Document ID: EPA-HQ-OW-2012-0217-0071
Agency: epa
Document Type: Notice
Title: Drinking Water Contaminant Candidate List 4-Final
Posted Date: 2016-11-17T05:00Z

[Federal Register Volume 81, Number 222 (Thursday, November 17, 2016)]
[Notices]
[Pages 81099-81114]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-27667]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OW-2012-0217; FRL-9955-27-OW]

Drinking Water Contaminant Candidate List 4--Final

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is publishing a 
final list of contaminants that are currently not subject to any 
proposed or promulgated national primary drinking water regulation. 
These contaminants are known or anticipated to occur in public water 
systems and may require regulation under the Safe Drinking Water Act 
(SDWA). This list is the Fourth Contaminant Candidate List (CCL 4) 
published by EPA since the SDWA amendments of 1996. This Final CCL 4 
includes 97 chemicals or chemical groups and 12 microbial contaminants.

FOR FURTHER INFORMATION CONTACT: For information on chemical 
contaminants contact Meredith Russell, Office of Ground Water and 
Drinking Water, Standards and Risk Management Division, at (202) 564-
0814 or email russell.meredith@epa.gov. For information on microbial 
contaminants contact Hannah Holsinger, Office of Ground Water and 
Drinking Water, Standards and Risk Management Division, at (202) 564-
0403 or email holsinger.hannah@epa.gov. For general information contact 
the EPA Safe Drinking Water Hotline at (800) 426-4791. The Safe 
Drinking Water Hotline is open Monday through Friday, excluding legal 
holidays, from 10 a.m. to 4 p.m. eastern time.

Abbreviations and Acronyms

CASRN--Chemical Abstract Services Registry Number
CCL--Contaminant Candidate List
CCL 1--EPA's First Contaminant Candidate List
CCL 2--EPA's Second Contaminant Candidate List
CCL 3--EPA's Third Contaminant Candidate List
CCL 4--EPA's Fourth Contaminant Candidate List
CFR--Code of Federal Regulations
CIS--Contaminant Information Sheet
DWC--Drinking Water Committee
EPA--United States Environmental Protection Agency
ESA--Ethanesulfonic acid
FR--Federal Register
HPC--Heterotrophic Plate Count
HRL--Health Reference Level
MCL--Maximum Contaminant Level
MCLG--Maximum Contaminant Level Goal
MRL-- Minimum Reporting Level
NAWQA--National Water-Quality Assessment
NDEA--N-Nitrosodiethylamine
NDMA--N-nitrosodimethylamine
NDPA--N-Nitroso-di-n-propylamine
NDPhA--N-Nitrosodiphenylamine
NDWAC--National Drinking Water Advisory Council
NIRS--National Inorganics and Radionuclides Survey
NRC--National Academy of Science's National Research Council
NPDWR--National Primary Drinking Water Regulation
NPYR--N-nitrosopyrrolidine
PCCL 4--Preliminary Contaminant Candidate List 4
PFOA--Perfluorooctanoic Acid
PFOS--Perfluorooctane Sulfonic Acid
PWS--Public Water System
RD--Regulatory Determination
RD 1--Regulatory Determination 1
RD 2--Regulatory Determination 2
RD 3--Regulatory Determination 3
SAB--Science Advisory Board
SDWA--Safe Drinking Water Act
SS--Screening Survey
TRI--Toxics Release Inventory
UCMR 1--First Unregulated Contaminant Monitoring Rule
UCMR 2--Second Unregulated Contaminant Monitoring Rule
UCMR 3--Third Unregulated Contaminant Monitoring Rule
USGS--United States Geological Survey
WBDO--Waterborne Disease Outbreaks

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. General Information
    A. Does this action apply to me?
    B. How can I get copies of this document and other related 
information?
    1. Docket
    2. Electronic Access
    C. What is the purpose of this action?

[[Page 81100]]

    D. Statutory Requirements for CCL, Regulatory Determination and 
Unregulated Contaminant Monitoring
    1. Interrelationship of the CCL, Regulatory Determination and 
Unregulated Contaminant Monitoring
    2. Contaminant Candidate List
    3. Unregulated Contaminant Monitoring
    4. Regulatory Determinations
    E. Where can I find information on previous CCLs and Regulatory 
Determinations?
    1. Summary of Previous CCLs and Regulatory Determinations
    2. Summary of the CCL 3
    3. Summary of the Regulatory Determination 3
II. What is on EPA's Drinking Water Contaminant Candidate List 4?
    The Final CCL 4 and a Cross-Walk of Contaminants Between the CCL 
4, Regulatory Determination 3, and UCMRs
III. Summary of the Approach Used To Identify and Evaluate 
Candidates for the Draft CCL 4
    A. Carry Forward of CCL 3 Contaminants
    B. Summary and Evaluation of CCL 4 nominated contaminants
    1. CCL 4 Nominations Summary
    2. How Nominated Contaminants Were Evaluated for the Draft CCL 4
    C. Evaluation of Previous Negative Regulatory Determinations
IV. What comments did EPA receive on the Draft CCL 4 and how did the 
Agency respond?
    A. Recommendations From the EPA Science Advisory Board
    B. Public Comments
    1. General Comments on CCL 4
    2. Chemical Contaminants
    a. Contaminants With Release Data
    b. Cyanotoxins
    c. Perfluorinated Compounds (PFOA and PFOS)
    d. Pesticides
    e. Manganese
    f. Nonylphenol
    3. Microbial Contaminants
    a. Overall Process Comments
    b. Pathogens for Inclusion
    c. Pathogens for Exclusion
V. Data Needs for CCL 4 Contaminants
    Categorization of Contaminants
    A. Health Effects
    B. Occurrence
    C. Analytical Methods
VI. Next Steps and Future Contaminant Candidate Lists
VII. References

I. General Information

A. Does this action apply to me?

    The Final CCL 4 will not impose any requirements on anyone. 
Instead, this action notifies interested parties of the EPA's Final CCL 
4 of unregulated drinking water contaminants and provides a summary of 
the major comments received on the February 4, 2015, Draft CCL 4 
Federal Register notice and EPA's responses (80 FR 6076 (USEPA, 
2015a)).

B. How can I get copies of this document and other related information?

1. Docket
    EPA has established a docket for this action under Docket ID No. 
EPA-HQ-OW-2012-0217. Although listed in the index, some information is 
not publicly available, e.g., CBI or other information whose disclosure 
is restricted by statute. Certain other material, such as copyrighted 
material, will be publicly available only in hard copy. Publicly 
available docket materials are available either electronically through 
www.regulations.gov or in hard copy at the Water Docket, EPA/DC, EPA 
West, Room 3334, 1301 Constitution Ave. NW., Washington, DC 20004. The 
Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The telephone number for the Public 
Reading Room is (202) 566-1744, and the telephone number for the EPA 
Docket Center is (202) 566-2426.
2. Electronic Access
    You may access this Federal Register document electronically from 
the Government Publishing Office under the Federal Register listings at 
FDsys (http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR).

C. What is the purpose of this action?

    The Safe Drinking Water Act (SDWA), as amended in 1996, requires 
EPA to publish a list every five years of currently unregulated 
contaminants that may pose risks for drinking water (referred to as the 
Contaminant Candidate List, or CCL). This list is subsequently used to 
make regulatory determinations on whether or not to regulate at least 
five contaminants from the CCL with national primary drinking water 
regulations (NPDWRs) ((SDWA section 1412(b)(1)). The purpose of today's 
action is to present EPA's final list of contaminants on the CCL 4, a 
summary of the major public comments received on the Draft CCL 4 and 
EPA's responses. Today's action only addresses the Final CCL 4. 
Regulatory Determination (RD) for contaminants on the CCL is a separate 
agency action.

D. Statutory Requirements for CCL, Regulatory Determination and 
Unregulated Contaminant Monitoring

1. Interrelationship of the CCL, Regulatory Determination and 
Unregulated Contaminant Monitoring
    Under the 1996 amendments to SDWA, Congress established a risk-
based approach for determining which contaminants would become subject 
to drinking water standards. The approach includes three components, 
the CCL, the Unregulated Contaminant Monitoring Rule (UCMR), and RD. In 
preparing the CCL, EPA screens and evaluates unregulated contaminants 
to identify those that may require future drinking water regulations. 
Inclusion on the CCL does not mean that any particular contaminant will 
necessarily be regulated in the future. The UCMR provides a mechanism 
to obtain nationally representative occurrence data for unregulated 
contaminants. The data provided by UCMR is one of the primary sources 
of occurrence information used to evaluate contaminants in the RD 
process.
    Under the RD process, EPA evaluates UCMR and other occurrence data 
along with health effects data for contaminants on the CCL to see which 
ones present the greatest public health concern and have sufficient 
information for the agency to make a regulatory determination. EPA must 
make regulatory determinations for at least five contaminants listed on 
the CCL every five years. Today's action addresses only the CCL 4 and 
not the UCMR or RD stages of the SDWA contaminant regulatory 
development process.
2. Contaminant Candidate List
    Section 1412(b)(1) of the SDWA, as amended in 1996, requires EPA to 
publish the CCL every five years. The SDWA specifies that the list must 
include contaminants that are not subject to any proposed or 
promulgated NPDWRs, are known or anticipated to occur in public water 
systems (PWSs), and may require regulation under the SDWA. The 
unregulated contaminants considered for listing shall include, but not 
be limited to, hazardous substances identified in section 101(14) of 
the Comprehensive Environmental Response, Compensation, and Liability 
Act of 1980, and substances registered as pesticides under the Federal 
Insecticide, Fungicide, and Rodenticide Act.
    The SDWA directs the agency to consider the health effects and 
occurrence information for unregulated contaminants to identify those 
contaminants that present the greatest public health concern related to 
exposure from drinking water. The statute further directs the agency to 
take into consideration the effect of contaminants upon subgroups that 
comprise a meaningful portion of the general population (such as 
infants, children, pregnant women, the elderly and individuals with a 
history of serious illness or other subpopulations) that are 
identifiable as being at greater risk of

[[Page 81101]]

adverse health effects due to exposure to contaminants in drinking 
water than the general population. Additionally, EPA's 1995 Policy on 
Evaluating Health Risks to Children states that the agency will 
consider the risks to infants and children consistently and explicitly 
as a part of risk assessments generated during its decision-making 
process, including the setting of standards to protect public health 
(USEPA, 1995a). EPA considers age-related subgroups as ``lifestages'' 
in reference to a distinguishable time frame in an individual's life, 
characterized by unique and relatively stable behavioral and/or 
physiological characteristics that are associated with development and 
growth. Thus, childhood is viewed as a sequence of lifestages, from 
conception through fetal development, infancy and adolescence (see 
http://www.epa.gov/children/early-life-stages).
3. Unregulated Contaminant Monitoring
    Section 1445(a)(2) of the SDWA mandates that EPA promulgate 
regulations (known as the Unregulated Contaminant Monitoring Rule or 
UCMR) to establish criteria for a monitoring program for unregulated 
contaminants. This section, as amended in 1996, requires that once 
every five years, EPA issue a list of no more than 30 unregulated 
contaminants to be monitored by PWSs. SDWA requires that EPA enter the 
monitoring data into the agency's publicly available National 
Contaminant Occurrence Database. EPA's UCMR program must ensure that 
systems serving a population larger than 10,000 people, as well as a 
nationally representative sample of PWSs serving 10,000 or fewer 
people, are required to monitor.
4. Regulatory Determination
    Section 1412(b)(1)(B)(ii) of the SDWA, as amended in 1996, requires 
EPA at five year intervals, to make determinations of whether or not to 
regulate no fewer than five contaminants from the CCL. EPA evaluates 
the CCL contaminants with sufficient health effects and occurrence 
information to determine whether a regulation is required or not 
required. The 1996 SDWA Amendments specify three criteria to determine 
whether a contaminant may require regulation:
     The contaminant may have an adverse effect on the health 
of persons;
     the contaminant is known to occur or there is a 
substantial likelihood that the contaminant will occur in PWSs with a 
frequency and at levels of public health concern; and
     in the sole judgment of the Administrator, regulation of 
such contaminant presents a meaningful opportunity for health risk 
reduction for persons served by PWSs.
    If EPA determines that these three statutory criteria are met and 
makes a final determination to regulate a contaminant, the agency has 
24 months to publish a proposed maximum contaminant level goal \1\ 
(MCLG) and NPDWR.\2\ After the proposal, the agency has 18 months to 
publish and promulgate a final MCLG and NPDWR (SDWA section 
1412(b)(1)(E)).\3\ For those contaminants without sufficient 
information to allow the agency to make a regulatory determination, EPA 
encourages research to provide the information needed to determine 
whether to regulate the contaminant.
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    \1\ The MCLG is the ``maximum level of a contaminant in drinking 
water at which no known or anticipated adverse effect on the health 
of persons would occur, and which allows an adequate margin of 
safety. MCLGs are non-enforceable health goals.'' (40 CFR 141.2; 42 
U.S.C. 300g-1)
    \2\ An NPDWR is a legally enforceable standard that applies to 
public water systems. An NPDWR sets a legal limit (called a maximum 
contaminant level or MCL) or specifies a certain treatment technique 
for public water systems for a specific contaminant or group of 
contaminants. The MCL is the highest level of a contaminant that is 
allowed in drinking water and is set as close to the MCLG as 
feasible, using the best available treatment technology and taking 
cost into consideration.
    \3\ The statute authorizes a nine month extension of this 
promulgation date.
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E. Where can I find information on previous CCLs, UCMRs, and Regulatory 
Determinations

1. Summary of previous CCLs, UCMRs, and Regulatory Determinations
    A brief summary of CCL 1, CCL 2, Regulatory Determination 1 (RD 1) 
and Regulatory Determination 2 (RD 2) was published in the Federal 
Register for the Draft CCL 4 notice (80 FR 6076, February 4, 2015 
(USEPA, 2015a)). Information on previous UCMRs, can be found at the 
following Web site: https://www.epa.gov/dwucmr.
2. Summary of the CCL 3
    The CCL 3 included 104 chemicals or chemical groups and 12 
microbiological contaminants. In developing the CCL 3, EPA implemented 
an improved process from the process used for CCL 1 and CCL 2. This new 
process built on evaluations used for previous CCLs and was based on 
substantial expert input and recommendations from the National Academy 
of Sciences' National Research Council (NRC) and the National Drinking 
Water Advisory Council (NDWAC). EPA used a multi-step CCL process to 
identify contaminants for inclusion on the Final CCL 3. The key steps 
included:
     Identifying a broad universe of potential drinking water 
contaminants (called the CCL 3 Universe). EPA initially considered 
approximately 7,500 potential chemical and microbial contaminants (more 
information on the identification of the CCL 3 Universe can be found in 
USEPA, 2009a and USEPA, 2009b).
     Applying screening criteria to the universe, EPA 
identified almost 600 of those contaminants that should be further 
evaluated (the preliminary CCL or PCCL) based on a contaminant's 
potential to occur in PWSs and the potential for public health concern 
(more information on the CCL 3 screening process can be found in USEPA, 
2009c and USEPA, 2009d).
     Selecting the final list of 116 contaminants from the PCCL 
to include on the CCL based on more detailed evaluation of occurrence 
and health effects and expert judgment as well as public input (this 
step of the CCL 3 process is called the classification process and more 
information can be found in USEPA, 2009e and USEPA, 2009f).
    The CCL 3 interpreted the criterion that contaminants are known or 
anticipated to occur in public water systems broadly. In evaluating 
this criterion, EPA considered not only public water system monitoring 
data, but also data on concentrations in ambient surface and ground 
waters, releases to the environment (e.g., Toxics Release Inventory 
(TRI)), and production. While such data may not establish conclusively 
that contaminants are known to occur in public water systems, EPA 
believes these data are sufficient to anticipate that contaminants may 
occur in public water systems and support their inclusion on the CCL. 
The agency considered adverse health effects that may pose a greater 
risk to life stages and other sensitive groups which represent a 
meaningful portion of the population. Adverse health effects associated 
with infants, children, pregnant women, the elderly, and individuals 
with a history of serious illness were evaluated as part of the 
screening and classification processes. A detailed summary of the CCL 3 
process can be found in the Draft CCL 3 (73 FR 9628, February 21, 2008 
(USEPA, 2008a) and Final CCL 3 (74 FR 51850, October 8, 2009 (USEPA, 
2009a)) Federal Register notices.
3. Summary of the Regulatory Determination 3
    EPA published the Announcement of Final Regulatory Determinations 
for Contaminants on CCL 3 in the Federal Register on January 4, 2016 
(81 FR 13

[[Page 81102]]

(USEPA, 2016a)). The agency made final determinations not to regulate 
four contaminants: 1, 3-dinitrobenzene; dimethoate; terbufos; and 
terbufos sulfone. The agency delayed the final regulatory determination 
for strontium in order to consider additional data and decide whether 
there is a meaningful opportunity for health risk reduction by 
regulating strontium in drinking water. These five contaminants are not 
included on the Final CCL 4.
    This section provides an overview of the process used for the Third 
Regulatory Determination (RD 3). A summary of the process can be found 
in the Federal Register notice announcing the preliminary regulatory 
determinations (79 FR 62716, October 24, 2014 (USEPA, 2014a)), and a 
detailed explanation of this process can be found in the ``Protocol for 
the Regulatory Determination 3'' support document (USEPA, 2014b). This 
overview of the RD process is provided to give an understanding of how 
contaminants have previously been evaluated after they have been listed 
on past CCLs. The RD 4 process may continue to follow this process 
although it is possible that some modifications may be made to this 
process. The RD process occurs subsequent to a Final CCL, and is a 
separate agency action. The RD 3 process, was divided into three 
phases: (1) The Data Availability Phase, (2) the Data Evaluation Phase 
and (3) the Regulatory Determination Assessment Phase.
    The purpose of the first phase, the Data Availability Phase, was to 
determine if the agency may have sufficient data to characterize the 
potential health effects and known or likely occurrence in drinking 
water. With regard to sufficient health effects data used to identify 
potential adverse health effect(s), the agency considered whether a 
peer reviewed health risk assessment was available or in process from 
an EPA or a comparable non-EPA source. In regard to sufficient 
occurrence data, the agency considered the availability of nationally 
representative finished water data and whether other finished water 
data were available that indicated known and/or likely occurrence in 
PWSs. After conducting the health and occurrence data availability 
assessments, the agency identified those contaminants and contaminant 
groups that meet the following Phase 1 data availability criteria:
    (a) A peer reviewed health assessment is available or in process, 
and
    (b) A widely available analytical method for monitoring exists, and
    (c) Either nationally representative finished water occurrence data 
are available, or other finished water occurrence data shows occurrence 
at levels greater than one-half of the CCL 3 health reference level 
(HRL).
    If a contaminant met these three criteria, it was placed on a 
``short list'' and proceeded to Phase 2. From the 116 CCL 3 
contaminants, the agency identified a short list of 37 contaminants (35 
CCL 3 contaminants and two non-CCL 3 contaminants \4\) to further 
evaluate in the second phase.
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    \4\ The non-CCL 3 contaminants, N-Nitroso-di-n-butylamine (NDBA) 
and N-Nitrosomethylethylamine (NMEA), were included because they are 
part of a larger group (nitrosamines) that also includes a number of 
CCL 3 contaminants.
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    During the second phase, the Data Evaluation Phase, the agency 
further evaluated each of the 37 contaminants on the short list to 
identify those that had sufficient data (or were expected to have 
sufficient data) for EPA to assess the three statutory criteria listed 
in section I.D.4 of this notice.
    To identify the contaminants that present the greatest public 
health concern, the agency specifically focused its efforts on 
identifying those contaminants or contaminant groups that are occurring 
or have substantial likelihood to occur at levels and frequencies of 
public health concern, based on the best available peer reviewed data. 
In addition to health and occurrence information data assessed in Phase 
1, the agency collected additional health and occurrence data and more 
thoroughly evaluated this information to identify a list of 
contaminants that should proceed to Phase 3. If the agency found that 
sufficient data were not available or not likely to be available to 
evaluate the three statutory criteria during the first and second 
phases, then the contaminant was not considered a candidate for making 
a regulatory determination during the current cycle, and the agency 
will conduct research, collect information or find other avenues to 
fill the data and information gaps. For these contaminants, additional 
data that becomes available in the future may be considered for future 
CCLs and RDs.
    If sufficient data were available for a contaminant to characterize 
the potential health effects and known or likely occurrence in drinking 
water, the contaminant was evaluated against the three statutory 
criteria (listed in section I.D.4) in the third phase of the process, 
the Regulatory Determination Assessment Phase.

II. What is on EPA's Drinking Water Contaminant Candidate List 4?

The Final CCL 4 and a Cross-Walk of Contaminants Between the CCL 4, 
Regulatory Determination 3, and UCMRs

    The Final CCL 4 includes 97 chemicals or chemical groups and 12 
microbes listed in Exhibit 1. Exhibit 1 also shows chemical abstract 
service registry numbers (CASRNs) of the contaminants on the Final CCL 
4 and their status across other EPA programs related to CCL (i.e., RD 
and UCMR). The list of contaminants is presented by CASRN when 
available, common name, or by aggregate groupings (e.g., cyanotoxins). 
Further data and information for the contaminants included on the CCL 4 
are available in the technical support documents and Contaminant 
Information Sheets available on EPA's CCL 4 Web site and in the docket 
for this action (EPA-HQ-OW-2012-0217). All contaminants listed on the 
Final CCL 4 were also included on CCL 3, with the exception of 
manganese and nonylphenol, which were nominated by the public and added 
to the CCL 4. Twenty-eight CCL 4 chemicals that were carried forward 
from CCL 3 had been further analyzed and evaluated under the RD 3 
process and included on the RD 3 Short List (further described in 
section I.E.3. of this notice). The RD 3 process also included an 
evaluation of occurrence data from the UCMR 2 for 13 CCL 4 chemicals. 
Twenty-one CCL 4 contaminants were monitored under UCMR 3 (19 chemicals 
and 2 microbes). The UCMR data will be used to further evaluate CCL 4 
contaminants during the RD 4 process. In addition, EPA has proposed 
gathering occurrence data for 16 individual CCL 4 chemicals and several 
cyanotoxins, including anatoxin-a, cylindrospermopsin, nodularin, total 
microcystin and several microcystin congeners under the proposed UCMR 
4.

[[Page 81103]]

                       Exhibit 1--Contaminants on the Final CCL 4, Regulatory Determination 3, UCMR 2, UCMR 3 and Proposed UCMR 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          CCL 4                                                           Proposed  UCMR
                 CASRN                   Chemical or chemical group     nomination    RD 3 short list       UCMR 2           UCMR 3           4 \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
630-20-6...............................  1,1,1,2-Tetrachloroethane.  ...............               X   ...............  ...............  ...............
75-34-3................................  1,1-Dichloroethane........  ...............  ...............  ...............               X   ...............
96-18-4................................  1,2,3-Trichloropropane....  ...............               X   ...............               X   ...............
106-99-0...............................  1,3-Butadiene.............  ...............  ...............  ...............               X   ...............
123-91-1...............................  1,4-Dioxane...............  ...............               X   ...............               X   ...............
57-91-0................................  17 alpha-Estradiol........  ...............  ...............  ...............  ...............  ...............
71-36-3................................  1-Butanol.................  ...............  ...............  ...............  ...............               X
109-86-4...............................  2-Methoxyethanol..........  ...............  ...............  ...............  ...............               X
107-18-6...............................  2-Propen-1-ol.............  ...............  ...............  ...............  ...............               X
16655-82-6.............................  3-Hydroxycarbofuran.......  ...............  ...............  ...............  ...............  ...............
101-77-9...............................  4,4'-Methylenedianiline...  ...............  ...............  ...............  ...............  ...............
30560-19-1.............................  Acephate..................  ...............               X   ...............  ...............  ...............
75-07-0................................  Acetaldehyde..............  ...............  ...............  ...............  ...............  ...............
60-35-5................................  Acetamide.................  ...............  ...............  ...............  ...............  ...............
34256-82-1.............................  Acetochlor................  ...............               X                X   ...............  ...............
187022-11-3............................  Acetochlor ethanesulfonic   ...............               X                X   ...............  ...............
                                          acid (ESA).
194992-44-4............................  Acetochlor oxanilic acid    ...............               X                X   ...............  ...............
                                          (OA).
107-02-8...............................  Acrolein..................  ...............  ...............  ...............  ...............  ...............
142363-53-9............................  Alachlor ethanesulfonic     ...............               X                X   ...............  ...............
                                          acid (ESA).
171262-17-2............................  Alachlor oxanilic acid      ...............               X                X   ...............  ...............
                                          (OA).
319-84-6...............................  alpha-                                   X   ...............  ...............  ...............               X
                                          Hexachlorocyclohexane.
62-53-3................................  Aniline...................  ...............  ...............  ...............  ...............  ...............
741-58-2...............................  Bensulide.................  ...............  ...............  ...............  ...............  ...............
100-44-7...............................  Benzyl chloride...........  ...............  ...............  ...............  ...............  ...............
25013-16-5.............................  Butylated hydroxyanisole..  ...............  ...............  ...............  ...............               X
133-06-2...............................  Captan....................  ...............  ...............  ...............  ...............  ...............
14866-68-3.............................  Chlorate..................  ...............               X   ...............               X   ...............
74-87-3................................  Chloromethane (Methyl       ...............  ...............  ...............               X   ...............
                                          chloride).
110429-62-4............................  Clethodim.................  ...............  ...............  ...............  ...............  ...............
7440-48-4..............................  Cobalt....................  ...............               X   ...............               X   ...............
80-15-9................................  Cumene hydroperoxide......  ...............  ...............  ...............  ...............  ...............
N/A....................................  Cyanotoxins \a\...........               X   ...............  ...............  ...............               X
141-66-2...............................  Dicrotophos...............  ...............  ...............  ...............  ...............  ...............
55290-64-7.............................  Dimethipin................  ...............  ...............  ...............  ...............               X
330-54-1...............................  Diuron....................  ...............               X   ...............  ...............  ...............
517-09-9...............................  Equilenin.................  ...............  ...............  ...............  ...............  ...............
474-86-2...............................  Equilin...................  ...............  ...............  ...............               X   ...............
114-07-8...............................  Erythromycin..............  ...............  ...............  ...............  ...............  ...............
50-28-2................................  Estradiol (17-beta          ...............  ...............  ...............               X   ...............
                                          estradiol).
50-27-1................................  Estriol...................  ...............  ...............  ...............               X   ...............
53-16-7................................  Estrone...................  ...............  ...............  ...............               X   ...............
57-63-6................................  Ethinyl Estradiol (17-      ...............  ...............  ...............               X   ...............
                                          alpha ethynyl estradiol).
13194-48-4.............................  Ethoprop..................  ...............  ...............  ...............  ...............               X
107-21-1...............................  Ethylene glycol...........  ...............  ...............  ...............  ...............  ...............
75-21-8................................  Ethylene Oxide............  ...............  ...............  ...............  ...............  ...............
96-45-7................................  Ethylene thiourea.........  ...............  ...............  ...............  ...............  ...............
50-00-0................................  Formaldehyde..............  ...............  ...............  ...............  ...............  ...............
7440-56-4..............................  Germanium.................  ...............  ...............  ...............  ...............               X
74-97-5................................  Halon 1011                  ...............  ...............  ...............               X   ...............
                                          (bromochloromethane).
75-45-6................................  HCFC-22...................  ...............  ...............  ...............               X   ...............
110-54-3...............................  Hexane....................  ...............  ...............  ...............  ...............  ...............
302-01-2...............................  Hydrazine.................  ...............  ...............  ...............  ...............  ...............
7439-96-5..............................  Manganese.................               X   ...............  ...............  ...............               X
72-33-3................................  Mestranol.................  ...............  ...............  ...............  ...............  ...............
10265-92-6.............................  Methamidophos.............  ...............  ...............  ...............  ...............  ...............
67-56-1................................  Methanol..................  ...............  ...............  ...............  ...............  ...............
74-83-9................................  Methyl bromide              ...............               X   ...............               X   ...............
                                          (Bromomethane).
1634-04-4..............................  Methyl tert-butyl ether...               X                X   ...............  ...............  ...............
51218-45-2.............................  Metolachlor...............  ...............               X                X   ...............  ...............
171118-09-5............................  Metolachlor ethanesulfonic  ...............               X                X   ...............  ...............
                                          acid (ESA).
152019-73-3............................  Metolachlor oxanilic acid   ...............               X                X   ...............  ...............
                                          (OA).
7439-98-7..............................  Molybdenum................  ...............               X   ...............               X   ...............
98-95-3................................  Nitrobenzene..............  ...............               X   ...............  ...............  ...............
55-63-0................................  Nitroglycerin.............  ...............  ...............  ...............  ...............  ...............
872-50-4...............................  N-Methyl-2-pyrrolidone....  ...............  ...............  ...............  ...............  ...............
55-18-5................................  N-Nitrosodiethylamine       ...............               X                X   ...............  ...............
                                          (NDEA).
62-75-9................................  N-Nitrosodimethylamine      ...............               X                X   ...............  ...............
                                          (NDMA).
621-64-7...............................  N-Nitroso-di-n-propylamine  ...............               X                X   ...............  ...............
                                          (NDPA).
86-30-6................................  N-Nitrosodiphenylamine....  ...............               X   ...............  ...............  ...............

[[Page 81104]]

 
930-55-2...............................  N-Nitrosopyrrolidine        ...............               X                X   ...............  ...............
                                          (NPYR).
25154-52-3 \b\.........................  Nonylphenol...............               X   ...............  ...............  ...............  ...............
68-22-4................................  Norethindrone (19-          ...............  ...............  ...............  ...............  ...............
                                          Norethisterone).
103-65-1...............................  n-Propylbenzene...........  ...............  ...............  ...............  ...............  ...............
95-53-4................................  o-Toluidine...............  ...............  ...............  ...............  ...............               X
75-56-9................................  Oxirane, methyl-..........  ...............  ...............  ...............  ...............  ...............
301-12-2...............................  Oxydemeton-methyl.........  ...............  ...............  ...............  ...............  ...............
42874-03-3.............................  Oxyfluorfen...............  ...............  ...............  ...............  ...............               X
1763-23-1..............................  Perfluorooctane sulfonic    ...............               X   ...............               X   ...............
                                          acid (PFOS).
335-67-1...............................  Perfluorooctanoic acid                   X                X   ...............               X   ...............
                                          (PFOA).
52645-53-1.............................  Permethrin................               X   ...............  ...............  ...............               X
41198-08-7.............................  Profenofos................  ...............  ...............  ...............  ...............               X
91-22-5................................  Quinoline.................  ...............  ...............  ...............  ...............               X
121-82-4...............................  RDX.......................  ...............               X                X   ...............  ...............
135-98-8...............................  sec-Butylbenzene..........  ...............  ...............  ...............  ...............  ...............
107534-96-3............................  Tebuconazole..............  ...............  ...............  ...............  ...............               X
112410-23-8............................  Tebufenozide..............  ...............  ...............  ...............  ...............  ...............
13494-80-9.............................  Tellurium.................  ...............  ...............  ...............  ...............  ...............
59669-26-0.............................  Thiodicarb................  ...............  ...............  ...............  ...............  ...............
23564-05-8.............................  Thiophanate-methyl........  ...............  ...............  ...............  ...............  ...............
26471-62-5.............................  Toluene diisocyanate......  ...............  ...............  ...............  ...............  ...............
78-48-8................................  Tribufos..................  ...............  ...............  ...............  ...............               X
121-44-8...............................  Triethylamine.............  ...............  ...............  ...............  ...............  ...............
76-87-9................................  Triphenyltin hydroxide      ...............  ...............  ...............  ...............  ...............
                                          (TPTH).
51-79-6................................  Urethane..................  ...............  ...............  ...............  ...............  ...............
7440-62-2..............................  Vanadium..................  ...............               X   ...............               X   ...............
50471-44-8.............................  Vinclozolin...............  ...............  ...............  ...............  ...............  ...............
137-30-4...............................  Ziram.....................  ...............  ...............  ...............  ...............  ...............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Anatoxin-a, cylindrospermopsin, nodularin, total microcystin and several microcystin congeners are proposed for monitoring under UCMR 4.
\b\ The organization that nominated ``nonylphenol'' for CCL 4 provided the CASRN of 25451-52-3. The name ``nonylphenol'' does not allow for a definitive
  identification of chemical structure since nonylphenol can exhibit two forms of isomerism. There are at least five CASRNs known to be associated with
  ``nonylphenol'': In addition to 25154-52-3 (which represents n-nonylphenol with the ortho-, meta-, or para-substitution unspecified), other CASRNs
  include: 104-40-5 (4-n-nonylphenol); 84852-15-3 (4-nonylphenol, branched); 91672-41-2 (2-nonylphenol, branched); and 139-84-4 (3-n-nonylphenol). None
  of these five CASRNs is adequately general enough to represent both forms of isomerism. For the sake of consistency, the CASRN provided by the
  nominator was selected and the additional possible CASRNs and structures are delineated here.

------------------------------------------------------------------------
                                             CCL 4
               Microbe *                   nomination         UCMR 3
------------------------------------------------------------------------
Adenovirus............................               X   ...............
Caliciviruses.........................  ...............               X
Campylobacter jejuni..................  ...............  ...............
Enterovirus...........................  ...............               X
Escherichia coli (O157)...............  ...............  ...............
Helicobacter pylori...................  ...............  ...............
Hepatitis A virus.....................  ...............  ...............
Legionella pneumophila................  ...............  ...............
Mycobacterium avium...................  ...............  ...............
Naegleria fowleri.....................               X   ...............
Salmonella enterica...................  ...............  ...............
Shigella sonnei.......................  ...............  ...............
------------------------------------------------------------------------
* There were no CCL 4 microbes monitored under UCMR 2, and none are
  proposed for monitoring under UCMR 4. The UCMR 4 Candidate
  Contaminants Information Compendium (USEPA, 2015b) provides a
  rationale for why contaminants, including microbes, were not included
  in the proposed UCMR 4. No CCL 4 microbes were included in the RD 3
  Short List. Norovirus, a member of the calicivirus family, was
  included on UCMR 3 pre-screen testing.

III. Summary of the Approach Used To Identify and Evaluate Candidates 
for the Draft CCL 4

    The Draft CCL 4 was published in the Federal Register on February 
4, 2015 (80 FR 6076 (USEPA, 2015a)). EPA used a three step evaluation 
and selection process to identify candidates for the Draft CCL 4: (1) 
Carry forward CCL 3 contaminants (except those with regulatory 
determinations), (2) seek and evaluate nominations from the public for 
additional contaminants to consider, (3) evaluate any new data for 
those contaminants with previous negative regulatory determinations 
from CCL 1 or CCL 2 for potential inclusion on the CCL 4. The CCL 3 
process is summarized in section I.E.2. A brief summary of steps 1-3 
that were used to develop the Draft CCL 4 is provided in the section 
that follows, and a more detailed summary is provided in the Draft CCL 
4 Federal Register notice (80 FR 6076 (USEPA, 2015a)). A summary of the 
public comments on the Draft CCL 4 and EPA's responses can be found in 
section IV.

[[Page 81105]]

A. Carry Forward of CCL 3 Contaminants to the Draft CCL 4

    EPA carried forward all contaminants listed on CCL 3 to the Draft 
CCL 4 with the exception of perchlorate, for which the agency made a 
positive regulatory determination, and the five CCL 3 contaminants with 
preliminary regulatory determinations at that time, pending their final 
regulatory determinations. This carry forward process is consistent 
with that previously used in CCL 2. The agency took this approach based 
on the following considerations: (1) In developing the CCL 3, the 
agency implemented a robust process recommended by the NRC and the 
NDWAC to screen and score the universe of potential contaminants; (2) 
EPA used the best available, peer reviewed data and information to 
evaluate contaminants for CCL 3; and (3) Carrying forward CCL 3 
contaminants allowed the agency to focus resources on evaluating 
contaminants nominated by the public for CCL 4 and review new data for 
CCL 1 or CCL 2 contaminants with previous negative regulatory 
determinations (68 FR 42897, July 18, 2003 (USEPA, 2003); 73 FR 44251, 
July 30, 2008 (USEPA, 2008b)). Carrying forward CCL 3 contaminants also 
allowed EPA to focus resources on UCMR 3 monitoring and analysis and RD 
3 analyses.

B. Summary and Evaluation of CCL 4 Nominated Contaminants

1. CCL 4 Nominations Summary
    EPA sought public nominations in a Federal Register notice on May 
8, 2012 (77 FR 27057), for contaminants to be considered for possible 
inclusion in the CCL 4 (USEPA, 2012)). EPA received nominations for 59 
unique contaminants for the CCL 4, including 54 chemical and five 
microbial contaminants. After carefully reviewing and evaluating the 
information and data for the nominated contaminants, EPA added two of 
the nominated chemicals (manganese and nonylphenol) to the Draft CCL 4. 
Detailed information on the nominations is contained in the ``Summary 
of Nominations for the Fourth Contaminant Candidate List'' support 
document (USEPA, 2016b).
2. How Nominated Contaminants Were Evaluated for the Draft CCL 4
    Four nominated contaminants were already covered by a proposed or 
existing NPDWR and were not eligible for the CCL 4 since the SDWA 
specifies that the CCL only include those contaminants without any 
proposed or promulgated NPDWRs. Seven of the nominated contaminants 
were on CCL 3 and were carried forward to the Draft CCL 4. EPA reviewed 
the nominations and supporting information to determine if any new data 
were provided that had not been previously evaluated for CCL 3. The 
agency also collected and evaluated additional data for the nominated 
contaminants, when it was available, including the seven nominated 
contaminants carried forward from CCL 3. The additional data was 
obtained from both updated CCL 3 data sources and from new data sources 
that were not available at the time the agency finalized CCL 3. These 
data sources are listed in the ``Data Sources for the Contaminant 
Candidate List 4'' support document (USEPA, 2016c).
    Nominated contaminants with new data were screened and scored using 
the same process used in CCL 3. Through this analysis, EPA added 
manganese and nonylphenol to the Draft CCL 4 because, as discussed in 
more detail in the Draft CCL 4 Federal Register notice (80 FR 6076 
(USEPA, 2015a)), EPA determined that the new and updated health effects 
information and additional occurrence data merited listing the 
contaminants. Detailed information on the data used to screen the 
nominated contaminants to determine whether or not they were included 
in the PCCL 4 is available in the ``Screening Document for the PCCL 4 
Nominated Contaminants'' (USEPA, 2016d). More detailed information on 
the process and the data used to evaluate nominated contaminants for 
listing on the CCL 4 can be found in the ``Contaminants Information 
Sheets (CISs) for the Final Contaminant Candidate List 4 (CCL 4)'' 
support documents (USEPA, 2016e).

C. Evaluation of Previous Negative Regulatory Determinations for the 
Draft CCL 4

    EPA evaluated the 20 contaminants from CCL 1 and CCL 2 for which 
the agency made negative regulatory determinations. EPA collected and 
evaluated new or updated data for the previous negative regulatory 
determination chemicals. Since RD 3 was recently published using the 
best available data, EPA did not include the RD 3 negative regulatory 
determinations in this evaluation. The agency concluded there was not 
sufficient new information for 19 of the 20 contaminants with previous 
negative regulatory determinations to justify including them on the 
Draft CCL 4. Because commenters also did not identify such information, 
EPA has not included these contaminants on the Final CCL 4. EPA added 
manganese, a previous negative regulatory determination from RD 1, to 
the Draft and Final CCL 4 as previously discussed in section III.B.

IV. What comments did EPA receive on the Draft CCL 4 and how did the 
Agency respond?

    EPA requested comment on the Draft CCL 4 and how to further improve 
upon the selection process developed for CCL 3 as a tool for future 
CCLs. The agency received 27 public comment letters on the Draft CCL 4. 
EPA considered all public comments and evaluated the data and 
information provided by commenters in selecting the Final CCL 4. EPA 
used the same process used in the CCL 3 to screen and score any 
contaminants with new data or information provided by commenters. EPA 
prepared responses to all public comments that are in the ``Comment 
Response Document for the Fourth Drinking Water Contaminant Candidate 
List (Categorized Public Comments)'' document, which is available in 
the docket for this action (USEPA, 2016f).
    Based on the analyses conducted as a result of public comments, EPA 
determined not to list three cancelled pesticides (disulfoton, 
fenamiphos, and molinate) on the Final CCL 4 that were included on the 
Draft CCL 4 because, as discussed more fully in the following sections, 
these chemicals are not known or anticipated to occur in PWSs and are 
not anticipated to require regulation. With the exception of these 
three pesticides, all of the contaminants listed on the Draft CCL 4 are 
listed on the Final CCL 4.
    A summary of some of the key public comments received, 
recommendations from EPA's Science Advisory Board (SAB) on the CCL 4, 
and EPA's responses are provided in this section. Data used to evaluate 
the contaminants for the CCL 4 can be found in the Contaminant 
Information Sheets (CISs) for the Final Fourth Contaminant Candidate 
List (CCL 4) (USEPA, 2016e), which can be found in the docket for this 
action available at www.regulations.gov by searching for docket EPA-HQ-
OW-2012-0217.

A. Recommendations From the EPA Science Advisory Board

    The EPA SAB and its Drinking Water Committee (DWC) reviewed the 
Draft CCL 4 and provided recommendations to the Administrator on 
January 11, 2016, in their report ``Review of the EPA's Draft Fourth 
Drinking Water Contaminant Candidate List (CCL 4)'' (USEPA, 2016g). On 
April 29-30, 2015, the SAB DWC held a public meeting to discuss 
responses to EPA charge

[[Page 81106]]

questions. During this meeting, EPA provided an overview of the process 
used to develop the Draft CCL 4 and answered questions from the 
Committee.
    The SAB's recommendations and comments on the overall CCL 4 process 
and documentation are summarized in the following bullet points:
     The SAB stated that the general protocol used to evaluate 
contaminants on the CCL 4 is well described and conceptually clear. 
They concluded the transparency and clarity of the process has improved 
since CCL 3 was finalized.
     The SAB said that the documentation for CCL 4 lacked 
specific information necessary in order to follow the decision-making 
process for listing an individual contaminant on the Draft CCL 4. 
Specific suggestions to improve transparency and clarity of the support 
documents include:
    [cir] Develop a summary table that consolidates summary information 
on all carried forward and nominated contaminants.
    [cir] Display results of the CCL 4 screening and classification 
process in a manner that explicitly outlines the scoring schemes used 
and the scientific rationale in applying the selection criteria.
    [cir] Provide examples for both microbial and chemical contaminants 
that display the process of how contaminants were included on or 
eliminated from the Draft CCL 4.
    [cir] Clearly describe and improve the process for removing 
contaminants from prior CCLs, where appropriate, when such lists serve 
as the basis for a new CCL.
    [cir] Explain the evaluation of CCL contaminants during the RD 
process.
     The SAB recommended that EPA should utilize data from UCMR 
3 monitoring as it becomes available.
     The SAB stated that the CCL 4 list includes a number of 
contaminants carried forward from the CCL 3 without providing a sense 
of the relative priority of the listed chemicals. The SAB recommended 
EPA prioritize the list to inform future regulatory decision-making and 
to help researchers focus their efforts.
    EPA Response: EPA has provided a more detailed response to the SAB 
in the document, ``Response to SAB recommendations on the Draft CCL 4'' 
(USEPA, 2016h), which can be found in the docket for this action 
available at www.regulations.gov by searching for docket EPA-HQ-OW-
2012-0217. This section summarizes EPA's response to some of the key 
SAB recommendations.
    The agency has updated the technical support documents for the CCL 
4 to increase the transparency of its decisions relative to the 
contaminants included on the Final CCL 4. For instance, the CIS support 
document provides examples showing the criteria and process for 
including or excluding chemical and microbial contaminants from the CCL 
4. Additionally, a summary table in the same support document presents 
factors used to determine how the CCL 4 contaminants were selected. The 
agency also summarizes the process used to evaluate contaminants under 
RD 3 in section I.E.3 of this notice.
    While EPA agrees with the SAB about the importance of using UCMR 
data to inform the CCL, the agency does not believe it is appropriate 
to use preliminary UCMR 3 data to make final CCL 4 decisions. The UCMR 
3 data set was not finalized within the timeframe for use and analysis 
under CCL 4. The UCMR 3 monitoring period ended in December 2015 and 
results are reported to EPA through 2016. After the monitoring period 
is completed, the results undergo review for quality assurance and are 
subject to change following further review by the analytical 
laboratory, the PWS, the State and EPA. The agency will perform further 
analysis of both the health effects and occurrence of contaminants 
monitored under UCMR 3 during the RD 4 and CCL 5 development process.
    EPA identified the current occurrence, health effects and 
analytical methods data needs of CCL 4 contaminants for RD 4 
evaluations in section V of this notice. This data needs table is 
presented to provide a sense of relative priority for listed 
contaminants by identifying those contaminants likely to have 
sufficient data for further evaluation under the next RD and those that 
have research needs. As the agency continues to evaluate contaminants 
on the CCL 4, EPA will work with agency and non-EPA scientists to 
develop and collect the best available science to support decision-
making for future determinations.

B. Public Comments

1. General Comments on CCL 4
    EPA received comments, both in support of and against the carry 
forward of contaminants from the CCL 3 to the Draft CCL 4. One 
commenter asked for more information on the decision to carry forward 
CCL 3 contaminants to the Draft CCL 4. Commenters not in support of the 
carry forward of CCL 3 contaminants thought EPA should reassess the 
science on all the CCL 3 contaminants. One commenter also thought EPA 
should limit the number of contaminants on the CCL so that research for 
the contaminants could be completed between one CCL and the next. One 
commenter supported the carry forward approach because the CCL 3 
contaminants already have data available that shows there may be a 
potential public health impact. They also suggested that EPA should 
continue to evaluate these contaminants until enough data are collected 
to support a regulatory determination.
    EPA response: The reasons for carrying forward contaminants from 
the CCL 3 to the CCL 4 are presented in section III.A of this notice. 
EPA has continued to collect data and further evaluate the science for 
many of the contaminants that were carried forward from the CCL 3 to 
the CCL 4. For example, since the listing of contaminants on CCL 3, EPA 
has monitored and collected occurrence data for several CCL 
contaminants through the UCMR program. EPA has also further analyzed 
and evaluated many of the CCL 3 contaminants that were carried forward 
to CCL 4 under the RD 3 process. Exhibit 1 in section II.A of this 
notice lists CCL 4 contaminants that were evaluated under these other 
agency efforts. Although EPA carried forward contaminants from the CCL 
3 to the CCL 4, EPA intends to collect new data and conduct further 
evaluations of unregulated contaminants for CCL 5.
    EPA does not agree that the CCL should be limited to a certain 
number of contaminants. The CCL identifies contaminants that are 
``known, or anticipated to occur in PWSs,'' and is the first step in 
identifying contaminants that may require regulation. Some of the 
contaminants on the list may have sufficient information to make 
regulatory determinations in the near term and some of the contaminants 
on the list need additional data in order to determine the appropriate 
agency action. While the SDWA does not limit the CCL to a particular 
number of contaminants, the agency recognizes the need to communicate 
data needs for contaminants included on the Final CCL 4. Therefore, EPA 
has provided a summary of the current data needs for RD 4 evaluations 
in section V of this notice. The agency will continue to evaluate data 
needs through the RD 4 process and will continue to work with internal 
and external researchers to discuss research needs and priorities.
2. Chemical Contaminants
a. Contaminants With Release Data
    EPA received comments that several contaminants listed based on

[[Page 81107]]

environmental release data for evaluating occurrence (e.g., ethylene 
oxide, ethylene glycol, and toluene diisocyanate) should not be on the 
CCL 4 because one or more of their intrinsic physical or chemical 
properties would result in limited occurrence in water. Commenters 
cited the hydrolysis and biodegradation rate, or quick volatilization 
from water as reasons these chemicals should be removed from the Final 
CCL 4. Additionally, commenters noted that some of these contaminants 
have relatively short half-lives in water or may not be long-lived in 
the environment and thus should not be listed on the Final CCL 4.
    EPA Response: EPA is including ethylene oxide, ethylene glycol, and 
toluene diisocyanate on the Final CCL 4 because these contaminants may 
be anticipated to occur in PWSs and may require regulation. Although no 
occurrence information in finished or ambient water is available for 
these contaminants, to be consistent with the CCL 4 protocol, EPA used 
total environmental release data reported in the TRI to evaluate and 
score the occurrence attributes. In response to comments citing that 
EPA should consider physical and chemical properties, EPA conducted 
additional analyses that considers physical and chemical properties and 
environmental fate parameters to provide an alternate score for the 
magnitude attribute. For this additional analysis on the specific 
contaminants commented on (e.g., ethylene oxide, ethylene glycol, and 
toluene diisocyanate), EPA used the persistence and mobility scoring 
protocol (which is the protocol used for those chemicals with only 
production data) as the basis for scoring the magnitude attribute as 
described in the Final CCL 3: Classification of the PCCL to the CCL 
(USEPA, 2009e), available in the docket for this action. The model 
results for these contaminants using this alternate magnitude score 
still indicated that the contaminants should be listed (for a summary 
of how the classification model results were used to select 
contaminants for CCL 4, please see USEPA, 2016e, available in the 
docket for this action). These additional analyses are further 
described in the ``Comment Response Document for the Fourth Drinking 
Water Contaminant Candidate List (Categorized Public Comments)'' 
document, which is available in the docket for this action (USEPA, 
2016f). Additionally, as the SAB (USEPA, 2016h) noted, ``contaminants 
with a half-life in drinking water sources of days to weeks may still 
pose a public health concern.''
    Considering the comments received on the Draft CCL 4, in future 
CCLs, EPA may refine analyses to consider if physical and chemical 
properties can be incorporated into the evaluations of contaminants 
listed based on environmental release data for occurrence.
b. Cyanotoxins
    EPA received comments supporting the inclusion of cyanotoxins on 
the CCL 4. Some comments requested that cyanotoxins be listed by 
individual toxins rather than including cyanotoxins as a group on the 
Final CCL 4 in order to prioritize research on health effects, 
analytical methods, occurrence and treatment. Comments specifically 
requested listing the key variants of microcystins, cylindrospermopsin, 
anatoxin-a, saxitoxin and euglenophycin.
    EPA Response: EPA agrees that cyanotoxins should be included on the 
CCL 4, and has included cyanotoxins as a group on the Final CCL 4. The 
group of cyanotoxins includes all toxins produced by cyanobacteria 
including but not limited to microcystins, cylindrospermopsin, 
anatoxin-a and saxitoxin. EPA has provided CIS sheets for microcystin-
LR, cylindrospermopsin, anatoxin-a and saxitoxin. Under CCL 3, 
cyanotoxins were listed as a group and EPA released CIS sheets for 
microcystin-LR, cylindrospermopsin and anatoxin-a. Based on data 
submitted in public comments, EPA updated previous CIS sheets and 
developed a CIS sheet for saxitoxin. EPA was unable to develop a CIS 
sheet for euglenophycin due to insufficient information on health and 
occurrence. EPA acknowledges the comments to list specific cyanotoxin 
compounds on the CCL instead of listing cyanotoxins as a group. 
However, because of the similar sources of cyanotoxins (i.e., 
cyanobacteria) their management may be similar. Furthermore, due to 
significant information gaps for some cyanotoxins (e.g., euglenophycin 
and nodularin and many microcystin congeners), EPA has determined it 
most appropriate to continue to list cyanotoxins as a group at this 
time. EPA agrees that microcystins, cylindrospermopsin, anatoxin-a and 
saxitoxin can be of concern for drinking water supplies. EPA 
acknowledges associated data gaps for euglenophycin as well as those 
for other cyanotoxins. EPA included total microcystins and six 
microcystin congeners (-LA, -LF, -LR, -LY, -RR, and -YR), 
cylindrospermopsin, anatoxin-a and nodularin on the proposed UCMR 4 for 
monitoring by PWSs. The occurrence information collected under the UCMR 
4 will be used to further evaluate the appropriate agency regulatory 
determination and research actions.
c. Perfluorinated Compounds (PFOA and PFOS)
    EPA received a comment supporting the inclusion of 
perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) 
on the CCL 4. EPA also received comments that PFOS and/or PFOA should 
not be listed on the Final CCL 4. The commenter supporting inclusion of 
these chemicals on the CCL 4 cited their persistence in the environment 
and toxicological effects as reasons to include them on the Final CCL 
4, and encouraged EPA to consider these chemicals for drinking water 
regulation. Commenters supporting removal of PFOA and/or PFOS from the 
CCL 4 cited the low frequency of detections of PFOA and/or PFOS under 
the UCMR 3 monitoring as of January 2015. Additional reasons cited by 
commenters that these chemicals should not be listed on the Final CCL 4 
are the voluntary efforts by manufacturers to reduce emissions and work 
towards elimination of these chemicals from products.
    EPA Response: EPA is including PFOA and PFOS on the Final CCL 4 
because these contaminants are known to occur in drinking water, are 
persistent in the environment and in the human body, have shown to be 
toxic in animal studies and may require regulation.
    As discussed in the summary of EPA responses to the SAB in this 
section (IV.A) of the notice, EPA did not use preliminary UCMR 3 
monitoring results for the CCL 4.
    EPA acknowledges the industry commitments to voluntarily reduce the 
use and production of PFOA and PFOS; however, there are still a limited 
number of ongoing uses of PFOA and PFOS. Additionally, these chemicals 
are persistent in the environment and in the human body, which 
indicates they may be present in water or migrate to drinking water 
sources even after uses and production have been reduced or ceased, and 
therefore potential exposure may still be of concern.
    In May 2016, EPA released lifetime health advisories for PFOA and 
PFOS (USEPA, 2016i, available in the docket for today's action) and 
Health Effects Support Documents based on the agency's assessment of 
the latest peer reviewed science. The health advisories provide 
federal, state, tribal and local officials with information on the 
health risks of these chemicals, occurrence,

[[Page 81108]]

analytical methods and treatment technologies so that they can 
determine what actions to take to protect consumers.
    In accordance with the SDWA, EPA will consider the occurrence data 
from the final UCMR 3 data set, along with the peer reviewed health 
effects assessments supporting the May 2016 PFOA and PFOS Health 
Advisories, to make a regulatory determination whether or not PFOA and 
PFOS require NPDWRs.
d. Pesticides
    Several public commenters requested that specific pesticides be 
removed from the Final CCL 4. EPA agrees with commenters that three of 
these pesticides (disulfoton, fenamiphos, and molinate) should not be 
listed on the Final CCL 4; therefore, EPA is removing them from the 
Final CCL 4. The evaluation of these three pesticides is summarized in 
the following paragraphs.
(i) Disulfoton
    EPA received a comment from the public that disulfoton should not 
be included on the Final CCL 4. The commenter noted that disulfoton had 
zero or very few detections nationally on any previous round of UCMR 
monitoring and therefore does not warrant national regulation.
    EPA Response: EPA agrees with the commenter that disulfoton should 
not be included on the Final CCL 4. Disulfoton sales and distribution 
were cancelled in the U.S., effective December 31, 2010, with remaining 
product stocks to be used until depleted (74 FR 48551, September 23, 
2009 (USEPA, 2009g)). The UCMR 1 finished water screening survey (SS) 
found no detections of disulfoton in 2,300 samples from 295 PWSs. The 
United States Geological Survey (USGS) has detected disulfoton 
infrequently in ambient water. During the 1992-2001 USGS National 
Water-Quality Assessment (NAWQA) Program monitoring, disulfoton was 
detected in only 17 sites out of 7,118 ambient water sites sampled (see 
the CIS for this contaminant (USEPA, 2016e)). Out of the 17 sites with 
detections, only two sites had detects at levels greater than the 
health reference level of potential concern for drinking water. Given 
that disulfoton was detected in those two sites prior to its 
cancellation, the agency expects that any potential disulfoton 
occurrence in water will likely continue to decrease in the future. 
Although persistent environmental contaminants may occur in a PWS after 
its uses are cancelled, based on its physical and chemical properties, 
disulfoton has low to moderate mobility in water and it is only 
moderately persistent in the environment (see the CIS for this 
contaminant (USEPA, 2016e), which can be found in the docket for this 
action). Therefore its occurrence is expected to decrease over time.
    EPA is not including disulfoton on the Final CCL 4 because it is 
not known or anticipated to occur in drinking water. Disulfoton likely 
has low potential for public health concern based on its cancellation 
status, zero detections in PWSs (from UCMR 1 data), and very few 
detections in ambient water from a large number of sites sampled (by 
the USGS NAWQA program).
(ii) Fenamiphos
    EPA received a comment from the public that fenamiphos should not 
be included on the Final CCL 4. The commenter stated that the 
registrant for fenamiphos agreed to cancel all uses, and all existing 
stocks are to be used by October 6, 2017. The commenter stated that 
very limited uses remain of products containing fenamiphos in the U.S. 
and use will be discontinued after 2017.
    EPA Response: EPA agrees with the commenter that fenamiphos should 
not be included on the Final CCL 4 because it is not anticipated to 
occur in drinking water and is not likely to require regulation. 
Fenamiphos product registrations were cancelled, and the sale and 
distribution of fenamiphos by the registrant was prohibited on May 31, 
2007. This cancellation followed a five- year phase-out period, 
beginning in 2003, intended to limit and reduce production of 
fenamiphos. The sale and distribution of any remaining stocks will be 
prohibited after October 6, 2017 (79 FR 59262, October 1, 2014; USEPA, 
2014c). Fenamiphos was not monitored under UCMR, thus no national scale 
monitoring has been conducted in PWSs. While fenamiphos was not 
included in the USGS NAWQA national-scale ambient water monitoring 
(1992-2001), based on the USGS Pesticide National Synthesis Project 
(USGS, 2012), fenamiphos use is estimated to have steadily declined. 
The USGS estimated a usage level of approximately 1.0 million pounds/
year of widespread use in certain regions per year in 1992, which 
declined to an estimated 0.2 million pounds/year in 2002 and further 
declined to an estimated 0.03 million pounds/year of limited regional 
uses in 2012. EPA expects fenamiphos occurrence in water will likely 
continue to decrease due to the declining trend in usage for many years 
and the prohibition on usage of existing stocks in the U.S. effective 
after October 6, 2017.
    In summary, due to its registration cancellation status, 
significant decline in usage (based on estimated data from 1992-2013), 
moderate persistence in the environment, and the prohibition of 
existing stocks (effective after October 6, 2017), EPA does not 
anticipate fenamiphos to occur in PWSs or to require regulation, 
therefore, it is not included on the Final CCL 4.
(iii) Molinate
    EPA received a comment from the public that molinate should not be 
included on the Final CCL 4. The commenter noted that molinate had zero 
or very few detections nationally on any previous round of UCMR 
monitoring and therefore does not warrant national regulation.
    EPA Response: EPA agrees with the commenter that molinate should 
not be included on the Final CCL 4. The UCMR 1 finished water 
assessment monitoring found only one sample with a detection of 
molinate out of 33,799 samples taken from 3,873 PWSs. The single sample 
detection was below the health reference level of potential concern for 
molinate in drinking water. Further, molinate sales and distribution 
were cancelled in the U.S. effective July 1, 2009, with remaining 
stocks required to be used by August 31, 2009, (73 FR 44261, July 30, 
2008 (USEPA, 2008c)). This cancellation action concluded a six-year 
scheduled phaseout of molinate. The agency is not including molinate on 
the Final CCL 4 because it is not anticipated to occur in PWSs at 
levels of public health concern. The agency expects the potential for 
molinate to occur in water will likely continue to decrease due to the 
prohibition on product use in the U.S. since 2009.
e. Manganese
    EPA received four comments that support the inclusion of manganese 
and two comments that do not support the inclusion of manganese on CCL 
4. Commenters supporting the inclusion of manganese on CCL 4 cited 
recent studies that showed neurological effects in children and infants 
exposed to excess manganese via drinking water. Commenters also noted 
manganese frequently occurs in water and should be included on CCL 4 so 
that national occurrence data can be obtained through UCMR monitoring. 
Commenters who did not support the inclusion of manganese on the CCL 4 
cited that the primary route of human exposure to manganese is through 
food, not drinking

[[Page 81109]]

water. Also, commenters question the link between the consumption of 
drinking water and developmental neurotoxicity from manganese exposure 
to warrant inclusion on the CCL 4.
    EPA Response: EPA agrees with the commenters that support manganese 
inclusion on the CCL 4, and is including manganese on the Final CCL 4 
because it is known to occur in PWSs and may require regulation. The 
evidence from the studies provided by commenters indicate that exposure 
to excess manganese may present a substantial health threat to children 
and infants. EPA is continuing to evaluate the potential risks to 
children and infants based on over 30 recent studies cited by the 
public during the nomination and comment period including those by 
Bouchard et al. (2011), Oulhote et al. (2014) and Kern and colleagues 
(2010, 2011), whom have indicated neurological effects stemming from 
the exposure to excess manganese.
    EPA also agrees with the commenters assertion that manganese is 
known to occur in PWSs. EPA has included the occurrence data used to 
evaluate manganese in the CIS for this contaminant. This data includes 
USGS monitoring of ambient water, as well as drinking water data from 
several states. The data indicates that manganese is known to occur in 
public drinking water supply wells and supports the previous 
information from the National Inorganics and Radionuclides Survey 
(NIRS). EPA has proposed to monitor manganese under UCMR 4.
    EPA has reviewed all of the current data submitted by commenters on 
the manganese health effects and found that the existing 2004 Health 
Advisory could warrant an update. Since manganese is not a regulated 
contaminant in drinking water, the Secondary Maximum Contaminant Level 
of 0.05 mg/L is not mandatory and does not require monitoring. The 
current IRIS assessment for manganese dates to 1995 (USEPA, 1995b) and 
the Health Advisory to 2004. The Agency for Toxic Substances and 
Disease Registry 2012 Toxicological Profile did not establish 
guidelines that applied to oral exposures and the Institute of Medicine 
(2001) provides Tolerable Upper Intake Levels for developmental 
lifestages and adults. The database of health effects studies for oral 
manganese exposures has expanded considerably since the last EPA 
assessment, therefore manganese is a good candidate for re-evaluation. 
EPA intends to evaluate the new toxicological findings and UCMR 4 
monitoring data and will use this information in future regulatory 
decision-making, and to revise the current Health Advisory, if 
appropriate. More detailed evaluations of the routes of exposure 
usually occur in the regulatory determination and regulatory 
development processes.
f. Nonylphenol
    EPA received two comments supporting the inclusion of nonylphenol 
and three comments that nonylphenol should not be included on the Final 
CCL 4. The commenters supporting inclusion of nonylphenol on the CCL 4 
cited new health effects and occurrence data as reasons to include them 
on the Final CCL 4 and stated that EPA has adequate justification to 
include nonylphenol on the CCL based on this information. The 
commenters requesting that nonylphenol not be included on the Final CCL 
4 cited a surface water monitoring study from 2002 and industry efforts 
to reduce surfactant usage as reasons nonylphenol should not be listed 
on the Final CCL 4. The main use of nonylphenol is in the manufacture 
of nonylphenol ethoxylates, which have been used in a wide range of 
industrial applications and consumer products including laundry 
detergents, cleaners, degreasers, paints and coatings and other uses 
(79 FR 59186, October 1, 2014 (USEPA, 2014d)).
    EPA Response: EPA is including nonylphenol on the Final CCL 4 as 
proposed because it is anticipated to occur in drinking water, has 
potential adverse health effects (Bontje et al., 2005), and may require 
regulation. EPA evaluated the 2002 USGS reconnaissance study (Kolpin et 
al., 2002) identified by the commenter and used it to evaluate the 
occurrence of nonylphenol. While there were more recent finished water 
studies available, EPA considers the 2002 USGS study as the most 
appropriate study to evaluate the occurrence of nonylphenol for CCL 4 
given the greater number of samples and larger geographic scale. 
Additionally, more recent studies indicate that nonylphenol has been 
detected in drinking water. While EPA appreciates the information from 
commenters on reduced usage of nonylphenol, we believe measured 
occurrence data from water sources are preferred over production or 
usage information when evaluating the likelihood of occurrence in 
drinking water.
3. Microbial Contaminants
a. Overall Process Comments
    EPA received comments arguing that the follow-through on the 
microbes listed in previous CCLs has been inadequate, that EPA should 
identify high priority pathogens on the CCL 4 and identify information 
gaps and barriers to obtaining information associated with each 
pathogen. EPA received comments requesting an open process for 
prioritizing and collecting information, to adopt a collaborative 
method development process and to rank microbes by treatability. EPA 
also received comments to focus priorities on distribution and plumbing 
system biofilm concerns and to evaluate microbial contaminants in the 
context of diverse water supplies such as drinking water sources from 
water reuse treatment facilities.
    EPA Response: EPA's criteria for evaluating and prioritizing 
pathogens for inclusion in the CCL 3 included health effects, 
waterborne disease outbreaks (WBDO) and occurrence information (73 FR 
9628 (USEPA, 2008a)). EPA developed and implemented a systematic 
strategy and set of criteria for selecting the pathogens for CCL 3. 
This is the screening and scoring process described in detail in the 
support documents in the docket of the Final CCL 3 (e.g., see the Final 
Contaminant Candidate List 3 Microbes: PCCL to CCL Process for more 
information on all of the scores). The CCL 3 and CCL 4 processes 
provided multiple opportunities for public input (e.g., nominations, 
public comment) to allow for an open process. In order to provide 
additional clarity to the scoring process, EPA is including an example 
schematic describing the process of evaluating a pathogen for inclusion 
on the list and a pathogen for exclusion from the list. This schematic 
can be found in the CIS's for the Final Fourth Contaminant Candidate 
List (USEPA, 2016e). EPA acknowledges the request to identify 
information gaps; therefore, data needs are described in section V of 
this Federal Register notice.
    The EPA's Office of Water coordinates with EPA's Office of Research 
and Development to discuss research needs and priorities. Research on 
distribution system and premise plumbing biofilm concerns has been 
incorporated into EPA's strategic research plan. EPA acknowledges the 
comments on diverse water supplies and method development and will 
consider these comments as it develops future research priorities.
b. Pathogens for Inclusion
    EPA received comments supporting the proposed inclusion of 
Mycobacterium avium, Legionella pneumophila, Naegleria fowleri, 
enteroviruses and Heterotrophic Plate Count (HPC). EPA also received

[[Page 81110]]

comments requesting recommendations for Legionella pneumophila 
management.
    EPA Response: EPA included Mycobacterium avium, Legionella 
pneumophila, Naegleria fowleri, and enteroviruses on the Final CCL 3 
and were therefore carried forward to the draft and Final CCL 4. While 
the broader issue of the management of Legionella pneumophila is 
outside the scope of today's action, the agency agrees it is of great 
importance and Legionella remains a risk to building water systems. In 
September 2016, EPA released a document reviewing the available 
technology to treat Legionella titled Technologies for Legionella 
Control in Premise Plumbing Systems: Scientific Literature Review 
(USEPA, 2016j). This document provides information to state and local 
decision-makers about how they might utilize treatment as part of their 
efforts to manage Legionella risks in building water systems.
    EPA disagrees that HPC should be included on CCL 4. The group of 
HPC usually includes a diverse group of microorganisms that are part of 
the natural environment in water. Available epidemiological evidence 
shows no relationship between gastrointestinal illness and HPC bacteria 
in drinking water (Calderon, 1988; Calderon and Mood, 1991; Payment et 
al., 1997; Bartram J et al., 2003). Thus, EPA considers the potential 
health risk of HPC bacteria in drinking water as likely negligible and 
is not including HPC on the Final CCL 4. In addition, HPC bacteria are 
addressed under the Surface Water Treatment Rule as a treatment 
technique where they can be monitored in lieu of a disinfectant 
residual because HPC is an alternative method of determining 
disinfectant residual levels.
c. Pathogens for Exclusion
    EPA received comments not supporting the proposed inclusion of 
Escherichia coli O157 and Helicobacter pylori, noting these pathogens 
were unlikely to occur in treated drinking water.
    EPA Response: EPA's criteria for evaluating and prioritizing 
pathogens for inclusion in the Draft CCL 3 Federal Register notice, 
included health effects, WBDO and occurrence information (73 FR 9628 
(USEPA, 2008a)). Treatability was not part of the scoring criteria 
considered for CCL 3 inclusion. Although some of the microbes listed in 
the Draft CCL 4 may be well controlled by drinking water treatment 
(i.e., disinfection), not all PWSs in the U.S. are required to treat. 
For example, approximately thirty percent of the 40,000 community 
ground water systems do not have disinfection treatment (USEPA, 2013). 
For the reasons discussed in detail in the Draft CCL 3 Federal Register 
notice (73 FR 9628 ((USEPA, 2008a)), EPA did not preclude pathogens 
from CCL 3 and CCL 4 based on their potential to be controlled by 
existing treatment technique regulations.

V. Data Needs for CCL 4 Contaminants

    After the listing process, the CCL 4 contaminants will be further 
evaluated in a separate action called Regulatory Determination 4 (RD 
4). The process used to previously evaluate CCL 3 contaminants under RD 
3 is described in section I.E.3 of this notice. EPA anticipates using a 
similar process to evaluate CCL 4 contaminants under RD 4, although it 
is possible that some modifications may be made to this process. In the 
initial phases of this process, EPA determines if sufficient data are 
available to meet the three RD criteria set forth in SDWA section 
1412(b)(1) and previously outlined in section I.D.4 of this notice. If 
sufficient data are available to meet all three statutory criteria, a 
regulatory determination may be made. As discussed in section I.D.4, 
SDWA requires EPA to make regulatory determinations every five years on 
at least five CCL contaminants.
    The SAB and other commenters have recommended additional 
prioritization of the CCL 4 contaminants to communicate research needs, 
help focus efforts for researchers, and inform future regulatory 
decision-making. EPA acknowledges that many contaminants on the CCL 4 
have substantial data and information needs to fulfill in order for the 
agency to make a regulatory determination in accordance with SDWA 1412 
(b)(1)(A). These current data needs are described in the following 
section, and are presented in Exhibit 2. By identifying those 
contaminants that need additional research and information, EPA is 
communicating to stakeholders both research priorities and gaps for 
these contaminants.
Categorization of Contaminants
    EPA assessed the data and information gathered on the CCL 4 
contaminants and generated a table (Exhibit 2) to help identify data/
information needs for further evaluation under RD 4. To develop this 
table, EPA began with the information contained in the data 
availability/Phase 1 table included in Appendix D of the Protocol for 
the RD 3 (USEPA, 2014b), which describes the status of the best 
available occurrence data and health effects assessments for CCL 3 
contaminants. EPA updated the occurrence data needs for CCL 4 
contaminants by including which contaminants were monitored on the UCMR 
3, and updated the health effects data needs based on available EPA or 
other non-EPA peer reviewed assessments as of May 2016. Since manganese 
and nonylphenol were nominated and added to the CCL 4 (not carried 
forward from CCL 3), data collected under CCL 4 was included in the 
Contaminant Information Sheets (USEPA, 2016e) for these contaminants 
and was used to assess the data needs. EPA characterized each chemical 
contaminant included on the Final CCL 4 based on their health effects, 
occurrence and analytical methods data needs.
    EPA then categorized contaminants into six categories depending 
upon the availability of their occurrence data and health assessment. 
Contaminants in Group A have nationally representative finished 
drinking water data and a peer reviewed health assessment and are 
likely to have sufficient data available to be placed on a short list 
for further assessment under RD 4. Contaminants in Group B have 
finished drinking water data that is not nationally representative and 
peer reviewed health assessments. These contaminants may have 
sufficient data to be placed on a short list for further assessment 
under RD 4, particularly if the non-nationally representative 
occurrence data shows detections at levels of public health concern. 
Contaminants in groups C, D, E, and F of Exhibit 2 that lack either a 
peer reviewed health assessment or finished water data have more 
substantial data needs and are unlikely to have sufficient information 
to allow further assessment under the RD 4. For these contaminants, EPA 
plans to identify them as research priorities and work to fill their 
research needs such as evaluating the potential for monitoring under 
the UCMR or identifying those contaminants as priorities for health 
effects research. The health effects and occurrence data sources used 
to classify data needs are featured in Appendix 6 of the CISs for the 
Final Fourth CCL in the docket (USEPA, 2016e). The following sections 
describe the types of data or information gaps outlined in Exhibit 2 
and provide examples.

A. Health Effects

    Under the RD process, EPA relies on external peer-reviewed health 
assessments to determine if and at what level a contaminant ``may have 
an adverse effect on the health of persons.'' Health effects data 
sources evaluated for

[[Page 81111]]

RD 3 included EPA health assessments, or peer reviewed health 
assessments developed by other organizations such as the National 
Academy of Sciences, the Agency for Toxic Substances and Disease 
Registry, World Health Organization, the California EPA's Office of 
Environmental Health Hazard Assessment, Registry of Toxic Effects of 
Chemical Substances, and/or supplemental data from a single study, if 
the health assessment is peer reviewed and uses comparable methods, 
standards and guidelines to an EPA health assessment.
    As shown in Exhibit 2, EPA categorized the health effects data 
needs in the following way:
    1. If a peer reviewed health assessment is available or is in the 
process of being revised, the contaminant is considered to have health 
effects data available.
    2. If a peer reviewed health assessment is not available, then the 
contaminant is considered to not have health effects data currently 
available.

B. Occurrence

    For RD evaluations, the occurrence data availability assessment is 
used to identify contaminants that may have sufficient data and 
information to characterize their status as known or likely to occur in 
PWSs. EPA uses data from many sources to evaluate occurrence for 
contaminants considered for RD (see Appendix C of USEPA, 2014b for 
occurrence data sources evaluated under RD 3). For this evaluation, EPA 
prefers to have nationally representative finished drinking water 
occurrence data, but finished drinking water data that are not 
nationally representative may also be used to determine if the 
contaminant occurs frequently at levels of public health concern. In 
addition, the agency evaluates supplemental sources of information 
(e.g., ambient/source water occurrence, production/use and 
environmental release data). For the purposes of identifying current 
data needs for RD 4, as shown in Exhibit 2, EPA categorized the 
occurrence data needs in the following way:
     Finished drinking water occurrence data that are 
nationally representative are available.
    [cir] Data sources may include UCMRs (i.e., UCMR 1, UCMR 2 and UCMR 
3), the Unregulated Contaminant Monitoring Program (Round 1 and Round 
2) and NIRS.
     Finished drinking water occurrence data that are not 
nationally representative are available. These data may include:
    [cir] Finished water assessments by federal agencies (e.g., EPA, 
the U.S. Department of Agriculture and USGS). These may include 
assessments that are geographically distributed across the nation but 
are not intended to be statistically representative of the nation 
(e.g., the Disinfection By-Product Rule Information Collection 
Request).
    [cir] State-level finished water monitoring data.
    [cir] Research performed by institutions and universities (e.g., 
scientific literature), including targeted or local monitoring studies.
    [cir] Various reports from the Centers for Disease Control and the 
scientific literature for microbes.
     Finished drinking water occurrence data are not available.
    [cir] The best available data sources may include environmental 
release data (such as TRI data or pesticide application data) or 
ambient water data.
    EPA has also indicated with a footnote in the occurrence data 
column, highlighting which contaminants are proposed for monitoring 
under the UCMR 4 from 2018-2020. Therefore, although some of the 
contaminants that may be monitored under UCMR 4 are shown in this table 
as currently having data gaps for occurrence (e.g., they only have 
drinking water data that is not nationally representative or release 
data), EPA has proposed to fill those occurrence data needs for future 
RD evaluations.

C. Analytical Methods

    To conduct nationally representative drinking water occurrence 
studies that could support a regulatory determination, EPA needs to 
have an analytical method that is suitable for the drinking water 
matrix and is robust enough to be used by many laboratories to conduct 
national studies and/or compliance monitoring. For the purpose of CCL 
4, EPA assessed the status of the development of analytical methods for 
drinking water and determined estimated reporting levels for each 
contaminant. EPA also assessed method sensitivity with respect to the 
HRL for the chemical contaminants. Method sensitivity is measured by 
using method specific reporting levels, lowest concentration minimum 
reporting levels, and promulgated minimum reporting level. While there 
are many methods for monitoring the CCL 4 pathogens available from 
scientific papers and consensus organizations, not all of them may be 
appropriate for use in drinking water or for a national monitoring 
effort. Of the CCL 4 pathogens, only enterovirus and caliciviruses have 
an EPA-approved method for drinking water. The status of drinking water 
analytical methods for the CCL chemical contaminants, as of May 2016, 
is presented in Exhibit 2. EPA categorized the analytical method needs 
in the following way:
     An EPA drinking water method, with estimated reporting 
levels that are adequate for analysis relative to the current HRL or 
health assessment is available.
     An EPA drinking water method is available but the minimum 
reporting level (MRL) does not allow for quantitation of the 
contaminant at a concentration below the current HRL. These methods are 
denoted in Exhibit 2 by ``(MRL>HRL)''.
     An EPA drinking water method is currently being developed.
     An EPA drinking water method is not available.
    Although not shown in Exhibit 2, EPA also considers other 
government and consensus methods (e.g., Standard Methods and ASTM, 
International) when considering analytical methods that may be used or 
modified for UCMR monitoring.

                Exhibit 2--Regulatory Determination Data/Information Needs for CCL 4 Contaminants
----------------------------------------------------------------------------------------------------------------
                                                 What is the best     Is a health
            CASRN                Common name         available        assessment     Is an EPA analytical method
                                                 occurrence data?     available?              available?
----------------------------------------------------------------------------------------------------------------
     (A) Contaminants with Nationally Representative Finished Water Occurrence Data and Peer Reviewed Health
                                                   Assessments
----------------------------------------------------------------------------------------------------------------
630-20-6....................  1,1,1,2-           National........  Yes \a\.........  Yes.
                               Tetrachloroethan
                               e.
96-18-4.....................  1,2,3-             National........  Yes.............  Yes (MRL > HRL).
                               Trichloropropane.
123-91-1....................  1,4-Dioxane......  National........  Yes.............  Yes.
16655-82-6..................  3-                 National........  Yes \b\.........  Yes.
                               Hydroxycarbofura
                               n.
34256-82-1..................  Acetochlor.......  National........  Yes.............  Yes.
187022-11-3.................  Acetochlor         National........  Yes \b\.........  Yes.
                               ethanesulfonic
                               acid (ESA).

[[Page 81112]]

 
194992-44-4.................  Acetochlor         National........  Yes \b\.........  Yes.
                               oxanilic acid
                               (OA).
142363-53-9.................  Alachlor           National........  Yes.............  Yes.
                               ethanesulfonic
                               acid (ESA).
171262-17-2.................  Alachlor oxanilic  National........  Yes \b\.........  Yes (MRL > HRL).
                               acid (OA).
14866-68-3..................  Chlorate.........  National........  Yes.............  Yes.
7440-48-4...................  Cobalt...........  National........  Yes \a\.........  Yes.
NA..........................  Enterovirus......  National........  Yes.............  Yes.
7439-96-5...................  Manganese........  National \ c\...  In Development..  Yes.
74-83-9.....................  Methyl bromide     National........  Yes \a\.........  Yes.
                               (Bromomethane).
51218-45-2..................  Metolachlor......  National........  Yes.............  Yes.
171118-09-5.................  Metolachlor        National........  Yes.............  Yes.
                               ethanesulfonic
                               acid (ESA).
152019-73-3.................  Metolachlor        National........  Yes.............  Yes.
                               oxanilic acid
                               (OA).
7439-98-7...................  Molybdenum.......  National........  In Development..  Yes.
98-95-3.....................  Nitrobenzene.....  National........  Yes.............  Yes.
55-18-5.....................  N-                 National........  Yes.............  Yes (MRL > HRL).
                               Nitrosodiethylam
                               ine (NDEA).
62-75-9.....................  N-                 National........  Yes \a\.........  Yes (MRL > HRL).
                               nitrosodimethyla
                               mine (NDMA).
621-64-7....................  N-Nitroso-di-n-    National........  Yes.............  Yes (MRL > HRL).
                               propylamine
                               (NDPA).
930-55-2....................  N-                 National........  Yes \a\.........  Yes.
                               nitrosopyrrolidi
                               ne (NPYR).
1763-23-1...................  Perfluorooctane    National........  Yes.............  Yes.
                               sulfonic acid
                               (PFOS).
335-67-1....................  Perfluorooctanoic  National........  Yes.............  Yes.
                               acid (PFOA).
121-82-4....................  RDX..............  National........  In Development..  Yes.
7440-62-2...................  Vanadium.........  National........  Yes \a\.........  Yes.
----------------------------------------------------------------------------------------------------------------
   (B) Contaminants With Non-Nationally Representative Finished Water Occurrence Data and Peer Reviewed Health
                                                   Assessments
----------------------------------------------------------------------------------------------------------------
71-36-3.....................  1-Butanol........  Non-National \c\  In Development..  Yes.
30560-19-1..................  Acephate.........  Non-National....  Yes.............  Yes.
107-02-8....................  Acrolein.........  Non-National....  Yes \a\.........  No.
NA..........................  Adenovirus.......  Non-National....  Yes.............  No.
319-84-6....................  alpha-             Non-National \c\  Yes.............  Yes (MRL > HRL).
                               Hexachlorocycloh
                               exane.
741-58-2....................  Bensulide........  Non-National....  Yes.............  Yes.
100-44-7....................  Benzyl chloride..  Non-National....  Yes \a\.........  No.
NA..........................  Caliciviruses....  Non-National....  Yes.............  Yes.
133-06-2....................  Captan...........  Non-National....  Yes.............  No.
NA..........................  Cyanotoxins......  Non-National \d\  Yes for           Yes.
                                                                    microcystins
                                                                    and
                                                                    cylindrospermop
                                                                    sin, no for
                                                                    other
                                                                    cyanotoxins.
141-66-2....................  Dicrotophos......  Non-National....  Yes.............  Yes.
330-54-1....................  Diuron...........  Non-National....  Yes.............  Yes.
13194-48-4..................  Ethoprop.........  Non-National \c\  Yes.............  Yes.
107-21-1....................  Ethylene glycol..  Non-National....  Yes.............  No.
96-45-7.....................  Ethylene thiourea  Non-National....  Yes.............  No.
50-00-0.....................  Formaldehyde.....  Non-National....  Yes.............  Yes.
NA..........................  Legionella         Non-National....  Yes.............  In Development.
                               pneumophila.
10265-92-6..................  Methamidophos....  Non-National....  Yes.............  Yes.
NA..........................  Mycobacterium      Non-National....  Yes.............  In Development.
                               avium.
86-30-6.....................  N-                 Non-National....  Yes \a\.........  No.
                               Nitrosodiphenyla
                               mine (NDPhA).
301-12-2....................  Oxydemeton-methyl  Non-National....  Yes.............  Yes.
42874-03-3..................  Oxyfluorfen......  Non-National \c\  Yes.............  Yes.
52645-53-1..................  Permethrin.......  Non-National \c\  Yes.............  Yes.
41198-08-7..................  Profenofos.......  Non-National \c\  Yes.............  Yes.
107534-96-3.................  Tebuconazole.....  Non-National \c\  Yes.............  Yes.
78-48-8.....................  Tribufos.........  Non-National \c\  Yes.............  Yes.
50471-44-8..................  Vinclozolin......  Non-National....  Yes.............  Yes.
137-30-4....................  Ziram............  Non-National....  Yes.............  No.
----------------------------------------------------------------------------------------------------------------
   (C) Contaminants With Nationally Representative Finished Water Occurrence Data Lacking Peer Reviewed Health
                                                   Assessments
----------------------------------------------------------------------------------------------------------------
75-34-3.....................  1,1-               National........  No \a\..........  Yes.
                               Dichloroethane.
106-99-0....................  1,3-Butadiene....  National........  No..............  Yes (MRL > HRL).
74-87-3.....................  Chloromethane      National........  No..............  Yes.
                               (Methyl
                               chloride).
474-86-2....................  Equilin..........  National........  No..............  Yes.
50-28-2.....................  Estradiol (17-     National........  No..............  Yes.
                               beta estradiol).
50-27-1.....................  Estriol..........  National........  No..............  Yes.
53-16-7.....................  Estrone..........  National........  No..............  Yes.
57-63-6.....................  Ethinyl Estradiol  National........  No..............  Yes.
                               (17-alpha
                               ethynyl
                               estradiol).
7440-56-4...................  Germanium........  National \c\....  No..............  Yes.
74-97-5.....................  Halon 1011         National........  No..............  Yes.
                               (bromochlorometh
                               ane).
75-45-6.....................  HCFC-22..........  National........  No..............  Yes.
1634-04-4...................  Methyl tert-butyl  National........  No..............  Yes.
                               ether (MTBE).
103-65-1....................  n-Propylbenzene..  National........  No \a\..........  Yes.

[[Page 81113]]

 
135-98-8....................  sec-Butylbenzene.  National........  No \a\..........  Yes.
13494-80-9..................  Tellurium........  National........  No..............  No.
----------------------------------------------------------------------------------------------------------------
 (D) Contaminants With Non-Nationally Representative Finished Water Occurrence Data Lacking Peer Reviewed Health
                                                   Assessments
----------------------------------------------------------------------------------------------------------------
57-91-0.....................  17alpha-estradiol  Non-National....  No..............  In Development.
75-07-0.....................  Acetaldehyde.....  Non-National....  No..............  Yes.
62-53-3.....................  Aniline..........  Non-National....  No \a\..........  No.
25013-16-5..................  Butylated          Non-National \c\  No..............  Yes.
                               hydroxyanisole.
517-09-9....................  Equilenin........  Non-National....  No..............  In Development.
114-07-8....................  Erythromycin.....  Non-National....  No..............  In Development.
110-54-3....................  Hexane...........  Non-National....  No \a\..........  No.
72-33-3.....................  Mestranol........  Non-National....  No..............  No.
NA..........................  Naegleria fowleri  Non-National....  No..............  No.
25154-52-3..................  Nonylphenol......  Non-National....  No..............  No.
68-22-4.....................  Norethindrone (19- Non-National....  No..............  In Development.
                               Norethisterone).
----------------------------------------------------------------------------------------------------------------
          (E) Contaminants With Peer Reviewed Health Assessments Lacking Finished Water Occurrence Data
----------------------------------------------------------------------------------------------------------------
107-18-6....................  2-Propen-1-ol....  Release \c\.....  Yes \a\.........  Yes.
110429-62-4.................  Clethodim........  Release.........  Yes.............  No.
55290-64-7..................  Dimethipin.......  Release \c\.....  Yes.............  Yes.
NA..........................  Escherichia coli   No Data.........  Yes.............  No.
                               (O157).
NA..........................  Helicobacter       No Data.........  Yes.............  No.
                               pylori \e\.
NA..........................  Hepatitis A virus  No Data.........  Yes.............  No.
302-01-2....................  Hydrazine........  Release.........  Yes \a\.........  No.
67-56-1.....................  Methanol.........  Release.........  Yes.............  No.
55-63-0.....................  Nitroglycerin....  Release.........  Yes \a\.........  No.
872-50-4....................  N-Methyl-2-        Release.........  Yes.............  No.
                               pyrrolidone.
75-56-9.....................  Oxirane, methyl-.  Release.........  Yes.............  No.
91-22-5.....................  Quinoline........  Release \c\.....  Yes.............  Yes (MRL > HRL).
112410-23-8.................  Tebufenozide.....  Release.........  Yes.............  Yes.
59669-26-0..................  Thiodicarb.......  Release.........  Yes.............  No.
23564-05-8..................  Thiophanate-       Release.........  Yes.............  No.
                               methyl.
76-87-9.....................  Triphenyltin       Release.........  Yes.............  No.
                               hydroxide (TPTH).
----------------------------------------------------------------------------------------------------------------
      (F) Contaminants Lacking Finished Water Occurrence Data and Current, Peer Reviewed Health Assessments
----------------------------------------------------------------------------------------------------------------
109-86-4....................  2-Methoxyethanol.  Release \c\.....  No \a\..........  Yes.
101-77-9....................  4,4'-              Release.........  No..............  No.
                               Methylenedianili
                               ne.
60-35-5.....................  Acetamide........  Release.........  No..............  No.
NA..........................  Campylobacter      No Data.........  No..............  No.
                               jejuni.
80-15-9.....................  Cumene             Release.........  No..............  No.
                               hydroperoxide.
75-21-8.....................  Ethylene oxide...  Release.........  No..............  No.
95-53-4.....................  o-Toluidine......  Release \c\.....  No \a\..........  Yes.
NA..........................  Salmonella         No Data.........  No..............  No.
                               enteric.
NA..........................  Shigella sonnei..  No Data.........  No..............  No.
26471-62-5..................  Toluene            Release.........  No..............  No.
                               diisocyanate.
121-44-8....................  Triethylamine....  Release.........  No..............  No.
51-79-6.....................  Urethane.........  Release.........  No..............  No.
----------------------------------------------------------------------------------------------------------------
Key to Exhibit:
National = Finished drinking water occurrence data that are nationally representative are available.
Non-National = Finished drinking water occurrence data that are not nationally representative are available.
In Development = Revised health assessment or analytical method is currently being developed.
\a\ Provisional Peer Reviewed Toxicity Value (PPRTV) in the form of chronic, oral RfD subchronic, oral RfD,
  cancer weight evidence, or cancer slope factor available.
\b\ The parent health assessment was used for the metabolite. There is no independent health assessment
  available for the metabolite.
\c\ Proposed for UCMR 4.
\d\ Evaluations of occurrence data availability for cyanotoxins in this table are based on anatoxin-a,
  cylindrospermopsin, and microcystin-LR. Cyanotoxins proposed for UCMR 4 monitoring include total microcystins
  (MC), MC-LA, MC-LF, MC-LR, MC-LY, MC-RR, MC-YR, nodularin, anatoxin-a and cylindrospermopsin.

VI. Next Steps and Future Contaminant Candidate Lists

    The CCL process is critical to shaping the future direction of the 
drinking water program. The agency will continue to gather information 
and evaluate contaminants on the CCL 4 to make regulatory 
determinations for at least five contaminants. The agency will also 
continue to refine the CCL process and gather more data to identify 
contaminants for CCL 5. EPA will continue to work to prioritize 
contaminants on the CCL 4, both for RD and for additional research and 
data collection.

References

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    Dated: November 9, 2016.
Joel Beauvais,
Deputy Assistant Administrator, Office of Water.
[FR Doc. 2016-27667 Filed 11-16-16; 8:45 am]
 BILLING CODE 6560-50-P