Exposure to chlorination disinfection byproducts (
DBPs) is potentially associated with an increased risk of
bladder cancer. Four halobenzoquinones (HBQs) have been detected in treated
drinking water and have shown potency in producing
reactive oxygen species and inducing damage to cellular
DNA and
proteins. These HBQs are unstable in
drinking water. The fate and behavior of these HBQs in
drinking water distribution systems is unclear. Here we report the high-resolution mass spectrometry identification of the transformation products of HBQs as halo-
hydroxyl-
benzoquinones (
OH-HBQs) in water under realistic conditions. To further examine the kinetics of transformation, we developed a solid-phase extraction with ultrahigh-performance liquid chromatography tandem mass spectrometry (SPE-UHPLC-MS/MS) method to determine both the HBQs and
OH-HBQs. The method provides reproducible retention times (SD < 0.05 min), limits of detection (LODs) at subnanogram per liter levels, and recoveries of 68%-96%. Using this method, we confirmed that decrease of HBQs correlated with increase of
OH-HBQs in both the laboratory experiments and several distribution systems, supporting that
OH-HBQs were more stable forms of HBQ
DBPs. To understand the toxicological relevance of the
OH-HBQs, we studied the in vitro toxicity with CHO-K1 cells and determined the IC50 of HBQs and
OH-HBQs ranging from 15.9 to 72.9 μM. While HBQs are 2-fold more toxic than
OH-HBQs, both HBQs and
OH-HBQs are substantially more toxic than the regulated
DBPs.