title: Combined genotoxicity of chlorinated products from tyrosine and benzophenone-4.
abstract: The toxicity of disinfection by-products (DBPs) from a single precursor was studied intensively. Here we examined the genotoxicity when two precursors (tyrosine (Tyr) and benzophenone-4 (BP-4)) were chlorinated together and separately. We sought to examine whether the genotoxicity of the mixture (GCM) could be estimated from the sum of the genotoxicities of the individual precursors (GCI), which were chlorinated separately. We determined the genotoxicity using the SOS/umu test. The results revealed that GCM was not identical to GCI. The difference in genotoxicity between GCM and GCI (GΔ) was observed to decrease with increasing pH. GCM was higher than GCI (GΔ>0) at pH 5.0-6.1, and lower than GCI (GΔ<0) at pH 6.3-8.0. We found that nitrogen-containing DBPs played a dominant role in determining GCM and GCI. We propose that the total organic nitrogen (TON) ratio, TON(chlorinatedmixture)/TON(thesumofchlorinatedindividuals), is useful to estimate GΔ.
authors: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Yangyang
authors: Y
authors: Chang
authors: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors: Yaohui
authors: Y
authors: Bai
authors: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Qinghua
authors: Q
authors: Ji
authors: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Yang
authors: Y
authors: Huo
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors: Huijuan
authors: H
authors: Liu
authors: Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, 828 West Peachtree Street, Atlanta, GA 30332, United States. Electronic address: john.crittenden@ce.gatech.edu.
authors: John C
authors: JC
authors: Crittenden
authors: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: jhqu@rcees.ac.cn.
authors: Jiuhui
authors: J
authors: Qu
keywords: Chlorination; Combined effects; Genotoxicity; N-DBPs; SOS/umu test