Chlorine and chlorination byproducts (trihalomethanes)
Water disinfection
Evidence level : Probable Drinking waterMechanism : Environmental / physical burden
🟡 Several human studies point the same way, with a plausible biological mechanism, but the evidence is not yet conclusive.
- Where it's found
- Treated tap water, noticeable chlorine smell or taste.
- Suspected mechanism
- Chlorine reacts with organic matter in water and forms trihalomethanes; some studies link these to adverse pregnancy outcomes.
- Suggested alternative
- Let water sit uncovered for a few hours, or filter with activated carbon: this reduces chlorine (but not nitrates or PFAS).
- Source
- Studies on trihalomethanes and pregnancy outcomes.
Map your everyday exposures in about ten minutes.
Take the questionnaireRelated factors
Including a factor does not mean it causes infertility: it is simply worth monitoring, depending on its level of evidence.
Content last updated: September 14, 2026