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Zhu X, Huo J, Zeng Z, Liu Y, Li R, Chen Y, Zhang L, Chen J. Determination of potential thresholds for N-ethyl-N-nitrosourea and ethyl methanesulfonate based on a multi-endpoint genotoxicity assessment platform in rats. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:85128-85142. [PMID: 35793016 PMCID: PMC9646607 DOI: 10.1007/s11356-022-21605-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
The main goal of the study was to investigate the genotoxic response of N-ethyl-N-nitrosourea (ENU) and ethyl methanesulfonate (EMS) at low doses in a multi-endpoint genotoxicity assessment platform in rats and to derive potential thresholds and related metrics. Male Sprague-Dawley rats were treated by daily oral gavage for 28 consecutive days with ENU (0.25 ~ 8 mg/kg bw) and EMS (5 ~ 160 mg/kg bw), both with six closely spaced dose levels. Pig-a gene mutation assay, micronucleus test, and comet assay were performed in several timepoints. Then, the dose-response relationships were analyzed for possible points of departure (PoD) using the no observed genotoxic effect level and benchmark dose (BMD) protocols with different critical effect sizes (CES, 0.05, 0.1, 0.5, and 1SD). Overall, dose-dependent increases in all investigated endpoints were found for ENU and EMS. PoDs varied across genetic endpoints, timepoints, and statistical methods, and selecting an appropriate lower 95% confidence limit of BMD needs a comprehensive consideration of the mode of action of chemicals, the characteristics of tests, and the model fitting methods. Under the experimental conditions, the PoDs of ENU and EMS were 0.0036 mg/kg bw and 1.7 mg/kg bw, respectively.
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Affiliation(s)
- Xuejiao Zhu
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu, Sichuan, China
| | - Jiao Huo
- Department of Nutrition and Food Safety, Chongqing Center for Disease Control and Prevention, Chongqing, China
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - Zhu Zeng
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- Chengdu Fifth People's Hospital, Chengdu, Sichuan, China
| | - Yunjie Liu
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Ruirui Li
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Yiyi Chen
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Lishi Zhang
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Jinyao Chen
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China.
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province, Chengdu, Sichuan, China.
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Zeng Z, Huo J, Zhu X, Liu Y, Li R, Chen Y, Zhang L, Chen J. Characterization of benzo[ a]pyrene and colchicine based on an in vivo repeat-dosing multi-endpoint genotoxicity quantitative assessment platform. Mutagenesis 2022; 37:213-225. [PMID: 35869703 DOI: 10.1093/mutage/geac012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/06/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
Two prototypical genotoxicants, benzo[a]pyrene (B[a]P) and colchicine (COL), were selected as model compounds to deduce their quantitative genotoxic dose–response relationship at low doses in a multi-endpoint genotoxicity assessment platform. Male Sprague-Dawley rats were treated with B[a]P (2.5–80 mg/kg bw/day) and COL (0.125–2 mg/kg bw/day) daily for 28 days. The parameters included were as follows: comet assay in the peripheral blood and liver, Pig-a gene mutation assay in the peripheral blood, and micronucleus test in the peripheral blood and bone marrow. A significant increase was observed in Pig-a mutant frequency in peripheral blood for B[a]P (started at 40 mg/kg bw/day on Day 14, started at 20 mg/kg bw/day on Day 28), whereas no statistical difference for COL was observed. Micronucleus frequency in reticulocytes of the peripheral blood and bone marrow increased significantly for B[a]P (80 mg/kg bw/day on Day 4, started at 20 mg/kg bw/day on Days 14 and 28 in the blood; started at 20 mg/kg bw/day on Day 28 in the bone marrow) and COL (started at 2 mg/kg bw/day on Day 14, 1 mg/kg bw/day on Day 28 in the blood; started at 1 mg/kg bw/day on Day 28 in the bone marrow). No statistical variation was found in indexes of comet assay at all time points for B[a]P and COL in the peripheral blood and liver. The dose–response relationships of Pig-a and micronucleus test data were analyzed for possible point of departures using three quantitative approaches, i.e., the benchmark dose, breakpoint dose, and no observed genotoxic effect level. The practical thresholds of the genotoxicity of B[a]P and COL estimated in this study were 0.122 and 0.0431 mg/kg bw/day, respectively, and our results also provided distinct genotoxic mode of action of the two chemicals.
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Affiliation(s)
- Zhu Zeng
- Department of Clinical Nutrition, Chengdu Fifth People’s Hospital , Chengdu, Sichuan , China
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
| | - Jiao Huo
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- Department of Nutrition and Food Safety, Chongqing Center for Disease Control and Prevention , Chongqing , China
| | - Xuejiao Zhu
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University , Chengdu, Sichuan , China
| | - Yunjie Liu
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
| | - Ruirui Li
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province , Chengdu, Sichuan , China
| | - Yiyi Chen
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- Infections Disease Prevention and Immunization Program Office, ChengHua Center for Disease Control and Prevention , Chengdu, Sichuan , China
| | - Lishi Zhang
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province , Chengdu, Sichuan , China
| | - Jinyao Chen
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University , Chengdu, Sichuan , China
- Food Safety Monitoring and Risk Assessment Key Laboratory of Sichuan Province , Chengdu, Sichuan , China
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Röhl C, Batke M, Damm G, Freyberger A, Gebel T, Gundert-Remy U, Hengstler JG, Mangerich A, Matthiessen A, Partosch F, Schupp T, Wollin KM, Foth H. New aspects in deriving health-based guidance values for bromate in swimming pool water. Arch Toxicol 2022; 96:1623-1659. [PMID: 35386057 PMCID: PMC9095538 DOI: 10.1007/s00204-022-03255-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 02/17/2022] [Indexed: 11/27/2022]
Abstract
Bromate, classified as a EU CLP 1B carcinogen, is a typical by-product of the disinfection of drinking and swimming pool water. The aim of this study was (a) to provide data on the occurrence of bromate in pool water, (b) to re-evaluate the carcinogenic MOA of bromate in the light of existing data, (c) to assess the possible exposure to bromate via swimming pool water and (d) to inform the derivation of cancer risk-related bromate concentrations in swimming pool water. Measurements from monitoring analysis of 229 samples showed bromate concentrations in seawater pools up to 34 mg/L. A comprehensive non-systematic literature search was done and the quality of the studies on genotoxicity and carcinogenicity was assessed by Klimisch criteria (Klimisch et al., Regul Toxicol Pharmacol 25:1-5, 1997) and SciRAP tool (Beronius et al., J Appl Toxicol, 38:1460-1470, 2018) respectively. Benchmark dose (BMD) modeling was performed using the modeling average mode in BMDS 3.1 and PROAST 66.40, 67 and 69 (human cancer BMDL10; EFSA 2017). For exposure assessment, data from a wide range of sources were evaluated for their reliability. Different target groups (infants/toddlers, children and adults) and exposure scenarios (recreational, sport-active swimmers, top athletes) were considered for oral, inhalation and dermal exposure. Exposure was calculated according to the frequency of swimming events and duration in water. For illustration, cancer risk-related bromate concentrations in pool water were calculated for different target groups, taking into account their exposure using the hBMDL10 and a cancer risk of 1 in 100,000. Convincing evidence was obtained from a multitude of studies that bromate induces oxidative DNA damage and acts as a clastogen in vitro and in vivo. Since statistical modeling of the available genotoxicity data is compatible with both linear as well as non-linear dose-response relationships, bromate should be conservatively considered to be a non-threshold carcinogen. BMD modeling with model averaging for renal cancer studies (Kurokawa et al., J Natl. Cancer Inst, 1983 and 1986a; DeAngelo et al., Toxicol Pathol 26:587-594, 1998) resulted in a median hBMDL10 of 0.65 mg bromate/kg body weight (bw) per day. Evaluation of different age and activity groups revealed that top athletes had the highest exposure, followed by sport-active children, sport-active adults, infants and toddlers, children and adults. The predominant route of exposure was oral (73-98%) by swallowing water, followed by the dermal route (2-27%), while the inhalation route was insignificant (< 0.5%). Accepting the same risk level for all population groups resulted in different guidance values due to the large variation in exposure. For example, for an additional risk of 1 in 100,000, the bromate concentrations would range between 0.011 for top athletes, 0.015 for sport-active children and 2.1 mg/L for adults. In conclusion, the present study shows that health risks due to bromate exposure by swimming pool water cannot be excluded and that large differences in risk exist depending on the individual swimming habits and water concentrations.
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Affiliation(s)
- C Röhl
- Institute of Toxicology and Pharmacology for Natural Scientists, Christiana Albertina University Kiel, Kiel, Germany.
- Department of Environmental Health Protection, State Agency for social Services (LAsD) Schleswig-Holstein, Neumünster, Germany.
| | - M Batke
- University Emden/Leer, Emden, Germany
| | - G Damm
- Department of Hepatobiliary Surgery and Visceral Transplantation, University Hospital, Leipzig University, Leipzig, Germany
| | - A Freyberger
- Research and Development, Pharmaceuticals, RED-PCD-TOX-P&PC Clinical Pathology, Bayer AG, Wuppertal, Germany
| | - T Gebel
- Federal Institute for Occupational Safety and Health (BAuA), Dortmund, Germany
| | - U Gundert-Remy
- Institute for Clinical Pharmacology and Toxicology, Universitätsmedizin Berlin, Charité Berlin, Germany
| | - J G Hengstler
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), TU Dortmund University, Dortmund, Germany
| | - A Mangerich
- Molecular Toxicology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - A Matthiessen
- Central Unit for Environmental Hygiene, University Hospital Schleswig-Holstein (UKSH), Kiel, Germany
| | - F Partosch
- Department of Toxicology, Fraunhofer-Institute for Toxicology and Experimental Medicine (ITEM), Hannover, Germany
| | - T Schupp
- Department of Chemical Engineering, University of Applied Science Muenster, Steinfurt, Germany
| | - K M Wollin
- Formerly Public Health Agency of Lower Saxony, Hannover, Germany
| | - H Foth
- Institute of Environmental Toxicology, University of Halle, Halle/Saale, Germany
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Black MB, Stern A, Efremenko A, Mallick P, Moreau M, Hartman JK, McMullen PD. Biological system considerations for application of toxicogenomics in next-generation risk assessment and predictive toxicology. Toxicol In Vitro 2022; 80:105311. [PMID: 35038564 DOI: 10.1016/j.tiv.2022.105311] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 12/17/2021] [Accepted: 01/10/2022] [Indexed: 10/19/2022]
Abstract
There is increasing interest in using modern 'omics technologies, such as whole transcriptome sequencing, to inform decisions about human health safety and chemical toxicity hazard. High throughput methodologies using in vitro assays offer a path forward in reducing or eliminating animal testing. However, many aspects of these technologies need assessment before they will gain the trust of regulators and the public as viable alternative test methods for human health and safety. We used a high throughput whole transcriptome sequence assay (TempO-Seq) to assess the use of three widely used cancer cell lines (HepG2, MCF7, and Ishikawa cells) as in vitro systems for determination of cellular modes of action for two well studied compounds with canonical liver responses: ketoconazole and phenobarbital. We evaluated transcriptomic data to infer points of departure for use in risk analyses of compounds. Both compounds displayed shortcomings in evidence for canonical liver-related responses in any cell line, despite a strong dose response in all three. This raises questions about the competence of simple, mono-cultured cancer cell lines as appropriate surrogates for some adverse effects or toxic endpoints. Points of departure derived from benchmark doses were highly consistent across all three cell lines however, indicating the use of transcriptomic BMD analyses for such purposes would be a reliable and consistent approach.
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Affiliation(s)
- Michael B Black
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America.
| | - Allysa Stern
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America; Cell Microsystems, 801 Capitola Dr., Suite 10, Durham, NC 27713, United States of America
| | - Alina Efremenko
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America
| | - Pankajini Mallick
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America
| | - Marjory Moreau
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America
| | - Jessica K Hartman
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America; Cell Microsystems, 801 Capitola Dr., Suite 10, Durham, NC 27713, United States of America
| | - Patrick D McMullen
- ScitoVation, 100 Capitola Drive, Suite 106, Durham, NC 27713, United States of America
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