National Drinking Water Database

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National Drinking Water Database - Chemical Contaminants

Chlorite

Status: Regulated - EPA has established a maximum legal limit in tapwater for this contaminant.

Chlorite is a disinfection byproduct resulting from water treatment with chlorine dioxide, or from the use of chlorine dioxide as a bleaching agent for cellulose, paper pulp, flour and oils. [read more]

Chlorite Chlorite is a disinfection byproduct of chlorine dioxide used to treat drinking water for pathogens. Chlorite also forms from chlorine dioxide used as a bleaching agent for textiles, paper pulp, flour and oils. In laboratory animals, chlorite, in the form of sodium chlorite, has been shown to cause changes in the size of the liver, adrenal gland, kidney and two important organs involved in immune response (the spleen and thymus). Chlorite also causes alterations in blood chemistry due to oxidative stress in the red blood cells (WHO 2004a), which can be a precursor to anemia. Rats exposed to sodium chlorite during development were underweight, less likely to survive and had delayed physical and sexual maturation (Integrated Risk Information System (IRIS) 2000).

	Detected	Found above health guidelines	Found above legal limit
States	22	7	5
Water utilities	113	23	7
People Served	3,957,125	405,670	184,594

Health Concerns for Chlorite:

• Cancer

Chlorite Exposure by State

Water utilities in 22 states have reported detecting Chlorite in treated tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies.

State	Water Suppliers with Chlorite contamination		Water suppliers reporting Chlorite above health-based limits
	Systems	Population	Systems	Population
North Carolina	5	172,976	3	160,545
Kentucky	7	133,396	3	97,401
California	7	509,750	1	53,550
Missouri	21	96,939	6	34,795
Iowa	12	134,923	6	30,956
Massachusetts	9	433,553	1	16,348
Illinois	10	130,930	3	12,075
Arizona	3	616,000	0	0
Virginia	9	536,066	0	0
Alabama	3	524,010	0	0
Florida	2	233,203	0	0
Arkansas	7	85,894	0	0
New Jersey	2	83,994	0	0
New York	3	80,578	0	0
Washington	1	65,000	0	0
Wyoming	2	58,672	0	0
Nebraska	1	21,600	0	0
Ohio	1	15,641	0	0
Minnesota	2	11,551	0	0
New Mexico	4	10,534	0	0
Maine	1	1,870	0	0
Oregon	1	45	0	0
Total	113	3,957,125	23	405,670

The Most Polluted Communities

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

Ranked by highest average Chlorite level

Rank	System	Population Served	Positive test results of total reported tests	Average Level (Range)
1	Brunswick County Water System Leland, NC	72,947	50 of 50	735.47 ppb (376.67 to 1016.67 ppb)
2	Paducah Water Works Paducah, KY	47,000	25 of 25	626.41 ppb (20 to 909.5 ppb)
3	Rend Lake Inter-City Water System Benton, IL	2,928	38 of 38	582.5 ppb (108.33 to 993.33 ppb)
4	Lamoni Municipal Utilities Lamoni, IA	2,554	64 of 66	581.92 ppb (0 to 1033.33 ppb)
5	Carlinville Carlinville, IL	5,685	13 of 13	578.21 ppb (350 to 980 ppb)
6	Cameron Cameron, MO	9,788	47 of 47	570.21 ppb (283.33 to 803.33 ppb)
7	Kinkaid Area Water System Murphysboro, IL	1	13 of 13	550.57 ppb (0.75 to 776.67 ppb)
8	City of Escondido Escondido, CA	140,000	1 of 1	550 ppb (550 ppb)
9	Osceola Water Works Osceola, IA	4,659	30 of 31	548.92 ppb (0 to 970 ppb)
10	Hamilton Hamilton, MO	1,750	47 of 47	545.18 ppb (50 to 910 ppb)

Health Based Limits for Chlorite

Standard	Description	Level
Maximum Contaminant Limit Goal (MCLG)	A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.	800 ppb
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
Maximum Contaminant Limit (MCL)	The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.	1000 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 Chlorite

Are tests routinely required for Chlorite by federal law?	Yes
Water suppliers reporting tests for Chlorite (2004-2009):	161 of 47,576
Average testing rate for water supplier reporting tests (2004-2009):	4.6 per year

Violation Summary for Chlorite

Data from the U.S. Environmental Protection Agency includes the following violations of federal standards for Chlorite since 2004

Maximum Contaminant Level Exceedance Violations	18
Monitoring Violations	0
Reporting Violations	0

Cancer

Type of concern:	Reference:
Mutagen - limited evidence	EPA Water Disinfection By-Products Carcinogenicity

Government, industry, academic studies and classifications

government/industry list/academic study	appears on list as	classification(s)
EPA Water Disinfection By-Products Carcinogenicity	CHLORITE	•Low to moderate concern for potential carcinogenicity

references

government/industry list/academic study	reference
EPA Water Disinfection By-Products Carcinogenicity	EPA (U.S. Environmental Protection Agency). 2006. EPA Water Disinfection By-Products with Carcinogenicity Estimates. Last updated: 10 April 2006.

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