Water disinfection effectively prevents outbreaks by killing pathogens, but it creates an unintended chemical risk from the formation of disinfection byproducts (DBPs). Epidemiological studies have shown an association of water disinfection byproducts with increased risk of bladder cancer. The DBPs responsible for the observed adverse health effects remain unknown. The quantitative structure and toxicity relationship analysis predicts that halobenzoquinones (HBQs) are potential carcinogens. Therefore, we have investigated the occurrence, formation, transformation, removal, and toxicity of HBQs as DBPs. Dichlorobenzoquinone (DCBQ) was detected in all the samples, while dibromobenzoquinone (DCBQ) detected in more than 70% of the samples collected from more than ten drinking water treatment plants (DWTPs). Analysis of HBQ formation potential of source waters collected from nine DWTPs support the widespread presence of precursors of HBQs. We further investigated the current treatment processes, including coagulation, filtration, granular activated carbon, ozonation, and UV irradiation, for removal of HBQ precursors. The results demonstrate that the combined treatments cannot substantially reduce HBQ precursor levels in water. Our <i>in vitro</i> studies have shown that HBQs induce greater cytotoxicity than most of the regulated DBPs though their generation of reactive oxygen species, damaging DNA and proteins in cells. HBQs are toxicologically relevant DBPs in drinking water that warrant monitoring.

Analytical and toxicological studies of emerging water disinfection byproducts halobenzoquinones

253rd National Meeting (2017)

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