Drinking Water Contaminant Candidate List 3-Final, 51850-51862 [E9-24287]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 74, Number 194 (Thursday, October 8, 2009)]
[Notices]
[Pages 51850-51862]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E9-24287]


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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OW-2007-1189 FRL-8963-6]
RIN 2040-AD99


Drinking Water Contaminant Candidate List 3--Final

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: The Environmental Protection Agency is publishing the third 
Contaminant Candidate List (CCL 3) since the Safe Drinking Water Act 
(SDWA) amendments of 1996. The CCL 3 is a list of contaminants that are 
currently not subject to any proposed or promulgated national primary 
drinking water regulations, that are known or anticipated to occur in 
public water systems, and which may require regulation under SDWA. 
Today's final CCL 3 includes 104 chemicals or chemical groups and 12 
microbiological contaminants.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OW-2007-1189. All documents in the docket are listed on 
https://www.regulations.gov. Although listed in the index, some 
information is not publicly available. For example, confidential 
business information or other information whose disclosure is 
restricted by statute is not publicly available. Certain other 
material, such as copyrighted material, is not placed on the Internet 
and is only in hard copy form. Publicly available docket materials are 
available either electronically through https://www.regulations.gov or 
in hard copy at the Water Docket, EPA/DC, EPA West, Room 3334, 1301 
Constitution Ave., NW., Washington, DC. 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.

FOR FURTHER INFORMATION CONTACT: For information on chemical 
contaminants contact Thomas Carpenter, Office of Ground Water and 
Drinking Water, Standards and Risk Management Division, at (202) 564-
4885 or e-mail carpenter.thomas@epa.gov. For information on microbial 
contaminants contact Tracy Bone, Office of Ground Water and Drinking 
Water, at (202) 564-5257 or e-mail bone.tracy@epa.gov. For general 
information contact the EPA Safe Drinking Water Hotline at (800) 426-
4791 or e-mail: hotline-sdwa@epa.gov.

Abbreviations and Acronyms

CASRN--Chemical Abstract Services Registry Number
CDC--Centers for Disease Control and Prevention
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
CERCLA--Comprehensive Environmental Response, Compensation, and 
Liability Act
CFR--Code of Federal Regulations
CSF--Cancer Slope Factor
DBP--disinfection byproduct
EPA--United States Environmental Protection Agency
ESA--ethanesulfonic acid
FDA--United States Food and Drug Administration
FIFRA--Federal Insecticide, Fungicide, and Rodenticide Act
FR--Federal Register
HRL--Health Reference Level
ICR--Information Collection Request
IUR--Inventory Update Rule
MCL--maximum contaminant level
MCLG--maximum contaminant level goal
NCFAP--National Center for Food and Agricultural Policy
NDWAC--National Drinking Water Advisory Council
NDMA--N-nitrosodimethylamine
NIRS--National Inorganic Radiological Survey
NRC--National Academies of Science's National Research Council
NPDWR--national primary drinking water regulation
OPP--Office of Pesticide Programs
PCCL--Preliminary CCL
PFOA--perfluorooctanoic acid
PFOS--perfluorooctane sulfonic acid

[[Page 51851]]

PWS--public water system
RAISHE--Risk Assessment Information System, Health Effects
RDX- Cyclotrimethylenetrinitramine
RfD--reference dose
RTECS--Registry of Toxic Effects for Chemical Substances
SAB--EPA Science Advisory Board
SDWA--Safe Drinking Water Act
TRI--Toxics Release Inventory
TNT--2, 4, 6-trinitrotoluene
UCMR--Unregulated Contaminant Monitoring Regulation
UCMR 1--First Unregulated Contaminant Monitoring Regulation
UCMR 2--Second Unregulated Contaminant Monitoring Regulation
UCM R1/2--Unregulated Contaminant Monitoring Round \1/2\
U.S.--United States of America
USGS--United States Geological Survey
WBDO--waterborne disease outbreak
WHO--World Health Organization

SUPPLEMENTARY INFORMATION:
I. General Information
    A. Does This Action Impose Any Requirements on My Public Water 
System?
    B. What Is the Purpose of this Action?
    C. SDWA Risk Management Provisions
    1. Contaminant Candidate List 3
    2. Regulatory Determinations
    3. Unregulated Contaminant Monitoring
II. What is on EPA's Drinking Water Contaminant Candidate List 3?
III. What Comments did EPA Receive on the Draft CCL 3 and How did 
the Agency Respond?
    A. Advisory from the EPA Science Advisory Board (SAB)
    B. Chemical Contaminants
    1. Pesticides and Degradates
    2. Cancelled Pesticides
    3. Perfluorinated Compounds
    4. Pharmaceuticals
    5. Perchlorate
    6. Disinfection Byproducts
    C. Microbial Contaminants
    1. Using the CDC WBDO's as a Scoring Criteria
    2. Mycobacterium avium
    3. Vibrio cholerae and Entamoeba hystolitica
    D. Other comments
    1. Data Sources for the Contaminant Candidate Lists
    2. Contaminant Candidate List and Unregulated Contaminants 
Monitoring Regulation
IV. Data Needs for CCL 3 Contaminants
    A. Chemical Contaminants
    1. Health Effects
    2. Occurrence
    3. Analytical Methods
    B. Microbial Contaminants
V. Next Steps/Future Contaminant Candidate Lists
VI. References

I. General Information

A. Does This Action Impose Any Requirements on My Public Water System?

    The final Contaminant Candidate List 3 (CCL 3) will not impose any 
requirements on anyone. Instead, this action notifies interested 
parties of the availability of U.S. EPA's final CCL 3, and provides 
information on the Agency's next steps to evaluate these contaminants.

B. What Is the Purpose of This Action?

    The purpose of this action is to present the final CCL 3, a summary 
of the comments received on the draft CCL 3, and a description of the 
Agency's process for identifying contaminants to be placed on the list. 
Pursuant to section 1412(b)(1)(B)(i) of SDWA, as amended in 1996, EPA 
is required to publish a list of contaminants (1) that are currently 
unregulated, (2) that are known or anticipated to occur in public water 
systems, and (3) which may require regulations under the Safe Drinking 
Water Act (SDWA). This section briefly summarizes the statutory 
requirements for CCL 3, and related activities surrounding the 
contaminants included on the final CCL 3.

C. SDWA Risk Management Provisions

1. Contaminant Candidate List 3
    SDWA section 1412(b)(1) requires that in the development of the 
CCL, EPA consider specific data sources and include the scientific 
community. EPA must evaluate substances identified in section 101(14) 
of the Comprehensive Environmental Response, Compensation, and 
Liability Act (CERCLA) of 1980 and substances registered as pesticides 
under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). 
SDWA also requires the Agency to consider the National Contaminant 
Occurrence Database established under section 1445(g) of SDWA. SDWA 
directs the Agency to consult with the scientific community, including 
the Science Advisory Board (SAB). In addition it 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.
    EPA interprets the criterion that contaminants are known or 
anticipated to occur in public water systems broadly. In evaluating 
this criterion, EPA considers not only public water system monitoring 
data, but also data on ambient concentrations in surface and ground 
waters, and releases to the environment (e.g., Toxics Release 
Inventory). 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 to place them on the CCL. Once contaminants 
have been placed on the CCL, EPA identifies if there are any additional 
data needs, including gaps in occurrence data.
    In selecting contaminants for the CCL 3, each of the above 
requirements was met. 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 for 
both chemicals and microbes.
2. Regulatory Determinations
    SDWA section 1412(b)(1) requires EPA to determine whether to 
regulate at least five contaminants from the CCL every five years. SDWA 
specifies that EPA shall regulate a contaminant if the Administrator 
determines that:
     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 public water 
systems 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 public water systems.
    EPA interprets these criteria as more rigorous than what is used to 
place contaminants on the CCL. Section IV of this notice presents the 
current data needs for regulatory determination for the CCL 3 
contaminants.
    If EPA makes a determination that a national primary drinking water 
regulation is needed, then the Agency has 24 months to publish a 
proposed Maximum Contaminant Level Goal (MCLG) \1\ and a proposed 
National Primary Drinking Water Rule (NPDWR).\2\ After the proposal, 
the Agency has 18 months to publish a final

[[Page 51852]]

MCLG and promulgate a final NPDWR (SDWA 1412(b)(1)(E)).\3\
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    \1\ An 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. Maximum contaminant level goals are non-enforceable health 
goals'' (40 CFR 141.2).
    \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 
(TT) for public water systems for a specific contaminant or group of 
contaminants.
    \3\ The statute authorizes a nine month extension of this 
promulgation date.
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3. Unregulated Contaminant Monitoring
    SDWA provides EPA with the authority to require all large and a 
subset of small systems to monitor for up to 30 unregulated 
contaminants every five years under the Unregulated Contaminant 
Monitoring Regulation (UCMR). The second unregulated contaminant 
monitoring rule (UCMR 2), which was promulgated on January 4, 2007 (72 
FR 367; USEPA, 2007a), requires monitoring for several pesticides and 
pesticide degradates, five polybrominated diphenyl ether (PBDE) flame 
retardants, a group of nitrosamines, and two munitions (TNT and RDX). 
All of the chemicals on UCMR 2 were included among the contaminants 
evaluated for CCL 3.
    Data collected under the UCMR are an important source of occurrence 
information for both the CCL and Regulatory Determination processes. 
There is an additional discussion of the relationship between CCL and 
UCMR in Section III. D of this Federal Register (FR) notice.

II. What Is on EPA's Drinking Water Contaminant Candidate List 3?

    The draft CCL 3 was published on February 21, 2008 (73 FR 9628; 
USEPA 2008a), and included 93 chemicals or chemical groups and 11 
microbiological contaminants. EPA provided information and sought 
comment on its efforts to expand and strengthen the underlying CCL 
listing process, the draft list, and EPA's efforts to improve the 
contaminant selection process for future CCLs.
    In developing the draft CCL 3, EPA implemented a new process from 
that used for CCL 1 and CCL 2. This new process builds on evaluations 
from previous CCLs, and was based on substantial expert input and 
recommendations from various groups, including the National Academy of 
Science's National Research Council (NRC) and the National Drinking 
Water Advisory Council (NDWAC). This process is summarized in the draft 
CCL 3 FR notice.
    In general, the criteria for including a contaminant on the CCL 
consisted of determining whether the occurrence or anticipated 
occurrence of a contaminant was likely at levels of concern to human 
health. The draft CCL 3 notice solicited input from the public, and 
specifically requested comments on (1) the approach EPA used to create 
the list; (2) contaminants on the list; and (3) on specific 
contaminants such as pharmaceuticals, perfluorinated compounds, and 
microbes.
    The final CCL 3 includes 104 chemicals or chemical groups and 12 
microbiological contaminants (Exhibit 1). The list includes, among 
others, pesticides, biological toxins, disinfection byproducts, 
chemicals used in commerce, and waterborne pathogens. The Agency 
considered the best available data and information on health effects 
and occurrence to evaluate 7,500 unregulated contaminants and selected 
116 candidates for the final CCL 3, which have the potential to present 
health risks through drinking water exposure.
    Exhibit 1. Final Contaminant Candidate List 3:

                          Chemical Contaminants
------------------------------------------------------------------------
                   CASRN                     Common name--registry name
------------------------------------------------------------------------
630206....................................  1,1,1,2-Tetrachloroethane.
75343.....................................  1,1-Dichloroethane.
96184.....................................  1,2,3-Trichloropropane.
106990....................................  1,3-Butadiene.
99650.....................................  1,3-Dinitrobenzene.
123911....................................  1,4-Dioxane.
57910.....................................  17 alpha-Estradiol.
71363.....................................  1-Butanol.
109864....................................  2-Methoxyethanol.
107186....................................  2-Propen-1-ol.
16655826..................................  3-Hydroxycarbofuran.
101779....................................  4,4'-Methylenedianiline.
30560191..................................  Acephate.
75070.....................................  Acetaldehyde.
60355.....................................  Acetamide.
34256821..................................  Acetochlor.
187022113.................................  Acetochlor ethanesulfonic
                                             acid (ESA).
184992444.................................  Acetochlor oxanilic acid
                                             (OA).
107028....................................  Acrolein.
142363539.................................  Alachlor ethanesulfonic acid
                                             (ESA).
171262172.................................  Alachlor oxanilic acid (OA).
319846....................................  Alpha-Hexachlorocyclohexane.
62533.....................................  Aniline.
741582....................................  Bensulide.
100447....................................  Benzyl chloride.
25013165..................................  Butylated hydroxyanisole.
133062....................................  Captan.
14866683..................................  Chlorate.
74873.....................................  Chloromethane (Methyl
                                             chloride).
110429624.................................  Clethodim.
7440484...................................  Cobalt.
80159.....................................  Cumene hydroperoxide.
NA........................................  Cyanotoxins.
141662....................................  Dicrotophos.
55290647..................................  Dimethipin.
60515.....................................  Dimethoate.
298044....................................  Disulfoton.
330541....................................  Diuron.
517099....................................  Equilenin.
474862....................................  Equilin.
114078....................................  Erythromycin.
50282.....................................  Estradiol (17-beta
                                             estradiol).
50271.....................................  Estriol.
53167.....................................  Estrone.
57636.....................................  Ethinyl Estradiol (17-alpha
                                             Ethynyl Estradiol).
13194484..................................  Ethoprop.
107211....................................  Ethylene glycol.
75218.....................................  Ethylene oxide.
96457.....................................  Ethylene thiourea.
22224926..................................  Fenamiphos.
50000.....................................  Formaldehyde.
7440564...................................  Germanium.
74975.....................................  Halon 1011
                                             (bromochloromethane).
75456.....................................  HCFC-22.
110543....................................  Hexane.
302012....................................  Hydrazine.
72333.....................................  Mestranol.
10265926..................................  Methamidophos.
67561.....................................  Methanol.
74839.....................................  Methyl bromide
                                             (Bromomethane).
1634044...................................  Methyl tert-butyl ether.
51218452..................................  Metolachlor.
171118095.................................  Metolachlor ethanesulfonic
                                             acid (ESA).
152019733.................................  Metolachlor oxanilic acid
                                             (OA).
2212671...................................  Molinate.
7439987...................................  Molybdenum.
98953.....................................  Nitrobenzene.
55630.....................................  Nitroglycerin.
872504....................................  N-Methyl-2-pyrrolidone.
55185.....................................  N-Nitrosodiethylamine
                                             (NDEA).
62759.....................................  N-nitrosodimethylamine
                                             (NDMA).
621647....................................  N-Nitroso-di-n-propylamine
                                             (NDPA).
86306.....................................  N-Nitrosodiphenylamine.
930552....................................  N-nitrosopyrrolidine (NPYR).
68224.....................................  Norethindrone (19-
                                             Norethisterone).
103651....................................  N-Propylbenzene.
95534.....................................  O-Toluidine.
75569.....................................  Oxirane, methyl-.
301122....................................  Oxydemeton-methyl.
42874033..................................  Oxyfluorfen.
14797730..................................  Perchlorate.
1763231...................................  Perfluorooctane sulfonic
                                             acid (PFOS).
335671....................................  Perfluorooctanoic acid
                                             (PFOA).
52645531..................................  Permethrin.
41198087..................................  Profenofos.
91225.....................................  Quinoline.
121824....................................  RDX.
135988....................................  Sec-Butylbenzene.
7440246...................................  Strontium.
107534963.................................  Tebuconazole.
112410238.................................  Tebufenozide.
13494809..................................  Tellurium.
13071799..................................  Terbufos.
56070167..................................  Terbufos sulfone.
59669260..................................  Thiodicarb.
23564058..................................  Thiophanate-methyl.
26471625..................................  Toluene diisocyanate.

[[Page 51853]]

 
78488.....................................  Tribufos.
121448....................................  Triethylamine.
76879.....................................  Triphenyltin hydroxide
                                             (TPTH).
51796.....................................  Urethane.
7440622...................................  Vanadium.
50471448..................................  Vinclozolin.
137304....................................  Ziram.
------------------------------------------------------------------------


                         Microbial Contaminants
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
Adenovirus
Caliciviruses
Campylobacter jejuni
Enterovirus
Escherichia coli (0157)
Helicobacter pylori
Hepatitis A virus
Legionella pneumophila
Mycobacterium avium
Naegleria fowleri
Salmonella enterica
Shigella sonnei
------------------------------------------------------------------------

III. What Comments Did EPA Receive on the Draft CCL 3 and How Did the 
Agency Respond?

    EPA received comments from 177 individuals or organizations on the 
draft CCL 3. Commenters identified several issues on the draft CCL 3 
and the process used to select contaminants for the list. Many 
commenters noted the substantial effort, overall improvement, improved 
scientific rigor, and increased stakeholder involvement employed by EPA 
to develop the draft CCL 3. Commenters also provided information and 
recommendations for the Agency to consider as it finalized the CCL 3. 
The Agency has provided responses to individual comments in the ``Final 
Comment Response Document for the Third Drinking Water Contaminant 
Candidate List 3 (Categorized Public Comments)'' document that is 
available in the docket (USEPA 2009c).

A. Advisory From the EPA Science Advisory Board

    The EPA SAB and its Drinking Water Committee reviewed the draft CCL 
3 during 2008, and provided an advisory to the Administrator on January 
29, 2009. EPA staff met with the SAB to provide an overview of the 
draft CCL 3, to answer questions from the Drinking Water Committee, and 
to clarify questions from the full SAB. The Agency also participated in 
teleconferences with SAB during the development of the ``SAB Advisory 
on EPA's Draft Third Drinking Water Contaminant Candidate List (CCL 
3)'' (USEPA 2009d). SAB comments on the overall CCL 3 process and 
documentation are summarized in the following paragraphs.
    The SAB noted that the process used to develop the draft CCL 3 
represents a major improvement over the previous CCL processes and 
recognized the adaptive management strategies employed by EPA as an 
appropriate approach that should continue to be used in future CCLs. 
However, the SAB also believes the documentation of the process used to 
develop the draft CCL 3 lacks transparency. For example, one suggestion 
stated that EPA should document and justify why each of the 
contaminants from previous CCL lists were excluded from the draft CCL 
3.
    The SAB also stated that the current list may be too large for 
chemicals; and it may include too few pathogens. The SAB acknowledged 
that the CCL 3 has dual goals of developing regulatory determinations 
and identifying longer-term research needs. They also recommended that 
EPA prioritize the list to better identify regulatory priorities, 
research needs, and longer term needs for the next CCL.
EPA Response to SAB Recommendations
    The Agency has updated the technical support documents for the CCL 
3 to increase the transparency of the process that was used to 
determine which contaminants to include on the final CCL 3. Several 
specific suggestions to improve the transparency of the process are 
addressed in the supporting documents and identified in Section III of 
this notice. Documents describing the process and tables that identify 
the data used to select contaminants can be found on EPA's Web site at: 
https://www.epa.gov/safewater/ccl/. More detailed information 
on the contaminants, such as the ``Final CCL 3 Contaminant Information 
Sheets.'', (USEPA, 2009e) and the ``Final Contaminant Candidate List 3 
Microbes: PCCL to CCL Process'' can be found in the docket (USEPA, 
2009g) and on EPA's Web site.
    In Section IV of this FR notice, the Agency has also identified 
which contaminants will need additional data and information on their 
occurrence, health effects, and analytical methods. As the Agency 
continues to evaluate contaminants on the CCL 3, we will work with EPA 
and non-EPA scientists to develop and collect the best available 
science to support decision making for future regulatory 
determinations.

B. Chemical Contaminants

    EPA evaluated data and information on chemical contaminants 
provided by commenters and collected by the Agency after the draft CCL 
3 was published. EPA used the same process described in the draft CCL 3 
FR notice (73 FR 9628, USEPA 2008a) to evaluate contaminants for which 
data became available after the publication of the draft CCL 3. Based 
on these analyses, EPA is taking the following actions on chemical 
contaminants: EPA is removing two pesticides from the CCL 3 that are no 
longer used in the United States, and the Agency is adding 13 chemical 
contaminants to the final CCL 3. EPA concluded that one antibiotic 
(erythromycin), nine hormones (17 alpha-estradiol, 17 beta-estradiol, 
equilenin, equilin, estriol, estrone, ethinyl estradiol, mestranol, and 
norethindrone), two potential disinfection byproducts (DBP) (Halon 1011 
(bromochloeromethane) and chlorate), and one perfluorinated compound 
(Perfluorooctanoic sulfonic acid (PFOS)) should be included on the CCL 
3 based on their potential adverse health effects and potential for 
occurrence in public water systems. The Agency has summarized the 
comments and information used to evaluate these contaminants in this 
section of the FR notice. The specific data used to evaluate these 
contaminants can be found in the response to comment document (USEPA, 
2009c) and the ``Final CCL 3 Contaminant Information Sheets'' in the 
docket (USEPA, 2009e).
1. Pesticides and Degradates
    EPA received more than 65 public comments on pesticides and their 
related degradates. Some commenters were concerned about the number of 
pesticides listed on the draft CCL 3. One commenter states, ``* * * in 
the process of narrowing the universe of 7,500 unregulated chemicals 
down to 93 * * * EPA selected nearly half (42 out of 93) to be 
pesticides or pesticide degradates.'' This and other commenters viewed 
the listing of pesticides as a selection bias and noted that EPA has 
not clearly demonstrated, in the process used to derive the draft CCL 
3, that these 42 pesticides and degradates pose the greatest public 
health concern. In addition, this commenter believed that the inclusion 
and proportional share of pesticides and their degradates on the draft 
CCL 3 should take into account the Agency's regulatory determination 
findings where none of the pesticides or degradates evaluated were 
ultimately determined to provide a meaningful opportunity to provide 
public health protection. In contrast, some commenters were in 
agreement with the pesticides included on the draft CCL 3, and in some 
cases, commenters

[[Page 51854]]

suggested placing additional pesticides on the final CCL 3.
    EPA Response: EPA does not agree with the commenter's statement 
that there is a selection bias for pesticides. The CCL 3 process was 
developed to evaluate contaminants from a broad universe of chemicals 
in accordance with the NRC and NDWAC recommendations. The chemicals are 
subject to consistent screening and evaluation based on chemical 
specific factors such as physical properties, health effects data, and 
their potential to occur in public water systems. SDWA requires EPA to 
evaluate substances registered as pesticides under FIFRA. All 
pesticides identified in the universe of chemicals were evaluated by 
EPA using the same process as other chemicals. Previous regulatory 
determinations not to develop a NPDWR for 10 pesticides or degradates 
in Regulatory Determinations 1 and 2 are irrelevant to other pesticides 
on the CCL 3. The regulatory determination process, like the CCL 
process, is data driven. To make a regulatory determination, EPA 
evaluates the available occurrence and health effects data for that 
contaminant against the criteria in SDWA Section 1412 (b)(1)(a). The 
Agency has responded to comments on specific pesticides in the response 
to comment document (USEPA, 2009c).
2. Cancelled Pesticides Registrations
    SAB and other public commenters suggested that specific pesticide 
active ingredients (Nitrofen and Ethion) should be removed from the CCL 
3 because they are no longer used in registered pesticides. The SAB 
also commented that EPA should consider removing pesticides from the 
CCL 3 that are no longer registered products or are in the process of 
being phased out of use. The pesticides identified by the commenters, 
Nitrofen and Ethion, are not included on the final CCL 3. The 
evaluation of these two pesticides is summarized in the following 
paragraphs.
a. Nitrofen
    EPA received comment from the public and the SAB that Nitrofen 
should not be included on the final CCL 3. Commenters noted that the 
available information on use, release, and potential environmental 
occurrence of Nitrofen indicate that it should not be anticipated to 
occur in public water systems (PWS).
    EPA Response: EPA agrees with the commenters that Nitrofen should 
be removed from the CCL 3. It is no longer manufactured or sold in the 
United States. Its inclusion on the draft list was based on a reported 
TRI release which, when investigated, indicated that Nitrofen stocks 
were recently found in a warehouse and properly disposed of in 
accordance with the Resource Conservation and Recovery Act Subtitle C 
landfill regulations. TRI requires that information on landfill 
releases, even releases in compliance with regulations, be reported; 
therefore, the Nitrofen release was incorporated in the total TRI data 
used in the CCL process. Based on this information, Nitrofen is not 
anticipated to occur in PWSs, and the Agency has not included Nitrofen 
on the final CCL 3.
b. Ethion
    Commenters noted that the registration for Ethion was cancelled and 
therefore EPA should not include Ethion on the final CCL 3.
    EPA Response: EPA agrees with the commenters and has not included 
Ethion on the final CCL 3. On March 22, 2002, EPA published a 
cancellation order discontinuing the manufacture of Ethion containing 
products as of October 1, 2003, and prohibiting the use of existing 
stocks after December 31, 2004 (67 FR 13328; USEPA, 2002). A July 23, 
2004 action revoked the remaining Ethion tolerances, as of October 1, 
2008 (69 FR 43918; USEPA, 2004). EPA notes that SDWA criteria consider 
whether a contaminant is known or anticipated to occur in PWSs and may 
have an adverse effect. It is possible for a contaminant to occur in a 
PWS even after its uses are canceled if it is very persistent in the 
environment. Ethion is moderately persistent in the environment, but is 
not likely to contaminate surface water through dissolved runoff. Based 
on laboratory and field data, including monitoring data compiled in 
EPA's Pesticides in Ground Water Database, EPA does not expect that 
Ethion will contaminate ground water (USEPA, 2001). Based on Ethion's 
discontinued registration status, prohibited use of stocks, and 
moderate persistence, the Agency does not anticipate that it will occur 
in PWSs; therefore, it is not included on the final CCL 3.
3. Perfluorinated Compounds
    In the draft CCL 3 FR notice, EPA sought comments on its proposed 
decisions to include perfluorooctanoic acid (PFOA) and not to include 
PFOS on the draft CCL 3 (73 FR 9652, USEPA 2008a). The majority of 
commenters agreed with the inclusion of PFOA on the CCL 3. Commenters 
pointed out that PFOA warrants inclusion on the CCL due to its known 
occurrence in drinking water supplies and systems and its potential 
adverse health effects. A number of these commenters also wrote in 
support of regulating PFOA under SDWA. The SAB also stated that PFOA 
should be a high priority for consideration by the Agency for the CCL 
3. One commenter argued that EPA did not use the most relevant 
information in the CCL 3 process to characterize PFOA's health effects 
and occurrence. Some of the commenters who were in support of including 
PFOA on the CCL also recommended adding PFOS and other perfluorinated 
compounds to the list. The SAB noted that perfluorochemicals may be a 
class of contaminants that the Agency should consider as a group based 
on their similar structures and chemical makeup.
    EPA Response: The Agency agrees with commenters that potential 
health effects based on animal studies and the occurrence of PFOA in 
drinking water supplies warrant its inclusion on the CCL 3. The Agency 
used the best available science and information to evaluate and list 
drinking water contaminant candidates. PFOA has been detected in a 
number of drinking water supplies and ambient waters. It is also highly 
persistent in the environment and has been shown to be toxic in animal 
studies. Based on these potential adverse health effects and occurrence 
information, EPA concludes that PFOA is known or anticipated to occur 
in public water systems and may require regulation. Therefore EPA has 
included PFOA on the final CCL 3.
    PFOS was not included on the draft CCL 3, but has been included on 
the final CCL 3. A major factor in EPA's decision to not include PFOS 
on the draft CCL 3 was the voluntary phase-out of production of PFOS in 
the U.S. between 2000 and 2002 (FR 73 9652; USEPA 2008a). However, EPA 
has evaluated new information from the October 9, 2007, significant new 
use rule (SNUR) that shows there are ongoing uses of PFOS that could 
lead to its occurrence in water (FR 72 57222-57235; USEPA 2007b). The 
Agency concluded, based upon this potential to occur in PWSs, existing 
data on environmental persistence, and toxicity in animal studies, that 
PFOS is known or anticipated to occur in public water systems and may 
require regulation. Therefore, EPA has included this compound on the 
final CCL 3.
    The Agency continues to analyze the data and information related to 
the possible adverse health effects associated with PFOA and PFOS. As 
noted in the draft CCL 3 FR notice, the SAB completed a review of a 
draft PFOA risk assessment in 2006 and made

[[Page 51855]]

recommendations for the further development of the risk assessment 
(USEPA, 2006a). A number of important studies are underway, and the 
Agency continues to participate in research regarding the toxicity of 
related perfluorochemicals, as well as research to help identify routes 
of human exposure. EPA is evaluating additional research and has not 
made any definitive conclusions on the risk assessment at this time. 
The Agency also issued ``Provisional Health Advisories for PFOA and 
PFOS'' (USEPA 2009f) to provide technical information to State and 
local officials, and PWSs for consideration in addressing local 
contamination of drinking water to protect public health. This 
information has been included in the docket and the ``Final CCL 3 
Contaminant Information Sheets'' for PFOA and PFOS (USEPA, 2009e).
    While the Agency did not specifically seek comment on other 
perfluorinated compounds in the draft CCL 3 FR notice, some of these 
compounds were included in the CCL 3 Universe. However, the Agency had 
only limited data on the potential occurrence of these compounds and 
potential adverse health effects. Commenters did not provide additional 
occurrence or health effects data than those already evaluated by the 
Agency; therefore, they are not listed on the CCL at this time. The 
Agency will continue to evaluate perfluorinated compounds to ascertain 
whether they possess similar toxicological properties and if they are 
anticipated or known to occur in public water systems.
4. Pharmaceuticals
    In the draft CCL 3 FR notice (73 FR 9652; USEPA, 2008a), EPA 
explained how pharmaceuticals were evaluated in the CCL 3 process, and 
sought additional data and information on the concentrations of 
pharmaceuticals in finished or ambient water. EPA also requested 
comment on how pharmaceuticals have been considered in the CCL 3 
process. In addition, EPA sent a letter to State public health and 
environmental departments requesting information on the States' 
activities and initiatives involving pharmaceuticals. The Agency 
specifically requested information on pharmaceuticals in the areas of 
occurrence, human health effects research, analytical methods 
development, and stewardship. EPA received a number of comments on 
pharmaceuticals and the CCL 3. Commenters pointed out that additional 
research is needed to address the health effects and occurrence of 
pharmaceuticals in drinking water. Commenters also noted that the 
contaminants were detected at low levels. Commenters differed on 
whether pharmaceuticals should be included on the CCL 3. Some 
commenters provided references from the published literature on the 
occurrence of pharmaceuticals in water and on the health effects of 
pharmaceuticals. In its comments, the SAB noted that pharmaceuticals 
may be a class of contaminants that need special attention when 
considering them for CCL 3 or future CCLs, and recommended that EPA use 
additional data on occurrence of pharmaceuticals in water from the 
United States Geological Survey (USGS), or studies in the peer-reviewed 
literature (USEPA, 2009d).
    EPA Response: EPA is actively working to evaluate the potential 
risks to human health and aquatic life posed by trace amounts of 
pharmaceuticals and personal care products in water, and to identify 
measures to minimize their occurrence. The Agency has a number of 
activities underway and will continue to add activities as appropriate. 
All of these activities are described in further detail on our Web site 
located at https://www.epa.gov/waterscience/ppcp. Additional information 
on the Agency's research related to pharmaceuticals can be found at 
https://www.epa.gov/ppcp.
    In the CCL 3 process, EPA evaluated the potential adverse health 
effects of pharmaceuticals and their occurrence in public drinking 
water systems to determine if pharmaceuticals should be added to the 
list. Since the draft CCL 3 was published, several publications have 
focused on the occurrence of pharmaceuticals in ambient water and 
drinking water. In response to comments, EPA has conducted additional 
data collection efforts to comprehensively review recent published 
information from USGS and other sources, including those cited by 
commenters, to identify the best available occurrence information for 
pharmaceuticals. EPA identified new occurrence data for 81 contaminants 
from 22 sources. The Agency also conducted additional literature 
reviews to identify the best available health effects information and 
identified data from sources including: EPA Office of Pesticide 
Programs, the Food and Drug Administration (FDA) Center for Veterinary 
Medicine, the Joint Food and Agriculture Organization/World Health 
Organization (WHO) Expert Committee on Food Additives, and the European 
Medicines Agency, and the FDA Center for Drug Evaluation and Research. 
EPA used the new data in the same process that was described in the 
draft CCL 3 FR notice to further evaluate pharmaceutical contaminants.
    Based upon this re-evaluation with new data, EPA concluded that one 
antibiotic (erythromycin) and nine hormones (17 alpha-estradiol, 17 
beta-estradiol, equilenin, equilin, estriol, estrone, ethinyl 
estradiol, mestranol, and norethindrone), should be included on the CCL 
3 because these contaminants are known or anticipated to occur in 
public water systems and may require regulation. The specific data used 
to evaluate these contaminants can be found in the ``Final CCL 3 
Contaminant Information Sheets'' (USEPA, 2009e).
5. Perchlorate
    EPA received several comments on perchlorate in response to the 
draft CCL 3. Commenters noted that perchlorate should be included on 
the final CCL 3 and provided occurrence and health effects data. 
Commenters also identified potential sources of perchlorate in the 
environment.
    EPA Response: EPA included perchlorate on the first CCL in 1998 and 
on the second CCL in 2005. EPA is including perchlorate on CCL 3 while 
the Agency continues to evaluate scientific information related to a 
regulatory determination.
    EPA published a preliminary regulatory determination for 
perchlorate in the FR on October 10, 2008 (73 FR 60262; USEPA, 2008b). 
In this notice, EPA solicited public comment on its preliminary 
determination not to regulate perchlorate. The Agency issued an interim 
health advisory for perchlorate to provide technical information to 
State and local officials and PWSs for consideration in addressing 
local contamination of drinking water (USEPA, 2008c).
    EPA received more than 32,000 comments on the preliminary 
regulatory determination (73 FR 60262; USEPA 2008b). The majority of 
comments were submitted by individuals opposed to the decision. There 
were also unique comments that recommended further scientific 
evaluation of the information EPA used to make the preliminary 
determination. These commenters included EPA's NDWAC, SAB, and 
Children's Health Protection Advisory Committee. All of the comments 
received on the preliminary regulatory determination FR notice can be 
reviewed on www.regulations.gov. Refer to docket number EPA-HQ-OW-2008-
0692.
6. Disinfection Byproducts (DBP)
    EPA received several comments on unregulated disinfection 
byproducts.

[[Page 51856]]

Most comments supported the inclusion of N-nitrosodimethylamine (NDMA) 
and the other N-nitrosamines (N-nitrosodiethylamine, N-nitroso-di-n-
propylamine, N-nitrosodiphenylamine, N-nitrosopyrrolidine) on CCL 3, 
citing the evidence for their carcinogenicity and the overarching need 
to evaluate this risk. The SAB advised EPA to consider N-nitrosamines 
as a group because of their similar toxicities and likelihood to occur 
together. One commenter expressed concern that two N-nitrosamines: N-
nitroso-di-n-butylamine and N-nitroso-methylethylamine (which are 
included in UCMR 2) are not listed on the draft CCL 3. Several 
commenters expressed concern about the overall lack of DBPs on the 
draft CCL 3, citing their assumed presence as a result of drinking 
water disinfection. One commenter requested that the remaining halo-
acetic acids not covered under the current DBP regulation 
(bromochloroacetic acid, dibromochloroacetic acid, bromodichloroacetic 
acid, and tribromoacetic acid) be added to the CCL 3. Several 
commenters mentioned groups of chemicals, such as halo-nitriles, halo-
aldehydes, halo-nitromethanes, and other nitrogenous DBPs that they 
believed should be included on the CCL 3.
    EPA Response: The CCL 3 process took into consideration the 
potential formation of DBPs in disinfected and treated drinking water. 
Potential DBPs with available health information were added to the CCL 
Chemical Universe even if they did not have measured occurrence data. 
This is because DBPs were considered to have ``default'' occurrence for 
the Universe since they are potentially formed in treated drinking 
water supplies (USEPA 2009a). In screening chemicals from the Universe 
to the Preliminary CCL (PCCL), EPA added DBPs to the PCCL that lacked 
quantitative occurrence data but were in the Toxicity Category 1 or 
Toxicity Category 2 groupings because of their potential presence in 
disinfected and treated drinking water (USEPA 2009b). EPA attempted to 
identify additional health effects and occurrence data for these DBPs 
to determine whether to include them on the CCL 3. Quantitative 
occurrence data were needed in order for DBPs to be evaluated for 
inclusion on the CCL 3. The Agency sought comment on the approach and 
the data used to select contaminants in the draft CCL 3.
    EPA evaluated 85 chemicals in the groups of potential DBPs 
mentioned by the commenters, but the available data showed that most 
DBPs had limited or low levels of occurrence, or lacked health effects 
data. For example, the two UCMR 2 nitrosamines that are not on CCL 3 
lacked sufficient occurrence information for inclusion on the list. 
There is additional discussion of the interrelationship between the CCL 
and UCMR in Section III.D of this FR notice.
    Several commenters mentioned chemicals that were not included in 
the Universe data compilation, but they did not submit the health 
effects and/or occurrence information that would be necessary to 
support their inclusion on the final CCL 3.
    In addition to the data used by the Agency in the draft CCL 3, such 
as the May 14, 1996, DBP Information Collection Rule (ICR) (61 FR 
24354, USEPA 1996), EPA used drinking water occurrence data from the 
State of California Department of Health Services ICR and studies cited 
by commenters (Krasner et al., 2006) to evaluate the occurrence of 
DBPs. The Agency also sought and identified new health effects 
information. A study EPA requested during the development of the Stage 
2 Rule on chlorate was completed (NTP 2008) and occurrence information 
on bromochloromethane (Halon 1011) was also identified. EPA concluded 
that chlorate and bromochloromethane are known or anticipated to occur 
in PWSs and may require regulation. Therefore the Agency added these 
two contaminants to the CCL 3.
    EPA continues to participate in research concerning the toxicity, 
occurrence, exposure, and treatment of unregulated disinfection 
byproducts. This research will inform the development of future CCLs 
and the regulatory determination process, as well as future reviews of 
existing drinking water regulations.

C. Microbial Contaminants

    EPA is including twelve pathogens on the final CCL 3, one more than 
the eleven pathogens on the draft CCL 3. The Agency is adding 
Adenovirus, Enterovirus, and Mycobacterium avium to the final CCL 3, 
and is removing Vibrio cholerae and Entamoeba histolytica from the 
final CCL 3.
    The protocol EPA used to select the microbial contaminants for the 
CCL 3 is described in detail in the draft CCL 3, notice (73 FR 9631, 
9644; USEPA, 2008a). Except for a minor change discussed in Section 
III.C.1, the protocol for selecting pathogens for the final CCL 3 
remains the same as the protocol for the draft CCL 3; EPA selected the 
pathogens based on their health effects and occurrence in drinking 
water.
    Based on public comment, EPA modified the waterborne disease 
outbreak (WBDO) protocol. The Agency removed older, Centers for Disease 
Control (CDC) reported WBDOs (prior to 1990) from the occurrence 
analysis to account for the impact of drinking water regulations that 
have been implemented since 1990. This change in the WBDO protocol 
resulted in the exclusion of Vibrio cholerae and Entamoeba hystolitica 
from the final CCL 3 and the inclusion of Adenovirus and Enterovirus to 
the final CCL 3.
    Based on public comment, EPA reviewed the health score for 
Mycobacterium avium. After re-evaluating the health effects 
information, EPA determined that a higher health effects score was 
appropriate for this pathogen.
1. Using the CDC WBDO's as a Scoring Criterion
    A commenter recommended the use of outbreak data tied to the 
implementation of the SDWA and its amendments (i.e., after 1990). The 
commenter, as well as SAB, also encouraged EPA to develop its own 
occurrence database instead of relying on CDC reported WBDOs. A few 
commenters noted that, in general, the information on occurrence of 
pathogens in drinking water is limited, and that EPA should develop 
more occurrence information.
    EPA Response: EPA agrees in part with this recommendation, and 
recognizes that after implementation of SDWA and its amendments, PWSs 
should have changed their practices resulting in fewer outbreaks. 
Therefore, early outbreaks (i.e., before 1990) may not represent the 
current situation and controls at PWSs operating under these 
regulations. EPA removed CDC WBDOs prior to 1990 from the occurrence 
analysis. This change resulted in the exclusion of Vibrio cholerae and 
Entamoeba hystolitica from the final CCL 3 because their WBDO scores 
were reduced due to the removal of older documented WBDOs from 
consideration (USEPA, 2009e).
    EPA disagrees with abandoning the CDC database and continues to use 
the CDC documented WBDOs in the CCL 3 pathogen scoring process. CDC 
collects statistical data on WBDOs every year (since 1920). CDC has 
consistently applied a definition for WBDO as well as consistently 
investigated and verified epidemiological information related to 
illnesses. This consistency in definitions and methods allows EPA to 
consistently compare the WBDO data. In contrast, individual research 
studies on isolated outbreaks may have different methods and goals, and 
therefore disparate study designs, making evaluation of the results 
difficult from a

[[Page 51857]]

national perspective. No other national database on drinking-water 
related illnesses exists.
    EPA contributes and collaborates with CDC on the Morbidity and 
Mortality Weekly Report's annual surveillance summary, and is confident 
of the quality of the information in the report. EPA agrees with the 
commenter that there is a need for more information on occurrence of 
pathogens in drinking water; however, EPA believes that the CDC WBDO 
data is the best available information at this time.
2. Mycobacterium Avium
    EPA received more than a dozen comments requesting that EPA re-
examine the health effects score for Mycobacterium avium and to include 
the pathogen on the final CCL 3. Commenters pointed to the long 
treatment duration and the severity of the disease particularly for the 
elderly population. Commenters also cited the increased incidence of 
disease, particularly amongst the elderly.
    EPA Response: EPA re-evaluated Mycobacterium avium's health effects 
information and increased the health effects score for one of the 
sensitive life stages, or populations; specifically, the elderly. The 
Agency agrees with commenters that the potential health effects on the 
elderly and the occurrence of Mycobacterium avium in drinking water 
supplies warrant its inclusion on the CCL 3. The health effects score 
was increased based on the severity and treatment duration on the 
elderly as described in Murray 2007 (USEPA, 2009g). Based on this 
information, EPA anticipates that Mycobacterium avium may occur in PWSs 
and require regulation. Therefore the Agency has included Mycobacterium 
avium on the final CCL 3.
3. Vibrio cholerae and Entamoeba hystolitica
    EPA received a few comments recommending the exclusion of both 
Vibrio cholerae and Entamoeba hystolitica from the final CCL 3. 
Commenters recommended that EPA not include these pathogens because 
cholera and amebiasis are currently rare in the United States, even 
though they are still common in other countries. Also, commenters felt 
that current treatment practices (i.e., disinfection) will provide 
sufficient protection against Vibrio cholerae. However, one commenter 
supported keeping Vibrio cholerae because its occurrence is likely to 
increase and expand as climate change continues.
    EPA Response: Based on public comment discussed earlier, EPA 
changed the WBDO protocol. The Agency removed older, CDC reported WBDOs 
(prior to 1990) from the occurrence analysis to account for recently 
implemented regulations (e.g., Surface Water Treatment Rule, Total 
Coliform Rule). This change in the WBDO protocol resulted in the 
reduction of the WBDO score for both Vibrio cholerae and Entamoeba 
hystolitica, and their exclusion from the final CCL 3. However, EPA did 
not consider treatment as one of the parameters for inclusion or 
exclusion of a pathogen onto the CCL 3 because many public water 
systems are not required to treat, as discussed in the draft CCL 3 FR 
notice (73 FR 9648; USEPA, 2008a). Further, EPA acknowledges the 
potential impact climate change may have on water quality; however, at 
this time EPA does not have enough information to assess the risk.

D. Other Comments

1. Data Sources for Contaminant Candidate Lists
    Several commenters noted that EPA used occurrence data sources that 
could only identify a contaminant's potential to occur in PWSs. These 
included data from the TRI, National Center for Food and Agricultural 
Policy (NCFAP), modeled occurrence data for pesticides, and chemical 
production data. While some commenters urged EPA to rely on this type 
of data, other commenters suggested that production data should only be 
used to identify chemicals for initial consideration (i.e., inclusion 
on the CCL 3 Universe) and more rigorous data should be used to screen 
or include chemicals on the CCL.
    EPA response: The Agency used data from the TRI and modeled 
occurrence data for pesticides developed by the Office of Pesticide 
Programs (OPP) to support the inclusion of contaminants on the CCL 3, 
but EPA did not rely on the Chemical Update System (CUS) and the 
Inventory Update Rule (IUR) data (i.e., production volume).
    In developing the CCL, SDWA requires that EPA consider unregulated 
contaminants that are known or anticipated to occur in PWSs and may 
require regulation. EPA believes that the TRI and the OPP data are 
sufficient for it to anticipate that a contaminant that is released 
into the environment may occur in a PWS. The Agency coupled these data 
with health effects information to evaluate contaminants. The NRC 
(2001) and NDWAC (2004) reports included specific recommendations on 
data and information that the Agency could use to anticipate the 
occurrence of contaminants in PWSs. Both of these panels cited the 
importance of identifying contaminants that did not yet have occurrence 
information indicating detections in source waters or drinking water. 
NDWAC recognized that the Agency could apply a hierarchy to the use of 
detected occurrence over potential occurrence, but also noted that the 
use of these types of data enables the Agency to be proactive in 
protecting public health.
    EPA also conducted several reviews of the data sources and 
information used to develop the CCL 3. EPA sought contaminants for the 
Agency to consider in its FR notice, seeking nominations (71 FR 65573, 
USEPA 2006b). The Agency published a list of data sources including the 
TRI, CUSIUR, and NCFAP. Many of the nominated contaminants are 
chemicals included solely on those lists. The Agency also conducted 
several expert panels to review the types of data and information it 
used to evaluate contaminants. While these panels provided 
recommendation to qualify these types of data, which the Agency 
implemented, the panels did not recommend excluding these data sources. 
Based on this input from stakeholders and expert reviews, the Agency 
included 51 contaminants with TRI and/or modeled occurrence data for 
pesticides to support inclusion on the CCL 3 because EPA anticipates 
that these contaminants may occur in PWSs and may require regulation.
2. Contaminant Candidate List and Unregulated Contaminant Monitoring 
Regulation
    Several commenters requested clarification on the interrelationship 
between the UCMR and the CCL. Commenters wanted to know whether the CCL 
draws from chemicals on the UCMR, or the UCMR draws from chemicals on 
the CCL to develop the respective lists. One commenter encouraged EPA 
to ``improve correlation between the CCL and the UCMR.''
    EPA response: The 1996 amendments to SDWA instituted the CCL and 
UCMR programs to provide information EPA needs to determine which 
drinking water contaminants have the greatest potential to present a 
meaningful opportunity to reduce health risk through a NPWDR. The CCL 
is the primary mechanism for the identification of contaminants that 
may require regulation, while UCMR provides EPA with the data necessary 
to determine if a contaminant occurs at a frequency and at levels of 
public health concern. The CCL and UCMR are parts

[[Page 51858]]

of the risk management process, and they support and inform each other.
    The UCMR sampling program was designed to consider the technical 
difficulty and expense of analyzing up to 30 contaminants as well as 
their potential to occur in treated drinking water at levels of public 
health concern. The UCMR approach includes three different sampling 
design options, with the determination of the appropriate option for 
each contaminant based primarily on the difficulty and expense of the 
analytical methods used, and the associated issue of laboratory 
capacity. The sampling designs described below are discussed in detail 
in the proposed UCMR 2 (70 FR 49094; USEPA 2005). Assessment monitoring 
is the most extensive, and is used when the technology of the 
analytical methods is in common use in drinking water laboratories. 
Screening monitoring relies more on identifying a statistically valid 
representation of the universe of PWSs in order to reduce the number of 
utilities impacted by the monitoring. It is designed to assure the 
necessary laboratory capacity in those cases where the analytical 
technology is more complex and/or expensive. The pre-screening 
monitoring option detailed in the UCMR program is based on assessing 
the vulnerability of selected PWSs and may be used when the analytical 
techniques are so complex that commercial laboratory capacity is 
severely limited; this option has not been exercised to date.
    EPA promulgated UCMR 2 on January 4, 2007 (72 FR 367; USEPA 2007a). 
The UCMR program was developed in coordination with the development of 
the CCL. Both programs consider the adverse health effects a 
contaminant may pose through drinking water exposures.
    Sixteen contaminants on the UCMR 2 monitoring list are also on the 
final CCL 3. The final CCL 3 includes acetochlor and its degradates, 
alachlor degradates, dimethoate, 1,3-dinitrobenzene, metolachlor and 
its degradates, RDX, terbufos sulfone, and four of the nitrosamines 
that are a part of UCMR 2. In addition to the health effects data and 
potential occurrence, the UCMR 2 also considers analytical method 
availability and cost, availability of analytical standards, and 
laboratory capacity to support a nationwide monitoring program in 
selecting contaminants.
    The UCMR 2 includes nine contaminants that are not on the final CCL 
3. The five polybrominated flame retardants can be measured by the same 
analytical method used for terbufos sulfone. The polybrominated flame 
retardants are listed on UCMR 2 because of concern that these have 
become more widespread environmental contaminants (Darnerud et al., 
2001). The polybrominated flame retardants lacked sufficient occurrence 
information to be listed on final CCL 3 (73 FR 9628; USEPA 2008a). This 
UCMR 2 monitoring data will provide information for future CCLs. 
Similarly, 2,4,6-trinitrotoluene (TNT) and two of the nitrosamines not 
on CCL 3 are also measured by an analytical method in the UCMR 2. 
Alachor was listed on UCMR 2 for monitoring along with its degradates 
to allow for the measurement of co-concurrence between the parent 
compound and its degradates. It was removed from consideration for CCL 
3 because it is currently regulated. The Agency will use the results 
from UCMR 2 as a source of occurrence information during the 
development of CCL 4, as well as for CCL 3 regulatory determinations.

IV. Data Needs for CCL 3 Contaminants

    After the listing process, the CCL 3 contaminants are evaluated 
further to determine if a contaminant has sufficient data to meet the 
regulatory determination criteria set forth in SDWA section 1412(b)(1) 
and previously outlined in Section I.C of this notice. If the data are 
sufficient, a regulatory determination may be made. EPA must make 
regulatory determinations on at least five CCL 3 contaminants every 
five years.
    The SAB and other commenters have indicated that the CCL 3 may be 
too large and recommended additional priority ranking of contaminants 
to focus resources. EPA acknowledges that many contaminants on the CCL 
3 have substantial data and information needs that will have to be met 
before the Agency can make a regulatory determination in accordance 
with SDWA 1412 (b)(1)(A). Currently, several of the CCL 3 contaminants 
have data or information needs. These are described in the following 
section.

A. Chemical Contaminants

    EPA assessed the data and information gathered on the CCL 3 
chemical contaminants and generated a table (Exhibit 2) to help 
identify data/information needs for further regulatory determination 
evaluations. In general, EPA characterized each chemical contaminant 
included on the final CCL 3 for their data needs in three categories; 
health effects, occurrence, and analytical methods. The data needs were 
characterized as no data needs, specific data needs, or substantial 
data needs. The health effects, occurrence, and analytical methods 
data/information used to classify data needs are featured in the 
supporting documentation and in the ``Final CCL 3 Contaminant 
Information Sheets'' in the docket (USEPA, 2009e). Blank cells in 
Exhibit 2 generally indicate that there is no data need for that 
contaminant in that category. Cells with a ``2'' indicate that the data 
are under evaluation by EPA and the contaminant has a specific need. 
Cells with a ``1'' indicate that there is a data need for that 
contaminant, and that need may be substantial. The following sections 
describe the types of data or information gaps outlined in Exhibit 2 
and provide examples.
1. Health Effects
    EPA categorized the health effects data needs for Exhibit 2 using 
the following set of assumptions. Any chemical that had an existing EPA 
quantitative assessment (Reference Dose (RfD) or Cancer Slope Factor 
(CSF)) for the oral route of exposure is identified on the table as not 
having a health effect data need based on the assumption that EPA will 
be able to use the existing data along with more recent studies to 
develop a quantitative health effects assessment. These chemicals are 
designated with a blank cell in the health effects column. There may 
well be opportunities to further elucidate mode of action or to reduce 
uncertainty for the analyses associated with these contaminants, but 
such data would not be necessary to develop an assessment. Similarly, 
any chemical that has an assessment being developed by EPA is not 
identified on the table as having a data need, and is represented by a 
blank cell because that work is currently ongoing.
    The next category of chemicals with health effects data needs have 
quantitative assessments conducted by other government agencies such as 
WHO, and Agency for Toxic Substances and Disease Registry. These 
chemicals are designated with a ``2'' in the health effects column on 
the table, signifying that an EPA assessment is needed and sufficient 
information may be available to initiate the assessment. These data 
apply to oral exposures that can be used to support a quantitative 
assessment of risk; however, EPA has not yet thoroughly evaluated the 
existing risk assessment to determine if it and the supporting data 
meet EPA data quality guidelines and is compatible with EPA risk 
assessment policies. For example, at t