United States
Environmental Protection Office of Water EPA 815-F-97-001
Agency 4607 October 1997
£EPA DRINKING WATER CONTAMINANT
CANDIDATE LIST- OPEN FOR COMMENT
The Safe Drinking Water Act (SDWA), as amended in 1996, requires that, when selecting
drinking water contaminants for regulation, the Environmental Protection Agency gives priority
to those that present the greatest public health concern, especially to vulnerable populations such
as infants, the elderly and those with serious illness. To achieve this, we are developing a
Drinking Water Contaminant Candidate List (CLL). We have published a draft list in the
October 6,1997 Federal Register (62 FR 52193) and seek input from the public before finalizing
it by February 1998.
What is the Drinking Water Contaminant Candidate List?
The CCL is a list of contaminants known or anticipated to occur in public water systems.
Contaminants listed on the CCL will undergo a selection process which will determine our
priorities for research, guidance and possible regulation. At the time of publication, these
contaminants are not subject to any proposed or promulgated national primary drinking water
regulation (NPDWR), but they may require regulation under the SDWA. The draft CCL was
developed with considerable input from the scientific community and other interested parties. It
is currently open for comment and will be finalized no later than February 1998. A new CCL will
be published every five years.
If a candidate is on the list, will it be regulated?
Not necessarily. If a contaminant is listed on the CCL, a team of scientists and other experts will
use the list to
• select contaminants for possible regulation, guidance development and health advisories,
• monitor when and where these contaminants occur and where more data is needed,
• determine our research priorities.
By 2001, EPA must select five or more candidates from the CCL and determine whether or not
to regulate them. This determination is based on whether regulating the contaminant would
present a meaningful opportunity for health risk reduction. In addition to selecting candidates for
possible regulation, we will identify a maximum of 30 contaminants from the list for unregulated
monitoring. This data will be used hi our drinking water research.
How were the contaminants identified for the draft Contaminant List, and who was
involved in the process?
In December 1996, the EPA called a meeting of the new National Drinking Water Advisory
Committee (NDWAC) Working Group on Occurrence and Contaminant Selection. The working
group includes representatives of public water utilities, environmental and public interest groups,
state regulatory agencies, public health offices, and other interested parties. At the December
stakeholders meeting, the group suggested using the following criteria identify candidates:
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• 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?
When will the CCL be finalized, and what happens next?
The CCL will be published no later than February 1998, after the public has the opportunity to
comment. Once the CCL is finalized, the next step will be to select five or more contaminants
and determine whether or not a regulation is needed. This step will be followed by proposal and
ultimate promulgation of regulations for those contaminants where a determination has been
made to regulate. The CCL will be revised every five years, with considerable input from the
public, and the regulatory selection process will repeat.
What other tools will EPA use in its contaminant selection process?
In developing future CCLs, the EPA will use the National Contaminant Occurrence Database
(NCOD) and a new regulation for Unregulated Contaminant Monitoring (UCM). EPA is
working to establish both the NCOD and the UCM regulation by August 1999, as required by
SDWA. The database will include 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
database is also expected to support the review of existing regulations and monitoring
requirements every six years.
EPA is required by the SDWA, as amended in 1996, to list and develop regulations for
monitoring of certain unregulated contaminants by August 1999, and every 5 years thereafter
[Section 1445(a)(2)]. The list must not exceed 30. Contaminants on the CCL that need additional
occurrence data will be used as the source of contaminants for the list of unregulated
contaminants. Data will be collected and maintained in the National Drinking Water
Contaminant Occurrence Database. Criteria for determining which contaminants on the CCL will
be chosen for the unregulated contaminant monitoring list will be developed as part of this
regulation.
How can I get involved?
Send us your comments — we need your input! We are specifically looking for comments on (1)
the approach we used to create this list and suggestions on our process for future lists; (2)
contaminants on the list; (3) data needs categories (refer to the Federal Register notice); and (4)
whether to include perchlorate on the CCL. Comments must be received or postmarked by
midnight December 5, 1997. To submit comments by mail, send an original and three copies of
your comments and enclosures (including references), in hard copy or on a disc in WordPerfect
5.1 or ASCII file format, to
Comment Clerk To submit comments electronically (you can
Docket Number W-97-11 do this at Federal Depository Libraries):
Water Docket (MC4101) • Use ASCII format,
USEPA, 401 M. St., SW • Avoid using special characters and any
Washington, DC, 20460 form of encryption,
• Specify the docket number W-97-11,
• Send to: ow-docket@epamail.epa.gov.
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Draft Drinking Water Contaminant Candidate List
Inorganic Contaminants (8)
Aluminum 7429-90-5
Boron 7440-42-8
Manganese 7439-96-5
Nickel
Zinc 7440-66-6
Sodium 7440-23-5
Vanadium 7440-62-2
Sulfate
Synthetic Organic Contaminants (26)
1,1,2,2-tetra-chloroethane 79-34-5
1,2,4-trimethylbenzene 95-63-6
1,1-dichloro-ethane 75-34-3
1,1-dichloro-propene 563-58-6
1,2-diphenylhydrazine 122-66-7
1,3-dichloropropane 142-28-9
2,4,6-trichlorophenol 88-06-2
2,2-dichloro-propane 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
2,6-di-tert-butyl
-p-benzoquinone 719-22-2
2-methyl-Phenol (o-cresol) 95-48-7
Acetone 67-64-1
Bromobenzene 108-86-1
Cumene (isopropylbenzene) 98-82-8
p-Cymene
(p-isopropyltoluene) 99-87-6
HexachJoro-butadiene 87-68-3
Methyl bromide 74-83-9
Methyl-t-butyl ether (MTBE) 1634-04-4
Naphthalene 91-20-3
Nitrobenzene 98-95-3
Organo tins
RDX 121-82-4
Rhodamine WT
Pesticides (24)
1,3-Dichloropropene
(telone or 1,3-D) 542-75-6
Acetochlor 34256-82-1
Alachlor ES A (a degradation
product of the pesticide alachlor)
Pesticides, continued...
Alidcarb, Aldicarb sulfoxide,
Aldicarb sulfone)
Aldrin 309-00-2
Atrazine-desethyl (a triazine
dedgradation product) 6190-65-4
Cyanazine 21725-46-2
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
Dimethoate 60-51-5
Disulfoton 298-04-4
Diuron 330-54-1
EPIC 759-94-5
Fonofos 944-22-9
Linuron 330-55-2
Metolachlor 51218-45-2
Metribuzin 21087-64-9
Molinate 2212-67-1
*Perchlorate
Prometon 1610-18-0
Terbacil 5902-51-2
Terbufos 13071-79-9
Microbiological Contaminants (13)
Acanthamoeba (guidance expected for
contact lens wearers)
adenoviruses
Aeromonas hydrophila
caliciviruses
coxsackieviruses
Cyclospora cayetanensis
echoviruses
Helicobacter pylori
hepatitis A virus
Legionella (in ground water)
Microsporidia (Enferocytozoon & Septata)
Mycobacterium avium intracellulare (MAC)
Toxoplasma gondii
* Under evaluation for addition to the CCL.
See Federal Register notice for details.
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Figure 1. Illustration of Decision Tool Used to Develop the Draft
Contaminant Candidate List
391 drawn from: 1991 DWPL, health
advisories, IRIS, CERCLA, TRI,
OPP Ranking, PWS data, Stakeholders,
SDWA Hotline, and literature
391
contaminants
including
25 microorganisms
262
chemical
contaminants
Criteria focused
on occurrence
in water at levels
of health concern,
or indications
of occurrence
(production,
release, coupled
with properties).
Health effects
concentrations
were used to
determine
significance
of occurrence.
additional
contaminants
sulfate, nickel,
and aldicarbs
21
solely suspected of
endocrine disrpution
Deferred
83
6 SDWA Hotline
77 duplicates, or regulated
Removed from consideration
Data & information
gathering & evaluation
using Criteria
Expert Panel
microbial
contaminants
29
chemical
contaminants
No data available
EPA sought input
from international panel
of professional
microbiologists. The
input was presented to
the Working Group
for review & approval.
143
chemical
contaminants
Not Recommended
for the List
based on data evaluation
35
pesticides
Deferred
71
contaminants
13 microbiological
58 chemical
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