Where It Comes From
Forms when disinfectants react with natural organic matter and bromide/iodide in source water; includes the regulated HAA5 plus four additional HAAs [1][2].
How You Are Exposed
Mainly by drinking tap water; smaller amounts from skin contact during bathing or swimming [3][4].
Why It Matters
EPA limits HAA5 in public water to reduce health risks; animal studies link some HAAs to liver, reproductive, and developmental effects, with limited evidence for cancer in humans [1][4].
Who Is at Risk
Infants and children, pregnant people, high water consumers, people with liver disease, and communities with warm, bromide-rich waters [4][2].
How to Lower Your Exposure
Use reverse osmosis or activated carbon filters certified to reduce haloacetic acids; use cold tap water for drinking/cooking; flush taps; review your utility’s water quality report or UCMR data [1][2][3].
References
- [1]U.S. EPA. National Primary Drinking Water Regulations: Disinfectants and Disinfection Byproducts (HAA5). https://www.epa.gov/dwreginfo/disinfection-disinfection-byproducts
- [2]U.S. EPA. Fourth Unregulated Contaminant Monitoring Rule (UCMR 4): HAA5/HAA9. https://www.epa.gov/dwucmr/fourth-unregulated-contaminant-monitoring-rule
- [3]CDC. Disinfection By-Products (DBPs) in Drinking Water. https://www.cdc.gov/healthy-water/drinking/public/water_disinfection.html
- [4]WHO. Guidelines for Drinking-water Quality: Disinfection by-products. https://www.who.int/publications/i/item/9789241549950