Drinking water chlorite

Other Uses. As a biocide, chlorine dioxide is more effective than chlorine over a wider pH range. Chlorine dioxide is also less corrosive and more compatible with some materials of constmction. Chlorine dioxide has a wide variety of small appHcations in drinking water, food processing (qv), cooling towers, and oil recovery. In these areas, chlorite is the preferred source of chlorine dioxide. 

Sodium chlorite is not Hsted by the USEPA or any regulatory authority as a carcinogen. Studies conducted ia mice and rats did not show an increase in tumors in animals exposed to sodium chlorite in thek drinking water. Sodium chlorite has been found to have mutagenic activity in some in vitro test systems such as the Ames Salmonella reverse mutation assay without the presence of metaboHc activators. The significance of these test results in regard to human health is not clear because of the oxidizing effects of the chlorite ion (149). 

B. Slootmaekers, S. Tachiyashiki, D. Wood, and G. Gordon, "The Removal of Chlorite Ion and Chlorate Ion from Drinking Water," in Chlorine Dioxide Scientific, Tegulatory and Application Issues, American Water Works Association, International Sjmposium, Denver, Colo., Nov. 1—2,1989. 

The use of chlorine dioxide in water systems results in its reduction to chlorite and chloride. In the UK the Drinking Water Inspectorate (DWI) restricts the use of chlorine dioxide in potable water supplies to a maximum of 0.5ppm total oxidants expressed as chlorine dioxide. This ensures that chlorite (and any chlorate) concentrations do not reach levels of potential harm to humans. 

Determination of Chlorine Dioxide and Chlorite Ion in Drinking Water using Lissamine Green B and Horseradish... 

A few DBFs, such as bromate, chlorate, iodate, and chlorite, are present as anions in drinking water. As a result, they are not volatile and cannot be analyzed by GC/MS. They are also difficult to separate by LC, but will separate nicely using ion chromatography (IC). At neutral pH, HAAs are also anions and can be separated using 1C. A number of methods have been created for these DBFs using both IC/ inductively coupled plasma (ICF)-MS and IC/ESl-MS. Fretreatment to remove interfering ions (e.g., sulfate and chloride), along with the use of a suppressor column prior to introduction into the MS interface, is beneficial for trace-level measurement. 

Because chlorine dioxide is a very reactive chemical, it is able to kill bacteria and microorganisms in water. About 5% of large water treatment facilities (serving more than 100,000 people) in the United States use chlorine dioxide to treat drinking water. It is estimated that about 12 million people may be exposed in this way to chlorine dioxide and chlorite ions. In communities that use chlorine dioxide to treat water for drinking uses, chlorine dioxide and its by-product, chlorite ions, may be present at low levels in tap water. 

In this profile, the term chlorite will be used to refer to chlorite ion, which is a water-soluble ion. Chlorite ion will combine with metal ions to form solid salts, (e.g., sodium chlorite). In water, sodium chlorite is soluble and will dissolve to form chlorite ions and sodium ions. More than 80% of all chlorite (as sodium chlorite) is used to make chlorine dioxide to disinfect drinking water. Sodium chlorite is also used as a disinfectant to kill germs. 

Chlorine dioxide is added to drinking water to protect people from harmful bacteria and other microorganisms. Most people will be exposed to chlorine dioxide and its disinfection by-product, chlorite ions, when they drink water that has been treated with chlorine dioxide. The EPA has set the maximum concentration of chlorine dioxide and chlorite ion in drinking water at 0.8 and 1.0 milligrams per liter (mg/L), respectively. However, the concentrations of chlorine dioxide and chlorite ion in your drinking water may be lower or higher than these levels. For additional information about how you might be exposed to chlorine dioxide and chlorite, see Chapter 6. 

Chlorine dioxide and chlorite usually enter the body when people drink water that has been disinfected with chlorine dioxide. It is not likely that you would breathe air containing dangerous levels of chlorine dioxide, but if you did, it could be absorbed across your lungs. You are not likely to encounter chlorite in the air you breathe. It is not known whether chlorine dioxide or chlorite on your skin would be absorbed to any great extent. 

Families that drink water treated with chlorine dioxide may reduce the risk of exposure to chlorine dioxide and chlorite ions by drinking bottled water that has not been treated with chlorine dioxide or chlorite ions. 

OSHA regulates the level of chlorine dioxide in workplace air. The occupational exposure limit for an 8-hour workday, 40-hour workweek is 0.1 parts per million (0.28 milligrams per cubic meter [mg/m ]). The EPA has set a maximum contaminant level of 1 milligram per liter (mg/L) for chlorite in drinking water and a goal of 0.8 mg/L for both the maximum residual disinfectant level for chlorine dioxide and the maximum contaminant level for chlorite in drinking water treated with chlorine dioxide as a disinfectant. 

EPA has set the maximum concentration of chlorine dioxide and chlorite ion for drinking waters at 0.8 and 1.0 mg/L, respectively. However, the concentrations of chlorine dioxide and chlorite ion in drinking water may be higher or lower than these levels. 

Neurodevelopmental effects appear to be of greatest toxicological concern, particularly in light of the fact that chlorine dioxide and chlorite may be used as disinfectants for drinking water. Therefore, the following brief discussion includes only developmental effects. The reader is referred to Section 3.2, Discussion of Health Effects by Route of Exposure, for additional information regarding the potential for other chlorine dioxide- or chlorite-induced health effects. 

Abdel-Rahman and coworkers (Abdel-Rahman et al. 1984b Couri and Abdel-Rahman 1980) also exposed male rats to sodium chlorite in the drinking water, 20 hours/day for up to 1 year, at concentrations that resulted in estimated doses of 1 or 10 mg/kg/day. Both dose levels resulted in increased mean corpuscular hemoglobin concentration (after 7, but not 9 months) and decreased osmotic fragility after 7-9 months). Erythrocyte glutathione levels were significantly decreased at dose levels 0.1 mg/kg/day by the end of the... 

Moore and Calabrese (1982) found no significant alterations in hematological parameters within groups of mice exposed to chlorine dioxide in the drinking water for 30 days, at a concentration that resulted in an estimated dose of 25 mg/kg/day. However, when similarly examining the hematotoxicity of chlorite, Moore and Calabrese (1982) found significant increases in mean corpuscular volume and osmotic fragility at a dose level of 19 mg/kg/day. 

Limited information is available regarding hepatic effects in animals following oral exposure to chlorine dioxide or chlorite. Daniel et al. (1990) exposed male and female rats to chlorine dioxide in the drinking water for 90 days at concentrations that resulted in estimated doses of 1.9, 3.6, 6.2, or 11.5 mg/kg/day for males and 2.4, 4.6, 8.2, or 14.9 mg/kg/day for females. Significantly depressed mean absolute liver weights were observed in males at doses 3.6 mg/kg/day and females of the 8.2 mg/kg/day dose group. However, these groups also exhibited decreased water consumption. 

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