Identification, Occurrence, and Cytotoxicity of Haloanilines: A New Class of Aromatic Nitrogenous Disinfection Byproducts in Chloraminated and Chlorinated Drinking Water

Identifying disinfection byproducts (DBPs) with high health risk is an unresolved challenge. In this study, six members of a new class of aromatic nitrogenous DBPs-2-chloroaniline, 2-bromoaniline, 2,4 dichloroa niline, 2-chloro-4-bromoaniline, 4-chloro-3-nitroaniline, and 2-chloro-4-nitroaniline-are reported as DBPs in drinking water for the first time. Haloanilines completely degraded within 1 h in the presence of chlorine (1 mg/L), while about 20% remained in the presence of chloramine (1 mg/L) after 120 h. Haloanilines showed high stability in the absence of disinfectants, with <30% degradation at pH 5-9 over 120 h. Eight haloanilines were determined in chloraminated finished water and tap water at total concentrations of up to 443 ng/L. The most abundant was 2-bromoaniline, with a median concentration of 104 ng/L. The cytotoxicity of eight haloanilines and regulated trichloromethane and dichloroacetic acid (DCAA) was evaluated using Hep G2 cell assay. The EC50 values of eight haloanilines were 1-2 orders of magnitude lower than those of the regulated DBPs. The lowest toxic concentration of 2-chloro-4-nitroaniline was 1 mu M, 500 times lower than that of DCAA. The formation and control of haloanilines in drinking water warrant further investigation.

Automated summary

This study reports the presence of six new aromatic nitrogenous disinfection byproducts (DBPs) in drinking water. Haloanilines completely degrade in the presence of chlorine within 1 hour, but about 20% remains in the presence of chloramine after 120 hours. Haloanilines show high stability in the absence of disinfectants at pH 5-9. Eight haloanilines were detected in chloraminated finished water and tap water, with the highest total concentration reaching 443 ng/L. The cytotoxicity of haloanilines was lower than that of regulated DBPs. The formation and control of haloanilines in drinking water call for further investigation.