Disinfection byproducts · in your tap water
Brominated TTHM — more potent
BDCM forms when bromide-containing source water is chlorinated. Brominated TTHMs are generally treated as a greater health concern per microgram than the purely chlorinated ones — reflected in much stricter health guidelines (EWG sets BDCM at 0.06 ppb vs 0.4 ppb for chloroform). IARC classifies BDCM as Group 2B (possibly carcinogenic to humans) and the U.S. National Toxicology Program lists it as 'reasonably anticipated to be a human carcinogen.'
Brominated TTHMs are the worst sub-class. RO at the tap is the strongest play.
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Every source below was checked to make sure the link works and backs the claim it's next to. These are the primary regulators and peer-reviewed studies — not our opinion.
EWG health guideline of 0.06 ppb; cancer + harm to fetal growth/development.
IARC classifies BDCM as Group 2B, 'possibly carcinogenic to humans.'
Forms from chlorine + bromide; NTP 'reasonably anticipated' carcinogen; liver/kidney targets.
Lists the TTHM MCL of 0.080 mg/L (80 ppb) and HAA5 MCL of 0.060 mg/L (60 ppb).
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Get my free water report Book a free checkupThis page is general water-quality education, not medical advice. Health classifications and limits are attributed to the EPA, EWG, IARC, ATSDR/CDC, WHO and the cited studies. Contaminant levels vary by water system and home — the only way to know what's in your water is to test it. Prepared by SwiftPro Heating, Cooling & Plumbing.