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National Drinking Water Database - Chemical Contaminants

Chlorine dioxide

Status: Unregulated - EPA has not established a maximum legal limit in tapwater for this contaminant.

Chlorine dioxide is used as drinking water disinfection agent and as a bleaching agent for cellulose, paper pulp, flour and oils; in water, it rapidly decomposes into toxic disinfection byproducts chlorite and chlorate. [read more]

Chlorine dioxide Chlorine dioxide is used as a drinking water disinfectant that kills microbes such as E. coli. Chlorine dioxide is also used as a bleaching agent for cellulose, paper pulp, flour and oils (WHO 2004a). When added to water, chlorine dioxide quickly breaks down into chlorite (ClO2-), chlorate (ClO3-) and chloride (Cl-) ions, part of a category of contaminants collectively referred to as chlorination byproducts (CBPs). Chorine dioxide breakdown products can be toxic and, similar to chlorine, they can combine with the organic matter in polluted source water to produce additional harmful disinfection byproducts (Hua 2007; Krasner 2006). In people, drinking water treated with chlorine dioxide has been associated with weight loss early in life (Tuthill 1982), neonatal jaundice and increased risk of having small head size and body length in infants (Kanitz 1996). In 2004, the U.S. EPA's Toxics Release Inventory (TRI) reported that, in 2002, U.S. industrial facilities released 560,142 pounds of chlorine dioxide. Together, the paper and food industries accounted for the largest percentage of released chlorine dioxide, totaling 495,872 pounds or 89 percent (USEPA 2009i).

	Detected	Found above health guidelines	Found above legal limit
States	2	1	-
Water utilities	6	2	-
People Served	4,432,204	3,978,953	-

Health Concerns for Chlorine dioxide:

• Occupational hazards
• Persistence and bioaccumulation
• Organ system toxicity (non-reproductive)
• Developmental/reproductive toxicity
• Cancer
• Irritation (skin, eyes, or lungs)
• Ecotoxicology
• Miscellaneous
• Multiple, additive exposure sources

Chlorine dioxide Exposure by State

Water utilities in 2 states have reported detecting Chlorine dioxide in treated tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies.

State	Water Suppliers with Chlorine dioxide contamination		Water suppliers reporting Chlorine dioxide above health-based limits
	Systems	Population	Systems	Population
California	5	4,194,814	2	3,978,953
Alabama	1	237,390	0	0
Total	6	4,432,204	2	3,978,953

The Most Polluted Communities

6 water utilities reported detecting Chlorine dioxide in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Chlorine dioxide level

Rank	System	Population Served	Positive test results of total reported tests	Average Level (Range)
1	Los Angeles Department of Water and Power Los Angeles, CA	3,828,700	3 of 3	1966.67 ppb (1700 to 2400 ppb)
2	City of Corona Corona, CA	150,253	2 of 2	1404 ppb (1367 to 1441 ppb)
3	Montgomery Water Works Montgomery, AL	237,390	10 of 11	129.09 ppb (0 to 203.33 ppb)
4	City of Napa Napa, CA	70,000	4 of 7	89.29 ppb (0 to 350 ppb)
5	City of Daly City Daly City, CA	92,311	9 of 14	57.14 ppb (0 to 190 ppb)
6	Carlsbad Mwd Carlsbad, CA	53,550	821 of 1,081	46.98 ppb (0 to 480 ppb)

Health Based Limits for Chlorine dioxide

Standard	Description	Level
Lifetime health-based limit, non-cancer risk	Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for a lifetime of exposure. The Lifetime health-based limit (or Health Advisory, HA) is based on exposure for a a 70-kg adult consuming 2 liters of water per day. Source: U.S. Environmental Protection Agency.	800 ppb
Children's health-based limit for 1-day exposure	Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.	840 ppb
Children's health-based limit for 10-day exposure	Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.	840 ppb
Drinking Water Equivalent Level	A lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.	1000 ppb

Testing Summary for Chlorine dioxide

Are tests routinely required for Chlorine dioxide by federal law?	No
Water suppliers reporting tests for Chlorine dioxide (2004-2009):	10 of 47,576
Average testing rate for water supplier reporting tests (2004-2009):	18.8 per year

Occupational hazards

Type of concern:	Reference:
Allowed workplace exposures restricted to very low doses	European Union - Classification & Labelling
Allowed workplace exposures restricted to very low doses	RTECS®- TLV/BEI,2007
Allowed workplace exposures restricted to very low doses	RTECS®- MSHA STANDARD-air: 3,46,1971
Allowed workplace exposures restricted to very low doses	RTECS®- OSHA PEL (Gen Indu): 29,1910 1994
Allowed workplace exposures restricted to very low doses	RTECS®- OSHA PEL (Fed Cont): 41,50-204 1994
Allowed workplace exposures restricted to low doses	European Union - Classification & Labelling

Persistence and bioaccumulation

Type of concern:	Reference:
Persistent, bioaccumulative in wildlife	Canada PBTs - Accelerated Reduction/Elimination of Toxics (ARET)
Not suspected to be persistent	Environment Canada Domestic Substance List
Not suspected to be bioaccumulative	Environment Canada Domestic Substance List

Organ system toxicity (non-reproductive)

Type of concern:	Reference:
Classified as expected to be toxic or harmful	Environment Canada Domestic Substance List
Classified as medium human health priority	Environment Canada Domestic Substance List
Classified as toxic or harmful	European Union - Classification & Labelling
Limited evidence of respiratory toxicity	National Library of Medicine HazMap
Limited evidence of respiratory toxicity	Agency for Toxic Substances and Disease Registry, 2004
One or more animal studies show classified as toxic effects at moderate doses (low dose studies may be unavailable for this ingredient)	EPA Toxic Release Inventory PBTs
One or more animal studies show sense organ effects at moderate doses (low dose studies may be unavailable for this ingredient)	RTECS®- JAT, Journal of Applied Toxicology 1982

Developmental/reproductive toxicity

Type of concern:	Reference:
Limited evidence of reproductive toxicity	US EPA, 9204
Limited evidence of developmental toxicity	US EPA, 9204

Cancer

Type of concern:	Reference:
One or more in vitro tests on mammalian cells show positive mutation results	RTECS®- Journal of Environmental Pathology, Toxicology and Oncology 1985
One or more in vitro tests on mammalian cells show positive mutation results	RTECS®- Food and Chemical Toxicology 1988
One or more in vitro tests on mammalian cells show positive mutation results	RTECS®- Mutagenesis 2004
One or more in vitro tests non-mammalian cells show positive mutation results	RTECS®- Food and Chemical Toxicology 1984
One or more in vitro tests non-mammalian cells show positive mutation results	RTECS®- Mutagenesis 2004
One or more in vitro tests on microorganisms show positive mutation results	RTECS®- Mutation Research 2004
One or more in vitro tests on microorganisms show positive mutation results	RTECS®- Mutation Research 2005
Cancer - not classifiable/not likely to be human carcinogen	EPA Integrated Risk Information System (IRIS)

Irritation (skin, eyes, or lungs)

Type of concern:	Reference:
Limited evidence of skin irritation	National Library of Medicine HazMap

Ecotoxicology

Type of concern:	Reference:
Wildlife and environmental toxicity	European Union - Classification & Labelling
Suspected to be an environmental toxin	Environment Canada Domestic Substance List

Miscellaneous

Type of concern:	Reference:
Occupational hazards related to handling	European Union - Classification & Labelling

Multiple, additive exposure sources

Type of concern:	Reference:
Designated as safe for general or specific, limited use in food	FDA Food Additive Status
Designated as safe for general or specific, limited use in food	FDA Everything Added to Food

Government, industry, academic studies and classifications

government/industry list/academic study	appears on list as	classification(s)
European Union - Classification & Labelling	CHLORINE DIOXIDE	•Oxidizing •Contact with combustible material may cause fire •Explosive with or without contact with air •Very toxic •Very toxic by inhalation •Corrosive •Causes burns •Dangerous for the environment •Very toxic to aquatic organisms
European Union - Classification & Labelling	CHLORINE DIOXIDE . . . %	•Toxic •Toxic if swallowed •Corrosive •Causes burns •Dangerous for the environment •Very toxic to aquatic organisms
European Union - Classification & Labelling	CHLORINE DIOXIDE	•Oxidizing •Contact with combustible material may cause fire •Causes burns •Dangerous for the environment •Very toxic to aquatic organisms
European Union - Classification & Labelling	CHLORINE DIOXIDE ... %	•Toxic •Toxic if swallowed •Corrosive •Causes burns •Dangerous for the environment •Very toxic to aquatic organisms
FDA Food Additive Status	CHLORINE DIOXIDE	• miscellaneous • Food additive: food additive for which a petition has been filed and a regulation issued • Used as an antimicrobial agent in poultry process water at a concentration not to exceed 3 parts per million residual chlorine dioxide. Used as an antimicrobial agent in water used to wash fruits and vegetables that are not raw agricultural commodities at a
Association of Occupational and Environmental Clinics	CHLORINE DIOXIDE	• o
FDA Everything Added to Food	CHLORINE DIOXIDE	• Fully up-to-date toxicology information has been sought.
Environment Canada Domestic Substance List	CHLORINE OXIDE (CLO2)	•This chemical was deemed a moderate human health priority and was flagged by CEPA for further attention. The chemical was flagged for suspected aquatic toxicity.
EPA Integrated Risk Information System (IRIS)	CHLORINE DIOXIDE	•Group D: Not classifiable as to human carcinogenicity (EPA classification)
EPA Integrated Risk Information System (IRIS)	CHLORINE DIOXIDE	•Carcinogenicity cannot be determined (EPA classification)
National Library of Medicine HazMap	CHLORINE DIOXIDE	•Dermatotoxin: Skin Burns; •Toxic Pneumonitis: Yes; •PEL (OSHA) - Permissible exposure limit (OSHA): 0.1 ppm; •STEL (ACGIH) - Short-term exposure limits (ACGIH): 0.3 ppm; •LC50 - Lethal concentration in 50% of animals tested: 416 ppm; •TLV (ACGIH) - Threshold limit value (ACGIH): 0.1 ppm; •IDLH (NIOSH) - Immediately Dangerous to Life or Health: 5 ppm; •Odor Threshold High - The lowest concentration at which a substance can be detected or recognized using the sense of smell: 15 ppm; •Odor Threshold Low - The lowest concentration at which a substance can be detected or recognized using the sense of smell: 0.1 ppm; •MAK - Maximum Allowable Concentration (Federal Republic of Germany): 0.1 ppm;
Canada PBTs - Accelerated Reduction/Elimination of Toxics (ARET)	CHLORINE OXIDE	•Toxicant of concern under Canada's Accelerated Reduction/Elimination of Toxics program - targeted for elimination or reduction
EPA Toxic Release Inventory PBTs	CHLORINE OXIDE	•Toxic, U.S. Environmental Protection Agency Toxics Release Inventory programs
Agency for Toxic Substances and Disease Registry, 2004	CHLORINE DIOXIDE	•Respiratory toxicity hazards: suspected
US EPA, 9204	CHLORINE DIOXIDE	•Reproductive toxicity hazards: suspected
US EPA, 9204	CHLORINE DIOXIDE	•Developmental toxicity hazards: suspected
RTECS®- TLV/BEI,2007	CHLORINE DIOXIDE	• occupationally related - ACGIH TLV (human TWA)
RTECS®- Food and Chemical Toxicology 1984	CHLORINE DIOXIDE	• mutagenic - Positive mutation assay: Mutation in Micro-organism (Salmonella typhimurium )
RTECS®- Food and Chemical Toxicology 1988	CHLORINE DIOXIDE	• mutagenic - Positive mutation assay: Micronucleus test (mouse ipr)
RTECS®- JAT, Journal of Applied Toxicology 1982	CHLORINE DIOXIDE	• sense organ - Primary eye irritant (rabbit )
RTECS®- Journal of Environmental Pathology, Toxicology and Oncology 1985	CHLORINE DIOXIDE	• mutagenic - Positive mutation assay: DNA Inhibition (rat orl)
RTECS®- MSHA STANDARD-air: 3,46,1971	CHLORINE DIOXIDE	• occupationally related - MSHA STANDARD-air (human TWA)
RTECS®- Mutagenesis 2004	CHLORINE DIOXIDE	• mutagenic - Positive mutation assay: Mutation in Micro-organism (Saccharomyces cerevisiae ) • mutagenic - Positive mutation assay: DNA Damage ( human leu)
RTECS®- Mutation Research 2004	CHLORINE DIOXIDE	• mutagenic - Positive mutation assay: DNA Damage (other fish mul) • mutagenic - Positive mutation assay: Micronucleus test (other fish mul)
RTECS®- Mutation Research 2005	CHLORINE DIOXIDE	• mutagenic - Positive mutation assay: DNA Damage (other fish mul) • mutagenic - Positive mutation assay: Micronucleus test (other fish mul)
RTECS®- OSHA PEL (Fed Cont): 41,50-204 1994	CHLORINE DIOXIDE	• occupationally related - OSHA PEL (Fed Cont) (human TWA)
RTECS®- OSHA PEL (Gen Indu): 29,1910 1994	CHLORINE DIOXIDE	• occupationally related - OSHA PEL (Gen Indu) (human TWA)

references

government/industry list/academic study	reference
European Union - Classification & Labelling	CPS&Q (Consumer Products Safety & Quality) formely known as ECB (European Chemicals Bureau). 2008. Classification and Labelling: Chemicals: Annex VI of Directive 67/548/EEC through the 31st ATP.
FDA Food Additive Status	FDA (U.S. Food and Drug Administration) 2006. Food Additive Status List. Downloaded from http://www.cfsan.fda.gov/%7Edms/opa-appa.html, Oct 16, 2006.
Association of Occupational and Environmental Clinics	AOEC (Association of Occupational and Environmental Clinics). 2009. AEOC exposures codes and asthmagen designation.
FDA Everything Added to Food	FDA (U.S. Food and Drug Administration). 2008. EAFUS [Everything Added to Food]: A Food Additive Database. FDA Office of Food Safety and Applied Nutrition.
Environment Canada Domestic Substance List	EC (Environment Canada). 2008. Domestic Substances List Categorization. Canadian Environmental Protection Act (CEPA) Environmental Registry.
EPA Integrated Risk Information System (IRIS)	EPA (U.S. Environmental Protection Agency). 2008. Integrated Risk Information System (IRIS). Evidence for human carcinogenicity based on 1986-2005 guidelines.
National Library of Medicine HazMap	NLM (National Library of Medicine). 2006. HazMap — Occupational Exposure to Hazardous Agents.
Canada PBTs - Accelerated Reduction/Elimination of Toxics (ARET)	EC (Environment Canada). 1994. Accelerated Reduction/Elimination of Toxics (ARET). ARET substance list of persistent, bioaccumulative and toxic chemicals.
EPA Toxic Release Inventory PBTs	EPA (U.S. Environmental Protection Agency). 1999. Toxics Release Inventory Program. PBT Chemical Rule.
Scorecard.org Toxicity Information	Agency for Toxic Substances and Disease Registry. Minimal risk Levels for Hazardous Substances. January 2004. http://www.atsdr.cdc.gov/mrls.html, A Relational Database of Hazardous Chemicals and Occupational Diseases. Browse Haz-Map by Adverse Effects http://hazmap.nlm.nih.gov/hazmapadv.html, California EPA, Office of Environmental Health Hazard Assessment. Air Toxics Hot Spots Program Risk Assessment Guidelines, Part III: Technical Support Document 'Determination of Noncancer Chronic Reference Exposure Levels'. Includes all Chronic Reference Exposure Levels (CRELs) adopted by OEHHA as of August 2003 (http://www.oehha.ca.gov/air/chronic_rels/AllChrels.html, plus draft CRELS proposed through March 2004 (http://www.oehha.ca.gov/air/chronic_rels/index.html.
Scorecard.org Toxicity Information	US EPA. Roadmaps to Sources of Information on Chemicals Listed in the Emergency Planning Community and Community Right-to-Know Act (Also Known as SARA Title 3), Section 313 Toxic Release Inventory (for Microcomputers). (Report Number EPADFDK92040). 1991. Data file distributed in 2 diskettes by Office of Pollution, Prevention, and Toxics, Environmental Protection Agency, Washington, DC. NOTE: Datasource no longer being maintained by EPA; not currently available online., Frazier , L. and M. L. Hage (eds.). Reproductive Hazards of the Workplace, Wiley Europe, 1998. Table 10 (Partial List of Reproductive Toxicants) available at http://www.pharmacy.ohio-state.edu/homepage/safety/chemhygiene_table_repro.pdf.
Scorecard.org Toxicity Information	US EPA. Roadmaps to Sources of Information on Chemicals Listed in the Emergency Planning Community and Community Right-to-Know Act (Also Known as SARA Title 3), Section 313 Toxic Release Inventory (for Microcomputers). (Report Number EPADFDK92040). 1991. Data file distributed in 2 diskettes by Office of Pollution, Prevention, and Toxics, Environmental Protection Agency, Washington, DC. NOTE: Datasource no longer being maintained by EPA; not currently available online., Jankovic, J. A Screening Method for Occupational Reproductive Health Risk. American Industrial Hygiene Association Journal. 57: 641-649. 1996.
RTECS®- TLV/BEI,2007	RTECS®- TLV/BEI,2007
RTECS®- Food and Chemical Toxicology 1984	RTECS®- Food and Chemical Toxicology. (Pergamon Press Inc., Maxwell House, Fairview Park, Elmsford, NY 10523) V.20- 22,623,1984
RTECS®- Food and Chemical Toxicology 1988	RTECS®- Food and Chemical Toxicology. (Pergamon Press Inc., Maxwell House, Fairview Park, Elmsford, NY 10523) V.20- 26,487,1988
RTECS®- JAT, Journal of Applied Toxicology 1982	RTECS®- JAT, Journal of Applied Toxicology. (John Wiley & Sons Ltd., Baffins Lane, Chichester, W. Sussex PO19 1UD, UK) V.1- 2,160,1982
RTECS®- Journal of Environmental Pathology, Toxicology and Oncology 1985	RTECS®- Journal of Environmental Pathology, Toxicology and Oncology. (Chem-Orbital, POB 134, Park Forest, IL 60466) V.5(4)- 6(1),105,1985
RTECS®- MSHA STANDARD-air: 3,46,1971	RTECS®- MSHA STANDARD-air: 3,46,1971
RTECS®- Mutagenesis 2004	RTECS®- Mutagenesis. (Oxford Univ. Press, Pinkhill House, Southfield Road, Eynsham, Oxford OX8 1JJ, UK) V.1- 19,157,2004
RTECS®- Mutation Research 2004	RTECS®- Mutation Research. (Elsevier Science Pub. B.V., POB 211, 1000 AE Amsterdam, Netherlands) V.1- 557,119,2004
RTECS®- Mutation Research 2005	RTECS®- Mutation Research. (Elsevier Science Pub. B.V., POB 211, 1000 AE Amsterdam, Netherlands) V.1- 587,103,2005
RTECS®- OSHA PEL (Fed Cont): 41,50-204 1994	RTECS®- OSHA PEL (Fed Cont): 41,50-204.50,1994
RTECS®- OSHA PEL (Gen Indu): 29,1910 1994	RTECS®- OSHA PEL (Gen Indu): 29,1910.1000,1994

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