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. UV254 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.