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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