Effect of boiling on halogenated DBPs and their developmental toxicity in real tap waters

Abstract

The use of chlorine for disinfection results in the formation of halogenated disinfection by-products (DBPs) in tap water. Evidence has shown that halogenated DBPs may cause chronic adverse effects on human health, and brominated DBPs are generally significantly more toxic than their chlorinated analogues. Previously, the authors' group found that boiling of a simulated tap water for 5 min significantly reduced the overall levels of brominated and chlorinated DBPs, thus reducing the cytotoxicity of the simulated tap water to mammalian cells. In this study, we further investigated the effect of boiling on the level and developmental toxicity of halogenated DBPs in two "real" tap water samples. With a novel precursor ion scan approach using electrospray ionization-triple quadrupole mass spectrometry, the whole pictures of polar brominated and chlorinated DBPs in both tap water samples without and with boiling were revealed. After 5 min boiling, the concentrations of total organic bromine (a collective parameter for all brominated DBPs) in the two tap water samples decreased by 43.6% and 37.5%, respectively; the concentrations of total organic chlorine (a collective parameter for all chlorinated DBPs) in the two tap water samples decreased by 39.0% and 57.1%, respectively; the developmental toxicity of the two tap water samples decreased by 53.0% and 57.1%, respectively. This study suggests a simple way to reduce the adverse health effect of halogenated DBPs in humans through tap water ingestion.