Where It Comes From
Forms when chlorine dioxide or hypochlorite (bleach) is used or stored; also from paper/pulp processing, herbicide use/production, and some pyrotechnics. [1][4]
How You Are Exposed
Mainly through drinking water treated with chlorine dioxide/bleach and foods washed or processed with chlorinated water; workers may inhale it or get skin contact. [1][3]
Why It Matters
High doses can cause methemoglobinemia, hemolysis, and kidney injury; repeated lower exposures have been linked to thyroid effects in animals and underpin EPA’s chronic reference dose. [2][3][1]
Who Is at Risk
Bottle-fed infants, pregnant people, those with thyroid disease, anemia or G6PD deficiency, kidney disease, and workers handling chlorate. [1][3]
How to Lower Your Exposure
Check your water report; if chlorate is elevated, consider reverse osmosis or anion exchange treatment; use fresh, properly stored bleach; avoid soaking foods in bleach and rinse produce; at work, follow controls and wear appropriate PPE. [1][4][3]
References
- [1]WHO. Chlorate and chlorite in drinking-water: Background document for development of WHO Guidelines for Drinking-water Quality. 2017.
- [2]U.S. EPA IRIS. Chlorate (CASRN 14866-68-3).
- [3]CDC/NIOSH Pocket Guide to Chemical Hazards: Sodium chlorate.
- [4]U.S. EPA. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014, 1999.