Comparative toxicity of chloro- and bromo-nitromethanes in mice based on a metabolomic method
Introduction
Disinfection based on chlorine is widely applied in drinking water supply to protect public health (Sedlak and Gunten, 2011). However, disinfection also generates toxic disinfection byproducts (DBPs), and over 600 DBPs have been identified in drinking water. Adverse effects of some DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs) have been characterized (Shi et al., 2009, Linge et al., 2013). In recent years, in order to reduce human health risk of DBPs, some other disinfection processes based on the usage of chloramine, chlorine dioxide and ozone are developed to replace chlorine. Unfortunately, these disinfection approaches generate more nitrogenous disinfection byproducts (N-DBPs), which have received more and more attentions due to their high toxicity (Richardson et al., 2007). Halonitromethanes (HNMs), as one typical class of N-DBPs, are widely detected in drinking water (0.1–3.0 μg L−1) and effluents of wastewater treatment plant (0.9–1.5 μg L−1) (Plewa et al., 2004, Song et al., 2010). In a U.S. nationwide survey at drinking water treatment plants, the HNMs have been listed in 50 high priority monitored DBPs (Hu et al., 2010).
Although the concentration of HNMs in drinking water is low, recent researches based on mammalian cell culture found that HNMs could induce 1–2 orders of magnitude higher cytotoxicities and genotoxicities than currently regulated DBPs, such as THMs and HAAs (Plewa et al., 2004, Muellner et al., 2007). However, data on HNMs toxicity from in vivo animal experiments on is limited. Only few reports on trichloronitromethane (TCNM) are available, which showed that TCNM could react with biological thiols in mouse liver tissue (Sparks et al., 1997). Thus, toxic effects on other HNMs in animals should be further characterized. Besides, toxicities of DBPs are associated with halogeno-groups. For examples, brominated THMs (Pegram et al., 1997), HAAs (Zhang et al., 2010) and haloacetamides (HAcAms) (Plewa et al., 2008) were found to have higher genotoxic and carcinogenic effects than chlorinated counterparts. For HNMs, their cytotoxicity and genotoxicity in cell lines showed the same conclusion that brominated forms of HNMs are more toxic than their chlorinated analogues (Plewa et al., 2004, Liviac et al., 2009). However, these results were from the in vitro tests. It is necessary to identify whether the differences could be found in in vivo animals, and determine the underlying mechanism(s).
Metabolomics is a powerful approach for gaining a comprehensive understanding of biological mechanisms, including toxicity (Lindon et al., 1999, Jones et al., 2008). Recently, the nuclear magnetic resonance (NMR) - based metabolomics approach has been used to reveal the toxicities of N-DBPs, such as monohaloacetamides and trichloroacetamide, and found the altered metabolites are associated with lipid, xenobiotics, amino acid and energy metabolisms. Moreover, the bromo-acetamide induced higher changes in metabolic profiles than chloro-acetamide (Deng et al., 2014, Zhang et al., 2013). However, there is no report that apply metabolomics approach to characterize toxic effects of HNMs, and compare the differences of chloro- and bromo-HNMs toxicities.
Objective of this study is to evaluate and compare in vivo toxicities of HNMs, and determine their underlying mechanisms. Since acute toxicity of HNMs is limited, oral LD50 values of nine HNMs was firstly predicted based on their molecular structure. Then three HNMs were chosen and exposed to mice. Hepatic toxicity and serum metabolic profiles were determined to reveal toxic effects and mechanisms of the three HNMs. Results of this study could provide the insights to the toxic effects and risk assessment of HNMs in drinking water.
Section snippets
Acute toxicity prediction of HNMs
Nine HNMs were studied in this study, which include TCNM, bromonitromethane (BNM), bromochloronitromethane (BCNM), chloronitromethane (CNM), dichloronitromethane (DCNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM), dibromochloronitromethane (DBCNM) and bromodichloronitromethane (BDCNM). Their oral LD50 values were estimated by toxicity estimation software tool (T.E.S.T. version 4.2.1) (//www.epa.gov/chemical-research/toxicity-estimation-software-tool-test
Oral LD50 values of HNMs
Oral LD50 values of TCNM and DBNM were obtained from literature (Daniel et al., 1994, Condie et al., 1994). The T.E.S.T. was applied to predict oral LD50 values of other seven HNMs. Results are shown in Table S1. Oral LD50 values of HNMs ranged from 85.92 mg kg−1 (DBNM) to 387.6 mg kg−1 (DCNM). Bromo-HNMs had higher toxicity than chloro-HNMs. Increase in number of substituents could decrease toxicity of HNMs. Based on above results, this study chose TCNM, BNM and BCNM as target HNMs for animal
Discussion
Current literature show that HNMs have high cytotoxicity and genotoxicity, even higher than the regulated DBPs, such as THMs and HAAs (Plewa et al., 2004, Muellner et al., 2007). However, data on in vivo toxicity of HNMs is limited. The T.E.S.T. analyses showed that oral LD50 values of HNMs could be classified into toxicity category II (moderately toxic) according to EPA toxicity categories (Kamrin, 1997). Moreover, oral LD50 values indicated toxicities of three HNMs used in this study are
Conclusions
This study analyzed the in vivo toxicity of BNM, BCNM and TCNM. The three HNMs could induce liver injury. BNM had the highest toxicity, followed by BCNM and TCNM. HNMs exposure could damage hepatic antioxidant defense system and increase 8-OHdG levels. Metabolomics analysis found that amino acid metabolism and carbohydrate metabolism were disturbed by HNMs exposure. Some altered metabolites in these metabolisms are relative with oxidative stress and damage. Additionally, energy metabolism and
Acknowledgements
This work was supported by Major Program of National Natural Science Foundation of China (Grant number: 51290282), National Natural Science Foundation of China (Grant number: 21577061), Natural Science Foundation of Jiangsu Province (Grant number: BK20131271), and Fundamental Research Funds for the Central Universities of Nanjing University.
References (50)
- et al.
Serine and glycine metabolism in cancer
Trends Biochem. Sci.
(2014) - et al.
Oxidative stress and antioxidant defense
World Allergy Organ. J.
(2012) - et al.
Quercetin, a flavonoid antioxidant, prevents and protects streptozotocin-induced oxidative stress and β-cell damage in rat pancreas
Pharmacol. Res.
(2005) - et al.
Halonitromethane formation potentials in drinking waters
Water Res.
(2010) - et al.
A metabolomics based approach to assessing the toxicity of the polyaromatic hydrocarbon pyrene to the earthworm Lumbricus rubellus
Chemosphere
(2008) - et al.
Lipoic acid increases glutamate uptake, glutamine synthetase activity and glutathione content in C6 astrocyte cell line
Int. J. Dev. Neurosci.
(2013) - et al.
NMR spectroscopy of biofluids
Annu. Rep. NMR Spectros.
(1999) - et al.
Formation of halogenated disinfection by-products during microfiltration and reverse osmosis treatment: implications for water recycling
Sep. Purif. Technol.
(2013) - et al.
Genotoxicity analysis of two halonitromethanes, a novel group of disinfection by-products (DBPs), in human cells treated in vitro
Environ. Res.
(2009) - et al.
Protein measurement with the Folin phenol reagent
J. Biol. Chem.
(1951)
Mechanisms through which sulfur amino acids control protein metabolism and oxidative status
J. Nutr. Biochem.
Evaluation of antioxidant enzymes activities and lipid peroxidation in schizophrenic patients treated with typical and atypical antipsychotics
Neurosci. Lett.
Comparison of taurine and pantoyltaurine as antioxidants in vitro and in the central nervous system of diabetic rats
Exp. Toxicol. Pathol.
GlutathioneS-transferase-mediated mutagenicity of trihalomethanes in Salmonella typhimurium:contrasting results with bromodichloromethane and chloroform
Toxicol. Appl. Pharmacol.
Chloropicrin-induced toxic responses in human lung epithelial cells
Toxicol. Lett.
Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: a review and roadmap for research
Mutat. Res. Rev. Mutat.
In vitro toxicity of surface water disinfected by different sequential treatments
Water Res.
Halonitromethanes formation in wastewater treatment plant effluents
Chemosphere
Not just a circle: flux modes in the plant TCA cycle
Trends Plant Sci.
Assessment of the cytotoxicity and genotoxicity of haloacetic acids using microplate-based cytotoxicity test and CHO/HGPRT gene mutation assay
Mutat. Res. Gen. Tox. En.
Arsenic-associated oxidative stress, inflammation, and immune disruption in human placenta and cord blood
Environ. Health Perspect.
Modulation of the cytotoxicity and genotoxicity of the drinking water disinfection byproduct iodoacetic acid by suppressors of oxidative stress
Environ. Sci. Technol.
Cold on-column injection coupled with gas chromatography/mass spectrometry for determining halonitromethanes in drinking water
Anal. Meth.
Ten and ninety-day toxicity studies of chloropicrin in Sprague-Dawley rats
Drug Chem. Toxicol.
Ten and ninety-day toxicity studies of 1, 2-dichloroethane in Sprague-Dawley rats
Drug Chem. Toxicol.
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2022, Journal of Cleaner ProductionCitation Excerpt :HNMs concentrations are at a level of μg L−1 (e.g., less than 10 μg L−1 in drinking water), which are not regulated seriously, whereas the cytotoxicity and genotoxicity of HNMs to creatures are 1–2 orders of magnitude higher than those of non-nitrogenous analogs with strict regulation (Hong et al., 2015b; Plewa et al., 2004; Yin et al., 2017). It is known that bromide ion (Br−) is widely distributed in various water environments, and HNMs can be occupied by more brominated species that are more toxic than chlorinated species while the production of brominated halonitromethanes (Br-HNMs) is markedly promoted in the presence of Br− during the chlorination process (Chen et al., 2001; Gao et al., 2020; Yin et al., 2017). Therefore, it is crucial for us to investigate the formation of Br-HNMs during the disinfection process in the presence of Br−, which can help to reduce the yields of Br-HNMs generated in drinking water or wastewater.
Genotoxic effects of chlorinated disinfection by-products of 1,3-diphenylguanidine (DPG): Cell-based in-vitro testing and formation potential during water disinfection
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