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Water: Contaminant Candidate List

Contaminant Candidate List 3 - CCL

CCL 3 is a list of contaminants 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). The list includes, among others, 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. EPA used a multi-step process to select 116 candidates for the final CCL 3. The final CCL 3 includes 104 chemicals or chemical groups and 12 microbiological contaminants.


Overview of CCL 3 Process

In developing the CCL 3, 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 Science's National Research Council (NRC) and the National Drinking Water Advisory Council (NDWAC).

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). EPA initially considered approximately 7,500 potential chemical and microbial contaminants.
  • Applying screening criteria to the universe 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.
  • 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.
  • EPA incorporated information from the public, expert input, and expert review in the CCL process.

CCL 3 Process Flow Diagram & Technical Support Documents

The CCL 3 Process Flow Diagram provides a visual overview of the CCL 3 and links to the support documents pertaining to each step in the process. Click the diagram to view/download the support documents for CCL 3.

The CCL 3 Process Flow Diagram provides a visual overview of the CCL 3 and links to the support documents pertaining to each step in the process. Click the diagram to view/download the support documents for CCL 3.

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

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CCL 3 List

Chemical Contaminants

Substance Name CASRN Use
1,1,1,2-Tetrachloroethane 630-20-6 It is an industrial chemical used in the production of other substances.
1,1-Dichloroethane 75-34-3 It is an industrial chemical used as a solvent.
1,2,3-Trichloropropane 96-18-4 It is an industrial chemical used in paint manufacture.
1,3-Butadiene 106-99-0 It is an industrial chemical used in rubber production.
1,3-Dinitrobenzene 99-65-0 It is an industrial chemical and is used in the production of other substances.
1,4-Dioxane 123-91-1 It is used as a solvent or solvent stabilizer in the manufacture and processing of paper, cotton, textile products, automotive coolant, cosmetics and shampoos.
17alpha-estradiol 57-91-0 It is an estrogenic hormone and is used in pharmaceuticals.
1-Butanol 71-36-3 It is used in the production of other substances, and as a paint solvent and food additive.
2-Methoxyethanol 109-86-4 It is used in consumer products, such as synthetic cosmetics, perfumes, fragrances, hair preparations, and skin lotions.
2-Propen-1-ol 107-18-6 It is used in the production of other substances, and in the manufacture of flavorings and perfumes.
3-Hydroxycarbofuran 16655-82-6 It is a carbamate, and is a pesticide degradate. The parent, carbofuran, is used as an insecticide.
4,4'-Methylenedianiline 101-77-9 It is used in the production of other substances, and as a corrosion inhibitor and curing agent for polyurethanes.
Acephate 30560-19-1 It is used as an insecticide.
Acetaldehyde 75-07-0 It is used in the production of other substances, and as a pesticide and food additive.
Acetamide 60-35-5 It is used as a solvent, solubilizer, plasticizer, and stabilizer.
Acetochlor 34256-82-1 It is used as an herbicide for weed control on agricultural crops.
Acetochlor ethanesulfonic acid (ESA) 187022-11-3 Acetochlor ESA is an acetanilide pesticide degradate. The parent, acetochlor, is used as an herbicide for weed control on agricultural crops.
Acetochlor oxanilic acid (OA) 184992-44-4 Acetochlor OA is an acetanilide pesticide degradate. The parent, acetochlor, is used as an herbicide for weed control on agricultural crops.
Acrolein 107-02-8 It is used as an aquatic herbicide, rodenticide, and industrial chemical.
Alachlor ethanesulfonic acid (ESA) 142363-53-9 Alachlor ESA is an acetanilide pesticide degradate. The parent, alachlor, is used as an herbicide for weed control on agricultural crops.
Alachlor oxanilic acid (OA) 171262-17-2 Alachlor OA is an acetanilide pesticide degradate. The parent, alachlor, is used as an herbicide for weed control on agricultural crops.
alpha-Hexachlorocyclohexane 319-84-6 It is a component of benzene hexachloride (BHC) and was formerly used as an insecticide.
Aniline 62-53-3 It is used as an industrial chemical, as a solvent, in the synthesis of explosives, rubber products, and in isocyanates.
Bensulide 741-58-2 It is used as an herbicide.
Benzyl chloride 100-44-7 It is used in the production of other substances, such as plastics, dyes, lubricants, gasoline and pharmaceuticals.
Butylated hydroxyanisole 25013-16-5 It is used as a food additive (antioxidant).
Captan 133-06-2 It is used as a fungicide.
Chlorate 14866-68-3 Chlorate compounds are used in agriculture as defoliants or desiccants and may occur in drinking water related to use of disinfectants such as chlorine dioxide.
Chloromethane (Methyl chloride) 74-87-3 It is used as a foaming agent and in the production of other substances.
Clethodim 110429-62-4 It is used as an herbicide.
Cobalt 7440-48-4 It is a naturally-occurring element and was formerly used as cobaltus chloride in medicines and as a germicide.
Cumene hydroperoxide 80-15-9 It is used as an industrial chemical and is used in the production of other substances.
Cyanotoxins (3)*
Toxins naturally produced and released by cyanobacteria ("blue-green algae"). Various studies suggest three cyanotoxins for consideration: Anatoxin-a, Microcystin-LR, and Cylindrospermopsin.
Dicrotophos 141-66-2 It is used as an insecticide.
Dimethipin 55290-64-7 It is used as an herbicide and plant growth regulator.
Dimethoate 60-51-5 It is used as an insecticide on field crops, (such as cotton), orchard crops, vegetable crops, in forestry and for residential purposes.
Disulfoton 298-04-4 It is used as an insecticide.
Diuron 330-54-1 It is used as an herbicide.
equilenin 517-09-9 It is an estrogenic hormone and is used in pharmaceuticals.
equilin 474-86-2 It is an estrogenic hormone and is used in pharmaceuticals.
Erythromycin 114-07-8 It is used in pharmaceutical formulations as an antibiotic.
Estradiol (17-beta estradiol) 50-28-2 It is an estrogenic hormone and is used in pharmaceuticals.
estriol 50-27-1 It is an estrogenic hormone and is used in veterinary pharmaceuticals.
estrone 53-16-7 It is an estrogenic hormone and is used in veterinary and human pharmaceuticals.
Ethinyl Estradiol (17-alpha ethynyl estradiol) 57-63-6 It is an estrogenic hormone and is used in veterinary and human pharmaceuticals.
Ethoprop 13194-48-4 It is used as an insecticide.
Ethylene glycol 107-21-1 It is used as an antifreeze, in textile manufacture and is a cancelled pesticide.
Ethylene oxide 75-21-8 It is used as a fungicidal and insecticidal fumigant.
Ethylene thiourea 96-45-7 It is used in the production of other substances, such as for vulcanizing polychloroprene (neoprene) and polyacrylate rubbers, and as a pesticide.
Fenamiphos 22224-92-6 It is used as an insecticide.
Formaldehyde 50-00-0 It has been used as a fungicide, may be a disinfection byproduct, and can occur naturally.
Germanium 7440-56-4 It is a naturally-occurring element and is commonly used as germanium dioxide in phosphors, transistors and diodes, and in electroplating.
Halon 1011 (bromochloromethane) 74-97-5 It is used as a fire-extinguishing fluid and to suppress explosions, as well as a solvent in the manufacturing of pesticides. May also occur as a disinfection by-product in drinking water.
HCFC-22 75-45-6 It is used as a refrigerant, as a low-temperature solvent, and in fluorocarbon resins, especially in tetrafluoroethylene polymers.
Hexane 110-54-3 It is used as a solvent and is a naturally-occurring alkane.
Hydrazine 302-01-2 It is used in the production of other substances, such as rocket propellants, and as an oxygen and chlorine scavenging compound.
Mestranol 72-33-3 It is an estrogenic hormone and is used in veterinary and human pharmaceuticals.
Methamidophos 10265-92-6 It is used as an insecticide.
Methanol 67-56-1 It is used as an industrial solvent, a gasoline additive and also as anti-freeze.
Methyl bromide (Bromomethane) 74-83-9 It has been used as a fumigant as a fungicide.
Methyl tert-butyl ether 1634-04-4 It is used as an octane booster in gasoline, in the manufacture of isobutene and as an extraction solvent.
Metolachlor 51218-45-2 It is used as an herbicide for weed control on agricultural crops.
Metolachlor ethanesulfonic acid (ESA) 171118-09-5 Metolachlor ESA is an acetanilide pesticide degradate. The parent, metolachlor, is used as an herbicide for weed control on agricultural crops.
Metolachlor oxanilic acid (OA) 152019-73-3 Metolachlor OA is an acetanilide pesticide degradate. The parent, metolachlor, is used as an herbicide for weed control on agricultural crops.
Molinate 2212-67-1 It is used as an herbicide.
Molybdenum 7439-98-7 It is a naturally-occurring element and is commonly used as molybdenum trioxide as a chemical reagent.
Nitrobenzene 98-95-3 It is used in the production of aniline, and also as a solvent in the manufacture of paints, shoe polishes, floor polishes, metal polishes, explosives, dyes, pesticides and drugs (such as acetaminophen), and in its re-distilled from (oil of mirbane) as an
Nitroglycerin 55-63-0 It is used in pharmaceuticals, in the production of explosives, and in rocket propellants.
N-Methyl-2-pyrrolidone 872-50-4 It is a solvent in the chemical industry, and is used for pesticide application and in food packaging materials.
N-nitrosodiethylamine (NDEA) 55-18-5 It is a nitrosamine used as an additive in gasoline and in lubricants, as an antioxidant, as a stabilizer in plastics, and also may be a disinfection byproduct.
N-nitrosodimethylamine (NDMA) 62-75-9 It is a nitrosamine and has been formerly used in the production of rocket fuels, is used as an industrial solvent and an anti-oxidant, and also may be a disinfection byproduct.
N-nitroso-di-n-propylamine (NDPA) 621-64-7 It is a nitrosamine and may be a disinfection byproduct.
N-Nitrosodiphenylamine 86-30-6 It is a nitrosamine chemical reagent that is used as a rubber and polymer additive and may be a disinfection byproduct.
N-nitrosopyrrolidine (NPYR) 930-55-2 It is a nitrosamine used as a research chemical and may be a disinfection byproduct.
Norethindrone (19-Norethisterone) 68-22-4 It is a progresteronic hormone used in pharmaceuticals.
n-Propylbenzene 103-65-1 It is used in the manufacture of methylstyrene, in textile dyeing, and as a printing solvent, and is a constituent of asphalt and naptha.
o-Toluidine 95-53-4 It is used in the production of other substances, such as dyes, rubber, pharmaceuticals and pesticides.
Oxirane, methyl- 75-56-9 It is an industrial chemical used in the production of other substances.
Oxydemeton-methyl 301-12-2 It is used as an insecticide.
Oxyfluorfen 42874-03-3 It is used as an herbicide.
Perchlorate 14797-73-0 It is both a naturally occurring and human-made chemical. Perchlorate is used to manufacture fireworks, explosives, flares and rocket propellant.
Perfluorooctane sulfonic acid (PFOS) 1763-23-1 PFOS was used in fire fighting foams and various surfactant uses; few of which are still ongoing because no alternatives are available.
Perfluorooctanoic acid (PFOA) 335-67-1 PFOA is used in the manufacture of fluoropolymers, substances which provide non-stick surfaces on cookware and waterproof, breathable membranes for clothing
Permethrin 52645-53-1 It is used as an insecticide.
Profenofos 41198-08-7 It is used as an insecticide and an acaricide.
Quinoline 91-22-5 It is used in the production of other substances, and as a pharmaceutical (anti-malarial) and as a flavoring agent.
RDX (Hexahydro-1,3,5-trinitro-1,3,5-triazine) 121-82-4 It is used as an explosive.
sec-Butylbenzene 135-98-8 It is used as a solvent for coating compositions, in organic synthesis, as a plasticizer and in surfactants.
Strontium 7440-24-6 It is naturally-occurring element and is used as strontium carbonate in pyrotechnics, in steel production, as a catalyst and as a lead scavenger.
Tebuconazole 107534-96-3 It is used as a fungicide.
Tebufenozide 112410-23-8 It is used as an insecticide.
Tellurium 13494-80-9 It is a naturally-occurring element and is commonly used as sodium tellurite in bacteriology and medicine.
Terbufos 13071-79-9 It is used as an insecticide.
Terbufos sulfone 56070-16-7 Terbufos sulfone is a phosphorodithioate pesticide degradate. The parent, terbufos, is used as an insecticide.
Thiodicarb 59669-26-0 It is used as an insecticide.
Thiophanate-methyl 23564-05-8 It is used as a fungicide.
Toluene diisocyanate 26471-62-5 It is used in the manufacture of plastics.
Tribufos 78-48-8 It is used as an insecticide and as a cotton defoliant.
Triethylamine 121-44-8 It is used in the production of other substances, and as a stabilizer in herbicides and pesticides, in consumer products, in food additives, in photographic chemicals and in carpet cleaners.
Triphenyltin hydroxide (TPTH) 76-87-9 It is used as a pesticide.
Urethane 51-79-6 It is used as a paint ingredient.
Vanadium 7440-62-2 It is a naturally-occurring element and is commonly used as vanadium pentoxide in the production of other substances and as a catalyst.
Vinclozolin 50471-44-8 It is used as a fungicide.
Ziram 137-30-4 It is used as a fungicide.

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Microbial Contaminants

Microbial Contaminant Name Information
Adenovirus Virus most commonly causing respiratory illness, and occasionally gastrointestinal illness
Caliciviruses Virus (includes Norovirus) causing mild self-limiting gastrointestinal illness
Campylobacter jejuni Bacterium causing mild self-limiting gastroentestinal illness
Enterovirus Group of viruses including polioviruses, coxsackieviruses and echoviruses that can cause mild respiratory illness
Escherichia coli (0157) Toxin-producing bacterium causing gastrointestinal illness and kidney failure
Helicobacter pylori Bacterium sometimes found in the environment capable of colonizing human gut that can cause ulcers and cancer
Hepatitis A virus Virus that causes a liver disease and jaundice
Legionella pneumophila Bacterium found in the environment including hot water systems causing lung diseases when inhaled
Mycobacterium avium Bacterium causing lung infection in those with underlying lung disease, and disseminated infection in the severly immunpcompromised
Naegleria fowleri Protozoan parasite found in shallow, warm surface and ground water causing primary amebic meningoencephalitis
Salmonella enterica Bacterium causing mild self-limiting gastrointestinal illness
Shigella sonnei Bacterium causing mild self-limiting gastrointestinal illness and bloody diarrhea

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CCL 3 Technical Support 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

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Contaminant Information Websites

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

  • 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.
  • 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.
  • 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.
  • ChemIDplus Advanced Exit EPA Disclaimer
    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.
  • 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.
  • World Health Organization (WHO): Guidelines for Drinking Water Quality Exit EPA Disclaimer
    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.

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