Contributions of Pharmaceuticals to DBP Formation and Developmental Toxicity in Chlorination of NOM-containing Source Water

Abstract

Pharmaceuticals have been considered a priority group of emerging micropollutants in source waters in recent years, while their role in the formation and toxicity of disinfection byproducts (DBPs) during chlorine disinfection remains largely unclear. In this study, the contributions of natural organic matter (NOM) and pharmaceuticals (a mixture of ten representative pharmaceuticals) to the overall DBP formation and toxicity during drinking water chlorination were investigated. By innovatively “normalizing” chlorine exposure and constructing a kinetic model, we were able to differentiate and evaluate the contributions of NOM and pharmaceuticals to the total organic halogen (TOX) formation for source waters that contained different levels of pharmaceuticals. It was found that at a chlorine contact time of 1.0 h, NOM (2 mg/L as C) and pharmaceuticals (total 0.0062–0.31 mg/L as C) contributed 79.8–99.5% and 0.5–20.2%, respectively, of TOX. The toxicity test results showed that the chlorination remarkably increased the toxicity of the pharmaceutical mixture by converting the parent compounds into more toxic pharmaceutical-derived DBPs, and these DBPs might contribute significantly to the overall developmental toxicity of chlorinated waters. This study highlights the non-negligible role of pharmaceuticals in the formation and toxicity of overall DBPs in chlorinated drinking water.

Water Analysis: Emerging Contaminants and Current Issues

“…A study by Li et al investigated DBPs (though the measurement of total organic halogen) and the accompanying developmental toxicity following the chlorination of 10 pharmaceuticals . Results showed that a chlorine contact time of 1 h along with 2 mg/L NOM and 0.0062–0.31 mg/L C of pharmaceuticals contributed 80–99.5% and 0.5–20% of total organic halogen, respectively.…”

“…Li et al explored the contribution of pharmaceuticals to the formation of DBPs during chlorination using experimental and modeling approaches . By “normalizing” chlorine exposure and using a kinetic model, the study quantified the contributions of NOM and pharmaceuticals to total organic halogen formation in waters with varying concentrations of pharmaceuticals.…”

Suspect and Nontarget Screening of Coexisting Emerging Contaminants and Aromatic Halogenated Disinfection Byproducts in Drinking Water Distribution Systems

“…The acute toxicity of halobenzoquinone was up to 200 times more potent than haloacetic acids when using zebrafish embryos as a developmental toxicity model, emphasizing the importance of understanding aromatic DBP formation. The formation of aromatic DBPs was investigated in drinking water distribution systems (DWDSs) via chlor(am)inating authentic drinking water under well-controlled laboratory conditions. , However, these studies are not effective in elucidating the variation in the occurrence and abundance of aromatic DBPs in real DWDSs. This is primarily because the contributions of multiple factors influencing DBP formation remain unknown, such as long transportation distances, prolonged reaction time, and unsuspected precursors.…”