Uratetd States
Erwaron
Agency
Fact Sheet: The Drinking Water
Contaminant Candidate List -- The
Source of Priority Contaminants for
the Drinking Water Program
EPA has drinking water regulations for more than 90 contaminants. The Safe Drinking Water
Act (SDWA) includes a process that we must follow to identify new contaminants which may
require regulation in the future. EPA must periodically release a Contaminant Candidate List
(CCL). EPA uses this list of unregulated contaminants to prioritize research and data collection
efforts to help us to determine whether we should regulate a specific contaminant.
In February 2005, we published the second CCL of 51 contaminants. We also provided an
update on our work to improve the CCL process for the future that is based, in part, on
recommendations from the National Research Council and the National Drinking Water
Advisory Council. In addition to making the process used for selecting contaminants easier to
understand, our goals for the future are to:
• • evaluate a wider range of information
•• screen contaminants more systematically, and
•• develop a more comprehensive CCL by expanding the number of contaminants being
reviewed for inclusion on the next CCL.
You can find more information on the CCL on EPA's website at www.epa.gov/safewater/ccl/
Questions and Answers
What is the drinking water CCL?
The drinking water CCL is the primary source of priority contaminants on which we conduct
research and make decisions about whether regulations are needed. The contaminants on the list
are known or anticipated to occur in public water systems. However, they are currently
unregulated by existing national primary drinking water regulations.
How often is the CCL published?
The Safe Drinking Water Act directs that we periodically publish a CCL. We published the first
CCL of 60 contaminants in March 1998 and the second CCL in February 2005 after deciding to
continue research on the list of contaminants on the first CCL.
What contaminants are included in CCL 2?
The CCL (published in 2005) carries forward 51 (of the original 60) unregulated contaminants
from the first CCL, including nine microbiological contaminants and 42 chemical contaminants
or contaminant groups (see table). In July 2003, EPA announced its final determination for a
subset of nine contaminants from the first CCL, which concluded that sufficient data and
Office of Water (4607M) EPAJUSjJ^DS^OCU February 2005 www.epa.gov/safewater
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information was available to make the determination not to regulate Acanthamoeba, aldrin,
dieldrin, hexachlorobutadiene, manganese, metribuzin, naphthalene, sodium, and sulfate. These
nine contaminants were not carried forward to the 2005 CCL.
Does the CCL impose any requirements on public water systems?
No. The CCL alone does not impose any requirements on public water systems. However, we
may regulate contaminants on the list in the future. Public water systems would have to follow
specific requirements to comply with a regulation.
What happens to contaminants on the CCL?
We carry out studies to develop analytical methods for detecting the contaminants, determine
whether they occur in drinking water, and evaluate treatment technologies to remove them from
drinking water. We also investigate potential health effects from the contaminants. These
efforts help us to determine if actions such as drinking water guidance, health advisories or
regulations need to be developed for contaminants on the CCL, or if no action is necessary at this
time.
What is a regulatory determination?
A regulatory determination is a formal decision on whether we should issue a national primary
drinking water regulation for a specific contaminant. The law requires that we make regulatory
determinations for five or more contaminants from the most recent CCL.
In 2003, we made regulatory determinations for nine contaminants from the first CCL. We plan
to propose the second cycle of preliminary regulatory determinations from the second CCL in
the summer of 2005 and make final regulatory determinations in August of 2006.
It is important to note that we are not limited to making regulatory determinations for only those
contaminants on the CCL. We can also decide to regulate other unregulated contaminants if
information becomes available showing that a specific contaminant presents a public health risk.
What criteria do EPA consider to make regulatory determinations?
When making a "determination" to regulate, the law requires that we consider three areas:
•• projected adverse health effects from the contaminant,
•• the extent of occurrence of the contaminant in drinking water, and
•• whether regulation of the contaminant would present a "meaningful opportunity" for
reducing risks to health.
What is EPA doing to improve future CCLs?
During development of the first CCL, we received comments that indicated a need for a broader,
more comprehensive approach for selecting contaminants. In response, we sought the advice of
the National Research Council (NRC) on how we could improve the process for selecting
contaminants. The NRC's 2001 report provided us with a framework for how we could evaluate
a larger number of contaminants and make decisions about those contaminants by applying
innovative technologies and expert advice.
Office of Water (4607M) EPAJUSjJ^DS^OCU February 2005 www.epa.gov/safewater
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We then asked the National Drinking Water Advisory Council (NDWAC) to advise us on how to
address the NRC's recommended classification process. The NDWAC's May 2004 report
provided us with a number of recommendations on how the process should be managed and
principles that we should use in developing future CCLs. We are reviewing the NDWAC
recommendations and are on schedule to meet the February 2008 deadline for the third CCL.
You can review the NDWAC report on EPA's web site at
www.epa.gov/safewater/ndwac/pdfs/report_ccl_ndwac_07-06-04.pdf.
Where can I find more information about this notice and the CCL?
For information on the CCL and the contaminant selection process, please visit
www.epa.gov/safewater/ccl/. For general information on drinking water, please visit the EPA
Safewater website at www.epa.gov/safewater or contact the Safe Drinking Water Hotline at 1-
800-426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding
legal holidays, from 9:00 a.m. to 5:00 p.m. Eastern time.
Office of Water (4607M) EiP/UyjSJMDISJDOl. February 2005 www.epa.gov/safewater
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Drinking Water Contaminant Candidate List 2
Microbial Contaminant Candidates
Adenoviruses
Aeromonas hydrophila
Caliciviruses
Coxsackieviruses
Cyanobacteria (blue-green algae), other freshwater algae, and their toxins
Echoviruses
Helicobacter pylori
Microsporidia (Enterocytozoon & Septata)
Mycobacterium avium intracellulare (MAC)
Chemical Contaminant Candidates
CASRN
1,1,2,2-tetrachloroethane
1,2,4-trimethylbenzene
1,1 -dichloroethane
1,1 -dichloropropene
1,2-diphenylhydrazine
1,3 -di chl oropropane
1,3 -di chl oropropene
2,4,6-trichlorophenol
2,2-di chl oropropane
2,4-dichlorophenol
2,4-dinitrophenol
2,4-dinitrotoluene
2,6-dinitrotoluene
2-methyl-Phenol (o-cresol)
Acetochlor
79-34-5
95-63-6
75-34-3
563-58-6
122-66-7
142-28-9
542-75-6
88-06-2
594-20-7
120-83-2
51-28-5
121-14-2
606-20-2
95-48-7
34256-82-1
Office of Water (4607M) EiP/UyjSJMDISJDOl. February 2005 www.epa.gov/safewater
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Chemical Contaminant Candidates
CASRN
Alachlor ESA & other acetanilide pesticide N/A
degradation products
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
Disulfoton 298-04-4
Diuron 330-54-1
EPIC (s-ethyl-dipropylthiocarbamate) 759-94-4
Fonofos 944-22-9
p-Isopropyltoluene (p-cymene) 99-87-6
Linuron 330-55-2
Methyl bromide 74-83-9
Methyl-t-butyl ether (MTBE) 1634-04-4
Metolachlor 51218-45-2
Molinate 2212-67-1
Nitrobenzene 98-95-3
Organotins N/A
Perchl orate 14797-73-0
Prometon 1610-18-0
RDX 121-82-4
Terbacil 5902-51-2
Terbufos 13071-79-9
Office of Water (4607M) EPA 815-F-05-001 February 2005 www.epa.gov/safewater
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Chemical Contaminant Candidates CASRN
Triazines & degradation products of triazines including, but not limited to Cyanazine
21725-46-2 and atrazine-desethyl 6190-65-4
Vanadium 7440-62-2
Office of Water (4607M) EiP/UyjSJMDISJDOl. February 2005 www.epa.gov/safewater
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