BACKGROUND: Water disinfection by-products have been associated with an increased cancer risk. Micronuclei (MN) frequency in lymphocytes is a marker of genomic damage and can predict adult cancer risk.

OBJECTIVE: We evaluated maternal exposure to drinking water brominated trihalomethanes (BTHM) in relation to MN frequency in maternal and cord blood lymphocytes.

METHODS: MN frequency was examined in 214 mothers and 223 newborns from the Rhea mother-child cohort in Crete, Greece, in 2007-2008. Residential BTHM water concentrations were estimated during pregnancy using tap water analyses and modeling. Questionnaires on water related habits were used to estimate BTHM exposure from all routes. Associations between BTHM and MN frequency were estimated using negative binomial regression.

RESULTS: BTHM concentrations in residential tap water during pregnancy ranged from 0.06 to 7.1 μg/L. MN frequency in maternal binucleated lymphocytes was found to increase with BTHM concentrations in residential water for exposure during the first [rate ratio (RR) for 1 μg/L=1.05; 95% CI: 1.00, 1.11] and second trimesters (RR for 1 μg/L=1.03; 95% CI: 1.00, 1.06), and through all routes of BTHM exposure during the first trimester (RR for 1 μg/week=3.14; 95% CI: 1.16, 8.50).

CONCLUSIONS: These findings suggest that exposure to BTHM may increase the frequency of MN in maternal binucleated lymphocytes.