Haloacetonitriles vs. regulated haloacetic acids: are nitrogen-containing DBPs more toxic?
Haloacetonitriles (HANs) are toxic nitrogenous drinking water disinfection byproducts (N-DBPs) and are observed with chlorine, chloramine, or chlorine dioxide disinfection. Using microplate-based Chinese hamster ovary (CHO) cell assays for chronic cytotoxicity and acute genotoxicity, we analyzed 7 HANs: iodoacetonitrile (IAN), bromoacetonitrile (BAN), dibromoacetonitrile (DBAN), bromochloroacetonitrile (BCAN), chloroacetonitrile (CAN), dichloroacetonitrile (DCAN), and trichloroacetonitrile (TCAN). The cytotoxic potency (%C1/2 values) ranged from 2.8 microM (DBAN) to 0.16 mM (TCAN), with a descending rank order of DBAN > IAN approximately BAN > BCAN > DCAN > CAN > TCAN. HANs induced acute genomic DNA damage; the single cell gel electrophoresis (SCGE) genotoxicity potency ranged from 37 microM (IAN) to 2.7 mM (DCAN). The rank order of declining genotoxicity was IAN > BAN approximately DBAN > BCAN > CAN > TCAN > DCAN. The accompanying structure-activity analysis of these HANs was in general agreement with the genotoxicity rank order. These data were incorporated into our growing quantitative comparative DBP cytotoxicity and genotoxicity databases. As a chemical class, the HANs are more toxic than regulated carbon-based DBPs, such as the haloacetic acids. The toxicity of N-DBPs may become a health concern because of the increased use of alternative disinfectants, such as chloramines, which may enhance the formation of N-DBPs, including HANs.
Muellner
Mark G
MG
College of Agricultural, Consumer and Environmental Sciences, Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Wagner
Elizabeth D
ED
McCalla
Kristin
K
Richardson
Susan D
SD
Woo
Yin-Tak
YT
Plewa
Michael J
MJ
D000085:Acetates / Q000633:toxicity*; D000097:Acetonitriles / Q000633:toxicity*; D000818:Animals; D016466:CHO Cells; D002452:Cell Count; D049109:Cell Proliferation / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D004203:Disinfection; D004586:Electrophoresis; D006846:Hydrocarbons, Halogenated / Q000633:toxicity*; D009152:Mutagenicity Tests; D021281:Quantitative Structure-Activity Relationship; D012044:Regression Analysis; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis
D000085:Acetates; D000097:Acetonitriles; D006846:Hydrocarbons, Halogenated