Identification of Toxicity Forcing Agents from Individual Aliphatic and Aromatic Disinfection Byproducts Formed in Drinking Water: Implications and Limitations

Recently, a study found that aromatic DBP fractions dominate the overall toxicity of chlorinated drinking water. However, key toxicity drivers have not been reported via comprehensive evaluation based on the formation of aliphatic and aromatic DBPs in drinking water. In this study, the occurrence of 37 aliphatic and 19 aromatic DBPs in drinking samples with different water characteristics collected in a Chinese megacity was explored. According to the individual DBP concentrations and cytotoxicity potencies as well as the “TIC-Tox” method, haloacetonitriles and halonitrophenols were found to be the toxicity drivers among the measured aliphatic and aromatic DBPs, respectively. However, when aromatic and aliphatic DBPs are taken into consideration together, aliphatic DBPs were calculated to present higher toxicity contribution than aromatic DBPs, which is inconsistent with the previous study. TOX showed significant positive correlations with most aliphatic DBPs but no aromatic DBPs, and the overall toxicity of the water sample concentrates is significantly related to the total calculated cytotoxicity and aliphatic DBPs, suggesting that current selected aromatic DBPs are insufficient to represent the overall aromatic DBPs. UV 254 and DOC rather than SUVA are better surrogates for predicting DBP formation potential for DOM with a lower humification degree as indicated by fluorescence results.