United States
Environmental Protection Office of Water EPA 815-F-98-002
Agency 4607 March 1998
4>EPA DRINKING WATER CONTAMINANT
CANDIDATE LIST
The Safe Drinking Water Act (SDWA), as amended in 1996, requires the Environmental
Protection Agency (EPA) to establish a list of contaminants to aid in priority-setting for the
Agency's drinking water program. In establishing the list, EPA has divided the contaminants
among those which are priorities for additional research, those which need additional occurrence
data, and those which are priorities for consideration for rulemaking. EPA published a draft of
the first Drinking Water Contaminant Candidate List (CCL) in the October 6,1997 Federal
Register (62 FR 52193). Comments submitted in response to-the draft CCL were reviewed and
considered in creating the final CCL, which was published in the March 2, 1998 Federal
Register (63 FR 10273).
What is the Drinking Water Contaminant Candidate List?
The CCL is a list of contaminants which, at the time of publication, are not subject to any
proposed or promulgated national primary drinking water regulation (NPDWR), are known or
anticipated to occur in public water systems, and may require regulations under SDWA.
The list (see Table 1) will be the primary source of priority contaminants for the Agency's
drinking water program. Contaminants for priority drinking water research, occurrence
monitoring, and guidance development, including health advisories, will be drawn from the
CCL. Certain contaminants on the list have also been designated as those from which the
Agency will determine whether to regulate specific contaminants by the year 2001. The list was
developed with considerable input from the scientific community and other interested parties.
How were the contaminants identified for the CCL, and who participated in the
identification process?
In December 1996, EPA held a stakeholder meeting and subsequently formed an advisory
working group under the National Drinking Water Advisory Council (NDWAC), called the
Working Group on Occurrence & Contaminant Selection. The stakeholders and Working Group
included representatives of public water utilities, environmental and public interest groups, state
regulatory agencies, public health offices, and other interested parties. EPA and the Working
Group developed criteria to identify contaminants for the CCL. The criteria were developed to
address the folio whig questions:
Does the contaminant adversely affect public health?
Is the contaminant known or substantially likely to occur in public water systems with a
frequency and at levels posing a threat to public health?
EPA published a draft CCL in the October 6, 1997 Federal Register (62 FR 52193), and sought
comments on (1) the approach EPA used to create the list and suggestions on the process for
future lists; (2) contaminants on the draft list; (3) data needs categories; and (4) whether to
include perchlorate on the final CCL. EPA received 71 comments in response to the notice on
the draft CCL. The majority were supportive of the CCL process and the development of this
first CCL, and provided suggestions on specific contaminants that should be included on, or
excluded from, the CCL. The comments, data, and information provided were taken into
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consideration in preparing the final CCL.
Now that the CCL is finalized, what happens next?
Table 2 divides the CCL into categories to represent the next steps and data needs for each
contaminant. The groupings in Table 2 are based on current information, and some movement
may occur between categories as more information is evaluated and analyzed. The categories are
the priorities for Regulatory Determinations, Research, and Occurrence.
The Agency will select five or more contaminants from the Regulatory Determination
Priorities list and determine, by August 2001, whether to regulate them. To support these
decisions, EPA will determine if regulating contaminants on the list would present a meaningful
opportunity to reduce health risk. The Agency will evaluate when and where these contaminants
occur, and the exposure and risk to public health. They will also determine the appropriate
measure for protecting public health, and the impact of potential regulations. If the Agency
determines regulations are necessary, they must be proposed by August 2003, and promulgated
by February 2005.
More data are needed for contaminants on the Occurrence and Research Priorities lists before
the Agency can determine whether to regulate them. Health, treatment, or analytical methods
data are needed for those on the research list; occurrence data are needed for those on the
Occurrence list. Obtaining this data will be the priority of our research and occurrence programs.
The next steps for the Agency are to determine which contaminants to address first in all
categories, and to outline plans of action for making regulatory decisions for five or more
contaminants by the year 2001. These steps will involve developing short-term and long-term
research plans on health, treatment, and analytical methods, developing an Unregulated
Contaminant Monitoring Regulation proposal (expected August 1998) for gathering occurrence
data, and planning special occurrence studies.
How does the CCL relate to the occurrence database and unregulated contaminant
monitoring?
EPA is working to establish both a National Drinking Water Contaminant Occurrence Database
(NCOD) and an Unregulated Contaminant Monitoring Regulation (UCMR) by August 1999, as
required by SDWA.
The NCOD will store data on the occurrence of both regulated and unregulated contaminants. It
will provide the basis for identifying contaminants that may be placed on future CCLs and
support the EPA Administrator's decisions to regulate contaminants in the future. The NCOD is
also expected to support the review of existing regulations and monitoring requirements every
six years.
EPA is required to list and develop regulations for monitoring certain unregulated contaminants
by August 1999, and .every five years thereafter. These contaminants will be listed in the
UCMR. The CCL Occurrence Priority list will be the primary source of contaminants for the
unregulated monitoring list, which must not exceed 30 contaminants. Data for the UCMR will be
stored in the NCOD. The criteria for determining which contaminants on the CCL will be chosen
for the UCMR list will be developed as part of the regulations for monitoring.
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Table 1. The Drinking Water Contaminant Candidate List
Chemical Contaminants CASRN
1,1,2,2-tetrachloroethane 79-34-5
1,2,4-trimethylbenzene 95-63-6
1,1-dichloroethane 75-34-3
1,1-dichloropropene 563-58-6
1,2-diphenylhydrazine 122-66-7
1,3-dichloropropane 142-28-9
1,3-Dichloropropene 542-75-6
2,4,6-trichlorophenol 88-06-2
2,2-dichloropropane 594-20-7
2,4-dichlorophenol 120-83-2
2,4-dinitrophenol 51-28-5
2,4-dinitrotoluene 121-14-2
2,6-dinitrotoluene 606-20-2
2-methyL-PhenoL 95-48-7
AcetochLor 34256-82-1
Alachlor ESA and other degradation products of
acetanitide pesticides N/A
Aldrin 309-00-2
Aluminum 7429-90-5
Boron 7440-42-8
Bromobenzene 108-86-1
DCPA mono-acid degradate 887-54-7
DCPA di-acid degradate 2136-79-0
DDE 72-55-9
Diazinon 333-41-5
Dieldrin 60-57-1
Disulfoton 298-04-4
Diuron 330-54-1
EPTC 759-94-4
Fonofos 944-22-9
Hexachlorobutadiene 87-68-3
p-Isopropyltoluene 99-87-6
Linuron 330-55-2
Manganese 7439-96-5
Chemical Contaminants
Methyl bromide
fietolachlor
Metribuzin
Mblinate
MTBE
Naphthalene
Nitrobenzene
Organotins
Perch lorate
Prometon
RDX
Sodium
Sulfate
Terbaci I
Terbufos
Triazines 8 degradation
not limited to
CASRN
74-83-9
51218-45-2
21087-64-9
2212-67-1
1634-04-4
91-20-3
98-95-3
N/A
N/A
1610-18-0
121-82-4
7440-23-5
14808-79-8
5902-51-2
13071-79-9
products (including,
but
Cyanazine, and atrazine-
Vanadium
desethyl)
7440-62-2
Microbiological Contaminants
Acanthamoeba (guidance expected for contact lens
wearers)
Adenovi ruses
Aeromonas hydrophila
Cyanobacteria (Blue-green algae), other freshwater
algae, and their toxins
Caliciviruses
Coxsackieviruses
Echovi ruses
Helicobacter pylori
Microsporidia (Enterocytozoon 8 Septata)
Mycobacterium avium intracellulare (MAC)
Figure I. The CCL and Next Steps
Actions/
Next Steps
2001 Decision
Regulate
Don't Regulate
JSL.5" ~"Sr ii^^^Su^' ^SS^x^^vJ^LJT ^ vi^
Other (guidance)
.^ ^ "**
(Health : 15,Treatment: 12, AnalyticalMethods: 15)
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