed to allow systems that were
installing alternative disinfection
technology that would allow the system
to meet these criteria to avoid enhanced
coagulation. The technology must be
installed prior to the compliance date
for Stage 2 D/DBPR. For example, a
system that already had a TOC of less
than 4.0 mg/1 and an alkalinity of
greater than 60 mg/1 would be allowed
to avoid enhanced coagulation if the
system committed to installation of
ozonation. This commitment must
include a clear and irrevocable financial
commitment not later than the effective
date for compliance with Stage 1 D/
DBPR to technologies that will limit the
levels of TTHMs and HAAS to no more
than 0.040 mg/1 and 0.030 mg/1,
respectively. Systems must submit
evidence of the financial commitment,
in addition to a schedule containing
milestones for installation and operation
of appropriate technologies, to the State
for approval. Violation of the approved
schedule will constitute a violation of
the National Primary Drinking Water
Regulation.
The schedule must be enforceable, but
should only contain significant
milestones. Types of schedule items that
should be included as enforceable
include award contract, begin
construction, end construction, pilot
operations, and full compliance. The
schedule should allow for minor
slippage, but must require compliance
by the compliance date for Stage 2. The
State may also require periodic progress
reports, but EPA recommends that these
not be part of the enforceable schedule
(and thus be a basis for finding the
system in violation for late submission
or failure to submit).
The cost of employing enhanced
coagulation to waters of this type is
higher than the base case examined as
part of the regulatory impact analysis for
this rule. It is assumed that systems
with this type of water quality will, in
general, achieve more cost effective
reduction of DBFs by use of alternative
treatment strategies than by use of
enhanced coagulation. The overall
purpose of this rule is to reduce the
levels of both DBFs that are known and
DBFs which are not known. The
criterion in this section is expected to
accomplish these goals.
40/30 with Chlorine. It is possible that
some types of TOC do not produce
significant levels of DBFs upon
chlorination. To account for this fact,
systems which use chlorine (and meet
the CT requirements under the SWTR or
ESWTR) and which achieve running
annual averages of less than 40 and 30
ug/L for TTHM and HAAS, respectively,
do not have to employ enhanced
coagulation. The type of precursors
normally encountered in surface waters
will produce TTHMs and THAAs higher
than the concentrations of 40 and 30 ug/
L if the TOC level is greater than 2.0 mg/
L and CT requirements are met. It is
expected that this criterion will not be
applicable to many surface water
systems.
4. Basis for GAG Definitions
Treatment with granular activated
carbon (GAG) has been found by many
researchers to remove organic DBF
precursors. For water treatment
applications, GAG is typically placed in
a gravity filter, not unlike granular
media filters for particle removal, and
operated in a downflow mode. The
design parameters most often specified
for the use of GAG are empty bed
contact time (EBCT) and regeneration
frequency (or equivalently, carbon use
rate). During the development of this
proposed rule, GAG was defined at two
levels of treatment to facilitate the
development of national cost data as
well as project expected national DBF
levels resulting from the use of GAG
treatment.
GAC10 means granular activated
carbon filter beds with an empty-bed
contact time of 10 minutes based on
average daily flow and a carbon
regeneration frequency of every 180
days. The GAC10 definition, which was
recommended by the TWG, was meant
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
to specify the design and operating
conditions of GAG that would be
necessary to remove approximately the
same amount of DBF precursors
(measured as TOG) as that achieved by
enhanced coagulation. As discussed
previously, the Negotiating Committee
agreed that enhanced coagulation or
GAC10, used in conjunction with
chlorine as the sole disinfectant, should
be the BATs corresponding to the Stage
\ MCLs of 80 and 60 ug/1 for TTHMs
and HAAS, respectively.
GAC20 means granular activated
carbon filter beds with an empty-bed
contact time of 20 minutes based on
average daily flow and a carbon
regeneration frequency of every 60 days.
The GAC20 definition, recommended by
the TWG, was meant to specify the
conditions by which at least 90% of the
systems in the U.S. would be able to use
this technology, with chlorine as the
sole disinfectant, and comply with the
Stage 2 MCLs of 40 and 30 |ig/l for
TTHMs and HAAS, respectively. The
ability of systems to use GAC20 and
achieve such performance was tested
and confirmed by the TWG using
national TOG occurrence data obtained
from the Water Industry Data Base
(WIDB) and the Water Treatment Plant
Simulation Model (USEPA 1992;
USEPA, 1994).
The Water Treatment Plant
Simulation Model predicts the
production of TTHMs and HAAS based
on water quality and treatment
conditions. GAG performance in the
model is based on equation parameters
developed as part of a TOC removal
study at Jefferson Parish, Louisiana.
Jefferson Parish is proposed as
representative of the "general case" for
TOG removal. TOC removal has been
demonstrated to be higher at Jefferson
Parish than at Manchester, NH; Miami,
FL; and the Metropolitan Water District
of Southern California. TOC removal
was lower at Jefferson Parish than at
Philadelphia, PA; Cincinnati, OH; and
Shreveport, LA.
The TWG participants who developed
these definitions also thought that it
would be conceivable for GAC10 to be
employed in a filter media replacement
mode. GAC20 was clearly not
compatible in a filter media replacement
mode and would have to be applied as
post-filter adsorbers.
EPA solicits comment on whether
GAC10 and GAC20 are reasonable
definitions of GAG performance? Do
they span the expected level of GAG
applications in drinking water treatment
for the control of TTHMs and HAAS? Is
it appropriate to consider Jefferson
Parish, Louisiana, TOC removal by GAG
representative of the "general case" of
TOC removal?
5. Basis for Monitoring Requirements
Monitoring for disinfection
byproducts, disinfectant residuals, and
total organic carbon must be conducted
during normal operating conditions.
Systems may not change their operating
conditions for the sole purpose of
meeting an MCL or MRDL and then
change back to an operating regime that
would not meet limits. For example, a
system may not reduce disinfectant feed
temporarily to meet the chlorine MRDL
and the TTHM and HAA5 MCLs (or
chlorine dioxide MRDL and chlorite
MCL) and then immediately revert to a
higher feed. However, systems are
allowed to modify operations to address
changing conditions and to protect
human health. For example, systems
must modify operations to address
changes in source water quality or
emergency conditions (such as
earthquakes and floods). Such
modifications have been made for
legitimate reasons and are included as
"normal operations".
Failure to monitor in accordance with
the monitoring plan is a monitoring
violation. Where compliance is based on
a running annual average of monthly or
quarterly samples or averages and the
system's failure to monitor makes it
impossible to determine compliance
with MCLs or MRDLs, this failure to
monitor will be treated as a violation for
the entire period covered by the annual
average. Systems whose monitoring is
substantially complete will not be in
violation for the entire period covered
by the annual average. Substantially
complete means that the State is able to
determine MCL/MRDL compliance. For
example, a system that missed a few
percent of its MRDL compliance
samples due to inability to sample at
required locations (or took all necessary
samples, but had minor deviations from
its monitoring plan) would be able to
determine compliance. These systems
would be in violation of monitoring
requirements, but only for the month or
quarter (depending on the particular
requirement). A system that did not take
samples or took samples at locations
that would be expected to produce
results that are not representative (e.g.,
not taking TTHM samples at the point
of maximum residence time) is in,
violation for the entire period covered
by the annual average.
a. TTHMs and HAAS. In general,
monitoring requirements for TTHMs
and HAAS follow closely the
requirements contained in the 1979
TTHM rule. In that rule, there were
provisions for routine and reduced
monitoring. In this proposal, the Agency
has included the same frequency of
monitoring for routine monitoring for
Subpart H systems serving at least
10,000 people as in the 1979 TTHM
rule, although the Committee did not
reach consensus on these specific
requirements. See below for (1) further
discussion and (2) requests for comment
on the monitoring requirements.
Subpart H systems serving 10,000 or
more persons must take four water
samples each quarter for each treatment
plant in the system, with at least 25
percent of the samples taken at locations
within the distribution system that
represent the maximum residence time
of the water in the system. The
remaining samples must be taken at
locations within the distribution system
that represent the entire system, taking
into account the number of persons
served, different sources of water, and
different treatment methods employed.
Initial monitoring for ground water
systems serving at least 10,000 people
will be less than what is required under
the 1979 TTHM rule, because of the
generally lower byproduct formation
shown over the life of the 1979 rule.
Systems that use a chemical disinfectant
must take one water sample each
quarter for each treatment plant in the
system, taken at locations within the
distribution system that represent the
maximum residence time of the water in
the system. Routine samples must be
taken at locations meant to reflect the
highest possible TTHM and HAAS
levels (i.e., at the maximum residence
time in the distribution system). If those
samples are below the MCL, the Agency
believes that the system should be
considered in compliance.
The Agency is also requiring systems
not regulated under the 1979 TTHM
rule to meet the requirements of this
proposed rule. Community water
systems serving fewer than 10,000
people will be covered, as will
nontransient noncommunity water
systems, a category that did not exist in
1979. Nontransient noncommunity
water systems must sample at the same
frequency and location as community
water systems of the same size.
Routine samples for these systems
must be taken at locations meant to
reflect the highest TTHM and HAAS
levels (i.e., at the maximum residence
time in the distribution system). If those
samples are below the MCL, the Agency
believes that the system should be
considered in compliance. Subpart H
systems serving from 500 to 9,999
persons must take one water sample •
each quarter for each treatment plant in
the system, taken at a point in the
distribution system that represents the
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38763
maximum residence time in the
distribution system.
Subpart H systems serving fewer than
500 persons must take one sample per
year for each treatment plant in the
system, taken at a point in the
distribution system reflecting the
maximum residence time in the
distribution system and during the
month of warmest water temperature,
when the formation rate of TTHMs and
HAAS is the fastest. This monitoring
requirement will allow for a worst case
sample, but will limit the monitoring
burden for these very small systems.
Systems using only ground water
sources not under the direct influence of
surface water that use a chemical
disinfectant and serve less than 10,000
persons must sample once per year for
each treatment plant in the system,
taken at a point in the distribution
system reflecting the maximum
residence time in the distribution
system and during the month of
warmest water temperature, as with
very small Subpart H systems.
All ground water systems may, with
State approval, consider multiple wells
drawing water from the same aquifer as
one plant for the purposes of
determining monitoring frequency. This
provision is the same as was in the 1979
TTHM rule. EPA requests comment on
whether any additional regulatory
requirements', guidance, or explanation
is required to define "multiple wells".
It was the intention of the Committee
that multiple wells include both
individual wells and well groups. This
was done because many ground water
systems are extremely decentralized,
with multiple entry points to the
distribution system, unlike most
Subpart H systems with only one or
several entry points. Also, EPA requests
comment on whether there should be an
upper limit of sampling frequency for
systems that either cannot determine
that they are drawing water from a
single aquifer or are drawing water from
multiple aquifers. For example, should
a system that must draw water from
many aquifers to satisfy demand be
allowed to limit monitoring as if they
were drawing from no more than four
aquifers (routine sampling would thus
be limited to four samples per quarter
from systems serving at least 10,000
people or to four samples per year for
systems serving fewer than 10,000
people)? Does EPA need to develop any
additional guidance for any other aspect
of this requirement?
Systems monitoring less frequently
than one sample per quarter per plant
must increase monitoring to one sample
per treatment plant per quarter until the
system meets criteria for reduced
sampling if the sample (or the average
of the annual samples, when more than
one sample is taken) exceeds the MCL.
Systems may sample more frequently
than one sample per quarter and more
frequently than required, but must take
at least 25 percent of the samples at a
location reflecting the maximum
residence time in the distribution
system. The remaining samples must be
taken at locations representative of at
least average residence time in the
distribution system. Any public water
system that samples once per quarter or
less, but more frequently than the
frequency required in this section, must
take all of its samples at a location
reflecting the maximum residence time
in the distribution system.
Taken together, these requirements
attempt to balance TTHM and HAAS
formation, system size and source
characteristics, and system monitoring
costs. As the number of required
samples decreases, the system is
required to take samples at locations
(and times, in some cases) where the
highest levels would be expected.
Reduced TTHM and HAAS
Monitoring. Some systems are not able
to reduce monitoring. Any Subpart H
system which has a source water TOG
level, before any treatment, of greater
than 4.0 mg/1 may not reduce its
monitoring. Subpart H systems serving
fewer than 500 people may not reduce
their monitoring to less than one sample
per plant per year. Should there be any
exceptions that would allow systems
with a TOC> 4.0 mg/1 to reduce
monitoring (e.g., the system has
installed nanofiltration)?
Systems may reduce monitoring (1) if
they have a running annual averages for
TTHMs and HAAS that are no more
than 0.040 mg/1 and 0.030 mg/1,
respectively, or (2) for systems using
ground water not under the direct
influence of surface water that serve
fewer than 10,000 persons and are
required to take only one sample per
year, if either (a) the average of two
consecutive annual samples is no more
than 0.040 mg/1 and 0.030 mg/1,
respectively, for TTHMs and HAAS or
(b) any annual sample is less than 0.020
mg/1 and 0.015 mg/1, respectively, for
TTHMs and HAAS. Systems must meet
these requirements for both TTHMs and
HAAS to qualify for reduced
monitoring. The system may reduce
monitoring only after the system has
.completed at least one year of
monitoring. This standard is more
stringent than that in the TTHM rule, in
which the system had only to
demonstrate that the TTHM
concentrations would be "consistently
below" the MCL. The Negotiating
Committee felt that a more objective set
of criteria were necessary.
Reduced monitoring frequency.
Subpart H systems serving 10,000
persons or more that are eligible for
reduced monitoring may reduce the
monitoring frequency for TTHMs and
HAAS to one sample per quarter per
treatment plant, with samples taken at
a point in the distribution system
reflecting the maximum residence time
in the distribution system. Subpart H
systems serving between 500 to 9,999
persons that are eligible for reduced
monitoring may reduce the monitoring
frequency for TTHMs and HAAS to one
sample per year per treatment plant,
with samples taken at a point in the
distribution system reflecting the
maximum residence time in the
distribution system and during the
month of warmest water temperature.
Systems using only ground water not
under the direct influence of surface
water and serving 10,000 persons or
more that are eligible for reduced
monitoring may reduce the monitoring
frequency for TTHMs and HAAS to one
sample per year per treatment plant,
with samples taken at a point in the
distribution system reflecting the
maximum residence time in the
distribution system and during the
month of warmest water temperature.
Systems using only ground water
sources not under the direct influence of
surface water and serving fewer than
10,000 persons may reduce the
monitoring frequency for TTHMs and
HAAS to one sample per three-year
monitoring cycle, with samples taken at
a point in the distribution system
reflecting the maximum residence time
in the distribution system and during
the month of warmest water
temperature.
EPA believes that this procedure of
taking worst-case samples less
frequently will adequately identify
systems with TTHM and HAAS
problems, since systems have to meet
relatively stringent criteria to be eligible
for reduced monitoring. Systems which
are on a reduced monitoring schedule
may remain on that reduced schedule as
long as the average of all samples taken
in the year (for systems which must
monitor quarterly) or the result of the
sample (for systems which must
monitor no more frequently than
annually) is no more than 75 percent of
the MCLs. Systems that do not meet
these levels must resume monitoring at
routine frequency. Also, the State may
return a system to routine monitoring at
the State's discretion.
During the negotiated rulemaking, the
Association of State Drinking Water
Administrators (ASDWA) expressed the
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38764 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
opinion that the reduced monitoring for
ground water systems serving fewer
than 10,000 people could be expanded
beyond what is in the proposal. These
are the systems usually having multiple
ground water sources, whose quality is
unlikely to change with respect to DBF
precursors and are most likely to benefit
from reduced monitoring. The
additional options presented below both
have as a basis the demonstration that
the ground water source in question has
a minimal likelihood of having
precursor material that could combine
with chlorine to form any significant
concentrations of THMs or HAASs. Each
option would rely on having each entry
point of the system go through three
years of routine monitoring to qualify
for reduced monitoring. After this
period, if the entry points meet
additional criteria, then the entry points
would be subject to minimal additional
monitoring. Option one would reduce
the monitoring to once every nine years
for THMs and HAASs in the distribution
system. This option would minimize the
expense of THM and HAAS monitoring
for these systems. Option two, which
specifies even more restrictive criteria,
would exempt systems from any
additional THM and HAAS monitoring
as long as the TOG criteria are met. This
option offers the largest cost savings and
eliminates the need for tracking and
enforcing monitoring requirements on
those systems that have historically had
the poorest monitoring compliance
records and are least likely to have
significant levels of DBFs. The Agency
would like to receive comments on the
following two options.
Option One: Any ground water
system serving fewer than 10,000 people
that has a raw water TOC of less than
1.0 mg/1, and has both TTHM and
HAAS values less than 25 percent of the
MCLs (20 ug/1 and 15 ug/1, respectively)
after three years of routine and reduced
monitoring, can reduce the monitoring
for TTHMs and HAASs to one sample
every nine years, taken at the maximum
distribution system residence time
during the wannest month.
Option Two: Any ground water
system serving fewer than 10,000 people
that has a raw water TOC of less than
0.5 mg/1, and has both TTHM and
HAAS values less than 25 percent of the
MCLs (20 ug/1 and 15 ug/1, respectively)
after three years of routine and reduced
monitoring, is exempt from the
distribution system monitoring
requirements for TTHMs and HAASs for
as long as TOC monitoring is conducted
once every three years and the raw
water TOC remains less than 0.5 mg/1.
These options are not mutually
exclusive, that is, both could be used
simultaneously or some hybrid could be
developed. The Agency seeks comment
on whether either or both of these
options are reasonable in adequately
protecting the public health and should
therefore be considered as criteria for
reduced monitoring. Are there other
options for reduced monitoring that
should be considered? What are they?
Consensus was not reached on certain
key aspects of monitoring and
compliance determination. Some
members of the Negotiating Committee
expressed concerns about the following
issues, especially (but not solely) as
related to TTHMs and HAAS
monitoring:
—Is the monitoring frequent enough to
adequately determine variations in
sample results caused by time and/or
location in the distribution system? If
not, what is a more appropriate
monitoring schedule? Should
requirements differ for systems based
on population served, raw water
source, or other factors? If so, should
the proposed requirements be
changed? How should they be
changed? If requirements should not
be based on these factors, what should
the requirements be?
—Does averaging of sample results
taken in various locations and
averaging over the course of a year to
determine compliance adequately
protect individuals that are in
locations that may regularly have
higher than average levels? If it does
not, how should the proposed
requirements be changed?
EPA solicits comment on the above
issues.
b. Basis for TOC Monitoring
Requirements With Enhanced
Coagulation or Enhanced Softening. In
order to demonstrate that the necessary
DBPP removal is accomplished (either
the percentage specified in Table IX—1
or the alternative minimum TOC
removal level determined by the AECL),
systems must monitor TOC on a
monthly basis, with both source water
and treated water (prior to continuous
disinfection) samples taken. At the same
time, systems must monitor for source
water alkalinity. Compliance is based on
a running annual average, computed
quarterly. Specifics on compliance
calculations are included in Section
VIII.
B. Bromate MCL and BAT
During the D/DBP negotiated
regulation, ozone was evaluated as an
alternative disinfectant to chlorine. In
particular, the use of ozone for primary
disinfection and chloramines for
residual disinfection were considered as
a disinfection scenario to significantly
minimize the formation of THMs,
HAAs, and TOX (Metropolitan Water
District of So. Calif, et al., 1989;
Ferguson et al., 1991; Glaze et al., 1993,
in press; Miltner, 1993; and Jacangelo et
al., 1989). In addition, when a "cancer-
risk bubble" was evaluated by
examining the theoretical risks
contributed by five compounds that
have been classified as B2 (i.e.,
"probable human") carcinogens (i.e.,
chloroform, bromodichloromethane,
bromoform, dichloroacetic acid [DCAA],
and bromate), it was shown that the
production of bromate during ozonation
may present less of a theoretical cancer
risk than the sum of the risks from the
individual chlorination DBFs. However,
such a determination largely depended
upon the risk attributed to DCAA
(which had not been finally established
by EPA). Also, the ability to detect
bromate at risk levels equivalent to risk
levels for chlorinated DBFs greatly
obscures this analysis.
As part of the TWG evaluation of
different technologies that might be
used to comply with the D/DBP Rule,
ozone/chloramines were evaluated
under a possible enhanced SWTR
scenario for large systems using surface
waters that filter but do not soften. It
was predicted that TTHMs would range
from 4 to 62 ug/L, with median, 75th,
and 90th percentile values of 15, 23, and
30 ug/L, respectively. In addition, it was
predicted that HAAS would range from
2 to 133 ug/L, with median, 75th, and
90th percentile values of 16, 26, and 41
Ug/L, respectively. The TWG believed
that use of alternative disinfectants
would provide a feasible means of not
only achieving the Stage 1 criteria of 80
Ug/L TTHMs and 60 ug/L HAAS but also
allow some systems the means of
complying with a proposed Stage 2
criteria of 40 ug/L TTHMs and 30 ug/L
HAAS. As discussed previously (Section
VLC.l.b.ii), the TWG also conducted an
analysis of bromate occurrence with use
of ozone technology and determined
that most systems, allowing for
modifications in treatment if necessary,
such as lowering of pH, could achieve
a bromate level of 10 ug/L (Krasner et
al., 1993).
A major issue, however, is the ability
to determine low levels of bromate
during compliance monitoring and
concern that the risk from bromate
could exceed the risk from chlorinated
DBFs for which risk estimates are
available. While Haag and Hoigne
discussed the theoretical basis for the
formation of bromate in their 1983
paper (Haag et al., 1983), an analytical
method sensitive enough to determine if
bromate was indeed formed in ozonated
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38765
drinking water was not available until a
few years ago (Pfaff et al., 1990). In
addition, the initial ion chromatography
(1C) method was unable to adequately
resolve low levels of bromate from very
high amounts of chloride. Because most
waters high in bromide can have very
high levels of chloride (Metropolitan
Water District of So. Calif, et al., 1989),
Kuo and colleagues developed a
modification to the 1C method in order
to remove chloride prior to bromate
analysis (Kuo et al., 1990). This
modification permitted quantitation of
bromate down to a concentration of 10
ug/L; subsequently quantitation has
been lowered in several research
laboratories to 3 or 5 ug/L (Gramith et
al., 1993). Using two different labor-
intensive concentration methods prior
to 1C analysis at EPA research facilities,
quantitation for bromate was lowered to
less than 1.0 ug/L (Sorrell et al., 1992
and Hautman, 1992).
Currently, though, a minimum
quantitation level for bromate by
conventional 1C is probably about 10 ug/
L in laboratories that might perform
compliance monitoring. During the D/
DBF negotiated rulemaking, some
members of the Negotiating Committee
expressed concern that setting an MCL
at 10 Ug/L would exceed the theoretical
10~4 risk level for bromate of 5 ug/L.
The regulation of bromate, at this time,
represents an unresolved issue.
However, the Negotiating Committee
was willing to propose an MCL for
bromate of 10 ug/L with the following
qualifications and reservations:
1. EPA is seeking data to show that a
lower quantitation level (at least down
to 5 ug/L) can be obtained by those
laboratories that will perform
compliance monitoring for bromate in
natural drinking water matrices.
Whether this improvement in sensitivity
is accomplished by improvements to the
official EPA method 300.0 (USEPA,
1993) or an alternative analytical
method, such data would need to
demonstrate appropriate precision and
accuracy, including a linear calibration
curve for the range of values to be
measured, quantitative and precise
measurements at the MCL (U.S. Office
of the Federal Register, 1987), intra- and
interlaboratory reproducibility, as well
as freedom from potential interferences
in natural matrices (e.g., other anions in
water such as chloride, and other ozone
byproducts such as organic acids). In
addition, this methodology would need
to be demonstrated in a number of
ozonated drinking water matrices and
tested in several laboratories
nationwide. If the improved
methodology uses equipment and/or
reagents that are not currently required
for EPA method 300.0, data to indicate
the commercial availability and costs of
these items would also need to be
presented.
2. In addition, EPA is soliciting
comments on a treatment technique that
could ensure that bromate can be kept
below 5 ug/L, even if quantitation at 5
ug/1 is not achievable under routine
laboratory conditions. A possible
treatment technique that could ensure
that all systems be able to produce <5
Ug/L bromate (the theoretical 10 ~4 risk
level), would be to construct a matrix of
predicted bromate concentration as a
function of bromide concentration
levels, ozone disinfection conditions
(CT), and pH levels under which
ozonation occurs. As the bromide and/
or inactivation criterion increased, the
pH of ozonation might need to be
decreased to ensure that the bromate
concentration was kept below 5 ug/1.
Under a treatment requirement, if a
system used ozone, it would be required
to operate within the specified matrix
conditions for bromide, CT, and pH
levels to achieve compliance. This
matrix would need to consider ozone
residuals sufficient to meet CT criteria
for a possible ESWTR.
Other treatment techniques which
allow ozone to meet disinfection and
oxidation requirements while
minimizing bromate formation are also
solicited. In addition, any proposed
treatment technique must be field-tested
in a number of representative natural
water matrices. A number of parameters
which can affect bromate formation and
must be evaluated in establishing a
treatment technique include TOC,
bromide, alkalinity, pH, ammonia, and
hydrogen peroxide levels of the water,
as well as the temperature and ozone
contact time (Krasner et al., Jan. 1993;
Amy et al., 1992-3; Haag et al., 1983;
Glaze et al., Jan. 1993; Krasner et al.,
1991; Miltner, Jan. 1993; Krasner et al.,
1993; Gramith et al., 1993; Miltner et al.,
1992; Siddiqui et al., 1993; and Von
Gunten et al., 1992). Because the
hydrodynamics of the ozone contactor
can significantly affect bromate
formation (Krasner et al., Jan. 1993;
Krasner et al., 1991; and Gramith et al.,
1993), the treatment technique may
need to be evaluated at pilot-,
demonstration-, and/or full-scale.
(Bench.-scale testing can be used in
preliminary evaluations of ozone/
bromide/bromate chemistry, but such
experiments cannot provide the sole
basis for determining an appropriate
treatment technique.)
Evaluation of the treatment technique
will also require quantitation of bromate
concentrations that are <5 ug/L. Thus,
appropriate quality assurance and
control will be required to ensure that
the data are precise and accurate.
3. Because the proposed bromate MCL
of 10 ug/L was determined to be feasible
based upon studies performed to date, if
sufficient data are presented to EPA to
indicate that a lower MCL and/or an
appropriate treatment technique can be
obtained, the feasibility and nationwide
regulatory impact would need to be
considered. For example, the cost of
chemical addition to lower the pH of
water before ozonation and to raise the
pH prior to distribution was not
considered in developing the national
cost data for systems using ozone to
meet the D/DBP Rule. This cost for pH
adjustment could be significant for
systems with high alkalinity. EPA
requests comment on the cost impact
that this requirement would have on
systems with both high alkalinity and
high bromide levels. The effect of a
treatment technique would also need to
be evaluated in terms of other water
quality impacts. Therefore, if a
treatment technique is developed, EPA
would revise the regulatory impact
analysis to reflect new costs and other
water quality impacts. EPA requests
comment on the relative costs of
adjusting pH to reduce bromate
formation versus the costs of other
technologies to meet the MCLs in this
proposed rule.
The following limited data suggest
that a significant increase in sensitivity
of the method for measuring bromate
may indicate that other disinfectant/
oxidants produce bromate, and/or that
bromate may be a contaminant in some
source waters. In a study conducted to
test a more sensitive method for
measuring bromate (Hautman, 1992), a
bromate concentration of 0.4 ug/L was
measured in one of the nine source
waters tested (i.e., before the point of
disinfection/oxidation). However, the
researcher did not rule out the
possibility of sample contamination of
this source water. Theoretical and
limited data suggest that chlorine
dioxide can react with bromide in the
presence of sunlight to form brominated
DBFs, including possibly bromate
(Cooper, 1990 and Kruithof, 1992).
Likewise, under alkaline conditions,
bromide reacts with hypochlorite to
form hypobromite which then
disproportionates to bromate (Bailar et
al, 1973). When the hypochlorite
solutions from 14 drinking water
utilities were surveyed for the presence
of oxyhalides (Bolyard et al., 1992),
bromate was measured in nine of the
hypochlorite solutions, at levels of 4 to
51 mg/L. However, the chlorinated
drinking water samples did not contain
bromate at concentrations above the 10
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ug/L quantitation level. Based on this
information, if the MCL for bromate is
lowered, analyses for the occurrence of
bromate may need to be extended to
sources other than ozonated water.
4. EPA plans to convene a second
meeting of interested parties to develop
a consensus on the second stage of the
D/DBP Rule in 1998. It is anticipated
that by that time, measurement for
bromate at concentrations <10 ug/L may
be practical, more health effects data on
this DBP will be available, and the
treatment to control bromate formation
will be appropriately developed and
field tested. EPA solicits comments on
the feasibility of developing a treatment
technique requirement for bromate,
lowering the MCL based upon improved
analytical techniques, and the time
frame under which such alternative
standards could be developed.
In the proposed D/DBP Rule, bromate
compliance will be based on a running
annual average value. This schedule is
analogous to that used for THMs and
HAAs. Because carcinogens represent a
risk based upon a lifetime exposure,
temporary peaks in exposure should not
affect the lifetime cancer risk. Unlike
THMs and HAAs, though, bromate will
be measured monthly rather than
quarterly and at the entry point to the
distribution system rather than in the
distribution system. THMs and HAAs
can increase in a distribution system as
DBP precursors continue to react with
the residual disinfectant, especially if
free chlorine is used. Because ozone and
other active oxidant residuals (e.g.,
hydroxyl radicals) are short-lived,
bromate formation should be complete
within the treatment plant. Once in the
distribution system, bromate should be
stable (Glaze et al., 1993, in press), so
analyzing samples in the distribution
system will provide no additional
information. Because there are many
water quality parameters and treatment
plant operations that can affect bromate
formation, it was not clear whether
quarterly monitoring would be adequate
to capture the variability in bromate
formation (Krasner et al., Jan. 1993,
Miltner, Jan. 1993, and Gramith et al.,
1993). However, EPA is proposing
reduced bromate monitoring where a
utility's average raw water bromide
level is less than 0.05 mg/L. This
reduction is based on limited data to
date to suggest that under typical
drinking water ozonation conditions of
water with <0.05 mg/L bromide (based
on pilot- and full-scale data) that
bromate will typically not be formed at
levels of 5 to 10 ug/L or higher (Krasner
et al., 1993).
C. Chlorite MCL and BAT
Chlorite is formed as a result of
treating source water with chlorine
dioxide. Many utilities use chlorine
dioxide because of specific water
quality characteristics that make the
water difficult to treat. These
characteristics include high hardness,
TOG, and bromide concentrations. For
example, at high pHs (above 9.0),
chlorine is much less effective as a
disinfectant and ozone residuals cannot
be maintained in solution long enough
for effective disinfection. Systems now
using chlorine dioxide may not be able
to meet the standards proposed in this
regulation, since in some cases, even
expensive precursor removal
technologies such as GAG or membrane
technology may not be able to remove
precursors adequately to meet DBP
MCLs and, in other cases, systems may
not be able to use the technologies due
to site restrictions (e.g., membranes not
feasible due to water limits—system
cannot afford loss of significant amounts
of water as membrane reject).
While research is underway on how
to reduce chlorite residuals at the
treatment plant, e.g., using ferrous iron
(Griese et al., 1992), additional work is
required. At this time, the only means
for reducing chlorite levels is to control
the use of chlorine dioxide.
During the negotiations, EPA had not
yet established a reference dose for
chlorite and, therefore, no MCLG was
considered at that time. However, EPA's
Office of Water staff stated that they
interpreted the available health effects
data to indicate the toxicological
endpoint of concern as oxidative stress
to red blood cells. This effect is
considered reversible, lasting a matter of
a few weeks or months.
Based on considerations that the
health effect was of relatively short
duration, and that some systems might
require chlorine dioxide, the
Negotiating Committee agreed to
propose a conditional MCL of 1.0 mg/
1. This MCL was selected based on a
recommendation from the TWG that 1.0
mg/1 is the lowest level achievable by
typical systems using chlorine dioxide,
and taking into consideration the
monitoring requirements to determine
compliance.
In agreeing to propose 1.0 mg/1 as the
MCL for chlorite, the Negotiating
Committee set certain qualifications and
reservations:
(1) If EPA proposed a MCLG for
chlorite of 1.0 mg/1 or higher, the
proposed MCL would be set at the
MCLG value. If EPA proposed a MCLG
for chlorite of less than 1.0 mg/1 based
on EPA's reference dose, the proposed
MCL would be set at 1.0 mg/1 based on
technological feasibility considerations.
(2) Additional research would be
conducted including a two-generation
reproductive effects study in animals
and a clinical study of humans exposed
to chlorite to determine what minimum
levels of exposure can be considered
safe. It was agreed that these studies
would be completed in time for
consideration of possible changes to the
MCL under the final Stage 1 rule. If the
studies indicate that a level of 1.0 mg/
1 of chlorite is safe, the MCL would
remain at 1.0 mg/1. If the studies
indicate that a level of 1.0 mg/1 of
chlorite is not safe or, if such a study is
not conducted, the MCL would be
reevaluated.
Based on a consideration that the
health effect is reversible and relatively
short term in duration, the Negotiating
Committee agreed that systems would
determine compliance by monitoring for
chlorite three times per month. Samples
would be taken at the following
locations: one near the first customer,
one in a location representative of
average residence time, and one near the
end of the distribution system reflecting
maximum residence time. Monitoring
would be conducted in the distribution
system since the concentration of
chlorite is likely to increase in the
distribution system. If the monthly
average of the three distribution system
samples exceeded the MCL, the system
would be in violation for that month. In
agreeing to propose these requirements,
the Negotiating Committee assumed
that, if a system were out of compliance
during one month but achieved
compliance during the following month,
that any health effects that might occur
from the short term exposure would
cease once the system achieved
compliance.
After the Negotiating Committee
agreed to propose the above MCL and
monitoring requirements at its last
meeting in June, 1993, EPA's Reference
Dose Committee met and determined a
different toxicological endpoint for
chlorite. The Reference Dose Committee
determined that chlorite poses an acute
developmental heath effect, which is a
neurobehavioral effect: depressed
exploratory behavior. Based on the new
reference dose, the MCLG for chlorite
would be 0.08 mg/1 (see section V of this
preamble). The derivation of the MCLG
includes a 1,000-fold uncertainty factor
to account for use of a LOAEL instead
of a NOAEL from an animal study. EPA
does not believe that the proposed MCL
of 1.0 mg/1 and monitoring requirements
agreed to by the Negotiating Committee
are adequate to protect the public from
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the acute developmental health effect,
unless new data indicate otherwise.
EPA is concerned about proposing an
MCL significantly ahove die MCLG,
especially since the MCLG is based on
acute health risks. EPA is proposing this
level to honor the agreement of the
Negotiating Committee. However, EPA
solicits comment on the following
approaches for promulgating a final
rule.
(1) EPA could promulgate an MCL at
the MCLG. Based on currently available
information, an MCL of 0.08 mg/1 would
probably rule out the use of chlorine
dioxide as a disinfectant, since it does
not appear possible for systems to meet
simultaneously disinfection
requirements and the resultant chlorite
MCL. If new data become available
indicating a NOAEL of 1 mg/kg/day, the
highest resultant MCLG and
corresponding MCL would likely be no
more than 0.3 mg/1. An MCL of 0.3 mg/
1 for chlorite ion would allow some
systems to be able to use chlorine
dioxide. However, other water systems,
because of water quality parameters that
affect chlorine dioxide demand and
chlorite ion control, will not be able to
find a feasible operating region to use
chlorine dioxide, at least on a year-
round basis. EPA would be concluding
that other technologies besides chlorine
dioxide are feasible for those systems for
meeting the Stage 1D/DBPR and SWTR
(orESWTR, if such a rule is necessary),
taking cost into consideration for
systems currently using chlorine
dioxide. A regulatory impact analysis
will have to be prepared to evaluate
technical feasibility, production of other
DBPs based on a different disinfectant,
and cost considerations.
(2) EPA could promulgate an MCL
lower than the proposed MCL of 1.0 mg/
1, but above the MCLG, depending upon
all data that became available in the
near term. In doing so, EPA would be
concluding that risks from other
alternatives are commensurate at this
level, or that other technologies, taking
costs into consideration, are not
available at the 0.08 mg/1 level, but are
available at a higher level. EPA would
thus be indicating that some systems
must use chlorine dioxide to meet
disinfection requirements, but can
maintain compliance by making
operational modifications that are not
available to all systems. This approach
would more narrowly limit the use of
chlorine dioxide to systems with very
specific source water or other
characteristics if use of chlorine dioxide
were considered essential versus use of
other disinfectants.
(3) Depending on new data that
become available, EPA could
promulgate an MCL at the proposed
MCL of 1.0 mg/1 if the Agency
determined that the systems currently
using chlorine dioxide could not meet
disinfection requirements in any other
feasible manner, taking cost into
consideration.
As part of any of the above
approaches, EPA could accelerate the
promulgation of NPDWRs for chlorine
dioxide and chlorite if the Agency
believed it necessary to avoid acute
health effects. Also, as part of the final
rule, EPA would consider the
appropriateness of the proposed
monitoring requirements and public
notification language in light of the
acute health effect. Monitoring changes
could include increasing the sampling
frequency, changing the location of
monitoring, and/or changing the
determination of compliance. These
changes may result in requirements
similar to those for chlorine dioxide
(e.g., daily measurements within the
distribution system to determine
compliance).
In making its final decision, EPA will
consider a number of factors: the risk
which would be posed from chlorite
and chlorine dioxide compared to the
risk from other contaminants if chlorine
dioxide were not used, the uncertainty
in those risk estimates, the feasibility of
using other means of control, and the
cost of those other control mechanisms.
EPA requests comments on the above
approaches for regulating chlorite.
Specifically, EPA requests comment on
the following:
—Is the basis for EPA's MCLG and
concern for acute health effects
appropriate? See Section V. for a
complete discussion.
—In light of the proposed MCLG and
concern for acute health risks that
were not apparent during the
negotiations, should EPA accelerate
the promulgation of NPDWRs for
chlorine dioxide and chlorite? If so,
should EPA set the MCL at the
proposed MCLG? Should EPA wait
until more data become available, as
agreed upon during the negotiations,
before promulgating an MCL? Such
data will be available through CMA.
CMA is conducting health effects
studies to fill data gaps for chlorine
dioxide and chlorite. EPA will
evaluate these data (which are
scheduled to be available prior to rule
promulgation) to help determine what
changes to the MRDLG and MRDL
may be warranted.
—Are there any particular water quality
characteristics for systems currently
using chlorine dioxide which make it
ineffective to use any other
disinfection technology?
What are the lowest chlorite levels these
systems can achieve? What
technologies would need to be
adopted and at what costs if such
systems with these particular water
quality characteristics would no
longer use chlorine dioxide to meet
the other regulatory criteria proposed
herein?
—Should EPA set the chlorite MCL at a
level so that chlorine dioxide remains
a viable disinfection alternative for
some systems even if this level is
above the MCLG? If so, what would be
the rationale for doing so?
—Is 1.0 mg/1 the lowest level that
systems needing chlorine dioxide can
reliably achieve?
—How should EPA change the
compliance monitoring requirements
for chlorite to reflect concern about
acute effects? Should such changes
include increasing the frequency or
changing the location of monitoring to
be similar to those for chlorine
dioxide? How would the MCL be
affected by changes in the monitoring
requirements?
—How should EPA change the public
notification requirements for chlorite
to reflect concern about acute effects?
D. Chlorine MRDL and BAT
The chlorine MRDL has been set at
the MRDLG of 4.0 mg/1, with
compliance being based on a running
annual average of monthly averages of
samples taken in the distribution
system. A running annual average was
used as the basis for compliance
because health effects are long term (see
Section V.).
There will be no additional
monitoring required by Subpart H
systems to comply with this
requirement, since samples that are
already required to be taken by systems
to comply with the Surface Water
Treatment Rule (see 40 CFR 141.74) may
be used to demonstrate compliance with
the MRDL. The samples required under
the SWTR are used to demonstrate
compliance with the requirement for
maintenance of a residual in the
distribution system (in effect, a floor or
minimum); the samples required under
this rule would set a maximum or
ceiling for chlorine levels.
Additional monitoring is required for
systems that use only ground water not
under the direct influence of surface
water to comply with this requirement,
since samples are not already required
to be taken by these systems. However,
this sampling may be required to
comply with the forthcoming Ground
Water Disinfection Rule (GWDR) to be
proposed at a later date. If such
monitoring is required by the GWDR,
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one set of samples will be allowed to be
used to demonstrate compliance with
both the MRDL in this rule and the
distribution system monitoring
requirements in the GWDR.
Since compliance is based on an
annual average, the MRDL does not
apply to individual samples, which are
allowed to be higher, than the MRDL. In
addition, allowing individual samples
to exceed the MRDL gives the system
operator the flexibility to address short-
term microbiological problems caused
by distribution system line breaks,
storm runoff events, source water
contamination, or cross connections.
EPA believes that it is essential that
system operators are aware of the
flexibility that this rule gives them in
addressing specific microbiological
threats without worrying about violating
an MRDL. For this reason, the definition
of "maximum residual disinfectant
level" proposed today in § 141.2
specifically allows higher disinfectant
levels for die two disinfectants with
long-term, but not short-term, effects
(chlorine and chloramines), while
pointing out that increasing levels of
chlorine dioxide to address short-term
problems is not allowed (because of the
short-term health effects—see Section
V.). The Agency believes that even if
systems must increase disinfectant
levels to address specific contamination
problems, they will be able to meet the
MRDL on an annual basis.
E. Chloramine MRDL and BAT
The chloramine MRDL has been set at
the MRDLG of 4.0 mg/1, with
compliance based on a running annual
average of monthly averages of samples
taken in the distribution system. A
running annual average was used as the
basis for compliance because health
effects are long term (see Section V.).
The Negotiating Committee considered
a range of 4 to 6 mg/1 and chose 4 mg/
1. This decision was based on
compliance being determined by a
running annual average rather than by
individual samples. Also, 4 mg/1 was
thought to be the lowest feasible MRDL
for some systems that would not
compromise microbial protection.
Residual disinfectant demand could be
reduced by additional precursor
removal, but the Negotiating Committee
agreed that precursor removal beyond
that achieved by enhanced coagulation
or enhanced softening should not be
required in Stage 1. EPA requests
comment on what level would be
feasible to achieve by most systems
without increasing microbial risk.
There will be no additional
monitoring required by Subpart H
systems to comply with this
requirement, since samples that are
already required to be taken by systems
to comply with the Surface Water
Treatment Rule (see 40 CFR 141.74) may
be used to demonstrate compliance with
the MRDL. The samples required under
the SWTR are used to demonstrate
compliance with the requirement for
maintenance of a residual in the
distribution system (in effect, a floor or
minimum); the samples required under
this rule would set a maximum or
ceiling for chloramine levels.
Additional monitoring is required for
systems that use only ground water not
under the direct influence of surface
water to comply with this requirement,
since samples are not already required
to be taken by these systems. However,
this sampling may be required to
comply with the forthcoming Ground
Water Disinfection Rule (GWDR) to be
proposed at a later date. If such
monitoring is required by the GWDR,
one set of samples will be allowed to be
used to demonstrate compliance with
both the MRDL in this rule and the
distribution system monitoring
requirements in the GWDR.
Since compliance is based on an
annual average, the MRDL does not
apply to individual samples, which are
allowed to be higher than the MRDL. In
addition, allowing individual samples
to exceed the MRDL gives the system
operator the flexibility to address short-
term microbiological problems caused
by distribution system line breaks,
storm runoff events, source water
contamination, or cross connections.
EPA believes that it is essential that
system operators are aware of the
flexibility that this rule gives them in
addressing specific microbiological
threats without worrying about violating
an MRDL. For this reason, the definition
of "maximum residual disinfectant
level" proposed today in § 141.2
specifically allows higher disinfectant
levels for the two disinfectants with
long-term, but not short-term, effects
(chlorine and chloramines), while
pointing out that increasing levels of
chlorine dioxide to address short-term
problems is not allowed (because of the
short-term health effects—see Section
V.). The Agency believes that even if
systems must increase disinfectant
levels to address specific contamination
problems, they will be able to meet the
MRDL on an annual basis.
F. Chlorine Dioxide MRDL and BAT
EPA has proposed the MRDLG for
chlorine dioxide at 0.3 mg/L (see section
V of this preamble). The derivation of
the MRDLG includes an uncertainty
factor of three to address one data gap
(i.e., lack of a 2-generation reproduction
study). In the near future, it is
tentatively planned that health effects
studies on the impact of chlorine
dioxide in drinking water will be
performed to resolve the data gap
concerning reproductive effects.
Chlorine dioxide is used in Europe as
a residual disinfectant, while in the U.S.
it is used for disinfection or oxidation
within the treatment plant. Because
chlorine dioxide residuals are short-
lived, they are typically not detected in
distribution systems. When chlorine
dioxide residuals are analyzed, the
presence of other oxidants (e.g.,
chlorine, chlorite, and chlorate) must be
subtracted out from a total oxidant
measurement. In a method where the
value is obtained by difference, there is
a limit to how low a quantitative
measurement can be made. The PQL for
chlorine dioxide residuals is probably in
the range of 0.5 to 1.0 mg/L.
Systems must monitor for chlorine
dioxide daily since there are acute
health effects. Monitoring must be
conducted at the entrance to the
distribution system, since the
concentration of chlorine dioxide will
not increase in the distribution system.
If monitoring indicates that the
concentration of chlorine dioxide
exceeds the MRDL, the system is then
required to conduct additional
monitoring in the distribution system.
This monitoring consists of three
samples taken the day following an
exceedance of the MRDL at specific
locations within the distribution system
considered to be those most likely to
have the highest levels and depend on
the type and location of residual
disinfection. For systems that use
chlorine dioxide or chloramines to
maintain a residual in the distribution
system, or that use chlorine with no
booster chlorination after the water
enters the distribution system, three
samples must be taken as close as
possible to the first customer at intervals
of at least six hours. For systems that
use chlorine to maintain a disinfectant
residual in the distribution system, and
have one or more locations within the
distribution system where additional
chlorine is added (i.e., booster
chlorination), samples must be taken at
the following locations: One as close as
possible to the first customer, one in a
location representative of average
residence time, and one near the end of
the distribution system reflecting
maximum residence time. These
additional samples must be taken each
day following any sample taken at the
entrance to the distribution system that
exceeds the MRDL.
Compliance is based on samples taken
both at the entrance to the distribution
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38769
system and in the distribution system. If
one or more of the samples taken in the
distribution system exceed the MRDL,
the system has an acute violation and
must take immediate corrective action
to lower the level of chlorine dioxide
and make appropriate public
notification. If two consecutive samples
taken at the entrance to the distribution
system exceed the MRDL (and none of
the required samples taken in the
distribution system exceed the MRDL),
the system has a nonacute violation and
must take corrective action to lower the
level of chlorine dioxide and make
appropriate public notification. If a
required sample is not taken, the system
must treat it as if the sample had been
taken and exceeded the MRDL.
Therefore, failure to take one or more of
the additional distribution system
samples the day following a sample
taken at the entrance to the distribution
system that exceeds the MRDL is
considered an acute violation. Failure to
take a sample at the entrance to the
distribution system the day following a
sample taken at the entrance to the
distribution system that exceeds the
MRDL is considered a nonacute
violation.
The Negotiating Committee agreed to
propose 0.8 mg/L as the MRDL for
chlorine dioxide with certain
qualifications and reservations:
(1) A two-generation reproductive
study would be completed for
consideration in the final Stage 1 rule.
If this study indicates there is no
concern from reproductive effects at the
proposed MRDL, unless public
comments otherwise influence the
Agency, then the proposed MRDL
would remain the same as proposed (0.8
mg/1).
(2) If no new health effects studies
become available on reproductive
effects, the chlorine dioxide MRDL will
be reassessed. It will be necessary to re-
examine the tradeoffs and regulatory
impacts of a lower chlorine dioxide
MRDL in light of the positive aspects of
chlorine dioxide disinfection and
control of chlorination DBFs. EPA
would probably promulgate a final
MRDL that is the higher of the MRDLG
or the detection level because the health
effects are acute. Issues that would be
considered include new information on
health effects of other disinfectants.
As part of the above approaches, EPA
could accelerate the promulgation of an
NPDWRs for chlorine dioxide if the
Agency believed it necessary to avoid
acute health effects. In making its final
decision, EPA will consider a number of
factors: The risk which would be posed
from chlorite and chlorine dioxide
compared to the risk from other
contaminants if chlorine dioxide were
not used, the uncertainty in those risk
estimates, the feasibility of using other
means of control, and the cost of those
other control mechanisms.
EPA requests comments on the above
approaches for regulating chlorite.
Specifically, EPA requests comment on
the issues identified earlier in the
chlorite subsection.
Regardless of the final MRDL value,
the Negotiating Committee agreed on
the following monitoring program to
protect against the risk of a reproductive
endpomt due to short-term exposure to
a high dose of chlorine dioxide: the
entry point to the distribution system
will be measured daily. If any day's
value exceeds the MRDL, sampling will
be initiated in the distribution system.
If the second-day plant effluent is also
above the MRDL, but distribution
system samples are less than the MRDL,
then the utility will be in violation (but
this would not be considered an acute
violation); the lower concentration of
chlorine dioxide in the distribution
system will minimize the risk to
consumers due to the lower level of
exposure. If chlorine dioxide is detected
at a level greater than the MRDL in the
distribution system, then the utility
would be considered in acute violation
because the risk to susceptible
consumers (i.e., pregnant women) is
higher. By monitoring chlorine dioxide
residuals daily in the treatment plant,
utilities can work best at minimizing
exposure in the distribution system.
G. Basis for Analytical Method
Requirements
The SDWA directs EPA to set an MCL
for a contaminant "if, in the judgment
of the Administrator, it is.economically
and technologically feasible to ascertain
the level of such contaminant in water
in public water systems." [SDWA
section 1401(l)(c)(ii)] To make this
threshold determination for the
disinfectants and disinfection by-
products (DBFs) proposed today, EPA
evaluated the availability, costs, and
performance of analytical techniques
which measure these disinfectants and
DBFs. This evaluation is discussed
below. EPA also considered the ability
of laboratories to measure consistently
and accurately at the maximum residual
disinfectant level (MRDL) or the
maximum contaminant level (MCL) of
each contaminant. The ability to
measure consistently and accurately at
25 and 50 percent of the total
trihalomethane (TTHM) and haloacetic
acid (HAAS) MCLs was also evaluated
in order to ensure that measurements for
allowing reduced monitoring can be
made reliably.
The reliability of analytical methods
is critical at the MRDL or MCL and at
levels which allow reduced monitoring.
Therefore, each analytical method was
evaluated for lack of bias (i.e. accuracy
or recovery) and precision (good
reproducibility) at these concentrations
for each contaminant. The primary
purpose of the evaluation was to .
determine: (1) Whether analytical
methods exist to measure disinfectants
and DBFs; (2) reasonable expectations of
technical performance by analytical
laboratories at the MRDL or MCL levels
and at the levels which allow reduced
monitoring for TTHMs and HAAS; and
(3) analytical costs.
In selecting analytical methods, EPA
considered the following factors:
(a) Reliability (i.e., precision/
accuracy) of the analytical results;
(b) Specificity in the presence of
interferences;
(c) Availability of enough equipment
and trained personnel to implement a
national monitoring program (i.e.,
laboratory availability);
(d) Rapidity of analysis to permit
routine use; and
(e) Cost of analysis to water supply
systems.
Several analytical methods are
described and discussed below. EPA
refers readers to the published methods
for additional information on the
precision, accuracy and quality control
requirements of the proposed analytical
methods.
1. Disinfectants
Today's rule proposes monitoring
requirements to ensure compliance with
proposed maximum residual
disinfectant levels for chlorine,
chloramines, and chlorine dioxide.
Analytical'methods, most of which have
been in use for years, exist to measure
these residuals. There are additional
analytical techniques available for
measuring disinfectant residuals
(AWWARF, 1992) that are not proposed
in today's rule because they are not
written in a standard format that is
readily available to the public. Nine
disinfectant methods are proposed in
today's rule (Table IX-2). Most of the
proposed methods are in use, because
they were promulgated with the Surface
Water Treatment Rule (SWTR). (54 FR
27486, June 29,1989)
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
TABLE IX-2.—PROPOSED METHODS
FOR DISINFECTANTS
Disinfectant
measurement
Chlorine as free or
total residual chlo-
rine, chloramines
as combined or
total residual chlo-
rine.
Chlorine as free resid-
ual chlorine.
Chlorine or
Chloramines as
total residual chlo-
rine.
Chlorine Dioxide as
residual chlorine di-
oxide.
Proposed methods
4500-CI D Ampero-
metric Titration.
4500-CI F DPD
Ferrous Tftrimetric.
4500-CI G DPD
Colorimetric.
4500-CI H
Syringaldazine
(FACTS).
4500-CI E Low-
Level Ampero-
metric.
4500-CI I
lodometric Elec-
trode.
4500-CIO2 C Amper-
ometric Titration.
4500-CIO2D DPD.
4500-CIO2 E Am-
perometric Titra-
tion.
Proposed methods are in "Standard Meth-
ods for the Examination of Water and
Wastewater," 18th Edition, American Public
Health Association, American Water Works
Association, and Water Environment Federa-
tion, 1992.
The disinfectant residual methods
proposed in today's rule were selected
based on evaluations that included the
results of an evaluation made for the
methods that were promulgated with
the SWTR. In today's rule, EPA
proposes to withdraw Standard Method
408F, which was promulgated for
measurement of chlorine residual under
the SWTR. EPA is also proposing two
methods (Standard Methods 4500-CI H
and 4500-CI I) that were inadvertently
omitted from the SWTR. Methods 4500-
CI H and I would he approved for
compliance monitoring under the SWTR
and the D/DBP rule. In addition, EPA
proposes to update all of the
disinfectant methods, which were
promulgated in 1989 with the SWTR, to
the versions that will be promulgated
with the D/DBP rule. This update will
allow laboratories to use the most recent
versions of these methods for all
compliance monitoring of disinfectant
residuals.
Standard Method 408F was dropped
from the 17th and subsequent editions
of Standard Methods because it is
difficult to use, and because there are
several other available methods that are
superior to it. Since EPA believes few,
if any, laboratories use Method 408F,
withdrawal should have little effect on
the regulated community.
In evaluating disinfectant residual
methods for use under the SWTR EPA
considered, but did not promulgate, five
EPA and two Standard Methods. The
seven methods were rejected for the
following reasons. EPA methods 330.1
to 330.5 for free and total chlorine
measurement were not promulgated
because equivalent methods published
by Standard Methods, which contained
more up-to-date and complete
descriptions of required analytical
procedures, were available. The five
EPA methods have not been updated
since 1979, while new editions of
Standard Methods are issued
periodically to include all applicable
improvements made to the methods
during the interim. Standard Method
4500-CI B (lodometric I) was not
promulgated with the SWTR because it
cannot measure chlorine accurately at
concentrations of less than 1 mg/L.
Standard Method 4500-CI C (lodometric
II) was not promulgated because it is not
sensitive enough for drinking water
analyses. For these same reasons, EPA is
not proposing these seven methods in
today's rule.
EPA is aware that all of the
disinfectant methods proposed today
are subject to interferences, especially
when used to measure low
concentrations of disinfectant residuals.
However, when procedures specified in
the methods are followed, the methods
can be used to indicate compliance with
the minimum disinfectant residual
concentrations proposed in today's rule
(AWWARF, 1992). EPA is soliciting
information on improvements which
may have been made to these methods,
but that are not reflected in the 18th
edition of Standard Methods. EPA is
also seeking information on new
methodology that may be applicable for
compliance monitoring. New methods
must provide demonstrated advantages
over the current methods and have the
potential for being distributed in a
standard format in the-time frame of this
regulation.
EPA is aware that several vendors
manufacture or may manufacture test
kits that are based on DPD colorimetric
Standard Methods 4500-CI G and 4500-
ClCb D. If Methods 4500-CI G and
4500-C1O2 D are promulgated under the
D/DBP rule, EPA proposes that kits
using the same chemistry as these
methods be approved for compliance
monitoring for chlorine and chlorine
dioxide, respectively, provided the State
also approves of their use.
EPA believes that the analytical
methods being proposed today are
within the technical and economic
capability of many laboratories. For
example, utility laboratories are
currently using the proposed
disinfectant methods to measure
disinfectant residuals under the SWTR.
The analytical cost is estimated at $10
to $20 per sample. Costs will vary with
the laboratory, analytical technique
selected, number of samples, and other
factors. EPA believes these costs are
affordable.
Below is a description of the
analytical methods proposed for
compliance with the proposed MRDLs.
The three disinfectant residuals are
measured and reported as follows:
chlorine as free or total chlorine;
chloramines as combined or total
chlorine; and chlorine dioxide as
chlorine dioxide. For information on the
precision and accuracy of these
methods, EPA refers the readers to the
written methods and to AWWARF,
1992. EPA requests public comments on
the technical adequacy of these
proposed analytical techniques.
a. Amperometric Titration Method
(SM 4500-CI D) for chlorine and
chloramines. Free residual chlorine is
measured by adjusting the pH of the
sample to between 6.5 and 7.5 followed
by titration to the endpoint with a
phenylarsine oxide reducing solution.
Total residual chlorine is measured by
adding potassium iodide to the sample,
adjusting the pH to between 3.5 and 4.5,
and titrating with phenylarsine oxide to
the endpoint. Chloramines, as combined
chlorine, are determined by subtracting
the result of the free residual chlorine
measurement from the total residual
chlorine measurement in the same
sample. A microammeter is used to
detect the endpoints in each titration.
Commercial titrators are considered to
have detection limits as low as 20 ug/
L (as C12), but the limit of detection
depends on the type of water sample
(AWWARF, 1992). Since interferences
may account for a high percentage of the
instrument response at low
concentrations, results in samples with
low concentrations of free or total
chlorine should be used with caution
(AWWARF, 1992). EPA believes the
working range for this method
adequately covers the proposed MRDLs
for free, combined, and total chlorine
residuals.
b. Low Level Amperometric Titration
Method (SM 4500-CI E) for chlorine and
chloramines measured as total residual
chlorine. This method utilizes the same
principle as the amperometric titration
method listed above. This method
modifies SM 4500-CI D by using a more
dilute concentration of phenylarsine
oxide titrant and a graphical procedure
to determine the endpoint. Use of this
method is recommended when the total
chlorine residual is less than or equal to
0.2 mg/L as C12. This method will show
a positive bias if other oxidizing
reagents are present in the water
sample. Since SM 4500-CI E is only
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38771
applicable to measuring total residual
chlorine, it cannot be used to
differentiate between free and combined
residual chlorine.
c. DPD Ferrous Titrimetric Method
(SM 4500-C1F) for chlorine and
chloramines. When the proper sample
pH is chosen, this method can
differentiate between free chlorine,
monochloramine, dichloramine, and
total chlorine. The color produced by
the reaction of the chlorine species with
the DPD dye slowly disappears as the
sample is titrated with ferrous
ammonium sulfate. The amount of
titrant corresponds to the concentration
of chlorine species being measured.
This method is proposed for the
determination of free, combined, and
total residual chlorine.
d. DPD Colorimetric Method (SM
4500-C1G) for chlorine and
chloramines. The method utilizes the
same principle as SM4500-C1F except
that the color produced is read by a
colorimeter and the concentrations of
free and total chlorine are calculated
after standardization. Combined
residual chlorine is the sum of the
monochloramine and dichloramine
measurements. Total residual chlorine
is the sum of free and combined
residual chlorine. This method is
proposed for the determination of free,
combined, and total residual chlorine.
e. Syringaldazine (FACTS) Method
(SM 4500-C1H) for chlorine. The
reagent, syringaldazine, is oxidized by
free chlorine on a 1:1 basis to produce
a color which is determined
colorimetrically. The pH of the sample
must be maintained at approximately
6.7 to stabilize the color formed. This
method is proposed for the
determination of free residual chlorine.
f. lodometric Electrode Technique
(SM 4500-C11) for chlorine and
chloramines. This method involves the
direct potentiometric (electrode)
measurement of iodine released when
potassium iodide is added to an
acidified sample containing chlorine. A
platinum-iodide electrode pair is used
in combination to measure the liberated
iodine. This method is proposed for the
determination of total residual chlorine.
g. Amperometric.Method I (SM 4500-
C1O2 C) for chlorine dioxide residuals.
This titration method is an extension of
SM 4500-C1D (which measures
chlorine). By sequentially performing
four titrations at different sample pH
with phenylarsine oxide, four chemicals
(free chlorine, monochloramine,
chlorite, and chlorine dioxide) may be
determined by a method of differences.
This method is proposed for the
determination of chlorine dioxide
residuals.
h. DPD Method (SM 4500-C1O2 D) for
chlorine dioxide. This method is an
extension of the DPD method for
chlorine (SM 4500-C1 F). Chlorine
dioxide appears in the first step of this
procedure, but only to the extent of one-
fifth of its available oxidation/reduction
potential. This potential arises from the
reduction of chlorine dioxide in the
sample to chlorite. After a pH
adjustment and the addition of a buffer,
a color is produced which corresponds
to the chlorine dioxide content of the
sample. This method is proposed for the
determination of chlorine dioxide
residuals.
i. Amperometric Method II (4500—
ClOa E) for chlorine dioxide. This
titration method is similar to SM 4500-
ClOa C which is described above. The
method can measure chlorine dioxide in
samples which contain free chlorine
and other interfering compounds. The
method can measure a wide range of
chlorine dioxide concentrations in
drinking water samples. Dilute (0.1 to
10 mg/L) and concentrated (10 to 100
mg/L) concentrations of chlorine
dioxide are measured by varying the
size of the drinking water sample and
the concentration of the titrating
solution. This method is proposed for
the determination of chlorine dioxide
residuals.
2. By-Products
Six analytical methods for
measurement of inorganic and organic
disinfection by-products (Table IX-3)
are proposed and discussed in parts 3
and 4.
TABLE IX-3.—PROPOSED METHODS
FOR DISINFECTION BY-PRODUCTS
Contaminant
Trihalomethanes
Haloacetic Acids
Bromate, Chlorite
Methods1
502.2,524.2,551.
552.1,62336.
300.0.
1 EPA Method 502.2 is in the manual "Meth-
ods for the Determination of Organic Com-
pounds in Drinking Water", EPA7600/4- 887
039, July 1991, NTIS publication PB91-
231480. EPA Method 551 is in the manual
"Methods for the Determination of Organic
Compounds in Drinking Water—Supplement
I", EPA/600/4-90/020, July 1990, NTIS PB91-
146027. EPA Methods 524.2 and 552.1 are in
the manual "Methods for the Determination of
Organic Compounds in Drinking Water—Sup-
plement II", EPA/600/R-92/129, August 1992,
NTIS PB92-207703. EPA Method 300.0 is in
the manual "Methods for the Determination of
Inorganic Substances in Environmental Sam-
ples", EPA/600/R/93/100—Draft, June 1993.
Standard Method 6233 B is in "Standard
Methods for the Examination of Water and
Wastewater," 18th Edition, American Public
Health Association, American Water Works
Association, and Water Environment Federa-
tion, 1992.
3. Organic By-Product Methods
EPA is proposing five methods (Table
IX-3) for the analysis of two classes of
organic disinfection by-products—total
trihalomethanes (TTHMs) and
haloacetic acids (five) (HAA5).
Compliance with the 0.08 mg/L TTHM
MCL will be determined by summing
the concentration of each of four
trihalomethanes (bromoform,
chloroform, dibromochloromethane and
bromodichloromethane) as measured in
a drinking water sample by EPA
Methods 502.2 or 524.2 or 551. EPA is
also proposing to withdraw approval of
two EPA methods which use older
technology and have been superseded
by Methods 502.2 and 551.
Compliance with the HAAS MCL of
0.060 mg/L will be determined by
summing the concentration of each of
five haloacetic acids (mono-, di-, and
trichloroacetic acids; mono- and
dibromoacetic acids) as measured in a
drinking water sample with EPA
Method 552.1 or Standard Method 6233
B. The haloacetic analytical methods
can also measure a sixth haloacetic
(bromochloroacetic) acid. Since this
acid may be considered in a future
disinfection by-product control
regulation, EPA encourages, but does
not require, water systems to measure
and report occurrences of
bromochloroacetic acid in samples
analyzed for HAAS MCL compliance
monitoring.
EPA believes the analytical methods
being proposed today are within the
technical capability of many
laboratories and within the economic
capability of the regulated community.
The analytical cost for trihalomethane
(THM) analysis is estimated to be from
$50 to $100 per sample. There is
generally no additional cost for THM
measurements if Method 502.2 or 524.2
is used to measure volatile organic
compounds (VOCs) in the same sample.
The analytical cost for haloacetic acid
analysis is estimated at $150 to $250 per
sample; adding bromochloroacetic acid
to the analysis should not significantly
change the cost. Actual costs may vary
with the laboratory, analytical technique
selected, the total number of samples,
and other factors.
Today's proposed requirements
would impose little or no extra
trihalomethane monitoring on
community water systems serving
populations of 10,000 or more because
most of these systems must routinely
monitor for THMs under the
Trihalomethane rule [44 FR 68264,
November 29,1979]. Monitoring for
haloacetic acids will increase each
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38772 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
system's analytical costs but EPA
believes these costs are affordable.
With the exception of EPA Method
551, the proposed methods for
measuring trihalomethanes are in
widespread use. More than 700
laboratories are presently certified to
measure THMs. Many of these
laboratories use Methods 502.2 and
524.2 to comply with VOC and THM
monitoring requirements and MCLs.
EPA believes there is adequate
laboratory capacity for trihalomethane
analysis. EPA expects that many of
these laboratories will become certified
to conduct analysis of haloacetic acids
in drinking water samples.
The methods for measuring haloacetic
acids are new and not in widespread
use. These compounds have been
included in several of EPA's Water
Supply (WS) performance evaluation
(PE) studies, and the number of
participants has increased with each
successive study. In the WS 31 study,
twenty-five laboratories reported data
for all five of the haloacetic acids
covered in today's proposed rule,
compared to sixteen laboratories in the
WS 29 study. These data were produced
using a liquid-liquid extraction method.
Based on the available PE data, EPA
believes the haloacetic acid methods
can provide reliable data at the
proposed MCLs. EPA is aware that
many utility laboratories are developing
analytical capability for haloacetic
acids, and commercial laboratories are
receiving requests from utilities for
haloacetic acid analyses. Therefore, EPA
believes there will be adequate
laboratory capability by the time
compliance monitoring for haloacetic
acids is required.
a. Trihalomethane Methods. Presently
EPA Methods 501.1, 501.2, 502.2, and
524.2 are approved for compliance with
total trihalomethane monitoring
requirements under 40 CFR 141.30. For
reasons discussed below, EPA proposes
to withdraw Methods 501.1 and 501.2,
and to approve a new method (EPA
Method 551) for trihalomethane
compliance measurements.
Method 502.2, Volatile Organic
Compounds in Water by Purge and Trap
Capillary Column Gas Chromatography
with Photoionization and Electrolytic
Conductivity Detectors in Series, and
Method 524.2, Measurement of
Purgeable Organic Compounds in Water
by Capillary Column Purge and Trap
Capillary Column Gas Chromatography/
Mass Spectrometry, are widely used for
THM and VOC analyses. Readers are
referred to previous notices, 52 FR
25690 (July 8,1987) and 56 FR 3548
(January 30,1991), for discussions and
descriptions of these methods. Method
502.2 requires a photoionization
detector and an electrolytic conductivity
detector, configured in series, to
measure aromatic or unsaturated VOCs
by photoionization, and other VOCs and
THMs by electrolytic conductivity. If
only THMs are to be determined in a
sample, Method 502.2 may be used
without the photoionization detector.
EPA proposes to withdraw approval
of EPA Methods 501.2 and 5,01.1 for
TTHM compliance monitoring. Method
501.2, which uses a liquid-liquid
extraction technique, and Method 501.1,
which uses a purge-and-trap sparging
technique, have not been updated since
1979. Both methods use packed column
technology. Packed columns have less
resolving power than capillary columns,
which often limits their use to very
simple analyses. This is one of the
reasons that Methods 501.1 and 501.2
are only promulgated for trihalomethane
monitoring.
Packed column technology is
becoming obsolete, and capillary
columns are required in most modern
gas chromatographic methods that have
been developed for compliance
monitoring. In a rule which was
published on August 3,1993 (58 FR
41344), EPA encourages the use of
capillary column methods for THM
analysis, and announces discontinuance
of technical support for packed column
methods. As laboratories replace their
gas chromatographs over the next few
years, EPA believes most, if not all,
laboratories will acquire capillary
column instruments because they offer
greater flexibility in the number of
analytes that can be measured [W.L.
Budde, 1992].
The Agency has promulgated (58 FR
41344) two capillary column methods
(EPA Methods 502.2 and 524.2) that can
replace Method 501.1. Today EPA is
proposing a capillary column method
(EPA Method 551) for trihalomethane
monitoring that can replace Method
501.2. Withdrawal of EPA Methods
501.1 and 501.2 would not become
effective until 18 months after today's
rule is promulgated, so laboratories
would be able to use these methods for
several more years. EPA does not
believe that withdrawal of the methods
will adversely affect laboratories over
this time frame.
EPA Method 551, Determination of
Chlorination Disinfection Byproducts
and Chlorinated Solvents in Drinking
Water by Liquid- Liquid Extraction and
Gas Chromatography with Electron
Capture Detection, is proposed for THM
compliance measurements. It is a liquid-
liquid extraction method applicable to
the determination of a variety of
halogenated organic compounds.
In Method 551 the ionic strength of a
35-mL drinking water sample aliquot is
adjusted using sodium chloride, and the
sample is extracted with 2-mL of
methyl-tert-butyl ether. If only THMs
are to be measured, pentane can be used
as the extracting solvent provided the
quality control requirements specified
in Method 551 are met. When pentane
is used, Method 551 is very similar to
liquid-liquid extraction Method 501.2.
EPA believes laboratories wishing to use
liquid-liquid extraction to measure
THMs will prefer Method 551 to
Method 501.2.
b. THM-Sample Dechlorination. All of
the promulgated and proposed methods
for THM compliance analysis require
that the THM formation reaction be
halted by addition of a reagent that
removes all free chlorine from the
sample. EPA provides the following
guidance to help laboratories correctly
preserve samples for compliance with
proposed and existing (40 CFR 141.30
and 141.133) THM monitoring
requirements. The Agency believes that
this guidance is warranted because
many preservation procedures are
available, depending on the method,
and because laboratories may wish to
measure VOCs and THMs in a single
.analysis.
Laboratories must carefully follow the
preservation procedure described in
each method, especially the order in
which reagents are added to the sample.
The methods allow analysts to choose
among four reagents (ammonium
chloride, ascorbic acid, sodium sulfite,
or sodium thiosulfate) to dechlorinate a
water sample. These reagents remain
available for use but, with one
exception, EPA strongly recommends
the use of sodium thiosulfate for the
analyses of THMs, since EPA has the
most performance data with this
chemical. The exception is that ascorbic
acid should be used when sulfur
dioxide will interfere with analyses that
are performed using a mass
spectrometer. Samples dechlorinated
with ascorbic acid must be acidified
immediately, as directed in the method.
c. Haloacetic Acid Methods. Standard
Method 6233 B and EPA Method 552.1
are relatively new, use capillary
columns, and are proposed today for
measurement of five haloacetic
(monochloroacetic, dichloroacetic,
trichloroacetic, monobromoacetic and
dibromoacetic) acids. As discussed
above, EPA recommends that
bromochloroacetic acid also be
measured with these methods.
Standard Method 6233 B, Micro
Liquid-Liquid Extraction Gas
Chromatographic Method for Haloacetic
Acids, was developed by several
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laboratories, including EPA. The
analytical procedures used in Method
6233 B are equivalent and very similar
to those used in the 30-mL extraction
option, which is described in EPA
Method 552, Determination of
Haloacetic Acids in Drinking Water by
Liquid-Liquid Extraction,
Derivatization, and Gas Chromatography
with Electron Capture Detection. EPA
considered proposing both methods;
however, Method 552 contains a 30-mL
and a 100-mL extraction option. EPA
believes that the 100-mL extraction
option uses a quantitation and
calibration procedure that will not
produce acceptable results for
compliance with today's monitoring
requirements. Also, the performance
data for the 30-mL extraction option is
more completely presented in Method
6233 B. For purposes of today's rule,
EPA believes that Method 6233 B is
more complete and easier to use than
Method 552. Laboratories, which have
been using the 30-mL extraction option
in Method 552, will have no trouble
switching to Method 6233 B. If EPA
revises Method 552, it may be approved
in the final rule.
In Method 6233 B, the pH of a 30-mL
drinking water sample is adjusted to 0.5
or less, and the ionic strength of the
sample is increased by adding sodium
sulfate. The acids are extracted into 3-
mL of methyl-tert-butyl ether (MTBE).
Exactly 2-mL of the extract is transferred
to a volumetric flask and the volume is
reduced to approximately 1.7-mL.
The haloacetic acids, which have
been concentrated in the MTBE extract,
are converted to methyl esters using a
dilute solution of diazomethane in
MTBE. The extract, which now contains
the methyl esters of the haloacetic acids,
is analyzed using capillary column gas
chromatography with electron capture
detection.
The analytical method is calibrated
and the haloacetic acids are quantitated
using standards with a known
concentration of each haloacetic acid.
These standards are called aqueous
procedural standards because they are
prepared in reagent water and treated
exactly like a drinking water sample.
This means that the standards are
carried through the extraction,
derivatization, and chromatographic
steps of the method. Aqueous standards
which are analyzed in this way
automatically correct for the method
bias that occurs when any of the
haloacetic acids are not completely
extracted from the drinking water
sample with the solvent MTBE.
EPA Method 552.1, Determination of
Haloacetic Acids and Dalapon in
Drinking Water by Ion-Exchange Liquid-
Solid Extraction and Gas
Chromatography with an Electron
Capture Detector, is a liquid-solid
extraction method which does not
require the use of diazomethane. It is
proposed today for five haloacetic acids.
In Method 552.1, a 100-mL sample
aliquot is adjusted to pH 5.0 and
extracted with a preconditioned
miniature anion exchange column. The
haloacetic acids are eluted from the
column with small aliquots of acidic
methanol. After the addition of a small
volume of MTBE as a co-solvent, the
acids are converted to their methyl
esters directly in the acidic methanol.
The methyl esters are partitioned into
the MTBE phase and identified and
measured by capillary column gas
chromatography with electron capture
detection.
4. Inorganic By-Product Method
EPA is proposing Method 300.0,
Determination of Inorganic Anions by
Ion Chromatography, for analysis of the
inorganic disinfection by-products
covered in today's proposed rule—
bromate and chlorite (Table IX-3).
Method 300.0 must be modified as
specified below to adequately measure
bromate at the MCL proposed in today's
rule. This method is presently approved
for the analysis of nitrate and nitrite in
drinking water under 40 CFR 141.23.
The method is described below;
additional information may be found in
the May 22,1989 notice [54 FR 22097].
Method 300.0 requires an ion
chromatograph and an ion
chromatographic column. Ion
chromatography is conducted in many
laboratories because it can
simultaneously measure many anions of
interest—bromide, chloride, fluoride,
nitrate, nitrite, orthophosphate, sulfate,
bromate, chlorite, and chlorate. Method
300.0 specifies the two columns that are
required to separate and measure the
ions of interest. The AS9 column is used
to measure chlorite, chlorate, and
bromate. This column has the advantage
that it separates the chlorate ion from
the nitrate ion.
EPA believes that Method 300.0 is
within the technical capability of many
laboratories and within the economic
capability of the regulated community.
The analytical cost of bromate and
chlorite analysis is estimated to range
from $50 to $100 per sample. Actual
costs may vary with the laboratory, the
total number of samples, and other
factors. EPA believes the analytical costs
for bromate and chlorite ion monitoring
are affordable.
Under the requirements set forth in
this proposed rule, monitoring for the
bromate ion would apply to water
systems using ozone in the treatment
train. Monitoring for the chlorite ion
would apply to systems using chlorine
dioxide. Since utilities rarely use both
ozone and chlorine dioxide, most
systems will use Method 300.0 to
measure only bromate or only chlorite
for compliance with the MCLs proposed
in today's rule.
EPA WS PE studies indicate that an
increasing number of laboratories have
the capability to measure bromate and
chlorite. The lowest concentration of the
bromate ion in a PE sample to date was
30 ug/L in WS 31. Twenty-three
laboratories reported data and 65% of
them were within ±50% of the true
value. Chlorite ion concentrations have
ranged from 100 to 460 ug/L in studies
WS 29 through WS 31. The percentage
of laboratories successfully meeting
±50% of the true value acceptance
criteria ranged from 85 to 96%. These
data indicate that adequate laboratory
capacity will be available by the time
the compliance monitoring
requirements proposed in this rule
become effective.
EPA has evaluated Method 300.0,
modifications to the method, and the
results from PE studies to determine the
feasibility of obtaining reliable
measurements at the MCLs proposed in
today's rule for chlorite and bromate.
Based on this evaluation, EPA believes
that Method 300.0 can easily provide
reliable data at the proposed MCL for
chlorite. To reliably measure bromate at
the proposed MCL, Method 300.0 must
be modified to improve the sensitivity
of the analysis. The modifications,
which are discussed below, involve
changes to the injection volume and to
the eluent.
a. Bromate Ion. EPA is aware that the
current version of Method 300.0 is not
sensitive enough to measure bromate
ion concentrations at the proposed
MCL. Method 300.0 is more sensitive to
bromate. if a weaker ion
chromatographic eluent is used. In a
recent EPA study, Hautman & Bolyard
[1992] successfully used a borate, rather
than a carbonate, eluent to
chromatographically measure bromate
ion concentrations in drinking water.
This alternate eluent reduced baseline
noise, thereby increasing the method
sensitivity. The detection limit for
bromate can be further reduced by
increasing the volume of sample that is
injected into the ion chromatograph
(from 50 to 200 |iL) and by further
decreasing the concentration of the
borate eluent to 18mM NaOH/72 mM
H3BO3 [Hautman, 1993]. These are
acceptable modifications to Method
300.0. The quality control requirements,
which must be met when a weaker
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 /Proposed Rules
eluent or a larger sample injection
volume is used, are specified in the
method.
A few utility, university, and
commercial laboratories are analyzing
ozonated drinking water for low
concentrations of the bromate ion.
According to verbal communications
with EPA, some of these laboratories are
able to quantitate bromate down to
concentrations of 5 to 10 ug/L, and they
can detect bromate down to
concentrations of 1 to 2 ug/L. In order
to achieve this sensitivity, the
laboratories are using the modifications
mentioned above and, in some cases,
the laboratories are also treating the
samples to remove a chloride
interference [Kuo et al., 1990].
Based on the information presented
above, EPA believes that Method 300.0
with the appropriate modifications can
be used to reliably determine
compliance with the proposed MCL for
bromate. Whether laboratories are able
to reliably measure bromate ion
concentrations at levels below the
proposed MCL under routine operating
conditions is presently unknown.
Laboratory performance data will be
collected as part of the proposed
Information Collection Rule (ICR) (59
FR 6332) so EPA will be able to more
accurately determine laboratory
capabilities for measuring bromate prior
to promulgation of today's proposed
rule.
EPA is aware of efforts to develop
more sensitive techniques for measuring
bromate ion concentrations in drinking
water. Two studies have demonstrated
the capability to measure bromate levels
of <1 ug/L using sample concentration
techniques prior to injection into the ion
chromatograph [Hautman, 1992; Sorrell
& Hautman, 1992]. However, these
techniques are labor-intensive and not
generally available to laboratories that
do routine analyses.using ion
chromatography. Efforts are underway
to develop an automated sample
concentration technology which may be
applicable to routine analyses [Joyce &
Dhillon, 1993]. EPA solicits comments
on whether use of a sample
concentration technology prior to ion
chromatographic analysis should be
considered as a new methodolgy or a
modification to Method 300.0 under
today's rule. EPA also solicits comments
on the applicability of sample
concentration technology to today's
proposed MCL for bromate.
EPA is aware that high concentrations
of the chloride ion interfere with the
measurement of the bromate ion. There
are currently two solutions to this
interference problem. The first solution
is based on a recent study [Hautman &
Bolyard, 1992] that successfully used a
borate eluent to chromatographically
separate bromate and chloride. The
study demonstrated that these
conditions can be used to measure other
anions for which ion chromatography is
an approved compliance monitoring
technique. The second solution to the
chloride interference is to remove
chloride from the sample by filtering it
through a silver filter before injecting it
into the ion chromatograph [Kuo et al.,
1990]. Both of these solutions are
permitted as part of EPA Method 300.0
provided the quality control
requirements, which are specified in the
method, are met. .
EPA prefers the first solution (borate
as eluent) to the chloride interference
problem, because it lowers the baseline
noise, thereby increasing the method's
sensitivity for all anions in the
analytical scope of the method.
However, in some waters, chloride ion
concentrations are too high, and a silver
filter must be used to remove excess
chloride. EPA cautions that silver will
leach from the filters into the sample. If
the leachate is not removed from the
sample, it will contaminate the ion
chromatographic column. Since a
contaminated column cannot be used to
measure chloride or bromide ion
concentrations, the leachate must be
removed by filtering the sample through
an ion chromatographic chelate
cartridge prior to injection into the ion
chromatograph [Hautman, 1992].
Another alternative is to dedicate an ion
chromatographic column to bromate
analysis, since silver interferes only
with the analysis of chloride and
bromide, not bromate, ions.
Compliance with the bromate MCL
under today's rule is determined by
analyzing samples collected at the
entrance point to the distribution
system. EPA does not believe an ozone
residual will exist at this sampling
point, so the reactions that cause
bromate formation should be complete.
Bromate does not decompose after it is
produced. As a result, Method 300.0
does not require the use of a
preservative for bromate samples. EPA
is soliciting any data that demonstrate
the need for a preservative in samples
collected at this sampling point for
measurement of bromate.
b. Chlorite Ion. EPA considered other
available methods for the measurement
of the chlorite ion. For example, chlorite
ion, chlorate ion, and the disinfectant
chlorine dioxide can be measured by
amperometric or potentiometric
measurements of iodine, which is
formed from the reaction of these
chemicals with iodide ion. EPA
recognizes that these methods may be
useful to utility operators for routine
operational monitoring of unit
processes. Their use is encouraged for
such work when an ion chromatograph
is not available at the treatment plant.
However, EPA does not believe that
these methods are suitable for
compliance monitoring, because
chlorite is determined by a method of
differences rather than direct
measurement. EPA believes that the ion
chromatography method is the
compliance technique of choice,
because it provides a direct
measurement of each inorganic DBP
anion. Method 300.0 is also a very
versatile method with an analytical
scope that includes several other ions
that are commonly present in drinking
water samples. Therefore, Method 300.0
is the only method proposed for chlorite
ion monitoring in today's rule.
Utilities using chlorine dioxide as a
disinfectant or oxidant will have the
ions, chlorite and chlorate, in the
treated water. Using Method 300.0,
chlorate can be measured along with
chlorite at little or no extra cost. Since
chlorate may be considered in a future
disinfection by-product control
regulation, utilities, are encouraged, but
not required, to obtain data on chlorate
concentrations in their water.
Since the chlorite ion reacts with free
residual chlorine and with metal ions
such as nickel and iron, it is not stable
in some drinking water matrices
[Hautman & Bolyard, 1992]. Method
300.0 addresses this problem by
requiring the addition of
ethylenediamine (EDA) as a
preservative, if samples cannot be
analyzed for the chlorite ion within 10
minutes of sample collection. If the
chlorite ion is measured in samples
with a chlorine dioxide residual, the
sample must also be sparged with
nitrogen at the time of collection to
remove the chlorine dioxide residual.
EPA is interested in learning whether
there are vendors who are willing, or
would be willing in the future, to sell
high purity chlorite standards to
laboratories performing analyses for
chlorite.
. Other Parameters—Total Organic
Carbon, Alkalinity and Bromide
TABLE IX-4.—PROPOSED ANALYTICAL
METHODS FOR OTHER PARAMETERS
Parameter
Total Organic Carbon
Method1
5310 C Persulfate-
Ultraviolet Oxida-
tion.
531OD Wet Oxida-
tion. .
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TABLE IX-4.—PROPOSED ANALYTICAL
METHODS FOR OTHER PARAM-
ETERS—Continued
Parameter
Alkalinity
• Bromide
Method1
2320 B, 31 0.1, D-
1067-88B
Titrimetric.
1-1030-85
Electrometric.
300.0 Ion Chroma-
tography.
1 EPA Method 300.0 is in the manual "Meth-
ods for the Determination of Inorganic Sub--
stances in Environmental Samples", EPA/600/
R/93/100—Draft, June 1993. EPA Method
310.1 is in the manual "Methods for Chemical
Analysis of Water and Wastes", EPA/600/4-
79-020, March 1983, NTIS PB84-128677.
Standard Methods 2320B, 531 OB and 531OC
are in Standard Methods for the Examination
of Water and Wastewater, 18th Edition, Amer-
ican Public Health Association, American
Water Works Association, and Water Environ-
ment Federation, 1992. Method D-1067-88B
is in the "Annual Book of ASTM Standards",
Vol. 11.01, American Society for Testing and
Materials, 1993. Method 1-1030-85 is in Tech-
niques of Water Resources Investigations of
the U.S. Geological Survey, Book 5, Chapter
A-1.3rd ed., U.S. Government Printing Office,
1989.
Total organic carbon, alkalinity, and
bromide are not covered by proposed
MRDLs or MCLs in today's rule. As
explained in Sections VIII and IX of this
notice, EPA is proposing monitoring
requirements for some or all of these
parameters at systems that need to use
the results to comply with certain
treatment requirements. To ensure
accurate measurement of these
parameters, EPA proposes the following
analytical methods.
a. Total organic carbon (TOC)
methods. Several analytical methods
exist to measure total organic carbon;
two Standard Methods are proposed in
today's rule (Table IX-4). TOC
measurements are conducted in many
laboratories. In a recent EPA Water
Pollution PE study (WP 30), 541
laboratories reported TOC data. EPA
believes this response indicates an
adequate potential laboratory capability
to comply with the requirements of
today's rule. EPA believes these
methods are within the technical and
economic capability of many
laboratories. The analytical cost for TOC
analyses is estimated to range from $50
to $75 per sample. Actual costs may
vary with the laboratory, analytical
technique selected, the total number of
samples, and other factors. EPA believes
that the costs for TOC monitoring are
affordable.
Today's rule proposes monitoring for
TOC, not dissolved organic carbon
(DOC). TOC is the sum of the
undissolved and dissolved organic
carbon in the water sample. DOC is
differentiated from TOC by filtering the
sample with a very fine (0.45-um) filter.
Today's rule specifies that TOC samples
are not to be filtered except to remove
turbidity, which is known to interfere
with accurate TOC measurement when
the sample turbidity is greater than 1
NTU. A TOC sample can be filtered to
remove turbidity provided a prewashed,
glass-fiber filter with a large (5- to 10-
um) pore size is used. As an alternative
to filtering, the TOC sample can be
diluted with organic-free reagent water
in order to reduce the turbidity
interference. EPA solicits comments on
the proposed turbidity threshold, and
on the sample filtration procedure as
described above and in the proposed
methods.
EPA has evaluated several methods to
determine the feasibility of obtaining
reliable TOC measurements. To meet
today's proposed requirements, a TOC
method must have a detection limit of
at least 0.5 mg/L, and more importantly
achieve a reproducibility of ±0.1 mg/L
over a range of approximately 2 to 5 mg/
L. This reproducibility is required
because some systems will have to
reliably measure 0.3 mg/L differences in
TOC removal in several jar test samples
to which progressively greater amounts
of coagulant have been added [R.
Miltner, 1993]. Reliable measurement of
0.3 mg/L differences requires that the
error bars on the analysis approach ±0.1
mg/L. When calculated as a percent, this
precision requirement becomes ±5% at
2 mg/L of TOC, and ±2% at 5 mg/L of
TOC. Data presented in Standard
Method 5310 C indicate that this is
feasible, and Standard Method 5310 D is
close to this level of performance.
In a PE sample prepared for EPA's
Water Pollution WP 27 study, 26 EPA
and State laboratories achieved a
precision of ±0.33 mg/L on a TOC
sample spiked at about 5 mg/L. In WP
30, a mean value of 8.74 ±0.79 mg/L was
measured by the 541 laboratories that
reported results. A subset of 27 EPA and
State laboratories in WP 30 reported a
precision of ±0.4 mg/L on the same
sample. EPA solicits comment on what
precision can be routinely expected on
differential TOC measurements of jar
test samples. EPA is also interested in
new methods or modifications to the
methods proposed today that would
improve tie reproducibility of TOC
measurement.
EPA considered, but is not proposing,
Standard Method 5310 B because the
stated detection limit is 1 mg/L, which
is 0.5 mg/L greater than the required
TOC detection limit. EPA is aware that
the instrumentation used in Method
5310 B is being improved. If this work
is successful, EPA will consider the next
version of Method 5310 B (or its
equivalent) for promulgation in the final
rule. The two methods proposed today
for TOC measurements are described
below.
Persulfate-Ultraviolet Oxidation
Method (SM 5310 C) measures organic
carbon via infrared absorption of the
carbon dioxide gas that is produced
when the organic carbon in the sample
is simultaneously reacted with a
persulfate solution and irradiated with
ultraviolet light. Inorganic carbon is
removed from the sample prior to
analysis by acidification with
phosphoric or sulfuric acid. Chloride
and low sample pH can impede the
analysis; precautions are specified in
the method. The lower limit of detection
of the method is 0.05 mg/L.
Wet-Oxidation Method (SM 5310 D)
has a detection limit of 0.10 mg/L and
is subject to the same interferences as
the persulfate-ultraviolet method.
Persulfate and phosphoric acid are
added to the sample; the sample is then
purged with pure oxygen to remove
inorganic carbon. The purged sample is
sealed in an ampule and combusted for
four hours in an oven at a temperature
that causes persulfate to oxidize organic
carbon to carbon dioxide. The ampule is
opened inside a TOC-analyzer, and TOC
is measured via infrared absorption of
carbon dioxide.
b. Alkalinity Methods. With two
minor exceptions, EPA is proposing all
of the methods (Table IX-4) which are
currently approved under 40 CFR
141.89 for measurement of alkalinity.
The exceptions are that EPA is
proposing more recent versions of the
alkalinity methods, which are published
by Standard Methods and the American
Society of Testing and Materials
(ASTM). In today's rule, EPA is
proposing Method 2320 B, which is in
the 18th edition of Standard Methods,
and Method D1067-88B, which is in the
1993 Annual Book of ASTM Standards,
in lieu of the versions cited at 40 CFR
141.89. There are no technical
difference between the proposed
versions and the currently approved
versions.
EPA is also aware that EPA Method
310.1, which uses the same technology
as Methods 2320 B and D1067-88B, has
not been updated since 1983. The
references in the EPA method are
becoming obsolete, and the equivalent
methods from ASTM and Standard
Methods are updated more regularly. To
allow laboratories the use of only the
most current versions of equivalent
methods, EPA may not promulgate
Method 310.1 with the final D/DBP rule,
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and EPA also may withdraw "approval of
it under 40 CFR 141.89.
To accurately measure alkalinity, the
sample pH at the source where the
sample was collected must be recorded.
It is important to accurately measure
carbon dioxide gas, which is dissolved
in the sample and is a major contributor
to the alkalinity of the sample. To
minimize loss of carbon dioxide, the
sample is collected in an air tight
container, and agitation of the sample is
kept to a minimum.
EPA believes that the proposed
alkalinity methods, which have been
used for years, are within the technical
and economic capability of many
laboratories. The analytical cost of
alkalinity analysis is estimated to range
from $5 to $10 per sample. Actual costs
may vary with the laboratory, analytical
technique selected, the total number of
samples and other factors. EPA believes
the analytical costs for alkalinity
monitoring are affordable.
EPA believes the working range for
each method adequately covers the
requirements proposed for alkalinity
monitoring in today's rule. All
procedures and precautions listed below
and in the methods must be followed
carefully. Descriptions and more
information on the methods are in the
notices of August 18,1988 [53 FR
31516] and October 19,1990 [55 FR
42409].
c. Bromide Method. EPA Method
300.0, Determination of Inorganic
Anions by Ion Chromatography, is
proposed for measurement of bromide
ion. This method is described above
under inorganic by-product methods for
chlorite and bromate. EPA believes the
working range for this method
adequately covers the requirements
proposed for bromide monitoring in
today's rule.
EPA believes that Method 300.0 is
within the technical and economic
capability of many laboratories. The
analytical cost of bromide analysis is
estimated to range from $50 to $100 per
sample. However, if other anions, such
as fluoride or chloride, are measured in
the same sample, the additional cost for
bromide analysis should be minimal.
Actual costs may vary with the
laboratory, analytical technique
selected, the total number of samples,
and other factors. EPA believes the
analytical costs for bromide ion
monitoring are affordable.
6. Sources and Scope of Future
Analytical Methods
The Standard Methods proposed in
today's rule are published in the 18th
edition of Standard Methods. EPA is
aware that these methods will be
updated when the 19th edition is
published. EPA is also gathering
additional performance data on several
EPA methods which are proposed in
today's rule. EPA will obtain these data
from occurrence studies, from
laboratory certification performance
evaluation sample analyses and from
other sources. To support pollution
prevention goals and to generally
improve the safety and efficiency of
analytical methods, EPA is working to
reduce the volume of solvents and the
amounts of potentially hazardous
reagents in EPA methods. Thus, EPA
may revise, improve, or expand several
EPA methods prior to promulgation of
the D/DBP rule. Examples of methods
that EPA or other organizations might
change are discussed below.
EPA may refine the solvent extraction
and sample preservation procedures in
Method 551, which is proposed today
for trihalomethanes. EPA may also
extend approval of EPA Method 551 to
compliance measurements of six
chemicals currently regulated under 40
CFR 141.24. The six contaminants are:
carbon tetrachloride, trichloroethylene,
tetrachloroethylene, 1,2-dibromoethane
(EDB), 1,2-dibromo-3-chloropropane
(DBCP), and 1,1,1-trichloroethane. EPA
may revise Method 552, merge it with
Method 552.1, and approve it for the
analysis of haloacetic acids. EPA may
revise Method 300.0 to improve the
detection limits for bromate and to
further eliminate some of the
interference problems in the method.
The Standard Methods organization
may incorporate more sensitive
instrumentation in later versions of TOG
method 5310 B.
To accommodate future
improvements in analytical methods,
EPA proposes that the methods in the
then current editions of books published
by Standard Methods and ASTM and
the then current versions of EPA
methods be cited in the final D/DBP rule
provided no unacceptable changes are
in the later versions of these methods.
H. Basis for Compliance Schedule and
Applicability to Different Groups of
Systems, Timing With Other Regulations
Under the negotiated rulemaking the
Negotiating Committee agreed to
propose three rules: (a) an information
collection requirements rule (ICR) (59
FR 6332), (b) an "interim" enhanced
surface water treatment rule (ESWTR)
(proposed in today's Federal Register),
and c) Disinfection/Disinfection By-
products (D/DBP) regulations, proposed
herein today. Table IX—5 indicates the
schedule agreed to by the Negotiating
Committee by which these rules would
be proposed, promulgated, and become
effective. Compliance dates for the ICR
are indicated under the columns of the
Stage 2 D/DBP rule and ESWTR to
reflect the relationship between these
rules.
The Negotiating Committee agreed
that more data, especially monitoring
data, should be collected under the ICR
to assess possible shortcomings of the
SWTR and develop appropriate
remedies, if needed, to prevent
increased risk from microbial disease
when systems began complying with the
Stage 1 D/DBP regulations. It was also
agreed that EPA would propose an
interim ESWTR (proposed elsewhere in
today's Federal Register) pertaining to
systems serving greater than 10,000
people, including a wide range of
regulatory options. Data gathered under
the ICR would form the basis for (a)
promulgating the most appropriate
criteria among the options presented in
the proposed interim ESWTR, and (b)
proposing at a later date a long-term
ESWTR pertaining to all system sizes.
Both of these rules, if needed, would be
proposed and promulgated so as to be
in effect at the same time that systems
of the respective size categories would
be required to comply with new
regulations for D/DBPs.
The Negotiating Committee also
agreed that additional data on the
occurrence of disinfectants, disinfection
byproducts (DBFs), potential surrogates
for DBPs, source water and within
treatment conditions affecting the
formation of DBPs, and bench-pilot
scale information on the treatability for
removal of DBF precursors would be
beneficial for developing the Stage 2 D/
DBP regulatory criteria.
Prior to promulgating the interim
ESWTR, EPA intends to issue a Notice
of Availability to: (a) discuss the
pertinent data collected under the ICR
rule, (b) discuss additional research that
would influence determination of
appropriate regulatory criteria, (c)
discuss criteria EPA considered
appropriate to promulgate in the interim
ESWTR (which would be among the
regulatory options of the proposed
interim ESWTR) and (d) solicit public
comment on the intended criteria to be
promulgated.
The Negotiating Committee believed
that the December 1996 scheduled date
for promulgating the Stage 1 D/DBP
Rule was within the shortest time
possible by which the interim ESWTR,
if necessary, could also be promulgated.
EPA is proposing that the Stage 1 D/DBP
regulations and the interim ESWTR (if
necessary) become effective on the same
date of June 30,1998 for systems using
surface water and serving greater than
10,000 people.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38777
TABLE IX-5.—PROPOSED D/DBP, ESWTR, ICR RULE DEVELOPMENT SCHEDULE
Time line
12/93
3/94
6/94
RMil
10/94
1/95
10/95
11/95
1/96
3/96
19/Qfi
6/97
10/97
12/97
fi/QA
12/98
6/00
1/02
Stage 1 •
DBP rule
Propose required enhanced coagulation
for systems with conventional treatment.
MCLs-TTHMs (80(ig/l), HAAS (60jig/l),
bromate, chlorite. Disinfectant limits.
Effective Effective for SW systems serv-
ing greater >10k, extended compliance
date for GAG or membrane technology.
Stage 1 limits effective for surface water
systems <10k, GW systems <10k.
Stage 1 limits effective for GW systems
>10k unless Stage 2 criteria supersede.
Stage 2
DBP rule
Propose information collection require-
ments for systems >1 00k.
Propose Stage 2. MCLs for TTHMs (40
fig/l), HAAS (30 ng/l), BAT is precursor
removal with chlorination.
Promulgate ICR
Systems >100k begin ICR monitoring
SW systems >100k, GW systems >50k
begin bench/pilot studies unless source
water quality criteria met.
Systems complete ICR monitoring
Notice of availability for Stage 2
reproposal.
Complete and submit results of bench/
pilot studies.
Initiate reproposal — begin with 3/94 pro-
posal.
Close of public comment period
Propose for CWSs, NTNCWSs
Promulgate Stage 2 for all CWSs,
NTNCWSs.
Stage 2 effective, compliance for GAG/
membranes by 2004.
ESWTR
Propose information collection require-
ments for systems >1 Ok.
Propose interim ESWTR for systems
>10k.
Promulgate ICR.
Public comment period for proposed
ESWTR closes.
Systems >100k begin ICR monitoring.
Systems 10-1 00k begin source water
monitoring.
NOA for monitoring data, direction of in-
terim ESWTR.
Systems >10k complete ICR monitoring.
End NOA public comment period.
Systems >100k complete ICR monitoring.
Promulgate interim ESWTR for systems
>10k.
Propose long-term ESWTR for systems
<10k, possible changes for systems
>10k.
Interim ESWTR effective for systems
>10k. 1994-6 monitoring data used to
determine treatment level.
Publish long-term ESWTR.
Long-term ESWTR effective for all system
sizes.
Although the Agency anticipates that
the ICR will be promulgated later than
the date indicated in Table IX-5, EPA
believes that the long-term schedule
will be adhered to and the final D/DBPR
will be promulgated in December, 1996.
EPA is proposing that systems using
surface water and serving fewer than
10,000 people comply with the Stage 1
D/DBP regulations by June 30,2000 to
allow such systems to also come into
compliance with the final ESWTR. EPA
believes that the June 30, 2000
compliance date reflects the shortest
time possible that would allow for the
final ESWTR to be proposed,
promulgated, and become effective;
thereby providing the necessary
protection from any downside microbial
risk that might otherwise result when
systems of this size attempt to achieve
compliance with the Stage 1 D/DBP
rule.
EPA is also proposing that systems
using ground water and serving greater
than 10,000 people would be required to
achieve compliance with the Stage 1D/
DBP rule by June 30,2000. EPA believes
this is the earliest date possible by
which all ground water systems of this
size could be expected to achieve
compliance with both the GWDR and
the Stage 1 D/DBP rule. Many ground
water systems would be expected to be
able to achieve compliance by an earlier
date but others, due to recently
installing or upgrading disinfection to
meet the GWDR, would require some
period of monitoring for DBFs in order
to adjust their treatment processes to
also meet the Stage 1 D/DBP standards.
For the same reasons as stated above,
EPA is proposing that systems using
ground water and serving 10,000 or less
people be required to meet the Stage 1
D/DBP rule beginning January 1, 2002.
The delayed date for the ground water
systems serving 10,000 or less people is
because of the much large number of
such systems in this size category, and
the time necessary for States and
systems to implement the GWDR.
/. Basis for Qualified Operator
Requirements and Monitoring Plans
EPA believes that systems that must
make treatment changes to comply with
requirements to reduce the
microbiological risks and risks from
disinfectants and disinfection
byproducts should be operated by
personnel who are qualified to
recognize and react to problems.
Therefore, in today's proposal, the
Agency is requiring that all systems
regulated under this rule be operated by
an individual who meets State-specified
qualifications, which may differ based
on size and type of the system. Subpart
H systems already are required to be
operated by qualified operators under
the provisions of the SWTR (40 CFR
141.70(c)). Current qualification
programs developed by the States
should, in many cases, be adequate to
meet this requirement for Subpart H
systems. In the upcoming Ground Water
Disinfection Rule, the Agency may
require some or all ground water
systems to also be operated by qualified
operators. If so, the qualification
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
programs for Subpart H systems may be
modified to account for the differences
between Subpart H systems and ground
water systems. Also, States must
maintain a register of qualified
operators.
EPA encourages States which do not
already have operator license
certification programs in effect to
develop such programs. The Negotiating
Committee and Technologies Working
Group believed that properly trained
personnel were an essential first step in
ensuring safer drinking water.
Also, systems are required to develop
and follow monitoring plans for
monitoring required under this
proposed rule. Systems may update
these plans for reasons including
changes to the distribution system or
changes in treatment.
/. Basis for Stage 2 Proposed MCLs
EPA is proposing lower MCLs for
TTHMs and total haloacetic acids
(THAAs) for Stage 2 to indicate the
desire to further decrease exposure from
these chemicals but also to lower the
exposure from other byproducts
resulting from chlorine reacting with
naturally occurring organics. Systems
which lower the levels of TTHMs and
THAAs are also likely to lower the
levels of many other chlorination
byproducts, some of which may pose
additional health risks.
The proposed 40/30 MCL is based on
what would be achievable by most
systems if they were to use the "best
available technology" (BAT) proposed
for Stage 2. The Negotiating Committee
agreed that the BAT in Stage 2 for
controlling TTHMs and THAAs include
either enhanced coagulation and
shallow bed granular activated carbon
(GAC10) or deep bed granular activated
carbon (GAC20) and chlorine as the
primary and residual disinfectant.
One of the major reasons for defining
BAT as including chlorine versus, for
example, defining BAT as including
alternative disinfectants, is to recognize
the many benefits of chlorine as a
disinfectant, especially in preventing
microbial disease. In addition to being
a strong primary disinfectant, a chlorine
residual in the distribution system helps
prevent bacterial growth and is an
excellent marker (when there is an
absence of chlorine) for indicating
potential contamination from outside
sources into the distribution system.
EPA believes that chlorine should be
included in the BAT definition at least
until there is more health effects
information on byproducts formed by
use of alternative disinfectants.
Currently it is not clear whether risks
from chlorination byproducts are more
significant than those formed from use
of alternative disinfectants. The
Negotiating Committee agreed that EPA
would repropose Stage 2 requirements
in 1998 to consider new information
that would become available, especially
data on the health effects of alternative
disinfectants.
X. Laboratory Certification and
Approval
EPA recognizes that the effectiveness
of today's proposed regulations depends
on the ability of laboratories to reliably
analyze the regulated disinfectants and
disinfection byproducts at the proposed
MRDL or MCL, respectively.
Laboratories must also be able to
measure the trihalomethanes and
haloacetic acids at the proposed
monitoring trigger levels, which are
between 25 and 50 percent of the
proposed MCLs for these compound
classes. EPA has established a drinking
water laboratory certification program
that States must adopt as a part of
primacy. (40 CFR 142.10(b)). EPA has
also specified laboratory requirements
for analyses, such as alkalinity and
disinfectant residuals, that must be
conducted by approved parties. (40 CFR
141.89 and 141.74). EPA's "Manual for
the Certification of Laboratories
Analyzing Drinking Water", EPA/570/
9-90/008, specifies the criteria which
EPA uses to implement the drinking
water laboratory certification program.
Today EPA is proposing MCLs for
total trihalomethanes, total haloacetic
acids (HAAS), bromate, and chlorite.
EPA is proposing that only certified
laboratories be allowed to analyze
samples for compliance with the
proposed MCLs. For the disinfectants
and other parameters in today's rule,
which have MRDLs or monitoring
requirements, EPA is requiring that
analyses be conducted by a party
acceptable to the State.
Performance evaluation (PE) samples,
which are an important tool in EPA's
laboratory certification program, are
provided by EPA or the States to
laboratories seeking certification. To
obtain and maintain certification, a
laboratory must use a promulgated
method and at least once a year
successfully analyze an appropriate PE
sample. In the drinking water PE
studies, EPA has samples for bromate,
chlorite, five haloacetic acids, four
trihalomethanes, free chlorine, and
alkalinity. EPA has total chlorine and
total organic carbon samples in the
wastewater PE studies and has the
potential to provide these samples for
drinking water studies. Due to the
lability of chlorine dioxide, EPA does
not expect a suitable PE sample can be
designed for chlorine dioxide
measurements.
A. PE-Sample Acceptance Limits for
Laboratory Certification
Historically, EPA has set minimum PE
acceptance limits based on one of two
criteria: statistically derived estimates or
fixed acceptance limits. Statistical
estimates are based on laboratory
performance in the PE study; fixed
acceptance limits are ranges around the
true concentration of the analyte in the
PE sample. Today's proposed rule
combines the advantages of these
approaches by specifying statistically-
derived acceptance limits around the
study mean, within specified minimum
and maximum fixed criteria.
EPA believes that specifying
statistically-derived PE acceptance
limits with upper and lower bounds on
acceptable performance will provide the
flexibility necessary to reflect
improvement in laboratory performance
and analytical technologies. The
proposed acceptance criteria will
maintain minimum data quality
standards (the upper bound) without
artificially imposing unnecessarily strict
criteria (the lower bound). Therefore,
EPA is proposing the following
acceptance limits for measurement of
bromate, chlorite, each haloacetic acid,
and each trihalomethane in a PE
sample.
EPA proposes to define acceptable
performance for each chemical
measured in a PE sample from estimates
derived at a 95% confidence interval
from the data generated by a statistically
significant number of laboratories
participating in the PE study. However,
EPA proposes that these acceptance
criteria not exceed ±50% nor be less
than ±15% of the study mean. If
insufficient PE study data are available
to derive the estimates required for any
of these'compounds, the acceptance
limit for that compound will be set at
±50% of the study true value. The true
value is the concentration of the
chemical that EPA has determined was
in the PE sample.
EPA recognizes that when using
multianalyte methods, the data
generated by laboratories that are
performing well will occasionally
exceed the acceptance limits. Therefore,
to be certified to perform compliance
monitoring using a multianalyte
method, laboratories are required to
generate acceptable data for at least 80%
of the regulated chemicals in the PE
sample that are analyzed with the
method. If fewer than five compounds
are included in the PE sample, data for
each of the analytes in that sample must
meet the minimum acceptance criteria
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38779
in order for the laboratory to be
certified.
B. Approval Criteria for Disinfectants
and Other Parameters
Today's rule proposes MRDLs for the
three disinfectants—chlorine,
chloramines, and chlorine dioxide. In
addition, monitoring requirements
(under conditions explained in sections
Vm and IX of this notice) are being
proposed for total organic carbon (TOC),
alkalinity, and bromide; there are no
MCLs proposed for these parameters. In
previous rules (40 CFR 141.28, .74, and
.89), EPA has required that
measurements of alkalinity, disinfectant
residuals, pH, temperature, and
turbidity be made with an approved
method and conducted by a party
approved (not certified) by the State. In
today's rule, EPA proposes that samples
collected for compliance with today's
requirements for alkalinity, bromide,
residual disinfectant, and TOG only be
conducted with approved methods and
by a party approved by the State.
C. Other Laboratory Performance
Criteria
For all contaminants and parameters
proposed for monitoring in today's rule,
the States may impose other
requirements for a laboratory to be
certified or a party to be approved to
conduct compliance analyses. EPA
solicits suggestions for other optional or
mandatory performance criteria that
EPA or the States should consider for
certification or approval of laboratories.
XI. Variances and Exemptions
A. Variances
Under section 1415(a)(l)(A) of the
SDWA, a State which has primary
enforcement responsibility (primacy), or
EPA as the primacy agent, may grant
variances from MCLs to those public
water systems that cannot comply with
the MCLs because of characteristics of
the water sources that are reasonably
available. At the time a variance is
granted, the State must prescribe a
compliance schedule and may require
the system to implement additional
control measure.s. The SDWA requires
that variances only be granted to those
systems that have installed BAT (as .
identified by EPA in the regulations).
Furthermore, before EPA or the State
may grant a variance, it must find that
the variance will not result in an
unreasonable risk to health (URTH) to
the public served by the public water
system. The levels representing an •
URTH for each of the contaminants and
disinfectants in this proposal will be
addressed in subsequent guidance. In
general, the URTH level would reflect
acute and subchronic toxicity for shorter
term exposures and high carcinogenic
risks for long-term exposures (as
calculated using the linearized
multistage model in accordance with
the Agency's risk assessment guidelines;
see URTH Guidance, 55 FR 40205,
October 2,1990).
Under section 1413(a)(4), States that
choose to issue variances must do so
under conditions, and in a manner, that
are no less stringent than EPA allows in
section 1415. Of Course, a State may
adopt standards that are more stringent
than the EPA standards. Before a State
may issue a variance, it must find that
the system is unable to (1) Join another
water system or (2) develop another
source of water and thus comply fully
with all applicable drinking water
regulations.
EPA specifies BATs for variance.
purposes. EPA may identify as BAT
different treatments under section 1415
for variances than BAT under section
1412 for MCLs. EPA's section 1415 BAT
findings may vary depending on a
number of factors, including the number
of persons served by the public water
system, physical conditions related to
engineering feasibility, and the costs of
compliance with MCLs. In this
proposal, EPA is not proposing a
different BAT for variances under
section 1415.
B. Exemptions
Under section 1416(a), EPA or a State
may exempt a public water system from
any requirements related to an MCL or
treatment technique of an NPDWR, if it
finds that (1) Due to compelling factors
(which may include economic factors),
the PWS is unable to comply with the
requirement; (2) the exemption will not
result in an unreasonable risk to health;
and (3) the PWS was in operation on the
effective date of the NPWDR, or for a
system that was not in operation by that
date, only if no reasonable alternative
source of drinking water is not available
to the new system.
If EPA or the State grants an
exemption to a public water system, it
must at the same time prescribe a
schedule for compliance (including
increments of progress) and
implementation of appropriate control
measures that the State requires the
system to meet while the exemption is
in effect. Under section 1416(a)(2), the
schedule must require compliance
within one year after the date of
issuance of the exemption. However,
section 1416(b)(2)(B) states that EPA or
the State may extend the final date for
compliance provided in any schedule
for a period not to exceed three years,
if the public water system is taking all
practicable steps to meet the standard
and one of the following conditions
applies: (1) The system cannot meet the
standard without capital improvements
that cannot be completed within the
period of the exemption; (2) in the case
of a system that needs financial
assistance for the necessary
implementation, the system has entered
into an agreement to obtain financial
assistance; or (3) the system has entered
into an enforceable agreement to
become part of a regional public water
system. For public water systems which
serve less than 500 service connections
and which need financial assistance for
the necessary improvements, EPA or the
State may renew an exemption for one
or more additional two-year periods if
the system establishes that it is taking
all practicable steps to meet the
requirements above.
Under section 1416(d), EPA is
required to review State-issued
exemptions at least every three years
and, if the Administrator finds that a
State has, in a substantial number of
instances, abused its discretion in
granting exemptions or failed to
prescribe schedules in accordance with
the statute, the Administrator, after
following established procedures, may
revoke or modify those exemptions and
schedules. EPA will use these
procedures to scrutinize exemptions
granted by States and, if appropriate,
may revoke or modify exemptions.
In addition to the conditions stated
above, EPA solicits comment on
whether exemptions to this rule should
be granted if a system could
demonstrate to the State, that due to
unique water quality characteristics, it
could not avoid through the use of BAT
the possibility of increasing its total
health risk by complying with the Stage
1 regulations. EPA solicits comment on
when such situations might occur. For
example, such situations might occur
for systems with elevated bromide
levels in raw water. In this case, it is
possible 'that the use of BAT could
result in the increase of total risk due to
increased concentrations of brominated
byproducts in the finished water. EPA
also solicits comment on what specific
conditions, if any, should be met for a .
system to be granted an exemption
under such a provision. What
provisions should EPA require of States
to grant these exemptions? Should such
exemptions be granted for a limited
period but be renewable by the State if
no new health risk information became
available?
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38780 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
XII. State Implementation
The Safe Drinking Water Act provides
that States may assume primary
implementation and enforcement
responsibilities. Fifty-five out of 57
jurisdictions have applied for and
received primary enforcement
responsibility (primacy) under the Act.
To implement the federal drinking
water regulations, States must adopt
their own regulations which are at least
as stringent as the federal regulations.
This section describes the regulations
and other procedures and policies that
States must adopt to implement this
proposed rule.
To implement this proposed rule,
States are required to adopt the
following regulatory requirements:
—Section 141.32, Public Notification;
—Section 141.64, MCLs for Disinfection
Byproducts;
—Section 141.65, MRDLs for
Disinfectants;
—Subpart L, Disinfectant Residuals,
Disinfectant Byproducts, and
Disinfection Byproduct Precursors.
In addition to adopting regulations no
less stringent than the federal
regulations, EPA is proposing that States
adopt certain requirements related to
this regulation in order to have their
program revision applications approved
by EPA. In several instances, the
proposed NPDWRs provide flexibility to
States in implementing of the
monitoring requirements of this rule.
EPA is also proposing changes to
State recordkeeping and reporting
requirements. EPA's proposed changes
are discussed below.
A. Special Primacy Requirements
To ensure that a State program
includes all the elements necessary for
an effective and enforceable program, a
State application for program revision
approval must include a description of
how the State will:
(1) Determine the interim treatment
requirements for systems granted
additional time to install GAG and
membrane filtration.
(2) Qualify operators of community
and nontransient noncommunity water
systems subject to this regulation.
Qualification requirements established
for operators of systems subject to 40
CFRPart 141 Subpart H (Filtration and
Disinfection) may be used in whole or
in part to establish operator
qualification requirements for meeting
Subpart L requirements if the State
determines that the Subpart H
requirements are appropriate and
applicable for meeting Subpart L
requirements.
(3) Approve percentage reduction of
TC-C levels lower than those required in
§ 141.135(a)(3) {i.e., how the State will
approve alternate enhanced coagulation
levels).
(4) Approve parties to conduct
analyses of water quality parameters
(pH, alkalinity, temperature, bromide,
and residual disinfectant concentration
measurements). The State's process for
approving parties performing water
quality measurements for systems
subject to Subpart H requirements may
be used for approving parties measuring
water quality parameters for systems
subject to Subpart L requirements, if the
State determines the process is
appropriate and applicable.
(5) Approve alternate analytical
methods for measuring residual
disinfectant concentrations for chlorine
and chloramines. State approval granted
under Subpart H (§ 141.74(a)(5)) for the
use of DPD colorimetric test kits for free
chlorine testing would be considered
acceptable approval for the use of DPD
test kits in measuring free chlorine
residuals as required in Subpart L.
(6) Define criteria to use in
determining if multiple wells are to be
considered as a single source. Such
criteria will be used in determining the
monitoring frequency for systems using
only ground water not under the direct
influence of surface water.
B. State Recordkeeping
The current regulations in § 142.14
require States with primacy to keep
various records, including analytical
results to determine compliance with
MCLs, MRDLs, and treatment technique
requirements; system inventories;
sanitary surveys; State approvals;
enforcement actions; and the issuance of
variances and exemptions. In this rule,
States would-be required to keep
additional records of the following,
including all supporting information
and an explanation of the technical
basis for each decision:
(1) Records of determinations made
by the State when the State has allowed
systems additional time to install GAG
or membrane filtration. These records
must include; the date by which the
system is required to have completed
installation.
(2) Records of systems that apply for
alternative Tt)C performance criteria
(alternate enhanced coagulation levels).
These records must include the results
of testing to determine alternative
limits.
(3) Records of systems that are
required to nieet alternative TOG
performance criteria (alternate enhanced
coagulation levels). These records must
include the alternative limits and
rationale for establishing the alternative
limits.
(4) Records of Subpart H systems
using conventional treatment meeting
any of the enhanced coagulation or
enhanced softening exemption criteria.
(5) Records of systems with multiple
wells considered to be one treatment
plant for purposes of determining
monitoring frequency.
(6) Register of qualified operators.
Pursuant to § 141.133(d), Subpart H
systems serving more than 3,300 people
are required to submit monitoring plans
to the State. EPA solicits comment on
whether the State should be required to
keep this plan on file at the State after
submission to make it available for
public review.
C. State Reporting
EPA currently requires in § 142.15
that States report to EPA information
such as violations, variance and
exemption status, and enforcement
actions. In addition to the current
reporting requirements, EPA is
proposing under § 142.15(c) that States
also report:
(1) A list of all systems required to
monitor for various disinfectants and
disinfection byproducts;
(2) A list of all systems for which the
State has granted additional time for
installing GAG or membrane technology
and the basis for the additional time;
(3) A list of laboratories that have
completed performance sample analyses
and achieved the quantitative results for
TOG, TTHMs, HAAS, bromate, and
chlorite;
(4) A list of all systems using multiple
ground water wells which draw from
the same aquifer and are considered a
single source for monitoring purposes;
(5) A list of all Subpart H systems
using conventional treatment which are
not required to operate with enhanced
coagulation, and the reason why
enhanced coagulation is not required for
each system, as listed in
§ 141.135(a)(l)(AMD); and
(6) A list of all systems with State-
approved alternate performance
standards (alternate enhanced
coagulation levels).
EPA believes that the State reporting
requirements contained in this proposal
are necessary to ensure effective
oversight of State programs. Public
comments on these proposed reporting
requirements are requested. EPA
particularly requests comment from the
States on whether the proposed
reporting requirements are reasonable.
XIII. System Reporting and
Recordkeeping Requirements
The current system reporting
regulations, 40 CFR 141.31, require
public water systems to report
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38781
monitoring data to States within ten
days after the end of the compliance
period. No changes are proposed to
those requirements.
Specific data required by this rule to
be reported by public water systems are
included in § 141.134. These data are
required to be submitted quarterly for
any monitoring conducted quarterly or
more frequently, and within 10 days of
the end of the monitoring period for less
frequent monitoring. Systems that are
required to do extra monitoring because
of the disinfectant used have additional
reporting requirements specified. This
applies to systems that use chlorine
dioxide (must report chlorine dioxide
and chlorite results) and ozone (must
report bromate results).
Subpart H systems that use
conventional treatment are required to
report either compliance/
noncompliance with disinfection
byproduct precursor (TOG) removal
requirements or report which of the
enhanced coagulation/enhanced
softening exemptions they are meeting.
There are additional requirements for
systems that cannot meet the required
TOC removals and must apply for an
alternate enhanced coagulant level.
These requirements are included in
§141.134(b)(6).
Calculation of compliance with the
TOC removal requirements is based on
normalizing the percent removals over
the most recent four quarters, since
compliance is based on that period.
Normalization is necessary since source
water quality changes will change the
percent removal requirements. To
illustrate this process, EPA has
developed a sample reporting and
compliance calculation sheet that will
be included in the (to be developed)
guidance manual. An example of
calculations using the sheet is included
in Section Vin (Description of the
Proposed D/DBP Rule).
XIV. Public Notice Requirements
Under Section 1414(c)(l) of the Act,
each owner or operator of a public water
system must give notice to persons
served by it of: (1) Any violation of any
MCL, treatment technique requirement,
or testing provision prescribed by an
NPDWR; (2) failure to comply with any
monitoring requirement under section
1445(a) of the Act; (3) existence of a
variance or exemption; and (4) failure to
comply with the requirements of a
schedule prescribed pursuant to a
variance or exemption.
The 1986 Amendments required that
EPA amend its current public
notification regulations to provide for
different types and frequencies of notice
based on the differences between
violations which are intermittent or
infrequent and violations which are
continuous or frequent, taking into
account the seriousness of any potential
adverse health effects which may be
involved. EPA promulgated regulations
to revise the public notification
requirements on October 28,1987 (52
FR 41534). The regulations state that
violations of an MCL, treatment
technique, or variance or exemption
schedule ("Tier 1 violations") contain
health effects language specified by EPA
which concisely and in non-technical
terms conveys to the public the adverse
health effects that may occur as a result
of the violation. States and water
utilities remain free to add additional
information to each notice, as deemed
appropriate for specific situations.
Today's proposed rule contains specific
health effects language for the
contaminants which are in today's
proposed rulemaking. EPA believes that
the mandatory health effects language is
the most appropriate way to inform the
affected public of the health
implications of violating a particular
EPA standard. The proposed mandatory
health effects language in § 141.32(e)
describes in non-technical terms the
health effects associated with the
proposed contaminants.
Under this rule, § 141.135 prescribes
treatment technique requirements.
Violations of these requirements are
considered Tier 1 violations. Tier 2
violations include monitoring
violations, failure to comply with an
analytical requirement specified by an
NPDWR, and operating under a variance
or exemption.
EPA requests comment on its
proposed rule language. Of particular
interest is the acute violation language
in § 141.32(e)(85) for violations of the
chlorine dioxide MCL. Also of interest
is the language in § 141.32(e)(86) for
violations of the TTHM and HAA5
MCLs and the enhanced coagulation
treatment technique requirement.
XV. Economic Analysis
A. Executive Order 12866
Under Executive Order 12866 (58 FR
51735, October 4,1993), the Agency
must determine if the regulatory action
is "significant" and therefore subject to
OMB review and the requirements of
the Executive Order. The Order defines
"significant regulatory action" as one
that is likely to result in a rule that may:
(1) Have an annual effect on the
economy of $100 million or more or
adversely affect in a material way the
economy, a sector of the economy,
productivity, competition, jobs, the
environment, public health or safety, or
State, local, or tribal governments or
communities;
(2) Create a serious inconsistency or
otherwise interfere with an action taken
or planned by another agency;
(3) Materially alter the budgetary
impact of entitlements, grants, user fees,
or loan programs or the rights and
obligations of recipients thereof; or
(4) Raise novel legal or policy issues
arising out of legal mandates, the
President's priorities, or the principles
set forth in the Executive Order.
Pursuant to the terms of Executive
Order 12866, it has been determined
that this rule is a "significant regulatory
action" because it will have an annual
effect on the economy of $100 million
or more. As such, this action was
submitted to OMB for review. Changes
made in response to OMB suggestions or
recommendations will be documented
in the public record.
B. Predicted Cost Impacts On Public
Water Systems
1. Compliance Treatment Cost Forecasts
Compliance treatment cost forecasts
were estimated by the TWG. The basis
for these estimates presented herein are
described in the Regulatory Impact
Analysis (USEPA, 1994). Tables XV-1 .
through XV—3 present summaries of the
estimated total national costs of
installing and operating treatment to
comply with both Stage I and Stage II
requirements. Table XV-1 is a summary
of estimated cost impacts for all public
water supplies affected (i.e., community
and nontransient noncommunity
systems) and represents a combination
of the estimates indicated in Table XV-
2 for community systems and Table XV—
3 for nontransient noncommunity
systems.
BILLING CODE 6560-60-P
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38782
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38783
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38784
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
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BILLING CODE 6560-SO-C
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38785
The rule would affect about 51,500
"non-purchased" community water
systems and 24,500 "non-purchased"
nontransient noncommunity water
systems. Non-purchased water systems
are those that produce and/or treat
water for distribution. Of the affected
community water systems, about 95%
serve fewer than 10,000 persons. It is
estimated that all but four of the affected
nontransient noncommunity water
systems serve fewer than 10,000
persons. As a group, the systems serving
fewer than 10,000 persons are projected
to account for about 40 percent of the
total annual cost of installing and
operating treatment to comply with the
rule and about 55 percent of the total
cost of monitoring and reporting to
comply with the rule. In terms of the
Regulatory Flexibility Act, this rule will
have a significant impact on a
substantial number of small systems.
Following EPA guidance, the Regulatory
Flexibility Act Analysis will be
presented within the Regulatory Impact
Analysis.
The Stage II DBF Rule—as proposed—
would apply only to non-purchased
community and NTNC surface water
systems serving more than 10,000
persons. The impact of the Stage II
requirements on these systems will
result in a combined total annual cost
(Stage I + Stage II) for installing and
operating treatment facilities of $1.77
billion per year. If the Stage II
requirements were extended to cover all
systems, the result would be a combined
total annual cost (Stage I + Stage II) for
installing and operating treatment
facilities of $2.56 billion per year.
Monitoring and state implementation
costs have not been estimated for Stage
II. Under this extended Stage II scenario,
systems serving fewer than 10,000
persons would account for nearly 40
percent of the total annual cost of
installing and operating treatment. In
terms of the total annual cost of
installing and operating treatment, the
Stage II extended scenario would be
about one-and-one-half times as
expensive as Stage I. The same ratio
applies to both size categories of
systems, i.e., those serving greater or
fewer than 10,000 people.
2. Compliance Treatment Forecast
Tables XV-4 and XV-5 present
summaries of the national forecasts of
treatment choices that were made to
support the development of the national
treatment cost estimates. The DBPRAM,
a Monte Carlo simulation model of
influent variability combined with a
treatment model to predict treatment
performance, was used to seed this
analysis. Initially, the DBPRAM
provided a default set of most likely
compliance choices based on a least cost
algorithm based on estimated costs of
different unit processes (Gelderloos et
al., 1992; Cromwell et al., 1992; USEPA,
1992). These choices were then adjusted
via a consensus process reflecting the
combined judgement of the TWG
(USEPA, 1994). While some
technologies, such as chlorine dioxide,
were recognized as possible means for
achieving compliance, insufficient data
were available to predict such
compliance choices. However, the TWG
believed that failure to consider
compliance choices other than those
listed in Tables XV-4 and XV-5 would
not significantly affect the total national
cost compliance cost estimates.
BILLING CODE 6560-50-P
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38786 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
£
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38787
BILLING CODE C560-SO-C
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38788
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Regarding Table XV-4, the DBPRAM
predicted that 60 percent of all systems
using surface water would at least use
enhanced coagulation to comply with
the Stage 1 requirements. Among the
systems using enhanced coagulation,
10% would also use chloramines as
their residual disinfectant (with
chlorine used as the primary
disinfectant), 6% would also use ozone
as their primary disinfectant and
chloramines as their residual
disinfectant, 1% would also use GAC10,
and 1% would also use GAC20. Among
the systems not using enhanced
coagulation, 3% would use chloramines
as a residual disinfectant (with chlorine
as the primary disinfectant), 5% would
use ozone as their primary disinfectant
and chloramines as their residual
disinfectant, and 4% would use
membrane technology. The predicted
compliance choices for systems serving
10,000 people or less are almost the
same as those for systems serving
greater than 10,000 people. One notable
difference is that because of large
economies of scale for GAC20, no
systems serving 10,000 people or less
are predicted to use GAC20; rather all
such systems (6%) requiring substantial
precursor removal are predicted to use
membrane technology.
Regarding Table XV-5, the DBPRAM
predicted that for systems using ground
water and seeking to comply with the
Stage 1 requirements, 8% would use
chloramines as their residual
disinfectant (with chlorine as the
primary disinfectant), 4% would use
membrane technology, and 0.04%
would use ozone for primary
disinfection with chloramines for
residual disinfection. While 2% of
systems serving greater than 10,000
people were predicted to use ozone and
chloramines, no systems serving 10,000
people or less were predicted to use this
technology (for these sized systems
membranes were considered a preferred
option to ozone and chloramines
because of the likely lower system level
cost and ease of use).
Unlike for surface water supplies, all
large ground water systems with high
DBF precursor levels are predicted to
use membrane technology in lieu of
GAG. This is because large ground water
systems are assumed to use multiple
wells, each being of small enough size
to be more cost effectively treated with
membrane technology than by GAG.
The percentage of systems affected by
the DBF regulations is markedly less
among those using ground waters than
those using surface waters. This is
because (1) Most ground waters have
much lower levels of DBF precursors
than surface waters, and (2) most
ground waters (i.e., those not under the
direct influence of surface water as
assumed in this analysis) are not
considered vulnerable to contamination
by protozoa and therefore require much
less disinfection. Also, some ground
water systems which are adequately
protected will be able to avoid
disinfection altogether and thereby
avoid needing to meet any regulatory
requirements pertaining to DBFs.
3. DBF Exposure Estimates
Table XV-6 presents three computer
generated profiles of exposure reflecting
the baseline condition, the Stage I rule,
and the Stage II rule. The change in
exposure is characterized in terms of
TOG, TTHMs, and HAAS. These data
are applicable only to large systems
(>10,000 population) which filter but do
not soften. The median and 95th
percentile values for effluent TOG are
shown to be reduced from 2.5 and 4.9
mg/1 under baseline conditions to 2.2
and 3.8 mg/1 at Stage I, and 2.0 and 3.3
mg/1 at Stage II. The median and 95th
percentile values for TTHMs are shown
to be reduced from 46 and 104 ng/1
under baseline conditions to 31 and 58
Ug/1 at Stage I, and 22 and 30 ug/1 at
Stage II. The median and 95th percentile
values for effluent HAAS are shown to
be reduced from 28 and 86 ug/1 under
baseline conditions to 20 and 43 ug/1 at
Stage I, and 14 and 22 ug/1 at Stage U.
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38789
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38790
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Quantitative changes in exposure
from TOC and DBFs were not predicted
for ground water systems because of
insufficient data. Treatment changes
that ground water systems make to
comply with the DBF regulations are
likely to result in lower reductions of
national median TOC and DBF levels
than in surface water supplies. This is
.because of the much smaller percentage
of ground water systems that are
affected. However, the resultant change
from the DBF regulations on the 95th
percentile of TOC and DBF levels in
ground water systems may be more
significant than in surface water
systems. This is because membrane
filtration, which would be used in the
systems with poorest quality, can,!
remove greater than 90% of TOC,
resulting in probably similar reductions
of TTHMs and HAAS (USEPA 1992).
4. System Level Cost Estimates
Tables XV-7 and XV-8 present the
unit cost estimates that were utilized for
each of the different treatment
technologies in each system size
category. The unit cost estimates were
derived from a cost model described in
the Cost and Technology document
(USEPA 1992) and adjusted per
discussion among TWG to reflectsite
specific factors (USEPA 1994). for
systems in size categories serving
greater than 10,000 people the estimated
system level costs for achieving
compliance ranged from $0.01/1000
gallons (chlorine/chloramines) to $1.87/
1000 gallons (membrane technology).
For systems in size categories serving
less than 10,000 people the estimated
system level costs for achieving
compliance ranged from $.03/1000
gallons (chlorine/chloramines) to $3.49/
1000 gallons. Although some
technologies are listed as costing more
than $3.49/1000 gallons in the smallest
size categories (because of large
economies of scale), no such
technologies would be used because
compliance could.be achieved with
membrane technology.
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38791
I
1
••e
4
i
VI
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38792
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:
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38793
5. Effect on Household Costs
Table XV-9 summarizes cost impacts
at the household level contained in
Figures XV-1 through XV-4 for systems
having to install and operate treatment.
The impacts presented for Stage II
represent the cumulative cost per
household of both Stage I and Stage II.
The household impacts are based solely
upon the community water system
analysis since the nontransient
noncommunity systems typically do not
serve households. These household
impacts do include, however, the
households in purchased water systems
that are served by the affected non-
purchased water systems. These
household costs reflect only the cost of
treatment and do not include the cost of
monitoring. Note also that costs of an
Enhanced Surface Water Treatment
Rule, if such a rule should become
necessary, are not included.
TABLE XV-9.—STAGE 1 AND STAGE 2 HOUSEHOLD COST IMPACT SUMMARY
Type of system
S/household/yr.
0
>0-10
>10-20
>20-40
>40
0
>0-10
>10-20
>20-40
>40
Large sur-
face water 1
1395
56
Number of
16.8
30.8
4.5
2.2
1.7
Number of
CO
13.4
25.2
6.2
6.7
4.5
Small sur-
face water1
4562
6.4
households exf
compliance
1.8
2.4
1.1
0.1
1.0
households ex|
mpliance with
(2)
(2)
(2)
(2)
(2)
Large
ground
water 1
1316
19
lected to pay s
with stage 1 i
16.0
2.0
0.2
0.2
0.6
seeled to pay £
stage 1 and sfe
(2)
(2)
(2)
(2)
(2)
Small
ground
water 1
44,310
12.3
pecific increas
n millions)
10.6
1.0
None
0.1
0.6
pecific increas
»ge 2 (in millior
(2)
(2)
(2)
(2)
(2)
Totals
51,583
93.7
3d costs for
45.2
36.2
5.8
2.6
3.9
ed costs for
is)
13.4
25.2
6.2
6.7
4.5
1 Large systems serve 10,000 or more persons. Small systems serve fewer than 10,000 persons. Surface water systems are Subpart H sys-
tems. Ground water systems are systems using only ground water not under the direct influence of surface water.
^Today's Stage 2 D/DBP Rule proposal only applies to Subpart H systems serving at least 10,000 persons. As proposed, there are no house-
hold compliance costs for other systems.
BILLINQ CODE 6560-50-P
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Figure XV-1
Stage I
Cumulative Distribution of Annual Costs for 56 Million Households
. Served by 1,395 Large Surface Water Systems
20% 30% 40% 50% 60% 70%
Cumulative Percentage of Households
80%
90%
100%
Stage I
Cumulative Distribution of Annual Costs for 6.4 Million Households Served
by 4,562 Small Surface Water Systems
20% 30% 40% 50% 60% 70%
Cumulative Percentage of Households
80%
90%
100%
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38795
Figure XV-2
Stage I
Cumulative Distribution of Annual Costs for 19 Million Households
.Served by 1,316 Large Ground Water Systems
83%
85%
88% 90% 93%
Cumulative Percentage of Households
95%
98%
100%
350
T 300
L.
ii 250 •-•
I 20°
1 150 -•
100
80%
Stage I
Cumulative Distribution of Annual Costs for 12.3 Million Households
Served by 44,310 Small Ground Water Systems
50 -~ —•
83% 85% 88% 90% 93%
Cumulative Percentage of Households
95%
98%
100%
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38796
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Figure XV-3
Stage H: 40/30
Cumulative Distribution of Annual Costs for 56 Million Households
. Served by 1,395 Large Surface Water Systems
30%
40%
50% 60% 70%
Cumulative Percentage of Households
80%
90%
100%
Stage H: 40/30
Cumulative Distribution of Annual Costs for 6.4 Million Households
If Extended to 4,562 Small Surface Water Systems
350 -r-
20% 30% 40% 50% 60% 70%
Cumulative Percentage of Households
80%
90%
100%
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Federal Register / Vol. 59, No. 145 /Friday, July 29, 1994 / Proposed Rules
38797
(MA/$)
p|oqasnoH
-------
38798
Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
s
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3
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CO CM CM
CJA/$)
BILLING CODE 6560-SO-C
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38799
EPA estimates that about 45 million
households (48% of the total served by
community water systems) will incur no
treatment costs for compliance with
Stage I. Of 49 million households
incurring treatment costs for compliance
with Stage 1,45.5 million will incur
costs of less than $50 per year, 1.3
million will incur costs of $50 to $100
per year, 1.0 million will incur costs of
$100 to $200 per year, 0.8 million will
incur costs of $200 to $300 per year, and
0.2 million will incur costs of more than
$300 per year.
EPA estimates that 13.4 million of the
56 million households served by large
surface water systems (24% of the total)
will incur no treatment costs for
compliance with Stage n as proposed
(applying only to large surface water
systems). Of the nearly 43 million
households incurring treatment costs for
compliance with Stage n as proposed,
39.8 million will incur costs of less than
$50 per year, 2.2 million will incur costs
of $50 to $100 per year, and 0.8 million
will incur costs of $100 to $200 per
year.
EPA estimates that 36.3 million
households (39% of the total served by
community water systems) will incur no
treatment costs for compliance with
Stage II if extended to all systems. Of
the 57.2 million households incurring
treatment costs for compliance with an
extended Stage II, 48.6 million will
incur costs of less than $50 per year, 2.7
million will incur costs of $50 to $100
per year, 2.6 million will incur costs of
$100 to $200 per year, 2.5 million will
incur costs of $200 to $300 per year, and
0.8 million will incur costs of more than
$300 per year. Annual household costs
above $200 are projected predominantly
for small systems that may be required
to install membrane treatment. Some of
these systems could find that there are
less expensive options available, such as
connecting into a larger regional water
system.
Impacts on Low Income Families. The
Negotiating Committee had several
discussions of the impact of the DBF
regulatory proposals on low income
households and reviewed the impact
estimates specifically in this light. An
analysis was presented that focused
exclusively on the impact on low
income households, using data on
families enrolled in the Aid to Families
with Dependent Children (AFDC)
program as an illustration.
Based on the 1992 Statistical Abstract
of the United States, there were 4.2
million AFDC families (this represents
about one- third of all families below
the poverty line). In the absence of
information to suggest otherwise, it was
assumed that these families are
distributed across water system types
and sizes in the same proportion as the
total population. The analysis was
performed to illustrate the impact of the
Stage IIDBP requirements under the
assumption that the 40/30 requirement
was extended to all water systems.
Results are presented in Figure XV-5.
The results in Figure XV-5 show the
distribution of impacts in terms of the
number of households that would have
a given level of impact on their
household income in terms of the
percent of AFDC income. Based on the
current level of AFDC payments, a $22
per year increase in the water bill is
equivalent to 0.5 percent of AFDC
income.
BILLING CODE 6560-50-P
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38800
Federal Register / Vol. 59, No. 145 /Friday, July 29, 1994 / Proposed Rules
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With the given assumptions about the projected that 1.7 million of the 4.2
distribution of AFDC households, it is million AFDC families would be served
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Federal Register / Vol. 59, No. 145 / Friday. July 29, 1994 / Proposed Rules 38801
by water systems that are unaffected by
the DBF regulations. This reflects a
general characteristic of the regulation
of DBFs—that it is not going to be a
problem in many systems that have
fortunate circumstances regarding raw
water characteristics.
Another 1.8 million of the 4.2 million
AFDC families are projected to be
served by water systems that will incur
costs of less than $22 per household per
year, or less than 0.5 percent of AFDC
income. This reflects another feature of
the DBF rule—that impacts might not be
too severe in many large urban water
systems with moderate levels of DBFs
and economies of scale. It is noted,
however, that the current Stage n cost
estimates are based upon generous use
of alternative disinfectants. If use of
alternative disinfectants becomes
unacceptable or inadequate for meeting
other concurrent criteria (such as DBF
precursor removal), greater use of
alternative precursor removal
technologies becomes necessary as a
means of achieving compliance and
utilities could incur expenses several
times as great.
About one-sixth of the 4.2 million
AFDC households (0.7 million) are
projected to be served by water systems
that will incur costs of more than $22
per household per year, or more than
0.5 percent of AFDC income. These
estimates are also based on an
assumption of extensive use of
alternative disinfectants that are less
expensive than precursor removal
technologies.
Important patterns are illustrated in
Figure XV-5. Most of the 700,000
households are concentrated in large
systems near the low end of the scale.
Nearly 75 percent (514,000 of the total
700,000 households) are projected to be
served by large water systems. Among
these 514,000 households, over 75
percent (390,000) will face costs of less
than 2 percent of AFDC income; nearly
half (248,000) will face costs of less than
1 percent of AFDC income. Less than
one-quarter of AFDC households in
large systems (124,000) will face costs
between 2 percent and 4.5 percent of
AFDC income. None will face costs
greater than 4.5 percent of AFDC
income. Again, these estimates assume
use of alternate disinfectants rather than
more costly precursor removal
technologies.
At the extreme right-hand side of
Figure XV-5, the most extreme impacts
on AFDC households are indicated to
occur in small water systems. Given the
assumptions of this analysis, it is
projected that there will be 147,000
AFDC households in small communities
that will face costs of between 6.0 and
7.0 percent of AFDC income. This
impact is more likely to occur in small
rural communities in declining
economic regions. Realistically, it is not
clear that such communities could raise
the required capital without some form
of government assistance that might
reduce the final cost per household.
6. Monitoring and State Implementation
Costs, Labor Burden Estimates
Table XV-10 summarizes the
monitoring and state implementation
cost and labor burden estimates. In
compliance with the Paperwork
Reduction Act, EPA estimates the total
labor burden of complying with
monitoring and reporting requirements
to be 1.5 million hours over six years,
averaging 250,000 hours per year. This
estimate equates to an average of 4
hours per system per year. The labor
burden for State program
implementation is estimated to total 2.5
million hours over six years, averaging
416,666 hours per year. This estimate
implies a per State average of 7,440
hours per year. However, the
implementation work load will not be
staggered evenly over the six year
period or by State.
BILLING CODE 6560-60-P
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38802 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38803
The total cost of compliance with the
monitoring requirements is estimated to
be $283 million over six years,
averaging $47 million per year. The total
cost of state implementation is
estimated to be $82 million over six
years, averaging $14 million per year.
The cost of monitoring and of state
implementation will not be evenly
spread over the six year period.
C. Concepts of Cost Analysis
The Negotiating Committee reviewed
the cost of capital assumptions normally
employed by EPA in analyzing drinking
water regulations. EPA typically
assumes a 7 percent interest rate and a
20-year term. These assumptions result
in a Capital Recovery Factor of 0.09439.
The Capital Recovery Factor is
multiplied times the capital cost to
arrive at the amount of the annual
payment required including principal
and interest. During the negotiation, it
was pointed out that the standard EPA
assumption is too low for investor
owned utilities considering other
carrying costs of capital investment
(e.g., taxes, depreciation), although it be
reasonable for municipal utilities
considering current interest rates. It was
also noted that the standard EPA
assumption is too low an estimate for
the cost of capital in small investor
owned systems and other small private
systems (e.g., homeowner's associations,
trailer parks, etc.) considering
differences in credit risk and access to
capital.
An analysis was presented by a
member of the Negotiating Committee
indicating that a Capital Recovery
Factor of 0.17172 is appropriate for large
investor owned utilities and that a
Capital Recovery Factor of 0.20105 is
appropriate for small privately owned
water systems. Based on current interest
rates for municipal bonds, the TWG
determined that Capital Recovery
Factors of 0.09439 and 0.10185 are
appropriate for large and small
municipally owned water systems,
respectively. EPA and NAWC data on
the mix of ownership types by system
size were then used to develop weighted
composite Capital Recovery Factors for
use in the analysis. The results are
summarized as follows:
Category
<1,000
1 ,000-1 0,000
10,000-100,000
100,000+
Ownership of
systems
publ 13
publ 75
publ 86
nriv/ 17 **
publ 82.5
Capital
recovery
factors
0.10185
0.10185
n 1 71 70
0 09439
0.09439
Composite
factors
. IOO1O
.12DDO
.10792
Capital costs are based on the EPA Cost
and Technology Document which
represents fourth quarter 1991 costs.
These costs were not adjusted for
inflation, but very little inflation has
occurred since then.
D. Benefits
Despite the enormous uncertainties
for estimating reductions in risk
resulting from different regulatory
strategies, the Negotiating Committee
recognized that the existing risks could
be large, and therefore should be
reduced. The Negotiating Committee
reached a consensus that the Stage 1
requirements were of sufficient benefit
to be proposed for all system sizes, but
could not agree on Stage 2 reductions.
Until extensive epidemiological and
lexicological studies have been
completed, it is not possible to draw
definitive quantitative conclusions
regarding the precise extent of cancer
and non-cancer adverse health effects
resulting from disinfection byproducts.
Nevertheless, based on exposure
estimates described above, an analysis
was developed to provide some
quantitative indication of the range of
possibilities implied by the Stage I and
Stage n proposals in terms of the cost-
per-case-of-cancer-avoided.
Toxicological and epidemiological
analyses can be applied to the exposures
predicted by the DBPRAM to suggest a
range of annual cancer incidence that
might be avoided if systems were to
comply with the proposed D/DBP
regulations.
During the regulatory negotiations,
some negotiators argued that the
national baseline incidence of cancer
attributed to DBFs in drinking water
may be less than 1 case per year; others
argued that over 10,000 cases per year
are linked to DBFs. The lower bound
baseline risk estimate was based on the
maximum likelihood estimates of
toxicological risk (best case estimates as
opposed to upper 95% confidence
bound estimates) associated with THM
levels (i.e., chloroform, bromoform,
bromodichloromethane, and
dibromochloromethane) predicted by
the DBPRAM (USEPA, 1994). Not
included in the lower bound estimate
were any risks resulting from exposure
to HAAs or other DBFs. Although
dichloroacetic acid has been classified
as a probable human carcinogen (see
Section V of this preamble), risks have
not been included for this chemical
because the Agency has not yet
quantified its carcinogenic potential.
Also, since cancer bioassays are only
currently underway for the brominated
HAAs, potential risks from their
exposure could not be quantified. No
national risk estimates were possible for
bromate because of the lack of national
occurrence data or model to predict
bromate formation.
An upper bound base-line estimate of
over 10,000 cancer cases per year was
considered based upon the central
tendency estimate of the pooled relative
risks from a meta-analysis study which
statistically combined the results of ten
previously published epidemiology
studies (Morris et al. 1992). The basis
for estimating risks from the meta-
analysis was questioned by some
members of the Negotiating Committee,
including EPA, because (a) the studies
used in the meta-analysis were of
different design and thus not subject to
a meta-analysis and (b) potential
confounding factors or bias may not
have been adequately controlled
(Farland and Gibb, 1993; Craun 1993;
Murphy 1993). Also, the epidemiologic
studies used in the meta-analysis
considered exposure to populations
before the advent of the 1979 MCLs for
TTHMs; that regulation significantly
reduced exposure to chlorinated DBFs
(McGuire et al 1989). Other members of
the Negotiating Committee, however,
commented that many of the "biases"
noted in studies used in the meta-
analysis would tend to underestimate
cancer risks and that, taken as a whole,
these studies are highly suggestive of a
link between DBFs and certain cancers.
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38804 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
They also noted that current THM rules
do not apply to most public water
systems (those serving fewer than
10,000 people) which serve about 20%
of the U.S. population. Also, these rules
do not necessarily control many other
DBFs which may be of health risk
significance.
While research is needed to establish
better risk estimates associated with
disinfected water, the above estimates
appear to reasonably bound the
potential for cancer risk (it should be
noted, however, using the upper bound
of the meta-analysis estimate would
have resulted in a higher baseline
cancer risk estimate). In order to
estimate the benefits of reducing DBF
exposure, EPA made certain
assumptions. All assumptions are based
on results of DBPRAM estimates of
conditions in large surface water
systems that filter but do not soften.
These systems represent about 80
percent of the population served by
surface water systems and over 50
percent of the population served by all
public water systems. However, this
analysis does not address the benefits to
consumers using smaller systems. One
approach used was to assume that the
percent reduction in TTHM and HAAS
median effluent concentrations reflects
an equivalent percent reduction in
cancer risk. A second approach was to
assume that the percent reduction in
median TOG effluent concentration
reflects an equivalent percent reduction
in cancer risk. These alternatives were
evaluated under the assumption that
there would be no compromising the
SWTR risk goal of no more than one
case of giardiasis per 10,000 people per
year. In other words, this microbial
treatment objective was used to
constrain the DBPRAM model while
predicting a) the baseline levels of
TTHMs, HAAS, and TOC under the
existing SWTR, and b) the new
concentrations of TTHMs, HAAS, and
TOC resulting from systems attempting
to meet the Stage 1 and Stage 2
requirements (USEPA, 1994). This
modeling constraint, which is in effect
an ESWTR consistent with the
objectives of the SWTR, avoids
increases in microbial risk and
simplifies the benefits analysis. The
preamble to the proposed ESWTR,
elsewhere in today's Federal Register,
discusses how the DPBRAM has also
been used to predict increases in
microbial risk that might result if
systems complied with more stringent
DBF standards without an ESWTR.
In Stage 1, the DBPRAM predicted
that the baseline median TTHM and
HAAS effluent concentrations would be
reduced by 33 and 29 percent,
respectively, while the TOC effluent
concentration would be reduced by 12
percent. Assuming that the change in
the median effluent TTHM and HAAS
levels reflects the same changes in
exposure from cancer risk (relative to
the respective toxicological and
epidemiological baseline risk levels
previously alluded to), the Stage I
proposal would result in avoidance of
between 0.29 to 0.33 cases per year and
2,900 to 3,300 cases per year. The lower
bound of cancer cases avoided per year
is likely to be understated because, in
the absence of risk estimates available
for other DBFs, it is assumed that all
cancer cases caused by exposure to
DBFs can be represented by the
maximum likelihood toxicological risk
estimate from exposure to THMs alone.
Under the assumptions described
above and assuming that the change in
median effluent TOC reflects the same
changes in exposure from cancer .risk,
the Stage I proposal would result in
avoidance of between 0.12 and 1,200
cases of cancer per year. In Stage 2, the
change in median TTHM and HAAS
effluent concentrations was a reduction
of 48 and 50 percent, respectively, from
the baseline prior to Stage 1, while the
change in TOC effluent concentration
was a reduction of 18 percent.
Assuming the change in median effluent
TTHM and HAAS levels reflects the
same change in exposure from cancer
risk, the Stage II proposal would result
in a cumulative (Stage 1 plus 2)
avoidance of between 0.50 to 0.52 cases
per year and 5,000 to 5,200 cases per
year. Assuming the change in median
effluent TOC reflects the change in
exposure from cancer risk, the Stage II
proposal would result in cumulative
avoidance of between 0.2 and 2,000
cases of cancer per year.
If the total annual cost of treatment is
$1.04 billion to meet Stage I targets,
then the cost per case of cancer avoided
ranges between $8.67 billion and
$867,000 per case, based on changes in
median effluent TOC. If based on Stage
I changes in median effluent TTHMs
and THAAs, the cost per case of cancer
avoided ranges between $3.59 billion
and $359,000. Assuming that DBFs
other than THMs pose some cancer risk,
the upper bound cost estimates per
cancer case avoided are likely to be
overstated. Similarly, until more
conclusive epidemiology data become
available, the lower bound cost estimate
per case will remain highly
controversial. If one were to assume
there is a 10 percent chance that the
baseline cancer risks suggested by
Morris et al. (1992) were true, then the
estimated costs per case of cancer
avoided would range from $8.67 million
per case (based on changes in median
TOC) to $3.59 million per case (based
on changes in median TTHMs). The lack
of better evidence for causality in the
epidemiological studies would indicate
there is a possibility that the
associations cited in the Morris study
are due to omitted variables or
deficiencies in the data, in which case
the cost effectiveness may be even
worse than these estimates.
In principle, the cost-effectiveness of
the rule should be evaluated in terms of
the expected (mean) outcome and the
likelihood of this and other outcomes.
Quantitative data on the likelihood of
different outcomes are unavailable,
however, and as a result EPA has been
able to quantify the expected cost
effectiveness only in terms of the ranges
reported here. EPA believes that likely
cost-effectiveness outcomes will fall in
this range. Whether the expected cost
effectiveness of the proposal is closer to
the high-end or low-end estimates
depends primarily on whether future
epidemiological or toxicological studies
can provide stronger evidence of a
causal effect of exposure to disinfected
(e.g., chlorinated) water on cancer risks.
Cost-effectiveness will be affected by
the size and the water quality of a
particular system, and the technology
used for achieving compliance.
Economies of scale for technologies
used to achieve compliance will make
household compliance costs higher in
smaller systems than in larger systems
(see Table XV-8). However, because
many large systems will already have
reduced exposure from DBFs under the
existing TTHM standard (which only
pertains to systems serving greater than,
10,000 people), reductions in exposure
from DBFs in many small systems is
also likely to be greater than in larger
system. Although the data are limited,
this presumption appears to be
supported by Figures VI-11 and VI-13
in section VI of this preamble. Figures
VI-11 and VI-13 suggest that a
substantial number of systems serving
less than 10,000 people have much
higher TTHM (and DBF) concentrations
than systems serving 10,000 people or
greater. EPA solicits data and comment
on the extent to which reductions in
exposure can be expected to differ
between systems serving 10,000 people
or more and systems serving less than
10,000 people.
For systems using enhanced
coagulation, the technology most likely
to be used to achieve compliance among
surface water supplies (see Table XV-4),
there are relatively small differences in
economies of scale (see Tables XV-6
and XV—7) and small differences in cost
effectiveness between small and large
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Federal Register / Vol. 59, No. 145 / Friday, July 29, Ij994 / Proposed Rules 38805
systems. Table XV-4 indicates that
approximately 17% of the surface water
supplies serving fewer than 10,000
people will use technologies (ozone or
membrane technology) that would result
in significantly higher household costs
than those expected in most larger-sized
systems. Similarly, Table XV-5
indicates that approximately 4% of the
ground water supplies serving fewer
man 10,000 people will use a
technology (membrane technology) that
would result in significantly higher
household costs than in most larger-
sized systems. Depending on the
reductions in exposure, which would be
very significant in systems using
membrane technology, the cost-
effectiveness in some small systems is
likely to be substantially less than in
larger-sized systems. EPA solicits
comments on what data and approaches
could be used for estimating differences
in cost-effectiveness for large versus
small systems complying with Stage I
requirements.
Maintaining the assumptions as
described above, if the total annual cost
of treatment is $2.56 billion to meet
Stage II targets (extended to all systems),
then the cost per case of cancer avoided
ranges between $5.3 billion and
$512,000 if based on changes in median
TTHM and HAAS effluent
concentrations. If based on Stage II
changes in median effluent TOG, the
cost per case of cancer avoided ranges
between $12.8 billion and $1.28 million
per case.
Under the above assumptions, the
Stage 1 requirements are significantly
more cost effective than the Stage 2
requirements for reducing risk,
whatever that risk may be. Despite the
enormous uncertainties for estimating
reductions in risk resulting from
different regulatory strategies, the
Negotiating Committee believed that the
Stage 1 requirements were of sufficient
benefit to be proposed for all system
sizes. Some negotiators argued that
Stage 2 controls should only be
proposed now for larger systems and
revisited when more information
became available; others argued that
such controls should be put in place
sooner. The ultimate decision was to
propose Stage 2 rules but to provide an
opportunity for consideration of more
data at a second regulatory negotiation
(or similar proceeding) before Stage 2 is
finalized.
XVI. Other Requirements
A. Consultation with State, Local, and
Tribal Governments
Two Executive Orders (E.0.12875,
Enhancing Intergovernmental
Partnerships, and E.O 12866, Regulatory
Planning and Review) explicitly require
Federal agencies to consult with State,
local, and tribal entities in the
development of rules and policies that
will affect them, and to document what
they did, the issues that were raised,
and how the issues were addressed.
As described in section II of today's
rule, SDWA section 1412 requires EPA
to promulgate NPDWRs for at least 25
contaminants every three years. The
contaminants listed in today's rule are
being proposed in response to that
Congressional mandate.
To comply with this rule, PWSs will
need to meet specified levels for total
trihalomethanes, haloacetic acids,
certain other byproducts, and certain
disinfectants. To meet these standards,
certain systems will need to employ
enhanced coagulation, enhanced
precipitative softening, and/or other
treatment technologies. The total annual
cost of the rule, including monitoring, is
expected to be about $1.1 billion per
year. Systems serving more than 10,000
persons are expected to come into
compliance in 1998 and 2000 and bear
$700 million of the cost. Systems
serving fewer than 10,000 persons are
expected to come into compliance in the
years 2000 to 2002 and bear about $400
million of the total cost.
The Agency first sought public input
to the rule in a strawman rule published
in October 1989. Comments received in
response to the strawman rule are
summarized in section IV of today's
rule. In June 1991 EPA issued a status
report designed to update the public on
the Agency's thinking on rule criteria.
Comments were also received on the
status report; they, too, are summarized
in section IV.
In 1992, EPA considered entering into
a negotiated rulemaking on this rule
primarily because no clear path for
addressing all the major issues
associated with the rule was apparent.
EPA hired a facilitator to explore this
option with external stakeholders and,
in November 1992, decided to proceed
with the negotiation. The 18 negotiators,
including EPA, met from November
1992 until June 1993 at which time
agreement was reached on the content
of the proposed rule. Today's proposed
regulatory and preamble language has
been agreed to by the 17 negotiators
who remained at the table through June
1993. A summary of those negotiations
is contained in section IV.
The negotiators included persons
representing State and local
governments. At the table were:
(1) Association of State Drinking
Water Administrators, a group
representing state government officials
responsible for implementing the
regulations,
(2) Association of State and Territorial
Health Officials, a group representing
statewide public health interests and the
need to balance spending on a variety of
health priorities,
(3) National Association of Regulated
Utilities Commissioners, a group
representing funding concerns at the
state level,
(4) National Association of County
Health Officials, a group representing
local government general public health
interests,
(5) National League of Cities, a group
representing local elected and
appointed officials responsible for
balancing spending needs across all
government services,
(6) National Association of State
Utility Consumer Advocates, a group
representing consumer interests at the
state level, and
(7) National Consumer Law Center, a
group representing consumer interests
at the local level.
In addition, several associations
representing public municipal and
investor-owned water systems also
served on the committee.
As part of the negotiation process,
each of these representatives was
responsible for obtaining endorsement
from their respective organization on
the positions they took at the
negotiations and on the final signed
agreement. During the negotiations, the
group heard from many other parties
who attended the public negotiations
and were invited to express their views.
As is true with any negotiation, all sides
presented initial positions which were
ultimately modified to obtain consensus
from all sides. However, all parties
mentioned above signed the final
agreement on behalf of their
associations. This agreement reflected
basic consensus that the cost of the rule
was offset by its public health benefits
and its promotion of responsible
drinking water treatment practices.
The only original negotiator who did
not sign the agreement left the
negotiations in March 1993. That
negotiator represented the National
Rural Water Association (NRWA), a
group representing primarily small
public and private water systems.
NRWA believed that since systems
serving populations under 10,000
persons are not subject to the current
trihalomethane standard, it would be
more reasonable to require that small
systems comply with the current
trihalomethane standards rather than
the standards proposed today. NRWA
objected to the costs of the rule on small
systems given its belief that the risks to
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humans from D/DBP are poorly
understood. NRWA in its letter of
resignation stated that "Where is
insufficient good, reliable scientific data
showing clear risks to human health
from the levels of D/DBP found on
average in drinking water." It should be
noted that although NRWA objected to
the cost of the rule, they had supported
an option with approximately the same
estimated cost earlier in the negotiation
process. The NRWA position that small
systems should meet the current
trihalomethane standard was rejected by
the remaining negotiators, several of
whom also represent small water
systems.
The contents of today's proposed rule
has been available to the public for
several months as part of the regulatory
negotiation signature process. EPA has
briefed numerous groups, including
government organizations, on its
contents. The Agency has received
several letters from public water
systems objecting to the cost of the
proposed rule and questioning its
potential health benefit. These letters
are contained in the public docket
supporting today's rule. The Agency
recognizes that many persons are
concerned whether the proposed rule is
warranted. The technical issues are
complex. The process needed to
develop a common level of
understanding among the negotiators as
to what was known and unknown and
what are reasonable estimates of
potential costs and benefits was time-
consuming. It is unreasonable to expect
persons not at the negotiating table to
have that same level of understanding
and to all share the same view.
However, the discussions throughout
the negotiated rulemaking process were
informed by a broad spectrum of
opinions. The Agency believes this
consensus proposal is not only the
preferred approach but one which will
generate informed debate and comment.
B. Regulatory Flexibility Act
The Regulatory Flexibility Act, 5
U.S.C. 602 et eq., requires EPA to
explicitly consider the effect of
proposed regulation on small entities.
By policy, EPA has decided to consider
regulatory alternatives if there is any
economic impact on any number of
small entities. The Small Business
Administration defines a "small water
utility" as one which serves fewer than
3,300 people. If there is a significant
effect on a substantial number of small
systems, the Agency must seek means to
minimize the effects.
In accordance with the Regulatory
Flexibility Act EPA has conducted a
Regulatory Flexibility Analysis
indicating what the predicted impacts
on small systemns could be and how
such impacts could be minimized. A
detailed description of this effort is
available in the Regulatory Impact
Analysis (USEPA, 1994). Following is a
summary of the key elements of the
Regulatory Flexibility Analysis.
Throughout the negotiated
rulemaking process, small systems were
defined as those serving fewer than
10,000 persons. This definition was
used because there is an existing SDWA
standard of 0.10 mg/1 for total
trihalomethanes that applies only to
systems serving at least 10,000 persons.
Systems serving fewer than 10,000
persons are presently unregulated with
respect to disinfection byproducts.
There are, as a result, two different
baseline conditions from which water
systems will approach additional
disinfection byproduct control. The
major impact will be the requirement to
install and operate water treatment
equipment to meet specific standards of
quality in the delivered water. These
requirements pertain primarily to
systems that actually treat water.
Systems that purchase treated water
from another source may see an increase
in their wholesale costs, but a data base
sufficient to track all the wholesale
treated water transactions in the country
does not exist. Impacts are therefore
evaluated in terms of the systems that
treat water. The data with which to
characterize the capacities and flows of
these facilities does exist and provides
an adequate basis for assessing total
capital and operating costs.
EPA estimates that there are a total of
76,051 community and nontransient
noncommunity water systems that treat
water. Of these, an estimated 73,336
(96%) serve fewer than 10,000 persons.
Despite their overwhelming dominance
in terms of industry structure, these
systems provide water to only 22
percent of the total population served by
public water supplies.
Of the total 68,171 small groundwater
systems, it is estimated that 8,324 (12%)
will have to modify treatment to comply
with the Stage 1 proposal. The TWG
forecast that 5,403 (8%) systems will
comply with the very inexpensive
technology of chloramines while 2,921
(4%) systems will require more
expensive membrane treatment systems.
Use of these technologies by small
systems will result in total capital costs
of $1.1 billion.
Of the total 5,165 small surface water
systems, it is estimated that 3,611 (70%)
will have to modify treatment to comply
with the Stage 1 proposal. The TWG
forecast that 3,318 (64%) systems will
comply with cost effective combinations
of enhanced coagulation, chloramines,
and ozone. Another 293 (6%) systems
will require more expensive membrane
treatment systems. This will result in
total capital costs of $0.6 billion.
EPA believes that the proposed rule
could have a significant impact on a
substantial number of small systems.
Therefore, the Agency has attempted to
provide less burdensome alternatives to
achieve the rule's goals for small
systems wherever possible; These
considerations, discussed in greater
detail in Section IX of this preamble and
in the Regulatory Impact Analysis
(USEPA, 1994), include:
(a) Less routine monitoring. Small
systems are required to monitor less
frequently for such contaminants as
TTHMs and HAA5. Also, ground water
systems (the large majority of small
systems) are required to monitor less
frequently than Subpart H systems of
the same size.
(b) Reduced monitoring. There are
reduced monitoring provisions for
systems that meet specified
prerequisites. EPA believes that many
small systems will qualify for this
reduced monitoring.
(c) Extended compliance dates.
Systems that use only ground water not
under the direct influence of surface
water serving at least 10,000 people and
Subpart H systems serving fewer than
10,000 people have 42 months from
promulgation of this rule to comply.
Systems that use only ground water not
under the direct influence of surface
water serving fewer than 10,000 people
have 60 months from promulgation of
this rule to comply. These staggered
compliance dates will allow smaller
systems to learn from the experience of
larger systems on how to most cost
effectively comply with the Stage 1 D/
DBP rule. Larger systems will generate
a significant amount of treatment and
cost effectiveness data under the
Information Collection Rule and in their
efforts to achieve compliance with the
Stage 1 requirements. EPA intends to
summarize this information and make it
available through guidance documents
that will assist smaller systems in
achieving compliance with both the
Stage 1 D/DBP rule and long-term
ESWTR.
The staggered compliance dates for
smaller systems will also enable them to
consider any new Stage 2 requirements,
scheduled to be proposed in 1998, while
achieving compliance with the Stage 1
requirements. The delayed compliance
schedule should facilitate the selection
of the most cost effective means for
achieving compliance with both the
Stage 1 and Stage 2 requirements.
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38807
(d) The Negotiating Committee
considered other options for systems
serving less than 10,000 people. These
ranged from requiring smaller systems
to meet the same compliance schedule
as for larger systems to only extending
the existing TTHM standard to systems
serving less than 10,000 people. The
Negotiating Committee rejected the
former option for the ahove reasons and
to enable the development of an ESWTR
(i.e., the long-term ESWTR rather than
the interim ESWTR) that would be more
reasonable for smaller systems to
comply with (see proposed ESWTR in
today's Federal Register, and the
proposed Information Collection Rule,
59 PR 6332; February 10,1994). The
Negotiating Committee rejected the
latter option, over the objections of the
National Rural Water Association,
because it believed that all systems
should be subject to the same level of
protection. Also, setting only a TTHM
standard in the absence of other criteria
could lead to increased exposure from
other DBFs that might pose greater
health risks.
C. Papenvork Reduction Act
The information collection
requirements in this proposed rule have
been submitted for approval to the
Office of Management and Budget
(OMB) under the Paperwork Reduction
Act, 44 U.S.C. 3501 etseq. An
Information Collection Request
document has been prepared by EPA
(ICR No. 270.33) and a copy may be
obtained from Sandy Fanner,
Information Policy Branch (MC:2136),
EPA, 401M Street SW., Washington, DC
20460, or by calling (202) 260-2740.
The reporting and recordkeeping
burden for this proposed collection of
information will be phased-in starting in
1997. The specific burden anticipated
for each category of respondent, by year,
is shown below:
2997
Public Water Systems—monitoring and
reporting
Hours per respondent: 0
Total hours: 0
Public Water Systems—recqrdkeeping
Hours per respondent: 0
Total hours: 0
State Program Costs—reporting
Hours per respondent: 2,650
Total hours: 148,424
State Program Costs—rec'ordkeeping
Hours per respondent: 1,500
Total hours: 84,000
1998
Public Water Systems—monitoring and
reporting
Hours per respondent: 5.3
Total hours: 328,605
Public Water Systems—recordkeeping
Hours per respondent: .05
Total hours: 3,319
State Program Costs—reporting
Hours per respondent: 11,643
Total hours: 652,032
State Program Costs—recordkeeping
Hours per respondent: 600
Total hours: 33,640
2999
Public Water Systems—monitoring and
reporting
Hours per respondent: 3.9
Total hours: 239,424
Public Water Systems—recordkeeping
Hours per respondent: .04
Total hours: 2,418
State Program Costs—reporting
Hours per respondent: 9,119
Total hours: 510,672
State Program Costs—recordkeeping
Hours per respondent: 0
Total hours: 0
Send comments regarding the burden
estimate or any other aspect of this
collection of information, including
suggestions for reducing this burden, to
Chief, Information Policy Branch
(MC:2136), EPA, 401 M Street, SW,
Washington, DC 20460; and to the
Office of Information and Regulatory
Affairs, OPM, Washington, DC 20503,
marked "Attention: Desk Officer for
EPA." The final rule will respond to any
OMB or public comments on the
information collection requirements
contained in the proposal.
D. National Drinking Water Advisory
Council and Science Advisory Board
In accordance with section 1412 (d)
and (e) of the Act, the Agency has
submitted this proposed rule to the
Science Advisory Board, National
Drinking Water Advisory Council
(NDWAC), and the Secretary of Health
and Human Services for their review.
The Agency will take their comments
into account in developing the final
rule. NDWAC supported the use of
regulatory negotiation to develop this
rule.
XVII. Request for Public Comment
The proposed rule represents criteria
that were agreed to be proposed by the
Negotiating Committee. Part A of this
Section lists the parts of the rule for
which members of the Negotiating
Committee, including EPA, requested
.comment. Part B of this Section lists the
parts of the rule that pertain to small
systems for which EPA requests public
comments but which were not requested
by Members of the Negotiating
Committee. Members of the Negotiating
Committee agreed not to file negative
comments on the settled portions of the
proposed rule or the preamble to the
extent that they have the same
substance and effect as the
recommended rule and preamble. Each
member of the Negotiating Committee
may comment in support of the settled
portions of the proposed rule. Each
member of the Negotiating Committee
may comment fully on or respond to
comments solicited in the preamble or
on issues that were not the subject of
negotiations. The public at large is
invited to comment on all aspects of the
rule or preamble including the
appropriateness of numerical criteria,
monitoring requirements, and
applicability. EPA will consider all
public comments received in
developing the final rule.
A. Request for Comment
Section V
The appropriateness of adopting the
term "MRDLG" in lieu of MCLGs for
disinfectants in the final rule.
—Any additional data on known
concentrations of chlorine in drinking
water, food, and air.
—The following issues concerning
chlorine: placing chlorine in Category
III for developing an MRDLG,
selection of the specified study and
NOAEL as the basis for the MRDLG,
the 80% RSC, the appropriateness of
the UF of 100, and the cancer
classification for chlorine.
—Any additional data on known
concentrations of chloramines in
drinking water, food, and air.
—The following issues concerning
chloramines: the proposed MRDLG
for chloramines and the RSC of 80%,
the significance of the findings of
immunotoxicity for setting the RfD
instead of the NTP study, the
significance of the finding of
mononuclear cell leukemia in female
F344 rats, the significance of the
finding of tubular cell neoplasms in
high-dose exposed mice, and whether
the adjusted MRDLG, which takes
into account the measurement of
monochloramine as total chlorine, is
appropriate.
—The significance of the
epidemiological studies with chlorine
and chloramines as indicators of risk.
EPA recognizes that there are different
interpretations of these
epidemiological studies and
specifically solicits comment on the
rationale for EPA's interpretations.
EPA further requests comments on the
studies suggesting a reproductive risk
related to disinfectant byproduct
exposure.
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—Any additional data on known
concentrations of chlorine dioxide,
chlorate, and chlorite in drinking
water, food, and air.
—For chlorine dioxide, the SAB's
suggestion that a child's body weight
of 10 kg and water consumption of 1
L/d may be more appropriate for
setting the MRDLG than the adult
parameters, given the acute nature of
the toxic effect. EPA also requests
comment on the appropriateness of
the 300-fold uncertainty factor, the
studies selected as the basis for the
RfD, and the 80% relative source
contribution.
—For chlorite, the SAB's suggestion that
EPA consider basing the MCLG on the
child body weight of 10 kg and water
consumption of 1 L/day instead of the
adult default values. EPA requests
comments on the SAB's suggestion,
along with the study selected as the
basis for the MCLG, the uncertainty
factor and the RSC of 80%.
—The decision not to propose an MCLG
for chlorate at this time.
—Any additional data on known
concentrations of chloroform in
drinking water, food, and air.
The basis for the proposed MCLG for
chloroform.
—Any additional data on known
concentrations of BDCM in drinking
water, food, and air.
—The basis of the proposed MCLG for
BDCM and the use of tumor data of
large intestine and kidney, but not
liver, in quantitative estimation of
carcinogenic risk of BDCM from oral
exposure.
—Any additional data on known
concentrations of DBCM in drinking
water, food, and air.
—The basis for the proposed MCLG for
DBCM, the RSC of 80%, and the
cancer classification for DBCM.
—Any additional data on known
concentrations of bromoform in
drinking water, food, and air.
—The different viewpoints between
IARC and EPA regarding bromoform's
carcinogenic potential.
—The basis for the proposed MCLG for
bromoform.
—Any additional data on known
concentrations of DCA in drinking
water, food, and air.
—The basis for the proposed MCLG for
DCA in drinking water and the cancer
classification of Group B2.
—Any additional data on known
concentrations of TCA in drinking
water, food, and air.
—The basis for the MCLG and the
cancer classification for TCA.
—Any additional data on known
concentrations of CH in drinking
water, food, and air.
—For CH, the Category II approach for
setting an MCLG, the extra safety
factor of 1 instead of 10 for a Category
II contaminant, and whether the
endpoint of liver weight increase and
hepatomegaly is a LOAEL or NOAEL
given the lack of histopathology.
—Any additional data on known
concentrations of bromate in drinking
water, food, and air.
—The MCLG of zero for bromate based
on carcinogenic weight of evidence
and the mechanism of action for
carcinogenicity related to DNA
adduct.
Section VIII
—The timetable for promulgation of the
final rule and the compliance dates
therein.
—How monitoring and compliance
requirements should be split among
wholesalers and retailers of water.
Does § 141.29 (consecutive systems)
provide the State adequate flexibility
and authority to address individual
situations? Are any specific federal
regulatory requirements necessary to
handle such situations? If so, what are
they?
—How the following situations should
be handled in compliance
determinations.
—When the monthly source water TOC
is less than 2.0 mg/1 and enhanced
coagulation is not required.
—When seasonal variations cause the
system to determine that TOC is not
amenable to any level of enhanced
coagulation and the system would be
eligible for a waiver of enhanced
coagulation requirements.
EPA believes that assigning a value of
1.00 for these months is a reasonable
approach.
Section IX
—Whether exemptions to this rule
should be granted if a system could
demonstrate to the State, that due to
unique water quality characteristics, it
could not avoid through the use of
BAT the possibility of increasing its
total health risk by complying with
the Stage 1 regulations. When might
such situations occur? What specific
conditions, if any, should be met for
a system to be granted an exemption
under such a provision. What
provisions should EPA require of
States to grant these exemptions?
Should such exemptions be granted
for a limited period but be renewable
by the State if no new health risk
information became available?
—Whether the TOC percent removal
levels in Table IX-1 are representative
of what 90 percent of systems
required to use enhanced coagulation
could be expected to achieve with
elevated, but not unreasonable,
coagulant addition.
—Whether filtration should be required
as part of the bench-/pilot-scale
procedure for determination of Step 2
enhanced coagulation. If so, what type
of filter should be specified for bench-
scale studies?
—Whether a slope of 0.3 mg/L of TOC
removed per 10 mg/L of alum added
should be considered representative
of the point of diminishing returns for
coagulant addition under Step 2. EPA
also solicits comment on how the
slope should be determined (e.g.,
point-to point, curve-fitting)..If the
slope varies above and below 0.3/10,
where should the Step 2 alternate
TOC removal requirement be set—at
the first point below 0.3/10? At some
other point?
—Whether any additional regulatory
requirements, guidance, or
explanation is required to define
"multiple wells". EPA requests
comment on whether there should be
an upper limit of sampling frequency
for systems that either cannot
determine that they are drawing water
from a single aquifer or are drawing
water from multiple aquifers. For
example, should a system that must
. draw water from many aquifers to
satisfy demand be allowed to limit
monitoring as if they were drawing
from no more than four aquifers
(routine sampling would thus be
limited to four samples per quarter
from systems serving at least 10,000
people or to four samples per year for
systems serving fewer than 10,000
people)? Does EPA need to develop
any additional guidance for any other
aspect of this requirement?
—How often bench-or pilot-scale
studies should be performed to
determine compliance under step 2.
Should such frequency of testing be
included in the rule or left to
guidance? Is quarterly monitoring
appropriate for all systems? What is
the best method to present the testing
data to the primacy agency that
reflects changing influent water
quality conditions and also keeps
transactional costs to a minimum?
How should compliance be
determined if the system is not
initially meeting the percent TOC
reduction required because of difficult
to treat water and a desire to
demonstrate alternative performance
criteria?
—Whether data are available on the use
of ferrous salts in the softening
process which can help define a step
2 for enhanced softening. For
softening plants, is enhanced
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softening properly defined by the
percent removals in Table IX-1 or by
10 mg/L removal of magnesium? Is
there a step 2 definition? Can ferrous
salts be used at softening pH levels to
further enhance TOG removals?
—Whether preoxidation is necessary in
water treatment to control water
quality problems such as iron,
manganese, sulfides, zebra mussels,
Asiatic clams, taste and odor. Will
allowing preoxidation before
precursor removal by enhanced
coagulation generate excessive DBF
levels?
—Whether biologically active filtration
following ozonation is sufficient to
remove most byproducts believed to
result from ozonation? What
parameters should be measured in
and/or out of the biologically active
filter to demonstrate that ozone
byproducts are being removed? For
example, would it be sufficient to
demonstrate greater than 90 percent
removal of formaldehyde to establish
that a filter is biologically active?
—Whether disinfection credit should be
allowed for chlorine dioxide used
prior to enhanced coagulation if
virtually no halogenated organic DBFs
are formed. Should some other limit,
in addition to or in lieu of that
proposed, be set (e.g., 5 u/L TTHMs)
on DBFs formed by high purity
chlorine dioxide to ensure sufficient
control for the production of
excessive halogenated organic DBFs if
disinfection credit were to be allowed
with chlorine dioxide prior to
enhanced coagulation?
—The appropriateness of allowing
systems to add a disinfectant before
enhanced coagulation when water
temperatures are less than or equal to
5 °C if excessive DBFs are not
produced or identification of
alternative means for addressing this
issue.
—Whether GAC10 and GAC20
reasonable definitions of GAG
performance? Do they span the
expected level of GAC applications in
drinking water treatment for the
control of TTHMs and THAAs? Is the
Jefferson Parish, Louisiana TOG
removal representative of the "general
case" of TOG removal?
—Whether any Subpart H systems with
a TOG >4.0 mg/1 should be allowed to
reduce monitoring? Under what
conditions (e.g., system has installed
nanofiltration)?
—Whether reduced monitoring for
ground water systems serving fewer
than 10,000 people could be
expanded beyond what is in the
proposal. The additional options
presented below would rely on having
each entry point of the system go
through three years of routine
monitoring to qualify for reduced
monitoring. After this period, if the
entry points meet additional criteria,
then the entry points would be subject
to minimal additional monitoring.
Option One: Any ground water
system serving fewer than 10,000 people
that has a raw water TOG of less than
1.0 mg/1, and has both TTHM and
HAAS values less than 25 percent of the
MCLs (20 ug/1 and 15 ug/1, respectively)
after three years of routine and reduced
monitoring, can reduce the monitoring
for TTHMs and HAASs to one sample
every nine years, taken at the maximum
distribution system residence time
during the warmest month.
Option Two: Any ground water
system serving fewer than 10,000 people
that has a raw water TOG of less than
0.5 mg/1, and has both TTHM and
HAAS values less than 25 percent of the
MCLs (20 ug/1 and 15 ug/1, respectively)
after three years of routine and reduced
monitoring, is exempt from the
distribution system monitoring
requirements for TTHMs and HAASs for
as long as TOG monitoring is conducted
once every three years and the raw
water TOG remains less than 0.5 mg/1.
These options are not mutually
exclusive, that is, both could be used
simultaneously or some hybrid could be
developed. The Agency seeks comment
on whether either or both of these
options are reasonable in adequately
protecting the public health and should
therefore be considered as criteria for
reduced monitoring. Are there other
options for reduced monitoring that
should be considered? What are they?
—Comment on the cost impact of pH
adjustment on systems with both high
alkalinity and high bromide levels.
—Comment on the relative costs of
adjusting pH to reduce bromate
formation versus the costs of other
technologies to meet the MCLs in this
proposed rule.
—Whether the monitoring is frequent
enough to adequately determine
variations in sample results caused by
time and/or location in the
distribution system? If not, what is a
more appropriate monitoring
schedule? Should requirements differ
for systems based on population
served, raw water source, or other
factors? If so, should the proposed
requirements be changed? How
should they be changed? If
requirements should not be based on
these factors, what should the
requirements be? Does averaging of
sample results taken in various
locations over the course of a year to
determine compliance adequately
protect individuals that are in
locations that may regularly have
higher than average levels? If it does
not, how should the proposed
requirements be changed?
—Data to show that a lower quantitation
level (at: least down to 5 ug/L) can be
obtained by those laboratories that
will perform compliance monitoring
for bromate in natural drinking water
matrices. If the improved .
methodology uses equipment and/or
reagents that are not currently
required for EPA method 300.0, data
to indicate the commercial
availability and costs of these items
would also need to be presented.
—A treatment technique that could
ensure that bromate can be kept below
5 ug/L, even if quantitation at 5 ug/1
is not achieveable under routine
laboratory conditions.
—Other treatment techniques which
allow ozone to meet disinfection and
oxidation requirements while
minimizing bromate formation.
—The feasibility of developing a
treatment technique requirement for
bromate, lowering the MCL based
upon improved analytical techniques,
and the time frame under which such
alternative standards could be
developed.
—The following approaches for
promulgating a final rule for chlorite:
(1) An MCL at the MCLG.
(2) An MCL lower than the proposed
MCL of 1.0 mg/1, but above the MCLG,
depending upon all data that became
available in the near term.
(3) Depending on new data that
become available, EPA could
promulgate an MCL at the proposed
MCL of 1.0 mg/1 if the Agency
determined that the systems currently
using chlorine dioxide could not meet
disinfection requirements in any other
feasible manner, taking cost into
consideration.
—The approaches for regulating
chlorite. Specifically, EPA requests
comment on the following:
—Is the basis for EPA's MCLG and
concern for acute health effects
appropriate? See Section V. for a
complete discussion.
—Are there any particular water quality
characteristics for systems currently
using chlorine dioxide which make it
ineffective to use any other
disinfection technology? What are the
lowest chlorite levels these systems
can achieve? What technologies
would need to be adopted and at what
costs if such systems with these
particular water quality
characteristics would no longer use
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38810 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
chlorine dioxide to meet the other
regulatory criteria proposed herein?
—Should EPA set the chlorite MCL at a
level so that chlorine dioxide remains
a viable disinfection alternative for
some systems even if this level is
above the MCLG? If so, what would be
the rationale for doing so?
—Is 1.0 mg/1 the lowest level that
systems needing chlorine dioxide can
reliably achieve?
—How should EPA change the
compliance monitoring requirements
for chlorite to reflect concern about
acute effects? Should such changes
include increasing the frequency or
changing the location of monitoring to
be similar to those for chlorine
dioxide? How would the MCL be
affected by changes in the monitoring
requirements?
—How should EPA change the public
notification requirements for chlorite
to reflect concern about acute effects?
—What level of residual chloramine
would be feasible to achieve by most
systems without increasing microbial
risk.
—Information on improvements which
may have been made to disinfectant
methods to measure low
concentrations of disinfectant
residuals, but that are not reflected in
the 18th edition of Standard Methods.
EPA is also seeking information on
new methodology that may be
applicable for compliance monitoring.
—The technical adequacy of the
analytical methods proposed for
compliance with the proposed
MRDLs.
—For bromate, whether use of a sample
concentration technology prior to ion
chromatographic analysis should be
considered as a new methodolgy or a
modification to Method 300.0 under
today's rule. EPA also solicits
comments on the applicability of
sample concentration technology to
today's proposed MCL for bromate.
—Data that demonstrate the need for a
preservative in samples collected at
the entrance point to the distribution
system for measurement of bromate.
—The proposed turbidity threshold of 1
NTU to remove turbidity, which is
known to interfere with accurate TOC
measurement when the sample
turbidity is greater than 1 NTU, and
on the sample nitration procedure
described in Section IX and in the
proposed methods.
—What precision can be routinely
expected on differential TOC
measurements of jar test samples. EPA
is also interested in new methods or
modifications to the methods
proposed today that would improve
the reproducibility of TOC
measurement.... ;; ;
Section X
—Other optional or mandatory
performance criteria that EPA or the
States should consider for
certification of laboratories, or
approval of analysts.
Section XI
—Whether exemptions to this rule
should be granted if a system could
demonstrate to -the State, that due to
unique water quality characteristics, it
could not avoid through the use of
BAT the possibility of increasing its
total health risk by complying with
the Stage 1 regulations. When might
such situations occur? What specific
conditions, if any, should be met for
a system to be granted an exemption
under such a provision. What
provisions should EPA require of
States to grant these exemptions?
Should such exemptions be granted
for a limited period'but be renewable
by the State if no new health risk
information became available?
Section XII
—The proposed State reporting
requirements. EPA particularly
requests comment from the States on
whether the proposed reporting
requirements are reasonable.
—Whether the State should be required
to keep the monitoring plan on file at
the State after submission to make it
available for public review?
Section XIV
—The proposed public notification rule
language. Of particular interest is the
acute violation language in
§ 141.32(e)(85) for violations of the
chlorine dioxide MCL. Also of interest
is the language in § I41.32(e)(86) for
violations of the TTHM and HAAS
MCLs and the enhanced coagulation
treatment technique requirement.
Section XV
—Data and comment on the extent to
which reductions in exposure to
TTHMs and DBFs can be expected to
differ between systems serving 10,000
people or more and systems serving
less than 10,000 people.
Section XVI
—The burden estimate or any other
aspect of this collection of
information, including suggestions for
reducing this burden.
B. Request for Additional Public
Comments by EPA
The Negotiating Committee
considered several regulatory options
for systems serving less than 10,000
people. These ranged from requiring
smaller systems to meet the same
compliance schedule as for larger
systems to only extending the existing
TTHM standard to systems serving less
than 10,000 people. The Negotiating
Committee rejected the former option
for reasons discussed in Section XVI of
this preamble. The Negotiating
Committee rejected the latter option,
over the objections of the National Rural
Water Association (which was initially
represented on the Negotiating
Committee but then withdrew from the
negotiations), because it believed that
all systems should be subject to the
same level of protection. Also, setting
only a TTHM standard in the absence of
other criteria could lead to increased
exposure from other DBFs that might
pose greater health risks.
EPA recognizes that several factors
still make it significantly more difficult
for smaller systems than larger systems
to achieve compliance with the Stage 1
requirements. Because the larger
systems already have substantial
experience with lowering TTHM levels,
they will be more familiar than smaller
systems with available technologies and
operating conditions for lowering DBF
levels. Because of economies of scale,
the costs for systems to achieve the
same incremental reduction in DBFs is
substantially greater in smaller systems
than in larger systems. For about 4% of
systems serving less than 3,300 people
(and less than 1% of the U.S. population
receiving public drinking water), costs
for compliance are estimated to be about
$300 per household per year. For these
reasons, EPA remains concerned about
the ability of small communities to
afford compliance and is interested in
comments on this issue as well.
Specifically, EPA is interested in further
comment on alternative regulatory
approaches for various small and
medium system sizes.
The parties reached consensus on the
approach for staggered compliance
schedules for systems serving fewer
than 10,000 people (i.e., June 2000 for
systems using surface water and ground
water under the direct influence of
surface water that serve fewer than
10,000 people and January 2002 for
ground water systems serving fewer
than 10,000 people). EPA is interested
in comments on these important issues.
Again, EPA recognizes the problems
faced by small- and medium-sized
systems and is interested in further
comment on alternative compliance
approaches and possible solutions for
various small and medium system.sizes
(e.g., <1,000; 1,000-3,300; >3,300-
10,000).
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38811
Because of the Agency's commitment
to develop rules based on the best
reasonably available scientific data, EPA
intends to conduct research on the best
way to reduce exposure from both DBFs
and pathogens in small systems cost
effectively. Based on information
collected under the ICR, EPA intends to
also refine models to more accurately
predict occurrence of DBFs as a function
of different treatment technologies,
including those used by small systems.
EPA intends to use available data in
refining its estimates and solicits
additional data on the occurrence of
DBFs in drinking water systems, the
concentration of pathogens in source
water, and the effectiveness of treatment
on microbial contaminants, especially
for smaller systems. Also, as part of the
major research effort leading to
negotiation of the Stage 2 D/DBP rule,
EPA intends to investigate technologies
to determine whether small systems will
be able to comply with D/DBP
regulations at lower costs in future
years.
XVIII. References and Public Docket
References in this section are
organized by type. Subsection A lists
Federal Register references. Subsection
B lists analytical method references.
Subsection C lists health criteria
document references. Subsection D lists
other references.
A. Federal Register References
1. U.S. Environmental Protection Agency.
National Interim Primary Drinking Water
Regulations; Control of Trihalomethanes in
Drinking Water. Vol. 44, No. 231. November
29,1979. pp. 68624-68707.
2. U.S. Environmental Protection Agency.
National Revised Primary Drinking Water
Regulations, Volatile Synthetic Organic
Chemicals in Drinking Water; Advanced
Notice of Proposed Rulemaking. Vol. 47, No.
43, Thursday, Mar. 4,1982—Part IV. pp.
9350-9358.
3. U.S. Environmental Protection Agency.
National Interim Primary Drinking Water
Regulations; Trihalomethanes. Vol. 48, No.
40. Monday, Feb. 28,1983. pp. 8406-8414.
4. U.S. Environmental Protection Agency.
National Primary Drinking Water
Regulations; Synthetic Organic Chemicals,
Inorganic Chemicals and Microorganisms:
Proposed Rule. Vol. 50, No. 219. Wednesday,
Nov. 13,1985—Part IV. pp. 46936-47025.
5. U.S. Environmental Protection Agency.
National Primary Drinking Water
Regulations—Synthetic Organic Chemicals;
Monitoring for Unregulated Contaminants;
Final Rule. Vol. 52, No. 130. July 8,1987—
Part II. pp. 25690-25717.
6. Federal Register. U.S. Environmental
Protection Agency. Drinking Water
Regulations; Public Notification; Final Rule.
Vol. 52, No. 208. Wednesday, Oct. 28,1987—
Part II. pp. 41534-41550.
7. U.S. Environmental Protection Agency.
National Primary Drinking Water
Regulations. Maximum Contaminant Level
Goals and National Primary Drinking Water
Regulations for Lead and Copper. Vol. 53,
No. 160. Thursday, Aug. 18,1988. pp.
31516-31578.
8. U.S. Environmental Protection Agency.
National Primary and Secondary Drinking
Water Regulations; Proposed Rule. Vol. 54,
No. 97. Monday, May 22,1989. pp. 22062-
22160.
9. U.S. Environmental Protection Agency.
Drinking Water; National Primary Drinking
Water Regulations; Filtration, Disinfection;
Turbidity, Giardia lamblia, Viruses,
Legionella, and Heterotrophic Bacteria; Final
Rule. Part II. Vol. 54, No. 124. Thursday, June
29,1989. pp. 27486-27541.
10. U.S. Environmental Protection Agency.
National Primary Drinking Water
Regulations; Synthetic Organic Chemicals
and Inorganic Chemicals; Proposed Rule.
Vol. 55, No. 143. Wednesday, July 25,1990—
Part II. pp. 30370-30448.
11. U.S. Environmental Protection Agency.
Notice of Availability of Proposed Guidance
for Determining Unreasonable Risk to Health.
Vol. 55, No. 191. Tuesday, Oct. 2,1990. p.
40205.
12. U.S. Environmental Protection Agency.
National Primary Drinking Water
Regulations: Lead and Copper. Notice of
Availability with Request for Comments. Vol.
55, No. 203. Friday, Oct. 19,1990. pp.42409-
42413.
13. U.S. Environmental Protection Agency.
National Revised 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. Vol. 56, No. 20. Wednesday, Jan.
30,1991. pp. 3526-3597.
14. U.S. Environmental Protection Agency.
National Primary and Secondary Drinking
Water Regulations; Synthetic Organic
Chemicals and Inorganic Chemicals; Final
Rule. Vol. 57, No. 138. Friday, July 17,
1992—Part III. pp. 31776-31849.
15. U.S. Environmental Protection Agency.
Intent to Form an Advisory Committee to
negotiate the Drinking Water Disinfection By-
products Rule and Announcement of Public
Meeting. Vol. 57, No. 179. September 15,
1992. pp. 42533-42536.
16. U.S. Environmental Protection Agency.
Establishment and Open Meeting of the
Negotiated Rulemaking Advisory Committee
for Disinfection By-Products. Vol. 57, No.
220. November 13,1992. p. 53866.
17. U.S. Environmental Protection Agency.
National Primary Drinking Water
Regulations: Analytical Techniques
(Trihalomethanes); Final Rule. Vol. 58, No.
147. August 3,1993. pp. 41344-41345.
18. U.S. Environmental Protection Agency.
Executive Order 12866: Regulatory Planning
and Review. Vol. 58, No. 190. October 4,
1993. 51735-51744.
B. Analytical Methods
1. APHA. 1992. American Public Health
Association. Standard Methods for the
Examination of Water and Wastewater (18th
ed.). Washington, D.C. (Including: 4500 Cl
D,E,F,G,H,I; 4500 C1O2 C,D,E; 5310 C,D;
6233B;2320B)
2. ASTM. 1993. Methods D-1067-88B, D-
2035-80. Annual Book of ASTM Standards.
Vol. 11.01, American Society for Testing and
Materials.
3. U.S. EPA. 1993. EPA Method 300.0. The
Determination of Inorganic Anions by Ion
Chromatography in the manual "Methods for
the Determination of Inorganic substances in
Environmental Samples," EPA/600/R/93/
100.
4. U.S. EPA. 1983. EPA Method 310.1.
Methods of Chemical Analysis of Water and
Wastes. Envir. Monitoring Systems
Laboratory, Cincinnati, OH. EPA 600/4-79-
020. 460 pp.
5. U.S. EPA. 1988. EPA Method 502.2.
Methods for the Determination of Organic
Compounds in Drinking Water. EPA 600/4-
88-039. PB91-231480. Revised July 1991.
6. U.S. EPA. 1992. EPA Methods 524.2,
552.1. Methods for the Determination of
Organic Compounds in Drinking Water—
Supplement II. EPA 600/R-92/129. PB92-
207703.
7. U.S. EPA. 1990. EPA Methods 551, 552.
Methods for the Determination of Organic
Compounds in Drinking Water—Supplement
I. EPA 600/4-90-020. PB91-146027.
8. USGS. 1989. Method 1-1030-85.
Techniques of Water Resources
Investigations of the U.S. Geological Survey.
Book 5, Chapter A-l, 3rd ed., U.S.
Government Printing Office.
C. Health Criteria Documents
1. USEPA. 1993b. Draft Drinking Water
Health Criteria Document for Bromate. Office
of Science and Technology, Office of Water.
Sep. 30,1993.
2. USEPA. 1994b. U.S. Environmental
Protection Agency. Draft Drinking Water
Health Criteria Document for Chloramines.
Office of Science and Technology, Office of
Water.
3. USEPA. 1994e. U.S. Environmental
Protection Agency. Draft Drinking Water
Health Criteria Document for Chlorinated
Acetic Acids/Alcohols/Aldehydes and
Ketones. Office of Science and Technology,
Office of Water.
4. USEPA. 1994a. U.S. Environmental
Protection Agency. Draft Drinking Water
Health Criteria Document for Chlorine,
Hypochlorous Acid and Hypochlorite Ion.
Office of Science and Technology, Office of
Water.
5. USEPA. 1994c. U.S. Environmental
Protection Agency. Final Draft Drinking
Water Health Criteria Document for Chlorine
Dioxide, Chlorite and Chlorate. Office of
Science and Technology, Office of Water.
March 31,1994.
6. U.S. Environmental Protection Agency.
1994d. Health and Ecological Criteria Div.,
OST. Final Draft for the Drinking Water
Criteria Document on Trihalomethanes. Apr.
8.1994.
D. Other References
1. Aieta, E. M., & Berg, J. D. 1986. A Review
of Chlorine Dioxide in Drinking Water
Treatment. Jour. AWWA, 78:6:62 (June 1986).
2. Aieta, E. M.; Roberts, P. V.; & Hernandez,
M. 1984. Determination of Chlorine Dioxide,
Chlorine, Chlorite, and Chlorate in Water.
Jour. AWWA, 76:1:64 (Jan. 1984).
3. Alavanja M, Goldstein I, Susser M. 1978.
A Case-Control Study of gastrointestinal and
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
urinary tract cancer mortality and drinking
water chlorination. In: Water Chlorination:
Environmental Impact and Health Effects,
Vol. 2. R.L. Jolley et al., editors. (Ann Arbor:
Ann Arbor Science Publishers), pp. 395-409.
4. Amy, G., et al. Nation-wide Survey of
Bromide Ion Concentrations in Drinking
Water Sources. Progress reports to
AWWARF, University of Colorado at
Boulder, Dept. of Civil, Environmental, and
Architectural Engineering, Boulder, Colo.
(1992-93).
5. Amy, G. L.; Chadik, P. A.; & Chowdhury,
Z. 1987. Developing Models for Predicting
Trihalomethane Formation Potential and
Kinetics. Jour. AWWA, 79:7:89 (July 1987).
6. Amy, G. L.; Tan, L.; & Davis, M. K. 1991.
The Effects of Ozonation and Activated
Carbon Adsorption on Trihalomethane
Speciation. Water Res., 25:2:191 (Feb. 1991).
7. Amy, G., et al. Biodegradability of
Natural Organic Matter: A Comparison of
Methods (BDOC and AOC) and Correlations
with Chemical Surrogates. Proc. 1992
AWWA Ann. Conf. (Water Research), pp.
523-542, Vancouver, B.C.
8. Aschengrau A, Zierler S, Cohen A. 1993.
Quality of Community Drinking Water and
the Occurrence of Late Adverse Pregnancy
Outcomes. Arch Env Health 48:105-113.
9. Atlas, E.; Schauffler, S. 1991. Analysis
of Alkyl Nitrates and Selected Halocarbons in
the Ambient Atmosphere Using a Charcoal
Preconcentration Technique, Environ. Sci.
Technol., Vol. 25, No. 1, pp. 61-7.
10. AWWA Water Industry Data Base
(WIDE). 1990. American Water Works
Association. User's Guide.
11. AWWA Water Industry Data Base
(WIDE). 1991. AWWA, Denver, CO.
12. AWWA Water Quality Division
Disinfection Committee. 1992. Survey of
Water Utility Disinfection Practices. Jour.
AWWA, 84:9:121 (Sept. 1992).
13. AWWA Disinfection Committee. 1983.
Disinfection, Water Quality Control, and
Safety Practices of the Water Utility Industry
in 1978 in the United States. Jour. AWWA,
75:1:51 (Jan. 1983).
14. AWWA. 1991. American Water Works
Association Disinfection Survey. Data Base.
15. AWWARF, 1992. AWWA Research
Foundation. Disinfectant Residual
Measurement Methods. Second Ed. Denver,
CO.
16. Bailar, J.C., Jr., et al, Eds. 1973.
Comprehensive Inorganic Chemistry (Vol. 2,
p.1407). Pergamon Press Ltd., Oxford,
England.
17. Bellar, TA, Lichtenberg, JJ, and Kroner,
RC. 1974. "The Occurrence of Organohalides
in Chlorinated Drinking Water", Jour.
AWWA, 66(12):703-706.
18. Bercz J.P., L. Jones, L. Murray et al.
1982. Subchronic toxicity of chlorine dioxide
and related'compounds in drinking water in
nonhuman primates. Environ. Health Persp.
46:47-55.
19. Boland, P.A. 1981. "National Screening
Program for Organics in Drinking Water Part
II: Data"; SRI International. Prepared for U.S.
Environmental Protection Agency under
Contract No. 68-01-4666; March, 1981.
20. Bolyard, M.; Fair, P. S.; & Hautman, D.
P. 1992. Occurrence of Chlorate in
Hypochlorite Solutions Used for Drinking
Water Disinfection. Environ. Sci. Technol.,
26:8:1663 (Aug. 1992).
21. Borum, D. 1991. U.S. Environmental
Protection Agency, Washington, D.C. Phone
Conversation with Greg Diachenko, Food and
Drug Administration, Washington, D.C.;
December 17,1991.
22. Bove F, Fulcomer M, Klotz J, Esmart J,
Dufficy E, Zagraniski R, Savrin JE. 1992b.
Public Drinking Water Contamination and
Birthweight, and Selected Birth Defects: A
Case-Control Study (Phase IV-B), New Jersey
Department of Health. May 1992.
23. Bove F, Fulcomer M, Klotz J, Esmart J,
Dufficy E, Zagraniski R, Savrin JE. 1992a.
Public Drinking Water Contamination and
Birthweight, Fetal Deaths, and Birth Defects:
A Cross-Sectional Study (Phase IV-A), New
Jersey Department of Health. April 1992.
24. Brass, HJ. 1981. Rural Water Surveys
Organics Data; Drinking Water Quality
Assessment Branch, Technical Support
Division, Office of Drinking Water, U.S.
Environmental Protection Agency. Memo to
Hugh Hanson, Science and Technology
Branch, CSD, ODW, U.S. Environmental
Protection Agency.
25. Brass, H.J.; Weisner, M.J.; Kingsley,
B.A. 1981. Community Water Supply Survey:
Sampling and Analysis for Purgeable
Organics and Total Organic Carbon (Draft);
American Water Works Assoc. Annual
Meeting, Water Quality Division; June 9,
1981.
26. Brass, H. J., et al. 1977. The National
Organic Monitoring Survey: Samplings and
Analyses for Purgeable Organic Compounds.
In Drinking Water Quality Enhancement
Through Source Protection (R. B. Pojasek,
editor). Ann Arbor Sci. Publ., Inc., Ann
Arbor, MI.
27. Brenniman GR, Vasilomanolakis-Lagos
J, Amsel J, Tsukasa N, Wolff AH (1980). Case-
Control Study of Cancer Deaths in Illinois
Communities Served by Chlorinated or Non-
chlorinated Water. In: R.L. Jolley et al.,
editors, Water Chlorination: Environmental
Impact and Health Effects, Vol. 3. (Ann
Arbor: Ann Arbor Science Publishrs). pp.
1043-1057.
28. Brodzinsky, R.; Singh, H.B. 1983.
Volatile Organic Chemicals in the
Atmosphere; An Assessment of Available
Data; U.S. Environmental Protection Agency,
Office of Research and Development,
Research Triangle Park, North Carolina; 1983.
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29. Budde, W.L., Memorandum on
capillary column technology, September 22,
1992.
30. Bull, R.J.; Kopfler, F.C. 1991. Health
Effects of Disinfectants and Disinfectant By-
Products. Prepared for: AWWA Research
Foundation; August, 1991.
31. Bull, R.J., I.M. Sanchez, M.A. Larson
and A.J. Lansing. 1990. Liver tumor
induction in B6C3F1 mice by dichloroacetate
and trichloroacetate. Toxicol. 63:341-359.
32. Cantor, K.P., R. Hoover, P. Hartge, T.J.
Mason, D.T. Silverman, and L.I. Levin. 1985.
Drinking Water Source and Bladder Cancer:
A Case-control Study. Chapter 12 in: Water
Chlorination: Chemistry, Environmental
Impact and Health Effects, Vol. 5. R.L. Jolley,
R.J. Bull, W.P. Davis, S. Katz, M.H. Roberts,
Jr., and V.A. Jacobs, editors. (Chelsea, MI:
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33. Cantor, K.P., R. Hoover, P. Hartge, T.J.
Mason, D.T. Silverman, R. Altman, D.F.
Austin, M.A. Child, C.R. Key, L.D. Marrett,
M.H. Myers, A.S. Narayana, L.I. Levin, J.W.
Sullivan, G.M. Swanson, D.B. Thomas, and
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34. Cantor, K.P., R. Hoover, P. Hartge, T.J.
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38. Connick, R.E. 1947. The Interaction of
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40. Cooper, W.J. 1990. Bromide Ion—
Oxidant Chemistry in Drinking Water: A
Review. Preprints of papers presented at the
200th Amer. Chem. Soc. Nat'l Meet., Div. of
Environ. Chem., Washington, DC (Aug.
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41. Cragle, D.L., C.M. Shy, R.J. Struba, and
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42. Craun, G.F. 1988. Surface Water
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43. Craun, G.F., P.A. Murphy, and J.A.
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Legumes, Milled and Low-Fat-Grain
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52. Daniel, F.B., A.B. DeAngelo, J.A.
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male B6C3F1 mouse. Fundam. Appl. Toxicol.
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54. Devesa, S.S., D.T. Silverman, J.K.
McLaughlin, C.C. Brown, R.R. Connelly, and
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Cancers. Cancer Causes and Control 1:133-
141.
55. Dharmarajah, H., etal. Empirical
Modeling of Chlorine and Chloramine
Residual Decay. Proc. 1991 AWWA Ann.
Conf. (Water Quality for the New Decade),
Philadelphia, Penn., pp. 569-588.
56. Dore, M.; Merlet, N.; Legube, B.; &
Crouo, J. Ph. 1988. Interactions Between
Ozone, Halogens and Organic Compounds.
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57. Druckrey, H. 1968. Chlorinated
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185. Scully, F. E. 1990. Reaction Chemistry
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186. Scully, F.E. and W.N. White. 1991.
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191. Singer, P. C., & Chang, S. D. 1989.
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193. Singh et al. 1983. Cited in Wallace,
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195. Spitzer, W.O.1991. Editorial. Meta-
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196. Stevens, A.A. 1981. "Reaction
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197. Stevens, A. A., et al. 1987. By-
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198. Stevens, A. A.; Moore, L. A.; &
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199. Summers, R. S., et al. 1993. Effect of
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200. Symons, J.M.; Bellar, T.A.; Carswell,
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204. Tate, C. H. 1991. Survey of Ozone
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208. Tuthill, R.W. and G.S. Moore. 1980.
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243. Zeighami, E.A., A.P. Watson, and G.F.
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19:49-58.
244. Zierler, S., L. Feingold, R.A. Danley,
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Massachusetts Related to Chlorinated and
Chloraminated Drinking Water: A Case-
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195-200.
245. Zierler, S., R.A. Danley, and L.
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Drinking Water and Patterns of Mortality in
Massachusetts. Environ. Health Perspect. 69:
275-279.
List of Subjects
40 CFR Part 141
Intergovernmental relations,
Reporting and recordkeeping
requirements, Water supply.
40 CFR Part 142
Adminstrative practice and
procedure, Reporting and recordkeeping
requirements, Water supply.
Dated: June 7,1994.
Carol M. Browner,
Administrator.
For the reasons set out in the
preamble, chapter I of title 40 of the
Code of Federal Regulations is proposed
to be amended as follows:
PART 141—NATIONAL PRIMARY
DRINKING WATER REGULATIONS
1. The authority citation for part 141
continues to read as follows:
Authority: 42 U.S.C. 300f, 300g-l, 300g-2
300g-3, 300g-4, 300g-5, 300g-6, 300J-4 and
300J-9.
2. Section 141.2 is amended by
adding the following definitions in
alphabetical order to read as follows:
Note: The definition for "subpart H
systems" has been proposed (59 FR 6332,
February 10,1994) and is included in this
proposal for the convenience of the reader.
§141.2 Definitions.
*****
Biologically active filtration (BAF)
means conventional filtration treatment
or direct filtration preceded by
continuous application of ozone (in
possible combination with hydrogen
peroxide), but no other continuous
chemical disinfectant, utilizing filtration
media and rate (i.e., empty bed contact
time) sufficient to remove substantial
levels of biodegradeable ozone
byproducts.
Enhanced coagulation means the
addition of excess coagulant for
improved removal of disinfection
byproduct precursors by conventional
filtration treatment.
Enhanced softening means the
improved removal of disinfection
byproduct precursors by precipitative
softening.
*****
GAC10 means granular activated
carbon filter beds with an empty-bed
contact time of 10 minutes based on
average daily flow and a carbon
reactivation frequency of every 180
days.
GAC20 means granular activated
carbon filter beds with an empty-bed
contact time of 20 minutes based on
average daily flow and a carbon
reactivation frequency of every 60 days.
*****
Haloacetic acids (five) (HAAS) mean
the sum of the concentrations in
milligrams per liter of the haloacetic
acid compounds (monochloroacetic
acid, dichloroacetic acid, trichloroacetic
acid, monobromoacetic acid, and
dibromoacetic acid), rounded to two
significant figures after addition. ,
*****
Maximum residual disinfectant level
(MRDL) means a level of a disinfectant
added for water treatment that may not
be exceeded at the consumer's tap
without an unacceptable possibility of
adverse health effects. For chlorine and
chloramines, a PWS is in compliance
with the MRDL when the running
annual average of monthly averages of
samples taken in the distribution
system, computed quarterly, is less than
or equal to the MRDL. For chlorine
dioxide, a PWS is in compliance with
the MRDL when daily samples are taken
at the entrance to the distribution
system and no two consecutive daily
samples exceed the MRDL. MRDLs are
enforceable in the same manner as
maximum contaminant levels under
section 1412 of the Safe Drinking Water
Act. There is convincing evidence that
addition of a disinfectant is necessary
for control of waterborne microbial
contaminants. Notwithstanding the
MRDLs listed in § 141.65, operators may
increase residual disinfectant levels of
chlorine or chloramines (but not
chlorine dioxide) in the distribution
system to a level and for a time
necessary to protect public health to
address specific microbiological
contamination problems caused by
circumstances such as distribution line
breaks, storm run-off events, source
water contamination, or cross-
connections.
Maximum residual disinfectant level
goal (MRDLG) means the maximum
level of a disinfectant added for water
treatment at which no known or
anticipated adverse effect on the health
of persons would occur, and which
allows an adequate margin of safety.
MRDLGs are nonenforceable health
goals and do not reflect the benefit of
the addition of the chemical for control
of waterborne microbial contaminants.
* * * * *
Subpart H systems means public
water systems using surface water or
ground water under the direct influence
of surface water as a source that are
subject to the requirements of subpart H
of this part.
*****
Total Organic Carbon (TOC) means
total organic carbon in mg/1 measured
by methods specified in subpart L of
this part using heat, oxygen, ultraviolet
irradiation, chemical oxidants, or
combinations of these oxidants that
convert organic carbon to carbon
dioxide, rounded to two significant
figures.
*****
3. Subpart B is amended by revising
§ 141.12 to read as follows:
§ 141.12 Maximum contaminant levels for
total trihalomethanes.
The maximum contaminant level of
0.10 mg/1 for total trihalomethanes (the
sum of the concentrations of
bromodichloromethane,
dibromochloromethane,
tribromomethane (bromoform), and
trichloromethane (chloroform)) applies
to Subpart H community water systems
which serve a population of 10,000
people or more until [insert date 18
months after date of publication of the
final rule in the Federal Register]. This
level applies to community water
systems that use only ground water not
under the direct influence of surface
water and serve a population of 10,000
people or more until [insert date 42
months after date of publication of the
final rule in the Federal Register].
Compliance with the maximum
contaminant level for total
trihalomethanes is calculated pursuant
to § 141.30. After [insert date 42 months
after date of publication of the final rule
in the Federal Register], this section
expires.
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38818 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
4. Section 141.30 is amended by
adding paragraph (g) to read as follows:
§ 141.30 Total trihalomethanes sampling,
analytical and other requirements.
* * * * *
(g) The requirements in paragraphs (a)
through (f) of this section apply to
Subpart H community water systems
which serve a population of 10,000 or
more until [insert date 18 months after
date of publication of the final rule in
the Federal Register]. The requirements
in paragraphs (a) through (f) of this
section apply to community water
systems which use only ground water
not under the direct influence of surface
water that add a disinfectant (oxidant)
in any part of the treatment process and
serve a population of 10,000 or more
until [insert date 42 months after date of
publication of the final rule in the
Federal Register]. After [insert date 42
months after date of publication of the
final rule in the Federal Register], this
section and Appendix A (Summary of
Public Comments and EPA responses on
Proposed Amendments to the National
Interim Primary drinking Water
Regulations for Control of
Trihalomethanes in Drinking Water),
Appendix B (Summary of Major
Comments), and Appendix C (Analysis
of Trihalomethanes) of this part expire.
5. Section 141.32 is amended by
revising paragraph (a) introductory text;
removing the word "MCLs" and adding,
in its place, the words "MCLs and
MRDL(s)" in paragraph (a)(l)(iii);
removing the words "maximum.
contaminant level" and adding, in its
place, the words "maximum
contaminant level and maximum
residual disinfectant level" in paragraph
(c); and adding paragraphs (a)(l)(iii)(E)
and (e)(83) through (88) to read as
follows:
Subpart D—Reporting, Public
Notification and Recordkeeping
§141.32 Public notification.
* * * •• * ' *
(a) Maximum Contaminant Levels
(MCLs), Maximum Residual Disinfectant
Levels (MRDLs), treatment technique,
and variance and exemption schedule
violations. The owner or operator of a
public water system which fails to
comply with an applicable MCL, MRDL,
or treatment technique established by
this part or which fails to comply with
the requirements of any schedule
prescribed pursuant to a variance or
exemption, shall notify persons served
by the system as follows:
(1) * * *
(iii)* * *
(E) Violation of the MRDL for chlorine
dioxide as defined in § 141.65 and
determined according to
§ 141.133(b)(2)(iii)(B).
* * * * *
(e)
.(83) Chlorine. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that chlorine is a health
concern at certain levels of exposure.
The Safe Drinking Water Act requires *
disinfection for all public water
systems. This chemical is used to
disinfect drinking water. Chlorine-is
added to drinking water to kill bacteria
and other disease-causing
microorganisms. Chlorine is also added
to provide continuous disinfection
throughout the distribution system!
However, at high doses for extended
periods of time, chlorine has been
shown to damage blood in laboratory
animals. EPA has set a drinking water
standard for chlorine to protect against
the risk of these adverse effects.
Drinking water which meets this EPA
standard is associated with little to none
of this risk and should be considered
safe with~respect to chlorine.
(84) Chloramines. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that chloramines are a ,
health concern at certain levels of
exposure. The Safe Drinking Water Act
requires disinfection for all public water
systems. This chemical is used to
disinfect drinking water. Chloramines '
are added to drinking water to kill
bacteria and other disease-causing
microorganisms. Chloramines are also
added to provide continuous
disinfection throughout the distribution
system. However, at high doses for
extended periods of time, chloramines
have been shown to damage blood and
the liver in laboratory animals. EPA has
set a drinking water standard for
chloramines to protect against the risk
of these adverse effects. Drinking water
which meets this EPA standard is
associated with little to none of this risk
and should be considered safe with .
respect to chloramines. •
(85) Chlorine dioxide. The United
States Environmental Protection Agency
(EPA) sets drinking water standards and
requires disinfection of drinking water.
The Safe Drinking Water Act also
requires disinfection of all public water
systems. Chlorine dioxide is used in
water treatment to kill bacteria and
other disease-causing microorganisms •
and can be used to control tastes and.
odors. However, -at high doses, chlorine
dioxide in drinking water has been
shown to damage blood in laboratory
animals. Also, high levels of chlorine
dioxide given to pregnant laboratory
animals in drinking water have been
shown to cause delays in development
of the nervous system of their offspring.
These effects may occur as a result of a
short term exposure to excessive
chlorine dioxide levels. To protect
against such potentially harmful
exposures, EPA requires chlorine
dioxide monitoring at the treatment
plant, where disinfection occurs, and at
representative points in the distribution
system serving water users. EPA has set
a drinking water standard for chlorine
dioxide to protect against the risk of
these adverse effects.
Note: In addition to paragraph (e)(85) of
this section, systems must include either
paragraph (e)(85)(i) or paragraph (e)(85)(ii) of
this section. Systems with a violation at the
treatment plant, but not in the distribution
system, are required to use the language in
paragraph (e)(85)(ij of this section and treat
the violation as a nonacute violation.
Systems with a violation at the treatment
plant and in the distribution system are
required to use the language in paragraph
(e)(85)(ii) of this section and treat the
violation as an acute violation.
(i) The chlorine dioxide violations
reported today are the result of
exceedances at the treatment facility
only, and do not include violations
within the distribution system serving
users of this water supply. Continued
compliance with chlorine dioxide levels
within the distribution system
minimizes the potential risk of these
violations to present consumers or
(ii) The chlorine dioxide violations
reported today include exceedances of
the EPA standard within the
distribution system serving water users.
Violations of the chlorine dioxide
standard within the distribution system
may harm human health based on short-
term exposures. Certain groups,
including pregnant women, may be
especially susceptible to adverse effects
of excessive chlorine dioxide exposure.
The purpose of this notice is to advise
that such persons should consider
reducing their risk of adverse effects
from these chlorine dioxide violations
by seeking alternate sources of water for
human consumption until such
exceedances are rectified. Local and
State health authorities are the best
source for information concerning
alternate drinking water.
(86) Disinfection byproducts and
treatment technique for DBFs. The
United States Environmental Protection
Agency,(EPA) sets drinking water
standards and requires the disinfection
of drinking water. The Safe Drinking
Water Act also requires disinfection for
all public water systems. However,
when used in the treatment of drinking
water, disinfectants combine with
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38819
organic and inorganic matter present in
water to form chemicals called
disinfection byproducts (DBFS). EPA
has determined that a number of DBFs
are a health concern at certain levels of
exposure. Certain DBFs, including some
trihalomethanes (THMs) and some
haloacetic acids (HAAs), have been
shown to cause cancer in rats. Other
DBFs have been shown to damage the
liver and the nervous system, and cause
reproductive or developmental effects in
laboratory animals. There is also some
evidence that exposure to certain DBFs
may produce adverse effects in people.
EPA has set standards to limit exposure
to THMs, HAAs, and other DBFs.
(87) Bromate. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that bromate is a health
concern at certain levels of exposure.
Bromate is formed as a by-product of
ozone disinfection of drinking water.
Ozone reacts with naturally occurring
bromide in the water to form bromate.
Bromate has been shown to produce
cancer in rats. EPA has set a drinking
water standard to limit exposure to
bromate.
(88) Chlorite. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that chlorite is a health
concern at certain levels of exposure.
Chlorite is formed from the breakdown
of chlorine dioxide, a drinking water
disinfectant. Chlorite in drinking water
has been shown to damage blood cells
and the nervous system. EPA has set a
drinking water standard for chlorite to
protect against these effects. Drinking
water which meets this standard is
associated with little to none of these
risks and should be considered safe
with respect to chlorite.
Subpart F—Maximum Contaminant
Level Goals
6. Subpart F is amended by adding
new §§ 141.53 and 141.54 to read as
follows:
§ 141.53 Maximum contaminant level goals
for disinfection byproducts.
(a) MCLGs are zero for the following
contaminants: .
(1) Chloroform;
(2) Bromodichloromethane;
(3) Bromoform;
(4) Bromate; and
(5) Dichloroacetic acid.
(b) MCLGs for the following
contaminants are as indicated:
Contaminant
Chloral hydrate
MCLG
(mg/l)
Contaminant
Chlorite
Dibromochloromethane
Trichloroacetic acid
MCLG
(mg/l)
008
006
0.3
§ 141.54 Maximum residual disinfectant
level goals for disinfectants.
The MRDLGs for disinfectants are as
follows:
Disinfectant residual
Chloramines
Chlorine
Chlorine dioxide
MRDLG (mg/l)
4 (as CI2)
4 (as CI2)
0.3 (as CICW
Subpart G—National Revised Primary
Drinking Water Regulations: Maximum
Contaminant Levels
7. Subpart G is amended by adding
§§ 141.64 and 141.65 to read as follows:
§ 141.64 Maximum contaminant levels for
disinfection byproducts.
(a) The following Maximum
Contaminant Levels (MCLs) for
disinfection byproducts apply to
community water systems and
nontransient, noncommunity water
systems; compliance dates are indicated
in paragraph (d)(l) of this section:
Contaminant
Bromate
Chlorite
Haloacetic acids (five) (HAAS)
Total trihalomethanes (TTHM)
MCL (mg/l)
0010
1.0
0.060
0.080
(b)(l) For Subpart H systems that
serve more than 10,000 people, the
HAAS and TTHM MCLs (the Stage 1
MCLs) in paragraph (a) of this section
will be superseded by the MCLs (the
Stage 2 MCLs) in paragraph (b) of this
section 18 months after publication of
the final MCLs in paragraph (b) of this
section in the Federal Register with
compliance as indicated in paragraph
(d)(2) of this section. The MCLs in
paragraph (a) of this section continue to
apply for all other systems.
Contaminant
Haloacetic acids (five)
Total trihalomethanes
MCL (mg/l)
0.030
0.040
0.04
(2) Prior to the publication of the final
MCLs in paragraph (b) of this section in
the Federal Register, the Administrator
shall conduct a second regulatory
negotiation or similar proceeding
intended to develop a consensus
rulemaking through negotiation to
review these levels. The Administrator
shall provide notice to the public of the
availability of the monitoring data
collected in accordance with §§ 141.140
through 141.142 and the results of
health effects research relating to
disinfectants and disinfection
byproducts completed during the period
1994-1996. Thereafter, the Agency shall
initiate the second regulatory
negotiation or similar proceeding to
ensure that the affected interests that
participated in the 1993 negotiated
rulemaking participate fully with the
Agency in the evaluation of the
proposed Stage 2 MCLs in light of the
monitoring data, health effects research,
and other information developed since
the proposal of the Stage 2 MCLs. If the
second negotiated rulemaking or similar
proceeding produces a consensus
among the affected interests, the Agency
will proceed in accordance with that
consensus. The Agency agrees to take
action on the proposed Stage 2 MCLs by
December 31,1998, and to publish
notice of that action in the Federal
Register. If data prior to this second
rulemaking warrants earlier action on
acute health effects, a meeting shall be
convened to review the results of these
data and to develop recommendations.
(c)(l) The Administrator, pursuant to
Section 1412 of the Act, hereby
identifies the following as the best
technology, treatment techniques, or
other means available for achieving
compliance with the maximum
contaminant levels for disinfection
byproducts identified in paragraph (a) of
this section:
Dis-
infec-
tion by-
product
TTHMs
HAAS .
Bro-
mate.
Chlorite
Best available technology
(stage 1)
Enhanced coagulation or enhanced
softening or GAC10, with chlorine
as the primary and residual dis-
infectant.
Enhanced coagulation or enhanced
softening or GAC10, with chlorine
as the primary and residual dis-
infectant.
Control of ozone treatment process
to reduce production of bromate.
Control of treatment processes to
reduce disinfectant demand and
control of disinfection treatment
processes to reduce disinfectant
levels.
(2) The Administrator, pursuant to
Section 1412 of the Act, hereby
identifies the following as the best
technology, treatment techniques, or
other means available for achieving
compliance with the maximum
contaminant levels for disinfection
byproducts identified in paragraph (b)
of this section:
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38820 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
Dis-
infec-
tion by-
product
TTHMs
HAAS
Best available technology
(stage 2)
Enhanced coagulation or enhanced
softening, and GAC10; or GAC20;
with chlorine as the primary and
residual disinfectant.
Enhanced coagulation or enhanced
softening, and GAC10; or GAC20;
with chlorine as the primary and
residual disinfectant.
§ 141.65 Maximum residual disinfectant
levels.
(a) The maximum residual
disinfectant levels (MRDLs) are as
follows:
(d) Compliance dates for community
water systems and nontransient
noncommunity water systems. (1)
Compliance with the MCLs in paragraph
(a) of this section. Subpart H systems
serving 10,000 or more persons must
comply with the MCLs contained in
paragraph (a) of this section beginning
[insert date 18 months after date of
publication of the final rule in the
Federal Register]. Subpart H systems
serving fewer than 10,000 persons or
systems using only ground water not
under the direct influence of surface
water serving 10,000 or more persons
must comply with the MCLs in
paragraph (a) of this section beginning
[insert date 42 months after date of
publication of the final rule in the
Federal Register]. Systems using only
ground water not under the direct
influence of surface water serving fewer
than 10,000 persons must comply with
paragraph (a) of this section beginning
[insert date 60 months after date of
publication of the final rule in the
Federal Register].
(2) Compliance with the MCLs in
paragraph (b) of this section. Subpart H
systems serving 10,000 or more persons
must comply with the listed MCLs or
alternative requirements as developed
under the negotiated rulemaking or
similar process contained in paragraph
(b) of this section beginning 18 months
after date of publication of the final
MCLs in paragraph Ob] of this section in
the Federal Register.
(3) A system that is installing GAG or
membrane technology to comply with
this section may apply to the State for
an extension of up to 42 months past the
dates in paragraphs (d) (1) or (2) of this
section, but jtiot to exceed 60 months
from the date of publication of the final
rule in the Federal Register. In granting
the extension, States must set a
schedule for compliance and may
specify any interim measures that the
system must take. Failure to meet the
schedule or interim treatment
requirements constitutes a violation of
National Primary Drinking Water
Regulations.
Disinfectant residual
Chloramines
Chlorine
Chlorine dioxide
MRDL (mg/l)
4.0 (as CI2)
4.0 (as CI2)
0.8 (as CIO2)
(b) The Administrator, pursuant to
Section 1412 of the Act, hereby
identifies the following as the best
technology, treatment techniques, or
other means available for achieving
compliance with the maximum residual
disinfectant levels identified in
paragraph (a) of this section: control of
treatment processes to reduce
disinfectant demand and control of
disinfection treatment processes to
reduce disinfectant levels.
(c) Compliance dates. (1) CWSs and
NTNCWSs. Subpart H systems serving
10,000 or more persons must comply
with this section beginning [insert date
18 months after date of publication of
the final rule in the Federal Register].
Subpart H systems serving fewer than
10,000 persons or systems using only
ground water not under the direct
influence of surface water serving
10,000 or more persons must comply
with this subpart beginning [insert date
42 months after date of publication of
the final rule in the Federal Register].
Systems using only ground water not
under the direct influence of surface
water and serving fewer than 10,000
persons must comply with this subpart
beginning [insert date 60 months after
date of publication of the final rule in
the Federal Register].
(2) Transient NCWSs. Subpart H
systems serving 10,000 or more persons
and using chlorine dioxide as a
disinfectant or oxidant must comply
with the chlorine dioxide MRDL
beginning [insert date 18 months after
date of publication of the final rule in
the Federal Register]. Subpart H
systems serving fewer than 10,000
persons and using chlorine dioxide as a
disinfectant or oxidant or systems using
only ground water not under the direct
influence of surface water serving
10,000 or more persons and using
chlorine dioxide as a disinfectant or
oxidant must comply with the chlorine
dioxide MRDL beginning [insert date 42
months after date of publication of the
final rule in the Federal Register].
Systems using only ground water not
under the direct influence of surface
water and serving fewer than 10,000
persons and using chlorine dioxide as a
disinfectant or oxidant must comply
with the chlorine dioxide MRDL
beginning [insert date 60 months after
date of publication of the final rule in
the Federal Register],
8. A new Subpart L is proposed to be
added to read as follows:
Subpart L—Disinfectant Residuals,
Disinfection Byproducts and
Disinfection Byproduct Precursors
Sec.
141.130 General requirements.
141.131-141.132 [Reserved]
141.133 Analytical and monitoring
requirements.
141.134 Reporting and recordkeeping
requirements.
141.135 Treatment technique for control of
Disinfection Byproduct Precursors
(DBF).
Subpart L—Disinfectant Residuals,
Disinfection Byproducts and
Disinfection Byproduct Precursors
§141.130 General requirements.
(a) The requirements of this subpart L
constitute national primary drinking
water regulations. Subpart L of this part
establishes criteria under which
community water systems (CWSs) and
nontransient, noncommunity water
systems (NTNCWSs) which add a
chemical disinfectant to the water in
any part of the drinking water treatment
process must modify, their practices to
meet MCLs and MRDLs in §§ 141.64 and
141.65 and must meet the treatment
technique requirements for disinfection
byproduct precursors in § 141.135. In
addition, subpart L of this part
establishes criteria under which
transient NCWSs that use chlorine
dioxide as a disinfectant or oxidant
must modify their practices to meet the
MRDL for chlorine dioxide in § 141.65.
MCLs for TTHMs and HAA5 and
treatment technique requirements for
disinfection byproduct precursors are
established to limit the levels of known
and unknown disinfection byproducts
which may have adverse health effects.
These disinfection byproducts may
include chloroform;
bromodichloromethane;
dibromochloromethane; bromoform;
dichloroacetic acid; trichloroacetic acid;
and chloral hydrate
(trichloroacetaldehyde).
(b) Compliance dates. (1) CWSs and
NTNCWSs. Unless otherwise noted,
compliance with the requirements of
this subpart shall begin as follows:
Subpart H systems serving 10,000 or
more persons must comply with this
subpart beginning [insert date 18
months after date of publication of the
final rule in the Federal Register],
Subpart H systems serving fewer than
10,000 persons or systems using only
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38821
ground water not under the direct
influence of surface water serving
10,000 or more persons must comply
with this subpart beginning [insert date
42 months after date of publication of
the final rule in the Federal Register].
Systems using only ground water not
under the direct influence of surface
water serving fewer than 10,000 persons
must comply with this subpart
beginning [insert date 60 months after
date of publication of the final rule in
the Federal Register].
(2) Transient NCWSs. Subpart H
systems serving 10,000 or more persons
and using chlorine dioxide as a
disinfectant or oxidant must comply
with any requirements for chlorine
dioxide in this subpart beginning [insert
date 18 months after date of publication
of the final rule in the Federal Register].
Subpart H systems serving fewer than
10,000 persons and using chlorine
dioxide as a disinfectant or oxidant or
systems using only ground water not
under the direct influence of surface
water serving 10,000 or more persons
and using chlorine dioxide as a
disinfectant or oxidant must comply
with any requirements for chlorine
dioxide in this subpart beginning [insert
date 42 months after date of publication
of the final rule in the Federal Register].
Systems using only ground water not
under the direct influence of surface
water and serving fewer than 10,000
persons and using chlorine dioxide as a
disinfectant or oxidant must comply
with any requirements for chlorine
dioxide in this subpart beginning [insert
date 60 months after date of publication
of the final rule in the Federal Register].
(c) Each CWS and NTNCWS regulated
under paragraph (a) of this section must
be operated by qualified personnel who
meet the requirements specified by the
State and are included in a State register
of qualified operators.
(d) Control of Disinfection
Byproducts. (1) All CWS and NTNCWS
must comply with MCLs in § 141.64.
(2) All CWS and NTNCWS must
comply with monitoring requirements
in § 141.133.
(e) Control of Disinfectant Residuals.
(1) All CWS and NTNCWS must comply
with MRDLs in § 141.65. All transient
NCWSs that use chlorine dioxide as a
disinfectant or oxidant must comply
with the chlorine dioxide MRDL in
§141.65.
(2) All CWS and NTNCWS must
comply with monitoring requirements
in § 141.133. All transient NCWSs that
use chlorine dioxide as a disinfectant or
oxidant must comply with the chlorine
dioxide monitoring requirements in
§141.133.
(3) Not withstanding the MRDLs in
§ 141.65, systems may increase residual
disinfectant levels in the distribution
system of chlorine or chloramines (but
not chlorine dioxide) to a level and for
a time necessary to protect public
health, to address specific
microbiological contamination problems
caused by circumstances such as, but
not limited to, distribution line breaks,
storm run-off events, source water
contamination, or cross-connections.
§§141.131-141.132 [Reserved]
§ 141.133 Analytical and monitoring
requirements.
(a) Analytical Requirements. Only the
analytical method(s) specified in this
paragraph (a), or otherwise approved by
EPA, may be used to demonstrate
compliance with the requirements of
this subpart. These methods are
effective for compliance monitoring
[insert date 30 days after date of
publication of the final rule in the
Federal Register].
(1) Disinfection Byproducts, (i)
Disinfection byproducts must be
measured by the methods listed below:
Approved Methods for Disinfection Byproduct Compliance Monitoring
Byproduct measured1
P&T/GC/EICD & PID
P&T/GC/MS
LLE/GC/ECD
LLE/GC/ECD
SPE/GC/ECD
1C
Methodology2
EPA
method3
502.2s
524.2
551
7 6233 B
552.1
300.0
TTHMs*
X
X
X
HAA55
X
X
Chlorite
X
Bromate
X
1X Indicates method is approved for measuring specified disinfection byproduct.
42pf^T?PurS?,?nd,traP: GCB3as chromatography; EICD=electrolytic conductivity detector; PID=photoionization detector; MS=mass spectrom-
eter; LLE-IiquId/liquid extraction; ECD=electron capture detector; SPE=solid phase extractor; IC=ion chromatography
3 As set forth in Methods for the Determination of Organic Compounds in Drinking Water, USEPA, 1988 (revised July 1991) (available through
National Technical Information Service (NTIS), EPA/600/4-88/039, PB91-231480) for Method 502.2; Methods for the Determination of Organic
Compounds in Drinking Water-Supplement II, USEPA, 1992, (available through NTIS, EPA/600/R-92/129, PB92-207703), for Methods 5242
and 552.1; Methods for the Determination of Organic Compounds in Drinking Water-Supplement I, USEPA, July 1990 (available through National
Technical Information Service (NTIS), EPA/600/4-90/020, PB91-146027) for Method 551; and Methods for 'the Determination of Inorganic Sub-
stances in Environmental Samples, EPA/600/R/93/100—August 1993 for Method 300.0.
4 Total trihalomethanes.
sTotal hatoacetic acids.
8 If TTHMs are the only analytes being measured in the sample, then a PID is not required.
7 Method 6233 B, as set forth in Standard Methods for the Examination of Water and Wi
soclation et al.
'astewater, 1992 (18th Ed.), American Public Health As-
(ii) Analysis under this section for
disinfection byproducts shall be
conducted by laboratories that have
received certification by EPA or the
State after meeting the following
conditions. To receive certification to
conduct analyses for the contaminants
in § 141.64(a) (1) through (4), the
laboratory must: annually analyze
performance evaluation (PE) samples
provided by EPA Environmental
Monitoring Systems Laboratory or
equivalent State samples, and achieve
quantitative results on a minimum of
80% of the analytes included in each PE
sample. The acceptance limit is defined
as the 95% confidence interval
calculated around the mean of the PE
study data between a maximum and
minimum acceptance limit of+/-50%
and +/ -15% of the study mean.
(2)(i) Disinfectant Residuals. Residual
disinfectant concentrations for free
chlorine, combined chlorine
(chloramines), and chlorine dioxide
must be measured by the methods listed
below:
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38822
Federal Register / Vol. 59, No. 145 l\ Friday, July 29, 1994 / Proposed Rules
APPROVED METHODS FOR DISINFECTANT RESIDUAL COMPLIANCE MONITORING
Methodology
Qurinnnlria7inA fFAfTTS^
lodometric Electrode
DPD Method .
Amperometric Tttration (proposed) .....
-V Residual measured 1 ,'.
Standard
method2
4500-CI D
4500-CI E
4500-CI F
4500-CI G
4500-CI H
4500-CI I
4500-CI02 C
4500-CIO2 D
4500-CIO2 E
Free chlo-
rine
X
X
X
X
Combined
chlorine
X
X
X
Total chlo-
rine
X
X
X
X
X
Chlorine di-
oxide
X
X
X
1X indicates method is approved for measuring specified disinfectant residual.
2 As set forth in Standard Methods for the Examination of Water and Wastewater, 1992 (18th Ed.), American Public Health Association et al.
(ii) Residual disinfectant
concentrations for chlorine and
chloramines may also be measured by
using DPD colorimetric test kits if
approved by the State. Measurement for
residual disinfectant concentration must
be conducted by a party approved by
EPA or the State.
(3) Additional Analytical Methods.
Systems required to analyze parameters
not included in paragraphs (a)(l) and (2)
of this section shall use the following
methods. Measurement for these
parameters must be conducted by a
party approved by EPA or the State.
(i) Alkalinity. All methods allowed in
§ 141.89(a) for measuring alkalinity.
(ii) Bromide. EPA method 300.0.
(in) Total Organic Carbon-Method
5310 C (Persulfate-ultraviolet Oxidation
Method) or Method 5310 D (Wet-
oxidation Method) as set forth in
Standard Methods for the Examination
of Water and Wastewater, 1992 (18th
Ed.), American Public Health
Association et al. Samples shall not be
filtered prior to this analysis. For
compliance monitoring, TOG and not
dissolved organic carbon (DOC) data are
required.
(b) Routine monitoring requirements
for disinfection byproducts, disinfectant
residuals, and total organic carbon. All
samples must be taken during normal
operating conditions. Failure to monitor
in accordance with the monitoring plan
required under the provisions of
§ 141.133(d) is a monitoring violation.
Where compliance is based on a
running annual average of monthly or
quarterly samples or averages and the
system's failure to monitor makes it
impossible to determine compliance
with MCLs or MRDLs, this failure to
monitor will be treated as a violation for
the entire period covered by the annual
average.
(1) Disinfection byproducts, (i)
TTHMs and HAAS. (A) Subpart H
systems serving 10,000 or more persons
shall take four water samples each
quarter for each treatment plant in the
system. At least 25 percent of all
samples collected each quarter,
including those samples taken in excess
of the required frequency, shall be taken
at locations within the distribution
system that represent the maximum
residence time of the water in the
system. The remaining samples shall be
taken at locations within the
distribution system that represent the .
entire system, taking into account the
number of persons served, different
sources of water, and different treatment
methods employed.
(B) Systems using only ground water
sources not under the direct influence of
surface water that use a chemical
disinfectant and serve 10,000 or more
persons shall take one water sample
each quarter for each treatment plant in
the system. Samples shall be taken at
locations within the distribution system
that represent the maximum residence
time of the water in the system. At least
25 percent of all samples collected each
quarter, if samples are taken in excess
of the required frequency, shall be taken
at locations within the distribution
system that represent the maximum
residence time of the water in the
system. The remaining samples must be
taken at locations representative of at
least average residence time in the
distribution system. Multiple wells
within a system drawing water from a
single aquifer shall, with State approval
in accordance with criteria developed
under § 142.16(f)(6), be considered one
treatment plant for determining the
minimum number of samples required.
(C) Subpart H systems serving from
500 to 9,999 persons shall take one
water sample each quarter for each
treatment plant in the system. Samples
shall be taken at a point in the
distribution system that represents the
maximum residence time in the
distribution system. At least 25 percent
of all samples collected each quarter, if
samples are taken in excess of the
required frequency, shall be taken at
locations within the distribution system
that represent the maximum residence
time of the water in the system. The ,
remaining samples must be taken at
locations representative of at least.
average residence time in the
distribution system.
(D) Subpart H systems serving fewer .
than 500 persons shall take one sample
per year for each treatment plant in the
system. Samples shall be taken at a
point in the distribution system
reflecting the maximum residence time
in the distribution system and during
the month of warmest water
temperature. If the sample (or average of
the annual samples, if more than one
sample is taken) exceeds 'the MCL, the
system must increase monitoring to one
sample per treatment plant per quarter,
taken at a point in the distribution
system reflecting the maximum
residence time in the distribution
system, until the system meets criteria
in paragraph (c) of this section for
reduced monitoring.
(E) Systems using only ground water
sources not under the direct influence of
surface water that use a chemical
disinfectant and serve less than' 10,000
persons shall sample once per year for
each treatment plant in the system.
Samples shall be taken at a point in the
distribution system reflecting the
maximum residence time in the
distribution system and during the
month of warmest water temperature. If
the sample (or the average of the annual
samples, when more than one sample is
taken) exceeds the MCL, the system
must increase monitoring to one sample
per treatment plant per quarter, taken at
a point in the distribution system ,
reflecting the maximum residence time
in the distribution system, until the
system meets criteria in paragraph (c) of
this section for reduced sampling.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules 38823
Multiple wells drawing water from a
single aquifer shall, with State approval
in accordance with criteria developed
under § 142.16(0(6), be considered one
treatment plant for determining the
minimum number of samples required.
(ii) Chlorite. Community and
nontransient noncommunity water
systems using chlorine dioxide, for
disinfection or oxidation, shall take
three samples each month in the
distribution system. One sample must
be taken at each of the following
locations: near the first customer, in a
location representative of average
residence time, and near the end of the
distribution system (reflecting
maximum residence time in the
distribution system). Any additional
sampling must be conducted in the
same manner (i.e., three-sample sets, at
the specified locations).
(Hi) Bromate. Community and
nontransient noncommunity systems
using ozone, for disinfection or
oxidation, shall take one sample per
month for each treatment plant in the
system using ozone. Samples must be
taken monthly at the entrance to the
distribution system while the ozonation
system is operating under normal
conditions.
(iv) Compliance. (A) TTHMs and
HAAS. For systems monitoring
quarterly, compliance with MCLs in
§ 141.64 shall be based oh a running
annual arithmetic average, computed
quarterly, of quarterly arithmetic
averages of all samples collected by the
system as prescribed by this section
under paragraphs (b)(l)(i)(A), (B), and
(C) of this section. If the arithmetic
average of quarterly averages covering
any consecutive four-quarter period
exceeds the MCL, the supplier of water
shall report to the State pursuant to
§ 141.134 and notify the public pursuant
to § 141.32. Systems on a reduced
monitoring schedule whose annual
average exceeds the MCL will revert to
routine monitoring immediately. For
systems monitoring less frequently than
quarterly, compliance shall be based on
an average of samples taken that year
under the provisions of
§ 141.133(b)(l)(i)(D) through (E) or
§ 141.133(c)(l)(iii)(C). If the average of
these samples exceeds the MCL, the
system must increase monitoring to
once per quarter per treatment plant. All
samples taken and analyzed under the
provisions of this section must be
included in determining compliance,
even if that number is greater than the
minimum required. If, during the first
year following the effective date, any
individual quarter's average will cause
the running annual average of that
system to exceed the MCL, the system
is out of compliance at the end of that
quarter.
(B) Bromate. Compliance shall be
based on a running annual arithmetic
average, computed quarterly, of monthly
samples (or, for months in which the
system takes more than one sample, the
average of all samples taken during the
month) collected by the system as
prescribed by paragraph (b)(l)(iii) of this
section. If the average of samples
covering any consecutive four-quarter
period exceeds the MCL, the system
shall report to the State pursuant to
§ 141.134 and notify the public pursuant
to § 141.32. If a PWS fails to complete
12 consecutive months' monitoring,
compliance with the MCL for the last
four-quarter compliance period shall be
based on an average of the available
data.
(C) Chlorite. Compliance shall be
based on a monthly arithmetic average
of samples as prescribed by paragraph
(b)(l)(ii) of this section. If the arithmetic
average of samples covering any month
exceeds the MCL, the system shall
report to the State pursuant to § 141.134
and notify the public pursuant to
§141.32.
(2) Disinfectant residuals, (i) Chlorine
and chloramines. (A) Subpart H systems
must measure the residual disinfectant
level at the same points in the
distribution system and at the same time
as total coliforms are sampled, as
specified in § 141.21. Systems may use
the results of residual disinfectant
concentration sampling conducted
under § 141.74(b)(6)(i) for unfiltered
systems or § 141.74(c)(3)(i) for systems
which filter, in lieu of taking separate
samples.
(B) Community and nontransient
noncommunity systems using only
ground water not under the direct
influence of surface water must measure
the residual disinfectant level at the
same points in the distribution system
and at the same time as total coliforms
are sampled, as specified in § 141.21.
(ii) Chlorine Dioxide. (A) Routine
Monitoring. Community, nontransient
noncommunity, and transient
noncommunity water systems must
monitor for chlorine dioxide only if
chlorine dioxide is used by the system
for disinfection or oxidation. If
monitoring is required, systems shall
take daily samples at the entrance to the
distribution system. For any daily
sample that exceeds the MRDL, the
system is required to take samples in the
distribution system the following day at
the locations required by paragraph
(b)(2)(ii)(B) of this section, in addition to
the sample required at the entrance to
the distribution system.
(B) Additional Distribution System
Monitoring. On each day following a
routine sample monitoring result that
exceeds the MRDL, the system is
required to take three chlorine dioxide
distribution system samples.
(1) If chlorine dioxide or chloramines
are used to maintain a disinfectant
residual in the distribution system, or if
chlorine is used to maintain a
disinfectant residual in the distribution
system and there are no disinfection
addition points after the entrance to the
distribution system (i.e., no booster
chlorination), three samples shall be
taken as close to the first customer as
possible at intervals of at least six hours.
(2) If chlorine is used to maintain a
disinfectant residual in the distribution
system and there are one or more
disinfection addition points after the
entrance to the distribution system (i.e.,
booster chlorination), one sample shall
be taken at each of the following
locations: as close to the first customer
as possible, in a location representative
of average residence time, and as close
to the end of the distribution system as
possible (reflecting maximum residence
time in the distribution system).
(C) CT credit prior to enhanced
coagulation or enhanced softening.
Subpart H systems required to operate
enhanced coagulation or enhanced
softening under the provisions of
§ 141.135 may receive credit for
compliance with CT requirements
specified by the State if the following
monitoring is completed and the criteria
in § 141.135(a)(2)(i)(B)(3) are met.
(1) For each chlorine dioxide
generator, the system must demonstrate
that the generator is achieving at least
95 percent chlorine dioxide yield and
producing no more than five percent
chlorine by measuring a minimum of
once per week. Measurements shall be
conducted by using Standard Method
4500-C1O22 E. Chlorine dioxide yield
and chlorine presence shall be
measured as described in Aieta et al,
Journal AWWA, 76:1, pp.66 and 67,
respectively. Guidance on generator
effluent sampling, safety, dilutions,
replication, and the measurement of
these and related species may be found
in [cite Hoehn's upcoming AWWARF
report] and in Aieta et al, Journal
AWWA, 76:1, pp.64 through 70, as
noted.
(2) On any day that a generator fails
to achieve at least 95 percent chlorine
dioxide yield and no more than five
percent chlorine, and on subsequent
days until these conditions are
achieved, the system may not receive
credit for compliance with CT
requirements in subpart H of this part.
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38824 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
(3) On any day that a generator fails
to achieve at least 95 percent chlorine
dioxide yield but achieves at least 90
percent conversion efficiency and/or
produces more than five percent
chlorine but less than 10 percent, the
system may take immediate corrective
action to achieve a minimum of 95
percent chlorine yield and a maximum
of five percent chlorine. If subsequent
measurements conducted on the same
day demonstrate at least 95 percent
chlorine dioxide yield and no more than
five percent chlorine, the system may
receive credit for compliance with CT
requirements in subpart H of this part
on that day. If the generator continues
to fail to demonstrate at least 95 percent
chlorine dioxide yield and no more than
five percent chlorine, the system may
not receive credit for compliance with
CT requirements in subpart H of this
part on that day.
(4) After achieving the conditions in
paragraph (b)(2)(ii)(C)U) of this section,
the system may operate no more than
one week without measurement. If
however, in the interim, the system
changes generator operating conditions
(e.g., changes chlorine dioxide dose,
changes conditions to match changing
plant flow rate) or generator conditions
(e.g., a new batch of sodium chlorite or
a different ratio of chlorite to chlorine
or acid is used), the system shall
remeasure for chlorine dioxide yield
and chlorine presence and meet the
conditions in paragraphs (b)(2)(ii)(C)(J)
or (3) of this section to receive CT
credit.
(iii) Compliance. (A) Chlorine and
chloramines. (1) Compliance shall be
based on a running annual arithmetic
average, computed quarterly, of
quarterly averages of all samples
collected by the system as prescribed in
this section. If the average of quarterly
averages covering any consecutive four-
quarter period exceeds the MRDL, the
system shall report to the State pursuant
to § 141.134 and notify the public
pursuant to § 141.32.
(2) In cases where systems switch
between the use of chlorine and
chloramines for residual disinfection
during the year, compliance shall be
determined by including together all
monitoring results of both chlorine and
chloramines in calculating compliance
pursuant to paragraph (b)(2)(iii)(C)(l) of
this section. Reports submitted pursuant
to § 141.134 will clearly indicate which
residual disinfectant was analyzed for
each sample.
(B) Chlorine dioxide. (1) Acute
violations. Compliance shall be based
on consecutive daily samples collected
by the system as prescribed in this
section. If any daily sample taken at the
entrance to the distribution system
exceeds the MRDL, and on the following
day one (or more) of the three samples
taken in the distribution system exceed
the MRDL, the system will be in
violation of the MRDL and shall take
immediate corrective action to lower the
level of chlorine dioxide below the
MRDL and will notify the public
pursuant to the procedures for acute
health risks in § 141.32(a)(l)(iii)(E).
Failure to take samples in the
distribution system the day following an
exceedance of the chlorine dioxide
MRDL at the entrance to the distribution
system shall also be considered an
MRDL violation and the system shall
notify the public of the violation in
accordance with the provisions for acute
violations under § 141.32(a)(l)(iii)(E).
(2) Nonacute violations. Compliance
shall be based on consecutive daily
samples collected by the system as
prescribed in this section. If any two
consecutive daily samples taken at the
entrance to the distribution system
exceed the MRDL and all distribution
system samples taken are below the
MRDL, the system will be in violation
of an MRDL and shall take corrective
action to lower the level of chlorine
dioxide below the MRDL at the point of
sampling and will notify the public
pursuant to the procedures for nonacute
health risks in § 141.32. Failure to
monitor at the entrance to the
distribution system the day following an
exceedance of the chlorine dioxide
MRDL at the entrance to the distribution
system shall also be considered an
MRDL violation and the system shall
notify the public of the violation in
accordance with the provisions for
nonacute violations under § 141.32.
(3) Disinfection Byproduct Precursors
(DBPP). (i) Subpart H systems.
Community and nontransient
noncommunity systems which use
conventional filtration treatment (as
defined in § 141.2) must monitor each
treatment plant water source for TOG
prior to any continuous disinfection
treatment; except that systems using
ozone followed by biologically active
filtration (as defined in § 141.2) may
measure TOG in the treated water
following biological filtration but before
the addition of a residual disinfectant
and systems using chlorine dioxide that
meet the standards for including CT
credit for its use prior to enhanced
coagulation or enhanced softening
contained in § 141.135(a)(2)(i)(B)(3) or
§ 141.135(a)(2)(ii)(B)(3) may measure
TOG in the treated water at any point
prior to the continuous addition of any
other disinfectant. All systems required
to monitor under paragraph (b)(3) of this
section must also monitor for TOG in
the source water prior to any treatment
at the same time as monitoring for TOG
in the treated water. These samples
(source water and treated water, prior to
disinfection) are referred to as paired
samples. At the same time as the source
water sample is taken, all systems must
monitor for alkalinity in the source
water prior to any treatment.
(ii) Frequency. All systems required to
monitor under paragraph (b)(3)(i) of this
section must take one paired sample per
month per plant at a time representative
of normal operating conditions and
influent water quality. At the same time,
the system must take a source water
alkalinity sample in order to make the
appropriate calculations required to
comply with § 141.135.
(iii) Compliance. Compliance shall be
determined as specified by § 141.135(b).
Systems may begin monitoring to
determine whether Step 1 TOG
removals can be met 12 months prior to
the compliance date for the system. This
monitoring is not required and failure to
monitor during this period is not a
violation. However, any system that:
Does not monitor during this period,
and then determines in the first 12
months after the compliance date that it
is not able to meet the Step 1
. requirements in § 141.135(a)(2) and
must therefore apply for alternate
performance criteria, is not eligible for
retroactive approval of alternate
performance-criteria as allowed
pursuant to § 141.135(a)(3). Systems
may apply for alternate performance
criteria any time after the compliance
date.
(c) Reduced monitoring requirements
for disinfection byproducts, disinfectant
residuals, and total organic carbon.
Systems may reduce monitoring, except
as otherwise provided, in accordance
with the following.
(1) Disinfectionbyproducts, (i)
Chlorite. Systems required to analyze
for chlorite may not reduce monitoring.
(ii) Bromate. Systems required to
analyze for bromate may reduce
monitoring from monthly to once per
quarter, if the system demonstrates that
the average raw water bromide
concentration is less than 0.05 mg/1
based upon representative monthly
measurements for one year.
(iii) TTHMs and HAA5. (A) Any
Subpart H system which has a source
water TOG level, before any treatment,
of greater than 4.0 mg/1 may not reduce
its monitoring.
(B) Systems may reduce monitoring if
they have a running annual average for
TTHMs and HAA5 that is no more than
0.040 mg/1 and 0.030 mg/1, respectively,
with the following exceptions. Systems
using ground water not under the direct
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1P94 / Proposed Rules
38825
influence of surface water that serve
fewer than 10,000 persons and are
required to take only one sample per
year may reduce monitoring if either:
the average of two consecutive
representative annual samples is no
more than 0.040 mg/1 and 0.030 mg/1 for
TTHMs and HAAS, respectively, or any
representative annual sample is less
than 0.020 mg/1 and 0.015 mg/1 for
TTHMs and HAAS, respectively.
Systems using surface water or ground
water under the direct influence of
surface water in whole or in part that
serve fewer than 500 persons may not
reduce their monitoring to less than one
sample per year. Systems must meet the
requirements for reduction of
monitoring for both TTHMs and HAAS
to qualify for reduced monitoring. The
system may reduce monitoring only
after the system has completed at least
one year of monitoring in accordance
with paragraph (b)(l)(i) of this section.
(C) Reduced monitoring frequency. (1)
Subpart H systems serving 10,000
persons or more that are eligible for
reduced monitoring in paragraph
(c)(l)(iii)(B) of this section may reduce
the monitoring frequency for TTHMs
and HAAS to one sample per quarter per
treatment plant. Samples shall be taken
at a point in the distribution system
reflecting the maximum residence time
in the distribution system.
(2) Systems using only ground water
not under the direct influence of surface
water and serving 10,000 persons or
more that are eligible for reduced
monitoring in paragraph (c)(l)(iii)(B) of
this section may reduce the monitoring
frequency for TTHMs and HAAS to one
sample per year per treatment plant.
Samples shall be taken at a point in the
distribution system reflecting the
maximum residence time in the
distribution system and during the
month of warmest water temperature.
(3) Subpart H systems serving
between 500 to 9,999 persons that are
eligible for reduced monitoring may
reduce the monitoring frequency for
TTHMs and HAAS to one sample per
year per treatment plant. Samples shall
be taken at a point in the distribution
system reflecting the maximum
residence time in the distribution
system and during the month of
warmest water temperature.
(4) Systems using only ground water
sources not under the direct influence of
surface water and serving fewer than
10,000 persons, may reduce the
monitoring frequency for TTHMs and
HAAS to one sample per three year
monitoring cycle, with this three-year
cycle beginning on the January 1
following the quarter in which the
system qualifies for reduced monitoring.
Samples shall be taken at a point in the
distribution system reflecting the
maximum residence time in the
distribution system and during the
month of warmest water temperature.
(D) Systems on a reduced monitoring
schedule may remain on that reduced
schedule as long as the average of all
samples taken in the year (for systems
which must monitor quarterly) or the
result of the sample (for systems which
must monitor no more frequently than
annually) is no more than 0.060 mg/1
and 0.045 mg/1 for TTHMs and HAA5,
respectively. Systems that do not meet
these levels must resume monitoring at
the frequency identified in
§ 141.133(b)(l) in the quarter
immediately following the quarter in
which the system exceeded 75 percent
of either MCL.
(E) The State may return a system to
routine monitoring at the State's
discretion.
(2) Disinfectant residuals. Monitoring
for disinfectant residuals may not be
reduced.
(3) TOG. Subpart H systems with a
treated water TOG of less than 2.0 mg/
1 for two consecutive years, or less than
1.0 mg/1 for one year, may reduce
monitoring for both TOG and alkalinity
to one paired sample per plant per
quarter.
(d) Monitoring plans. (1) Each system
required to monitor under this subpart
must develop and implement a
monitoring plan. The system shall
maintain title plan and make it available
for inspection by the State and the
feneral public no later than 30 days
allowing the applicable effective dates
in § 141.130(b). All Subpart H systems
serving more than 3300 people shall
submit a copy of the monitoring plan to
the State no later than the date of the
first report required under § 141.134.
The State may also require the plan to
be submitted by any other system. The
plan must include at least the following
elements.
(i) Locations for collecting samples for
any parameters included in this subpart.
(ii) How the system will calculate
compliance with MCLs and MRDLs.
(2) After review, the State may require
changes in any plan elements.
§ 141.134 Reporting and recordkeeping
requirements.
(a) Systems required to sample
quarterly or more frequently must report
to the State within 10 days after the end
of each quarter in which samples were
collected. Systems required to sample
less frequently than quarterly must
report to the State within 10 days after
the end of each monitoring period in
which samples were collected.
(b) Systems required to monitor for
the following compounds must report
the following information.
(1) TTHMs and HAA5.
(i) Systems monitoring for TTHMs
and HAAS under the requirements of
§§ 141.133(b) or (c) on a quarterly or
more frequent basis must report at least
the following information. The State
may choose to perform paragraphs
(b)(l)(i)(C) through (E) of this section in
lieu of having the system report that
information.
(A) the number of samples taken
during the last quarter,
(B) the location, date, and result of
each sample taken during the last
quarter,
(C) the arithmetic average of all
samples taken in the last quarter,
(D) the arithmetic average of the
arithmetic averages reported under
paragraph (b)(l)(i)(C) of this section for
the last four quarters, and
(E) whether the MCL was exceeded.
(ii) Systems monitoring for TTHMs
and HAAS under the requirements of
§ 141.133(b) or (c) less frequently than
quarterly (but at least annually) must
report at least the following information.
The State may choose to perform
paragraphs (b)(l)(ii)(C) through (D) of
this section in lieu of having the system
report that information.
(A) the number of samples taken
during the last year,
(B) the location, date, and result of
each sample taken during the last
quarter,
(C) the arithmetic average of all
samples taken over the last year, and
(D) whether the MCL was exceeded.
(iii) Systems monitoring for TTHMs
and HAAS under the requirements of
§ 141.133(c) less frequently than
annually must report at least the
following information:
(A) the location, date, and result of
the last sample taken, and
(B) whether the MCL was exceeded.
(2) Systems monitoring for chlorite
under the requirements of § 141.133(b)
must report at least the following
information. The State may choose to
perform paragraphs (b)(2)(iii) through
(iv) of this section in lieu of having the
system report that information.
(i) the number of samples taken each
month for the last 3 months,
(ii) the location, date, and result of
each sample taken during the last
quarter,
(iii) for each month in the reporting
period, the arithmetic average of all
samples taken in the month, and
(iv) whether the MCL was exceeded,
and which month it was exceeded.
(3) Systems monitoring for bromate
under the requirements of § 141.133(b)
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38826 Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
or (c) must report at least the following
information. The State may choose to
perform paragraphs (b)(3)(iii) through
(iv) of this section in lieu of having the
system report that information.
(i) the number of samples taken
during the last quarter,
(ii) the location, date, and result of
each sample taken during the last
quarter,
(iii) the arithmetic average of the
monthly arithmetic averages of all
samples taken in the last year, and
(iv) whether the MCL was exceeded.
(4) Systems monitoring for chlorine or
chloramines under the requirements of
§ 141.133(b) must report at least the
following information:
(i) the number of samples taken
during each month of the last quarter,
(ii) the monthly arithmetic average of
all samples taken in each month for the
last 12 months, and
(iii) the arithmetic average of all
monthly averages for the last 12 months,
and
(iv) whether the MRDL was exceeded.
(5) Systems monitoring for chlorine
dioxide under the requirements of
§ 141.133(b) must report at least the
following information:
(i) the dates, results, and locations of
samples taken during the last quarter,
(ii) whether the MRDL was exceeded,
and
(iii) whether the MRDL was exceeded
in any two consecutive daily samples
and whether the resulting violation was
acute or nonacute.
(6) Disinfection Byproduct Precursors
and enhanced coagulation or enhanced
softening.
(i) Reports from systems monitoring
monthly or quarterly for TOG under the
requirements of § 141.133(b)(3) and
required to meet the enhanced
coagulation or enhanced softening
requirements in § 141.135 (a)(2) or (a)(3j
must include at least the following
information. The State may choose to
perform paragraphs (b)(6)(i) (C) through
(E) of this section in lieu of having the
system report that information.
(A) the number of paired (raw water
and treated water, prior to continuous
disinfection) samples taken during the
last quarter,
(B) the location, date, and result of
each paired sample taken during the last
quarter and the associated source water
alkalinity,
(C) for each month in the reporting
period that paired samples were taken,
the arithmetic average of the percent
reduction of TOG for each paired
sample and the required TOG percent
removal,
(D) calculations for determining
compliance with the TOG percent
removal requirements, as provided in
§141.135(b)(l),and
(E) whether the system is in*
compliance with the enhanced
coagulation or enhanced softening
percent removal requirements in
§ 141.135(a) for the last four quarters.
(ii) Systems monitoring monthly or
quarterly for TOG under the
requirements of § 141.133(b) and
meeting one or more of the criteria in
§ 141.135(a)(l) for avoiding the
requirement for enhanced coagulation
and enhanced softening must report at
least the following information. The
State may choose to perform paragraphs
(b)(6)(ii) (D) through (I) of this section in
lieu of having the system report that
information.
(A) the criterion that the system is
using to avoid enhanced coagulation or
enhanced softening,
(B) the number of paired samples
taken during the last quarter,
(C) the location, date and result of
each sample (identified as either source
water or treated water) taken during the
last quarter,
(D) the monthly arithmetic average (or
quarterly sample result) of all treated
water samples taken in the quarter and
the running annual arithmetic average
based on monthly averages (or quarterly
samples) (for systems meeting the
criterion in § 141.135(a)(l)(i) for
avoiding enhanced coagulation or
enhanced softening),
(E) the monthly arithmetic average of
all treated water samples taken for each
month of the quarter, the quarterly :
average of the monthly averages, and the
running annual average of the quarterly
averages (for systems meeting the
criterion in § 141.135(a)(l)(ii) for
avoiding enhanced coagulation or
enhanced softening),
(F) the running annual average of' •
alkalinity of the source water (for •
systems meeting the criterion in
§ 141.135(a)(l)(ii) for avoiding enhanced
coagulation or enhanced softening),
(G) the running annual average for
both TTHMs and THAAs (for systems
meeting the criterion in § 141.135(a)(l)
(ii) or (iii) for avoiding enhanced ,
coagulation or enhanced softening),
(H) the running annual average of the
amount of magnesium hardness removal
(in mg/1) (for systems meeting the
criterion in § 141.135(a)(l)(iv) for
avoiding enhanced coagulation or
enhanced softening),
(I) whether the system is in
compliance with .the particular criterion
in § 141.135{a)(l) (i) through (iv) that
the system is using to avoid enhanced
coagulation or enhanced softening.
§ 141.135 Treatment technique for control
of Disinfection Byproduct Precursors
(DBF).
(a)(l) Subpart H systems using
conventional filtration treatment (as
defined in § 141.2) must operate with
enhanced coagulation or enhanced
softening to achieve the TOG percent
removal levels specified in this section
unless the system meets at least one of
the criteria listed in paragraphs (a)(l)(i)
through (iv) of this section:
(i) The system's treated TOG level,
measured according to § 141.133(b)(3),
is less than 2.0 mg/1, calculated
quarterly as a running annual average.
(ii) The system's source water TOG
level, measured as required by
§ 141.133(b)(3), is less than 4.0 mg/1,
calculated quarterly as a running annual
average; the source water alkalinity,
measured according to § 141.133(a)(4),
is greater than 60 mg/1, calculated
quarterly as a running annual average;
and, prior to the effective date for
compliance in § 141.130, either the
TTHM and HAAS running annual
averages areno greater than 0.040 mg/
1 and 0.030 mg/1, respectively, or the
system has made a clear and irrevocable
financial commitment not later than the
effective date for compliance in
§ 141.30(b) to use of technologies that
will limit tfie levels of TTHMs and
HAAS to no more than 0.040 mg/1 and
0.030 mg/1, respectively. Systems must
submit evidence of a clear and
irrevocable financial commitment, in
addition to a schedule containing
milestones and periodic progress reports
for installation and operation of
appropriate technologies, to the State for
approval not later than the effective date
for compliance in § 141.30(b) of this
part. These technologies must be
installed and operating not later than
the effective date for Stage 2 of the
Disinfectant/Disinfection Byproduct
Rule. Violation of the approved
schedule will constitute a violation of
the National Primary Drinking Water
Regulation.
flii) The TTHM and HAAS running
annual averages are no greater than
0.040 mg/1 and 0.030 mg/1, respectively,
and the system uses only chlorine for
disinfection.
(iv) Systems practicing softening and
removing at least 10 mg/1 of magnesium
hardness (as CaCOs), calculated
quarterly as a running annual average,
except those that use ion exchange, are
not subject to performance criteria for
the removal of TOG.
(2) Enhanced coagulation
performance requirements.
(i) Systems not practicing softening.
(A) Systems (except those noted in
paragraph (a)(2)(i)(D) of this section)
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
38827
must achieve the percent reduction of
TOG specified in paragraph (a)(2)(i)(E)
of this section between the raw water
source and the treated water prior to
continuous disinfection, unless the
State approves a system's request for
alternative performance standards under
paragraph (a)(3) of this section.
Continuous disinfection is defined as
the continuous addition of a chemical
disinfectant for the purposes of
achieving a level of inactivation credit
to meet the minimum inactivation/
removal treatment requirements of
subpart H of this part.
(B) Continuous disinfection does not
include: the addition of a chemical
disinfectant for filter maintenance
(when applied intermittently), or the
use of a disinfectant (other than
provided for in paragraph (a)(2)(i)(C) of
this section) as an oxidant for the
purposes of controlling water quality
problems such as iron, manganese,
sulfides, zebra mussels, Asiatic clams,
taste, and odor. In determining
compliance with the CT requirements
specified by the State, the system shall
not include any credit for disinfectants
used either for filter maintenance or for
controlling water quality problems
except as allowed below in paragraphs
(a)(2)(i)(B)(l) through (4) of this section.
(J) Systems may include CT credit
during periods when the water
temperature is below 5 °C and the
TTHM and HAAS quarterly averages are
no greater than 0.040 mg/1 and 0.030
mg/1, respectively.
12) Systems receiving disinfected
water from a separate entity as their
source water shall be allowed to include
credit for this disinfectant in
determining compliance with the CT ,
requirements. If the TTHM and HAAS
quarterly averages are no greater than
0.040 mg/1 and 0.030 mg/1, respectively,
systems may use the measured "C"
(residual disinfectant concentration)
and the actual contact time (as TIO). If
either the TTHM or HAAS quarterly
average is greater than 0.040 mg/1 or
0.030 mg/1, respectively, systems must
use a "C" (residual disinfectant
concentration) of 0.2 mg/1 or the
measured vahje, whichever is lower;
and the actual contact time (as TIO). This
credit shall be allowed from the
disinfection feedpoint, through a closed
conduit only, and ending at the delivery
point to the treatment plant.
(3) Systems using chlorine dioxide as
an oxidant or disinfectant may include
CT credit for its use prior to enhanced
coagulation or enhanced softening if the
following standards are met: the
chlorine dioxide generator must
generate chlorine dioxide on-site and
minimize the production of chlorine as
shown by complying with monitoring
and performance standards in
(4) Systems using ozone and
biologically active filtration may
include CT credit for its use prior to
enhanced coagulation or enhanced
softening.
(C) Systems not required to operate
with enhanced coagulation may
continue to include, in compliance
calculations, continuous addition of a
chemical disinfectant for the purposes
of achieving a level of inactivation
credit to meet the minimum
inactivation/removal treatment
requirements of subpart H of this part,
even when such addition is also made
for the purpose of controlling water
quality problems.
(D) Systems using ozone and
biologically active nitration must
achieve the TOC percent reduction
specified in paragraph (a)(2)(i)(E) of this
section before the addition of a residual
disinfectant. Systems using chlorine
dioxide that meet the requirements for
including CT credit specified in
paragraph (a)(2)(i)(B)(3) of this section
must achieve the TOC percent reduction
specified in paragraph (a)(2)(i)(E) of this
section before the addition of a residual
disinfectant.
(E) Required TOC reductions,
indicated in the table below, are based
upon specified source water parameters
measured in accordance with
§ 141.133(b)(3).
REQUIRED REMOVAL OF TOC BY EN-
HANCED .COAGULATION FOR SUB-
PART H SYSTEMS USING CONVEN-
TIONAL TREATMENT2
Source water
total organic car-
bon (mg/1)
>2.0-4.0 ....
>4.0-8.0
>8.0
Source water alkalinity
(mg/1)
0-60
(per-
cent)
40.0
45.0
50.0
>60-
120
(per-
cent)
30.0
35.0
40.0
>120'
(per-
cent)
20.0
25.0
30.0
1 Systems practicing softening must meet
the TOC removal requirements in this column.
2 Systems meeting at least one of the condi-
tions in §141.135(a)(1) (i) through (iv) are not
required to operate with enhanced coagula-
tion.
(ii) Systems practicing softening. (A)
Systems (except those noted in
paragraph (a)(2)(ii)(D) of this section)
must achieve the percent reduction of
TOC specified in paragraph (a)(2)(ii)(E)
of this section between the raw water
source and treated water prior to
continuous disinfection. Continuous
disinfection is defined as the
continuous addition of a chemical
disinfectant for the purposes of
achieving a level of inactivation credit
to meet die minimum inactivation/
removal treatment requirements of
subpart H of this section.
(B) Continuous disinfection does not
include: the addition of a chemical
disinfectant for filter maintenance
(when applied intermittently), or the
use of a disinfectant (other than
provided for in paragraph (a)(2)(ii)(C) of
this section) as an oxidant for the
purposes of controlling water quality
problems such as iron, manganese,
sulfides, zebra mussels, Asiatic clams,
taste, and odor. In determining
compliance with the CT requirements in
subpart H of this part, the system shall
not include any credit for disinfectants
used either for filter maintenance or for
controlling water quality problems
except as allowed by paragraphs
(a)(2)(ii)(B) (1) through (4) of this
section.
(1) Systems may include CT credit
during periods when the water
temperature is below 5°C and the TTHM
and HAA5 quarterly averages are no
greater than 0.040 mg/1 and 0.030 mg/
1, respectively.
(2) Systems receiving disinfected
water from a separate entity as their
source water shall be allowed to include
credit for this disinfectant in
determining compliance with the CT
requirements. If the TTHM and HAAS
quarterly averages are no greater than
0.040 mg/1 and 0.030 mg/1, respectively,
systems may use the measured "C"
(residual disinfectant concentration)
and the actual contact time (as TIO). If
either the TTHM or HAAS quarterly
average is greater than 0.040 mg/1 or
0.030 mg/1, respectively, systems must
use a "C" (residual disinfectant
concentration) of 0.2 mg/1 or the
measured value, whichever is lower;
and the actual contact time (as T10). This
credit shall be allowed from the
disinfection feed point, through a closed
conduit only, and ending at the delivery
point to the treatment plant.
(3) Systems using chlorine dioxide as
an oxidant or disinfectant may include
CT credit for its use prior to enhanced
coagulation or enhanced softening if the
following standards are met: the
chlorine dioxide generator must
generate chlorine dioxide on-site and
minimize the production of chlorine as
shown by complying with monitoring
and performance standards in
(4) Systems using ozone and
biologically active filtration may
include CT credit for its use prior to
enhanced coagulation or enhanced
softening.
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Federal Register / Vol. 59, No. 145 / Friday, July 29, 1994 / Proposed Rules
(C) Systems not required to operate
with enhanced softening may continue
to include, in compliance calculations,
continuous addition of a chemical
disinfectant for the purposes of
achieving a level of inactivation credit
to meet the minimum inactivation/
removal treatment requirements of
subpart H of this part, even when such
addition is also made for the purpose of
controlling water quality problems.
(D) Systems using ozone and
biologically active filtration must
achieve the TOG percent reduction
specified in paragraph (a)(2)(ii)(E) of
this section before the addition of a
residual disinfectant. Systems using
chlorine dioxide that meet the
requirements for including CT credit
specified in paragraph (a)(2)(ii)(B)(3) of
this section must achieve the TOG
percent reduction specified in
paragraph (a)(2)(ii)(E) of this section
before the addition of a residual
disinfectant.
(E) Required TOG reductions are
indicated in the table in paragraph
(a)(2)(i)(E) of this section. Systems
practicing softening are required to meet
the percent reductions in the far-right
column (Source water alkalinity >120
mg/1) for the specified source water
TOG.
(3) Non-softening Subpart H
conventional treatment systems that
cannot achieve the TOG removals
required by paragraph (a)(2) of this
section due to water quality parameters
or operating conditions must apply to
the State, within three months of failure
to achieve the TOG removals required
by paragraph (a) (2) of this section, for
alternative performance criteria. If the
State approves the alternate
performance criteria, the State may
make those criteria retroactive for the
purposes of determining compliance. If
the State does not approve the alternate
performance criteria, the system must
meet the TOG removals contained in
paragraph (a)(2)(i)(E) of this section.
(i) Such application must include, as
a minimum, results of bench-or pilot-
scale testing for alternate enhanced
coagulation level. "Alternate enhanced
coagulation level" is defined as
coagulation at a coagulant dose and pH
as determined by the method outlined
in paragraph (a)(3)(ii) of this section
such that an incremental addition of 10
mg/1 of alum (or equivalent amount of
ferric salt) results in a TOG removal of
0.3 mg/1. The percent removal of TOG
at this point on the "coagulant dose
versus TOG removal" curve is then
defined as the minimum TOG removal
required for the system. Once approved
by the State, this minimum requirement
supersedes the minimum TOG removal
required by the table in paragraph
(a)(2)(i)(E) of this section. This
requirement will be effective until such
time as the State approves a new value
based on the results of a new bench- and
pilot-scale test triggered by changes in
source water quality. Failure to achieve
State-set alternative minimum TOG
removal levels is a violation of
paragraph (a)(3) of this section.
(ii)(A) Bench- or pilot-scale testing of
enhanced coagulation shall be
conducted by using representative water
samples and adding 10 mg/1 increments
of alum (or equivalent amounts of ferric
salt) until the pH is reduced to a level
less than or equal to the enhanced
coagulation maximum pH shown in the
table below.
ENHANCED COAGULATION MAXIMUM
pH
Alkalinity (mg/1 as CaCO3)
0-60 ...
>60-120 ;
>120-240 ..:.
>240
Maxi-
mum
PH
5.5
6.3
7.0
7.5
(B) For waters with alkalinities of less
than 60 mg/1 for which addition of small
amounts of alum or equivalent addition
of iron coagulant drives the pH below
5.5 before significant TOG removal
occurs, the system must add necessary
chemicals to maintain the pH between
5.3 and 5.7 in samples until the TOG
removal of 0.3 mg/1 per 10 mg/1 alum
added or equivalent addition of iron,
coagulant is reached.
(iii) The system may operate at any
coagulant dose or pH necessary
(consistent with other NPDWRs) to
achieve the minimum TOG percent
removal determined under paragraph
(a)(3)(i) of this section.
(iv) If the TOG removal is consistently
less than 0.3 mg/1 of TOG per 10 mg/1
of incremental alum dose at all dosages
of alum or equivalent addition of iron
.coagulant, the water is deemed to
contain TOG not amenable to enhanced
coagulation. The system may then apply
to the State for a waiver of enhanced
coagulation requirements.
(b) Compliance calculations: (1)
Subpart H systems other than those
identified in paragraph (b)(2) of this
section shall comply with the TOG
compliance requirements contained in
paragraph (a) of this section. Systems
shall calculate compliance quarterly by
the following method:
(i) Determine actual monthly TOG
percent removal* equal to: (l-(treated
water TOC/source water TOG)) x 100.
(ii) Determine the required monthly
TOG percent removal (from either the
table in paragraph (a)(2)(i)(E) of this
section or from paragraph (a)(3) of this
section).
(iii) Divide paragraph (b)(l)(i) of this
section by paragraph (b)(2)(ii) of this
section.
(iv) Add together the results of
paragraph (b)(l)(iii) of this section for
the last 12 months and divide by 12.
(v) If paragraph (b)(l)(iv) of this
section <1.00, the system is not in
compliance with the TOG percent
removal requirements.
(2) Subpart H systems using
conventional treatment but not
operating enhanced coagulation must
comply with the DBF precursor
treatment technique identified in
paragraphs (a)(l) (i) through (iv) of this
section.
(c) Treatment technique requirements
for Disinfection Byproduct Precursors.
The Administrator identifies the
following as treatment techniques to
control the level of disinfection
byproduct precursors in drinking water
treatment and distribution systems: For
Subpart H systems using conventional
treatment, enhanced coagulation or
enhanced softening.
PART 142—NATIONAL PRIMARY
DRINKING WATER REGULATIONS
IMPLEMENTATION
1. The authority citation for Part 141
continues to read as follows:
Authority: 42 U.S.C. 300g, 300g-l, 300g-
2 300g-3, 300g-4, 300g-5, 300g-6, 300J-4
and 300J-9.
2. Section 142.14 is amended by
adding paragraphs (d)(12) and (d)(13) to
read as follows:
§142.14 Records kept by states.
*****
(d)* * *
(12) Records of the currently
applicable or most recent State
determinations, including all supporting
information and an explanation of the
technical basis for each decision, made
under the following provisions of 40
CFR part 141, subpart L for the control
of disinfectants and disinfection
byproducts. These records must also
include interim measures toward
installation.
(i) States must keep records of
systems that are installing GAG or
membrane technology in accordance
with § 141.64(d)(3). These records must
include the date by which the system is
required to have completed installation.
(ii) States must keep records of
systems that are required, by the State,
to meet alternative minimum TOG
removal requirements in accordance
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38829
with § 141.135(a}(3). Records must
include the alternative limits and
rationale for establishing such limits.
(iii) States must keep records of
Subpart H systems using conventional
treatment meeting any of the enhanced
coagulation or enhanced softening
exemption criteria in § 141.135(a)(l).
(iv) States must keep a register of
qualified operators that have met the
State requirements developed under
§ 142.16(f)(2).
(13) Records of systems with multiple
wells considered to be one treatment
plant in accordance with
3. Section 142.15 is amended by
adding paragraphs (c)(5) through (c)(8)
to read as follows:
§142.15 Reports by states.
*****
(c) * * *
(5) Reports of systems that must meet
alternative minimum TOG removal
levels and the alternate performance
criteria specified in § 141.135(a)(3).
(6) Any extensions granted for
compliance with MCLs in § 141.64 as
allowed by § 141.64(c)(3) and the date
by which compliance must be achieved.
(7) A list of systems required to
monitor for various disinfectants and
disinfection byproducts.
(8) A list of all systems using multiple
ground water wells which draw from
the same aquifer and are considered a
single source for monitoring purposes.
4. Section 142.16 is amended by
adding paragraph (fj to read as follows:
§ 142.16 Special primacy requirements.
*****
(f) Requirements for States to adopt 40
CFR part 141, subpart L. In addition to
the general primacy requirements
elsewhere in this part, including the
requirement that State regulations be at
least as stringent as federal
requirements, an application for
approval of a State program revision
that adopts 40 CFR part 141, subpart L,
must contain a description of how the
State will accomplish the following
program requirements:
(1) Section 141.64(d)(3) (interim
treatment requirements). Determine the
interim treatment requirements for those
systems electing to install GAG or
membrane filtration and granted
additional time to comply with
§141.64(a).
(2) Section 141.130(c) (qualification of
operators). Qualify operators of
community and nontransient-
noncommunity public water systems
subject to this regulation. Qualification
requirements established for operators
of systems subject to 40 CFR part 141,
Subpart H—Filtration and Disinfection,
may be used in whole or in part to
establish operator qualification
requirements for meeting requirements
of subpart L of this part if the State
determines that the requirements of
subpart H of this part are appropriate
and applicable for meeting requirements
of subpart L of this part.
(3) Approve alternative TOC removal
levels, as allowed under the provisions
of§141.135(a).
(4) Section 141.133(a)(2) (State
approval of parties to conduct analyses).
Approve parties to conduct pH,
alkalinity, temperature, and residual
disinfectant concentration
measurements. The State's process for
approving parties performing water
quality measurements for systems
subject to requirements of subpart H of
this part may be used for approving
parties measuring water quality
parameters for systems subject to
requirements of subpart L of this part,
if the State determines the process is
appropriate and applicable.
(5) Section 144.133(a)(2) (DPD
colorimetric test kits). Approve DPD
colorimetric test kits for free and total
chlorine measurements. Approval
granted under § 141.74(a)(5) for the use
of such test kits for free chlorine testing
would be considered acceptable
approval for the use of DPD test kits in
measuring free chlorine residuals as
required in subpart L of this part.
(6) Section 141.133(b)(3)(ii)(C)
(multiple wells as a single source).
Define the criteria to determine if
multiple wells are being drawn from a
single aquifer and therefore be
considered a single source for
compliance with monitoring
requirements.
[FR Doc. 94-17651 Filed 7-28-94; 8:45 am]
BILLING CODE e560-60-P
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