Contaminant Candidate List 3 - CCL 3

• that are currently not subject to any proposed or promulgated national primary drinking water regulations,
• that are known or anticipated to occur in public water systems, and
• which may require regulation under the Safe Drinking Water Act (SDWA).

• pesticides,
• disinfection byproducts,
• chemicals used in commerce,
• waterborne pathogens,
• pharmaceuticals, and
• biological toxins.

The agency considered the best available data and information on health effects and occurrence to evaluate thousands of unregulated contaminants. The EPA used a multi-step process to select 116 candidates for the CCL 3, that includes 104 chemicals or chemical groups and 12 microbial contaminants.

Read the Preliminary Regulatory Determinations for the CCL 3

Overview of CCL 3 Process

In developing the CCL 3, the EPA implemented an improved process from that which was used for CCL 1 and CCL 2. This new process builds on evaluations used for previous CCLs and was based on substantial expert input and recommendations from the National Academy of Sciences' National Research Council (NAS) and the National Drinking Water Advisory Council (NDWAC).

The EPA used a multi-step CCL process to identify contaminants for inclusion on the final CCL 3. The key steps include:

• Identifying a broad universe of potential drinking water contaminants (called the CCL 3 Universe). The EPA initially considered approximately 7,500 potential chemical and microbial contaminants.
• Applying screening criteria to the universe the EPA identified almost 600 of those contaminants that should be further evaluated (the preliminary CCL or PCCL) based on a contaminant's potential to occur in public water systems and the potential for public health concern.
• The EPA then selected 116 contaminants from the PCCL to include on the CCL based on more detailed evaluation of occurrence and health effects and expert judgment.
• The EPA incorporated information from the public, expert input, and expert review in the CCL process.

CCL 3 Process Flow Diagram

The CCL 3 Process Flow Diagram provides a visual overview of the CCL 3 pertaining to each step in the process.

The support documents pertain to each step in the process.

1. Universe Documents
2. Screening and PCCL Documents
3. Final CCL 3 (and other documents)

For additional CCL 3 support documents and more detailed information on the contaminants, visit docket number EPA-HQ-OW-2007-1189 at Regulations.gov.

CCL 3 List

Chemical Contaminants

* Correction: The CAS Registry Number for Acetochlor oxanilic acid (OA) is 194992-44-4.

Microbial Contaminants

Contaminant Information Websites

The list of websites below provides resources for general information on chemical contaminants.

• ATSDR Toxicity Profiles
  This U.S. Agency for Toxic Substances and Disease Registry (ATSDR) source lists toxicological profiles in PDF form for various chemicals under "Finalized Toxicological Profiles." These profiles include health effects; chemical and physical properties; production, import/export, use and disposal information; potential for human exposure; analytical methods; and regulations and advisories for a given chemical.
• Hazardous Substances Data Bank (HSDB)
  This U.S. National Library of Medicine (USNLM) source includes information on human health effects; emergency medical treatment; animal toxicity studies; metabolism/pharmacokinetics; environmental fate and exposure; environmental standards and regulations; chemical/physical properties; chemical safety and handling; manufacturing/use information; analytical laboratory methods; and synonyms and identifiers for a given chemical.
• Integrated Risk Information System (IRIS)
  This EPA site presents information from chronic health hazard assessments for non-carcinogenic effects and carcinogenicity assessments for lifetime exposure. Data elements for non-cancer data include RfD and RfC values, and specify critical organs and effects, type of study, animal model used, year of study, duration of study, and so on. Data elements for cancer data include oral slope factor values, drinking water unit risk values, dose-response relationships and cancer class.
• Pesticide Reregistration Status
  This EPA Office of Pesticide Programs provides fact sheets for pesticides in PDF form. Fact sheets include information in narrative and table form on use; health; risk (dietary, occupational, residential and ecological); and risk mitigation. Data elements include NOAEL, LOAEL, RfD, EEC, LD50, LC50 values, and critical effects for each of these. Also available are production, use and exposure assessment data.
• PubChem
  This U.S. National Library of Medicine source provides chemical structure; chemical classification (type of chemical or use); registry number; synonyms and names; toxicity information (such as LD50 and LC50) drawn from primary literature.
• Substance Registry System (SRS)
  This EPA site provides information on substances and how they are represented in the EPA regulations and information systems. The SRS is EPA's central system for information about regulated and monitored substances. The system provides a common basis for identification of chemicals, biological organisms, and other substances listed in EPA regulations and data systems, as well as substances of interest from other sources, such as publications. You can query for substances by common identifiers, names, or alternate identifiers.
• World Health Organization (WHO): Guidelines for Drinking Water Quality 
  This site provides information on international norms on water quality and human health. WHO sets guidelines that are used as the basis for regulation and standard setting in countries around the world.

Federal Register Notices

• Final Federal Register Notice: Drinking Water Contaminant Candidate List 3--Final, October 8, 2009
• Fact Sheet: CCL 3
• Draft Federal Register Notice: Drinking Water Contaminant Candidate List 3--Draft, February 21, 2008

Other Resources

Public Meeting Held On Preliminary Regulatory Determination for the Third Contaminant Candidate List (CCL3)
The EPA hosted a public stakeholder meeting on June 16, 2011, in Washington, DC, to discuss the Agency’s Regulatory Determinations 3. For more information see the slides presented.

• Slides Presented at the June 16th Public Meeting on Preliminary Regulatory Determinations for the Third Contaminant Candidate List (CCL3)