Drinking Water Contaminant Candidate List

CCL Highlights Regulatory Determination Priorities - The preliminary Regulatory Determinations have just been released for the first CCL. See the above link for more information and to view the Federal Register Notice. CCL Quick Find The Contaminate Candidate List Contaminant Identification and Selection Cycle   You will need Adobe Acrobat Reader to view the Adobe PDF files on this page. See EPA's PDF page for more information about getting and using the free Acrobat Reader

The Safe Drinking Water Act (SDWA) requires 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 1997 (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 notice about the Contaminant Candidate List
  (March 2, 1998, 63 FR 10273) (read online) (download PDF file)

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 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 was developed to address the following 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 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.

How Does the CCL relate to the occurrence database and unregulated contaminant monitoring?

EPA has established a National Drinking Water Contaminant Occurrence Database (NCOD) and an Unregulated Contaminant Monitoring Regulation (UCMR) as required by SDWA.

The NCOD stores data on the occurrence of both regulated and unregulated contaminants. It provides 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 developed regulations for monitoring certain unregulated contaminants in 1999. These contaminants are listed in the UCMR. The CCL Occurrence Priority list is the primary source of contaminants for the unregulated monitoring list, which must not exceed 30 contaminants.

Table 1. The Drinking Water Contaminant Candidate List

Microbiological contaminants
Acanthamoeba (guidance expected for contact lens wearers)
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 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 (o-cresol).............................. 95-48-7
Acetochlor........................................................ 34256-82-1
Alachlor ESA & other acetanilide pesticide degradation products................ 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 (s-ethyl-dipropylthiocarbamate)........... 759-94-4
Fonofos.......................................................... 944-22-9
Hexachlorobutadiene..................................... 87-68-3
p-Isopropyltoluene (p-cymene)...................... 99-87-6
Linuron........................................................... 330-55-2
Manganese.................................................... 7439-96-5
Methyl bromide............................................. 74-83-9
Methyl-t-butyl ether (MTBE)........................... 1634-04-4
Metolachlor................................................... 51218-45-2
Metribuzin..................................................... 21087-64-9
Molinate........................................................ 2212-67-1
Naphthalene................................................. 91-20-3
Nitrobenzene................................................ 98-95-3
Organotins................................................... N/A
Perchlorate.................................................. N/A
Prometon..................................................... 1610-18-0
RDX............................................................. 121-82-4
Sodium....................................................... 7440-23-5
Sulfate......................................................... 14808-79-8
Terbacil....................................................... 5902-51-2
Terbufos..................................................... 13071-79-9
Triazines & degradation products of triazines (including, but not limited to Cyanazine 21725-46-2, and atrazine-desethyl 6190-65-4)
Vanadium................................................ 7440-62-2

Table 2: Contaminant Candidate List - May 2000

* OPP = Chemicals deferred to the EPA Office of Pesticide Programs for health research and assessments.

** Suitable analytical methods must be developed prior to obtaining occurrence data.

*** Organotins include Monobutyl tin trichloride, Dibutyl tin dichloride, Monomethyl tin trichloride, Dimethyl tin trichloride

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