title: Toxic impact of bromide and iodide on drinking water disinfected with chlorine or chloramines.
abstract: Disinfectants inactivate pathogens in source water; however, they also react with organic matter and bromide/iodide to form disinfection byproducts (DBPs). Although only a few DBP classes have been systematically analyzed for toxicity, iodinated and brominated DBPs tend to be the most toxic. The objectives of this research were (1) to determine if monochloramine (NH2Cl) disinfection generated drinking water with less toxicity than water disinfected with free chlorine (HOCl) and (2) to determine the impact of added bromide and iodide in conjunction with HOCl or NH2Cl disinfection on mammalian cell cytotoxicity and genomic DNA damage induction. Water disinfected with chlorine was less cytotoxic but more genotoxic than water disinfected with chloramine. For both disinfectants, the addition of Br(-) and I(-) increased cytotoxicity and genotoxicity with a greater response observed with NH2Cl disinfection. Both cytotoxicity and genotoxicity were highly correlated with TOBr and TOI. However, toxicity was weakly and inversely correlated with TOCl. Thus, the forcing agents for cytotoxicity and genotoxicity were the generation of brominated and iodinated DBPs rather than the formation of chlorinated DBPs. Disinfection practices need careful consideration especially when using source waters containing elevated bromide and iodide.
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University , Beijing, P.R. China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Yukako
authors.initials: Y
authors.lastname: Komaki
authors.forename: Susana Y
authors.initials: SY
authors.lastname: Kimura
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Hu
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Wagner
authors.forename: Benito J
authors.initials: BJ
authors.lastname: Mariñas
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Plewa
mesh_terms: D000818:Animals; D001965:Bromides / Q000737:chemistry / Q000633:toxicity*; D016466:CHO Cells; D002700:Chloramines / Q000737:chemistry / Q000633:toxicity*; D002713:Chlorine / Q000737:chemistry / Q000633:toxicity*; D003412:Cricetulus; D004202:Disinfectants / Q000737:chemistry / Q000633:toxicity; D004203:Disinfection; D060766:Drinking Water / Q000737:chemistry; D054879:Halogenation; D007454:Iodides / Q000737:chemistry / Q000633:toxicity*; D018675:Toxicity Tests; D018508:Water Purification
chemical_list: D001965:Bromides; D002700:Chloramines; D004202:Disinfectants; D060766:Drinking Water; D007454:Iodides; D002713:Chlorine; C030816:chloramine