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Bloch D, Diel P, Epe B, Hellwig M, Lampen A, Mally A, Marko D, Villar Fernández MA, Guth S, Roth A, Marchan R, Ghallab A, Cadenas C, Nell P, Vartak N, van Thriel C, Luch A, Schmeisser S, Herzler M, Landsiedel R, Leist M, Marx-Stoelting P, Tralau T, Hengstler JG. Basic concepts of mixture toxicity and relevance for risk evaluation and regulation. Arch Toxicol 2023; 97:3005-3017. [PMID: 37615677 PMCID: PMC10504116 DOI: 10.1007/s00204-023-03565-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/26/2023] [Indexed: 08/25/2023]
Abstract
Exposure to multiple substances is a challenge for risk evaluation. Currently, there is an ongoing debate if generic "mixture assessment/allocation factors" (MAF) should be introduced to increase public health protection. Here, we explore concepts of mixture toxicity and the potential influence of mixture regulation concepts for human health protection. Based on this analysis, we provide recommendations for research and risk assessment. One of the concepts of mixture toxicity is additivity. Substances may act additively by affecting the same molecular mechanism within a common target cell, for example, dioxin-like substances. In a second concept, an "enhancer substance" may act by increasing the target site concentration and aggravating the adverse effect of a "driver substance". For both concepts, adequate risk management of individual substances can reliably prevent adverse effects to humans. Furthermore, we discuss the hypothesis that the large number of substances to which humans are exposed at very low and individually safe doses may interact to cause adverse effects. This commentary identifies knowledge gaps, such as the lack of a comprehensive overview of substances regulated under different silos, including food, environmentally and occupationally relevant substances, the absence of reliable human exposure data and the missing accessibility of ratios of current human exposure to threshold values, which are considered safe for individual substances. Moreover, a comprehensive overview of the molecular mechanisms and most susceptible target cells is required. We conclude that, currently, there is no scientific evidence supporting the need for a generic MAF. Rather, we recommend taking more specific measures, which focus on compounds with relatively small ratios between human exposure and doses, at which adverse effects can be expected.
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Affiliation(s)
- Denise Bloch
- Department of Pesticides Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany.
| | - Patrick Diel
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, Cologne, Germany
| | - Bernd Epe
- Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, Mainz, Germany
| | - Michael Hellwig
- Chair of Special Food Chemistry, Technical University Dresden, Dresden, Germany
| | - Alfonso Lampen
- Risk Assessment Strategies, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Angela Mally
- Department of Toxicology, University of Würzburg, Würzburg, Germany
| | - Doris Marko
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - María A Villar Fernández
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Sabine Guth
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Angelika Roth
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Rosemarie Marchan
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Ahmed Ghallab
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
- Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, South Valley University, Qena, 83523, Egypt
| | - Cristina Cadenas
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Patrick Nell
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Nachiket Vartak
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Christoph van Thriel
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Andreas Luch
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Sebastian Schmeisser
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Matthias Herzler
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Robert Landsiedel
- Department of Experimental Toxicology and Ecology, BASF SE, Ludwigshafen, Germany
- Pharmacy, Pharmacology and Toxicology, Free University of Berlin, Berlin, Germany
| | - Marcel Leist
- Department of In Vitro Toxicology and Biomedicine, Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Constance, Germany
| | - Philip Marx-Stoelting
- Department of Pesticides Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Tewes Tralau
- Department of Pesticides Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Jan G Hengstler
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
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Crosby ME, Ciurlionis R, Brayman TG, Kondratiuk A, Nicolette JJ. Exploring the molecular and functional cellular response to hydrazine via transcriptomics and DNA repair mutant cell lines. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2022; 63:336-350. [PMID: 36176055 PMCID: PMC9828720 DOI: 10.1002/em.22508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 09/23/2022] [Indexed: 05/04/2023]
Abstract
Hydrazine is a rodent carcinogen and is classified as a probable human carcinogen by IARC. Though hydrazine is positive in both in vitro and in vivo DNA strand break (comet) assays, hydrazine was reported to be negative in an in vitro mutation Muta Mouse lung epithelial cell (FE1) test, as well as in a regulatory-compliant, in vivo Big Blue mouse mutation test. In this article, mechanistic studies explored the cellular response to hydrazine. When tested in a regulatory-compliant mouse lymphoma assay, hydrazine yielded unusual, weakly positive results. This prompted an investigation into the transcriptional response to hydrazine in FE1 cells via RNA sequencing. Amongst the changes identified was a dose-dependent increase in G2/M DNA damage checkpoint activation associated genes. Flow cytometric experiments in FE1 cells revealed that hydrazine exposure led to S-phase cell cycle arrest. Clonogenic assays in a variety of cell lines harboring key DNA repair protein deficiencies indicated that hydrazine could sensitize cells lacking homology dependent repair proteins (Brca2 and Fancg). Lastly, hprt assays with hydrazine were conducted to determine whether a lack of DNA repair could lead to mutagenicity. However, no robust, dose-dependent induction of mutations was noted. The transcriptional and cell cycle response to hydrazine, coupled with functional investigations of DNA repair-deficient cell lines support the inconsistencies noted in the genetic toxicology regulatory battery. In summary, while hydrazine may be genotoxic, transcriptional and functional processes involved in cell cycle regulation and DNA repair appear to play a nuanced role in mediating the mutagenic potential.
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Affiliation(s)
- Meredith E. Crosby
- Pre‐Clinical Safety, AbbVie Inc.North ChicagoIllinoisUnited States
- Drug Safety and PharmacometricsRegeneron Pharmaceuticals Inc.TarrytownNew YorkUnited States
| | - Rita Ciurlionis
- Pre‐Clinical Safety, AbbVie Inc.North ChicagoIllinoisUnited States
| | | | | | - John J. Nicolette
- Pre‐Clinical Safety, AbbVie Inc.North ChicagoIllinoisUnited States
- Preclinical Sciences and Translational SafetyJanssen Research and DevelopmentRaritanNew JerseyUnited States
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Oesch F, Honarvar N, Fabian E, Berger FI, Landsiedel R. N-vinyl compounds: studies on metabolism, genotoxicity, carcinogenicity. Arch Toxicol 2021; 95:3143-3159. [PMID: 34091723 DOI: 10.1007/s00204-021-03081-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/17/2021] [Indexed: 11/29/2022]
Abstract
Several N-vinyl compounds are produced in high volumes and are widely employed in the production of copolymers and polymers used in chemical, pharmaceutical, cosmetic and food industry. Hence, information on their genotoxicity and carcinogenicity is requisite. This review presents hitherto available information on the carcinogenicity and genotoxicity of N-vinyl compounds as well as their metabolism potentially generating genotoxic and carcinogenic derivatives. The genotoxicity and carcinogenicity of the investigated N-vinyl compounds vary widely from no observed carcinogenicity tested in lifetime bioassays in two rodent species (up to very high doses) to carcinogenicity in rats at very low doses in the absence of apparent genotoxicity. Despite of the presence of the vinyl group potentially metabolized to an epoxide followed by covalent binding to DNA, genotoxicity was observed for only one of the considered N-vinyl compounds, N-vinyl carbazole. Carcinogenicity was investigated only for two, of which one, N-vinyl pyrrolidone was carcinogenic (but not genotoxic) and ranitidine was neither carcinogenic nor genotoxic. As far as investigated, neither a metabolically formed epoxide nor a therefrom derived diol has been reported for any of the considered N-vinyl compounds. It is concluded that the information collected in this review will further the understanding of the carcinogenic potentials of N-vinyl compounds and may eventually allow approaching their prediction and prevention. A suggestion how to prevent genotoxicity in designing of N-vinyl compounds is presented. However, the available information is scarce and further research especially on the metabolism of N-vinyl compounds is highly desirable.
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Affiliation(s)
- F Oesch
- Oesch-Tox Toxicological Consulting and Expert Opinions, 55263, Ingelheim, Germany
| | - N Honarvar
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
| | - E Fabian
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
| | - F I Berger
- Regulatory Toxicology of Chemicals, BASF SE, 67056, Ludwigshafen am Rhein, Germany
| | - Robert Landsiedel
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany.
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Bolt HM. Highlight Report: Adverse outcome pathways: the need of research on mechanisms of toxicity. Arch Toxicol 2019; 93:3385-3386. [PMID: 31637479 DOI: 10.1007/s00204-019-02596-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 10/08/2019] [Indexed: 11/26/2022]
Affiliation(s)
- Hermann M Bolt
- Leibniz Research Centre for Working Environment and Human Factors, Ardeystr. 67, 44139, Dortmund, Germany.
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5
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Review of the evidence for thresholds for DNA-Reactive and epigenetic experimental chemical carcinogens. Chem Biol Interact 2019; 301:88-111. [DOI: 10.1016/j.cbi.2018.11.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 11/06/2018] [Accepted: 11/22/2018] [Indexed: 01/01/2023]
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Metruccio F, Moretto A. Genotoxicity in risk assessment: is it time to use a threshold approach? CURRENT OPINION IN TOXICOLOGY 2018. [DOI: 10.1016/j.cotox.2018.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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7
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Gao J, Wang Z, Wang GJ, Gao N, Li J, Zhang YF, Zhou J, Zhang HX, Wen Q, Jin H, Qiao HL. From hepatofibrosis to hepatocarcinogenesis: Higher cytochrome P450 2E1 activity is a potential risk factor. Mol Carcinog 2018; 57:1371-1382. [PMID: 29917271 DOI: 10.1002/mc.22851] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 04/20/2018] [Accepted: 06/12/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Jie Gao
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Zhao Wang
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Gao-Ju Wang
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Na Gao
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Jing Li
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Yun-Fei Zhang
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
- Affiliated Cancer Hospital of Zhengzhou University; Zhengzhou Henan China
| | - Jun Zhou
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
- Affiliated Provincial People's Hospital of Zhengzhou University; Zhengzhou Henan China
| | - Hong-Xin Zhang
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Qiang Wen
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Han Jin
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
| | - Hai-Ling Qiao
- Institute of Clinical Pharmacology; Zhengzhou University; Zhengzhou Henan China
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Abstract
Since e-cigarettes appeared in the mid-2000s, some practitioners, researchers, and policy makers have embraced them as a safer alternative to conventional cigarettes and an effective way to stop smoking. While e-cigarettes deliver lower levels of carcinogens than do conventional cigarettes, they still expose users to high levels of ultrafine particles and other toxins that may substantially increase cardiovascular and noncancer lung disease risks, which account for more than half of all smoking-caused deaths, at rates similar to conventional cigarettes. Moreover, rather than stimulating smokers to switch from conventional cigarettes to less dangerous e-cigarettes or quitting altogether, e-cigarettes are reducing smoking cessation rates and expanding the nicotine market by attracting youth.
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Affiliation(s)
- Stanton A Glantz
- Center for Tobacco Control Research and Education and Department of Medicine, University of California, San Francisco, California 94143, USA;
| | - David W Bareham
- Lincolnshire Community Health Services NHS Trust, Louth, LN11 0EU, United Kingdom;
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9
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Gao J, Wang Z, Wang GJ, Zhang HX, Gao N, Wang J, Wang CE, Chang Z, Fang Y, Zhang YF, Zhou J, Jin H, Qiao HL. Higher CYP2E1 Activity Correlates with Hepatocarcinogenesis Induced by Diethylnitrosamine. J Pharmacol Exp Ther 2018; 365:398-407. [DOI: 10.1124/jpet.117.245555] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/08/2018] [Indexed: 01/18/2023] Open
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10
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Gao J, Wang GJ, Wang Z, Gao N, Li J, Zhang YF, Zhou J, Zhang HX, Wen Q, Jin H, Qiao HL. High CYP2E1 activity correlates with hepatofibrogenesis induced by nitrosamines. Oncotarget 2017; 8:112199-112210. [PMID: 29348818 PMCID: PMC5762503 DOI: 10.18632/oncotarget.22937] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/14/2017] [Indexed: 01/11/2023] Open
Abstract
Hepatofibrosis, which leads to cirrhosis and eventual hepatocellular carcinoma, is a common response to chronic toxin-mediated liver injury. Nitrosamines are potent hepatotoxic agents that cause necrosis and subsequent fibrosis in the liver as a result of cytochrome P450 2E1 (CYP2E1)-dependent metabolism, which generates toxic metabolites that form adducts with nucleic acids, leading to hepatotoxicity and mutagenesis. Herein, CYP2E1 activity and content were determined in fibrotic liver tissue from patients with hepatocellular carcinoma. The relationship between CYP2E1 innate activity and hepatofibrogenesis was evaluated, the effect of inhibition of CYP2E1 activity on hepatofibrosis was determined in a Sprague-Dawley rat model of diethylnitrosamine-induced hepatofibrosis. The results demonstrated that the CYP2E1 activities in human fibrotic tissues are significantly higher than that in normal liver tissues. In rats treated with diethylnitrosamine, the livers demonstrated various degree of fibrotic changes and collagen deposition in individual rats. The Ishak score, which determines the stage of fibrosis, correlated with CYP2E1 innate activity, with greater fibrosis in rat livers with higher CYP2E1 innate activity. Inhibition of CYP2E1 during diethylnitrosamine treatment decreased hepatofibrosis and there was an inverse correlation between the degree of inhibition and the extent of hepatofibrosis. Therefore, high CYP2E1 activity is a risk factor for hepatofibrogenesis induced by nitrosamines.
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Affiliation(s)
- Jie Gao
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Gao-Ju Wang
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Zhao Wang
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Na Gao
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Jing Li
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Yun-Fei Zhang
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China.,Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Jun Zhou
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China.,Affiliated Provincial People's Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Hong-Xin Zhang
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Qiang Wen
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Han Jin
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
| | - Hai-Ling Qiao
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, Henan, China
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Leist M, Ghallab A, Graepel R, Marchan R, Hassan R, Bennekou SH, Limonciel A, Vinken M, Schildknecht S, Waldmann T, Danen E, van Ravenzwaay B, Kamp H, Gardner I, Godoy P, Bois FY, Braeuning A, Reif R, Oesch F, Drasdo D, Höhme S, Schwarz M, Hartung T, Braunbeck T, Beltman J, Vrieling H, Sanz F, Forsby A, Gadaleta D, Fisher C, Kelm J, Fluri D, Ecker G, Zdrazil B, Terron A, Jennings P, van der Burg B, Dooley S, Meijer AH, Willighagen E, Martens M, Evelo C, Mombelli E, Taboureau O, Mantovani A, Hardy B, Koch B, Escher S, van Thriel C, Cadenas C, Kroese D, van de Water B, Hengstler JG. Adverse outcome pathways: opportunities, limitations and open questions. Arch Toxicol 2017; 91:3477-3505. [DOI: 10.1007/s00204-017-2045-3] [Citation(s) in RCA: 232] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/21/2017] [Indexed: 12/18/2022]
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12
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Bevan RJ, Harrison PT. Threshold and non-threshold chemical carcinogens: A survey of the present regulatory landscape. Regul Toxicol Pharmacol 2017; 88:291-302. [DOI: 10.1016/j.yrtph.2017.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/13/2016] [Accepted: 01/20/2017] [Indexed: 01/20/2023]
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13
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Sollazzo A, Shakeri-Manesh S, Fotouhi A, Czub J, Haghdoost S, Wojcik A. Interaction of low and high LET radiation in TK6 cells-mechanistic aspects and significance for radiation protection. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2016; 36:721-735. [PMID: 27631423 DOI: 10.1088/0952-4746/36/4/721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Most environmental, occupational and medical exposures to ionising radiation are associated with a simultaneous action of different radiation types. An open question remains whether radiations of different qualities interact with each other to yield effects stronger than expected based on the assumption of additivity. It is possible that DNA damage induced by high linear energy transfer (LET) radiation will lead to an opening of the chromatin structure making the DNA more susceptible to attack by reactive oxygen species (ROS) generated by the low LET radiation. In such case, the effect of mixed beams should be strongly expressed in cells that are sensitive to ROS. The present investigation was carried out to test if cells with an impaired capacity to handle oxidative stress are particularly sensitive to the effect of mixed beams of alpha particles and x-rays. Clonogenic cell survival curves and mutant frequencies were analysed in TK6 wild type (wt) cells and in TK6 cells with a knocked down hMYH glycosylase. The results showed a synergistic effect of mixed beams on clonogenic cell survival of TK6wt but not TK6MYH- cells. The frequencies of mutants showed a high degree of interexperimental variability without any indications for synergistic effects of mixed beams. TK6MYH- cells were generally more tolerant to radiation exposure with respect to clonogenic cell survival but showed a strong increase in mutant frequency. The results demonstrate that exposure of wt cells to a mixed beam of alpha particles and x-rays leads to a detrimental effect which is stronger than expected based on the assumption of additivity. The role of oxidative stress in the reaction of cells to mixed beams remains unclear.
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Affiliation(s)
- Alice Sollazzo
- MBW Department, Centre for Radiation Protection Research, Stockholm University, Sweden
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14
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Combes RD, Balls M. On the safety of e-cigarettes: "I can resist anything except temptation". Altern Lab Anim 2016; 43:417-25. [PMID: 26753944 DOI: 10.1177/026119291504300610] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Strategic policy decisions are being made about e-cigarettes, based on the plausibility of their greater safety, rather than on essential scientific evidence which would permit a proper risk assessment. If e-cigarettes are really ‘safer’, then their use should be recommended, but only after an intelligent analysis of their risk to human health, based on integrated in silico, in vitro and clinical studies for both scientific and logistical reasons
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15
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High exposure to inorganic arsenic by food: the need for risk reduction. Arch Toxicol 2015; 89:2219-27. [DOI: 10.1007/s00204-015-1627-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/26/2015] [Indexed: 01/29/2023]
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16
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Buekers J, De Brouwere K, Lefebvre W, Willems H, Vandenbroele M, Van Sprang P, Eliat-Eliat M, Hicks K, Schlekat CE, Oller AR. Assessment of human exposure to environmental sources of nickel in Europe: Inhalation exposure. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 521-522:359-371. [PMID: 25863314 DOI: 10.1016/j.scitotenv.2015.02.092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/24/2015] [Accepted: 02/26/2015] [Indexed: 06/04/2023]
Abstract
The paper describes the inhalation nickel (Ni) exposure of humans via the environment for the regional scale in the EU, together with a tiered approach for assessing additional local exposure from industrial emissions. The approach was designed, in the context of REACH, for the purpose of assessing and controlling emissions and air quality in the neighbourhood of Ni producers and downstream users. Two Derived No Effect Level (DNEL) values for chronic inhalation exposure to total Ni in PM10 (20 and 60ngNi/m(3)) were considered. The value of 20ngNi/m(3) is the current EU air quality guidance value. The value of 60ngNi/m(3) is derived here based on recently published Ni data (Oller et al., 2014). Both values are protective for respiratory toxicity and carcinogenicity but differ in the application of toxicokinetic adjustments and cancer threshold considerations. Estimates of air Ni concentrations at the European regional scale were derived from the database of the European Environment Agency. The 50th and 90th percentile regional exposures were below both DNEL values. To assess REACH compliance at the local scale, measured ambient air data are preferred but are often unavailable. A tiered approach for the use of modelled ambient air concentrations was developed, starting with the application of the default EUSES model and progressing to more sophisticated models. As an example, the tiered approach was applied to 33 EU Ni sulphate producers' and downstream users' sites. Applying the EUSES model demonstrates compliance with a DNEL of 60ngNi/m(3) for the majority of sites, while the value of the refined modelling is demonstrated when a DNEL of 20ngNi/m(3) is considered. The proposed approach, applicable to metals in general, can be used in the context of REACH, for refining the risk characterisation and guiding the selection of risk management measures.
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Affiliation(s)
- Jurgen Buekers
- Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium.
| | - Katleen De Brouwere
- Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Wouter Lefebvre
- Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Hanny Willems
- Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Marleen Vandenbroele
- ARCHE (Assessing Risks of Chemicals) Consulting, Stapelplein 70, 9000 Gent, Belgium
| | - Patrick Van Sprang
- ARCHE (Assessing Risks of Chemicals) Consulting, Stapelplein 70, 9000 Gent, Belgium
| | - Maxime Eliat-Eliat
- ARCHE (Assessing Risks of Chemicals) Consulting, Stapelplein 70, 9000 Gent, Belgium
| | - Keegan Hicks
- University of Waterloo, 200 University Avenue W, Waterloo, Ontario N2L 3G1, Canada
| | | | - Adriana R Oller
- NiPERA, 2525 Meridian Parkway, Suite 240, Durham, NC 27713, USA
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Thomas AD, Fahrer J, Johnson GE, Kaina B. Theoretical considerations for thresholds in chemical carcinogenesis. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 765:56-67. [PMID: 26281768 DOI: 10.1016/j.mrrev.2015.05.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/11/2015] [Accepted: 05/12/2015] [Indexed: 02/08/2023]
Abstract
There is increasing evidence for non-linear relationships for gene mutations, chromosomal aberrations and even tumor incidences in response to low doses of genotoxic carcinogens. To attain the biological relevance of such non-linear responses, there is a need to identify the underlying defense mechanisms that allow tolerance to low doses of genotoxicants. This communication discusses presumptive cancer prevention mechanisms that may contribute to thresholds, i.e. points of departure, for each endpoint, from initial DNA lesion to tumor formation. We discuss a sequential order of genome protection during carcinogenesis where genotoxicant scavenging, cellular efflux, DNA repair, elimination of damaged cells by apoptosis, autophagy, silencing by DNA damage-triggered replicative senescence, and finally, elimination of transformed (premalignant) cells by the immune system are thought to be responsible for a threshold in tumor formation. We highlight DNA repair, for which experimental evidence has been recently provided to dictate a role in PoDs. In conclusion, from a theoretical perspective it is reasonable to posit that tolerance to low dose levels exists for each requisite step of tumor formation and these tolerance mechanisms are critical in determining thresholds in chemical carcinogenesis.
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Affiliation(s)
- Adam D Thomas
- Institute of Toxicology, University Medical Centre, Mainz, Germany
| | - Jörg Fahrer
- Institute of Toxicology, University Medical Centre, Mainz, Germany
| | - George E Johnson
- Institue of Life Science, College of Medicine, Swansea, Wales, United Kingdom
| | - Bernd Kaina
- Institute of Toxicology, University Medical Centre, Mainz, Germany.
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Oller AR, Oberdörster G, Seilkop SK. Derivation of PM10 size-selected human equivalent concentrations of inhaled nickel based on cancer and non-cancer effects on the respiratory tract. Inhal Toxicol 2015; 26:559-78. [PMID: 25055843 DOI: 10.3109/08958378.2014.932034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abstract Nickel (Ni) in ambient air is predominantly present in the form of oxides and sulfates, with the distribution of Ni mass between the fine (particle aerodynamic diameter < 2.5 µm; PM2.5) and coarser (2.5-10 µm) size-selected aerosol fractions of PM10 dependent on the aerosol's origin. When deriving a long-term health protective reference concentration for Ni in ambient air, the respiratory toxicity and carcinogenicity effects of the predominant Ni compounds in ambient air must be considered. Dosimetric adjustments to account for differences in aerosol particle size and respiratory tract deposition and/or clearance among rats, workers, and the general public were applied to experimentally- and epidemiologically-determined points of departure (PODs) such as no(low)-effect concentrations, for both cancer and non-cancer respiratory effects. This approach resulted in the derivation of threshold-based PM10 size-selected equivalent concentrations (modified PODs) of 0.5 µg Ni/m(3) based on workers' cancer effects and 9-11 µg Ni/m(3) based on rodent respiratory toxicity effects. Sources of uncertainty in exposure extrapolations are described. These are not reference concentrations; rather the derived PM10 size-selected modified PODs can be used as the starting point for the calculation of ambient air reference concentrations for Ni. The described approach is equally applicable to other particulates.
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van Acker F, Messinger H, Bär A. Evaluation of vinyl laurate in a battery of in vitro and in vivo tests for genotoxicity. Regul Toxicol Pharmacol 2014; 72:77-84. [PMID: 25445001 DOI: 10.1016/j.yrtph.2014.09.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 09/15/2014] [Accepted: 09/16/2014] [Indexed: 12/22/2022]
Abstract
Vinyl laurate is a potential residual monomer in chewing gum base formulated with polyvinyl acetate vinyl laurate copolymer (PVAcVL). The genotoxic potential of vinyl laurate was examined in a battery of in vitro and in vivo genotoxicity tests. Vinyl laurate was not mutagenic in Ames tests. In addition, it was not mutagenic in the HPRT mutation assay in L5178Y cells. An in vitro mammalian chromosome aberration assay performed in CHO cells was equivocal. Vinyl laurate and/or its metabolites were not clastogenic in the mouse bone marrow micronucleus test. Kinetic data indicate that VL is metabolised to acetaldehyde and lauric acid. Both metabolites are well known and have been studied previously. Model calculations show, that any exposure to acetaldehyde from the consumption of PVAcVL containing chewing gum will remain far below levels of acetaldehyde exposure from food in which acetaldehyde occurs naturally. Direct exposure to VL will primarily be at the site of entry. The lack of toxicity in a 90-day repeated dose toxicity test, performed with VL doses up to approximately 3000 times higher than the maximal VL intake from the consumption of a typical piece of chewing gum, demonstrates a high safety margin.
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Affiliation(s)
| | | | - Albert Bär
- Bioresco Ltd., Bundesstrasse 29, 4054 Basel, Switzerland.
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20
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Waldmann T, Rempel E, Balmer NV, König A, Kolde R, Gaspar JA, Henry M, Hescheler J, Sachinidis A, Rahnenführer J, Hengstler JG, Leist M. Design principles of concentration-dependent transcriptome deviations in drug-exposed differentiating stem cells. Chem Res Toxicol 2014; 27:408-20. [PMID: 24383497 PMCID: PMC3958134 DOI: 10.1021/tx400402j] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
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Information on design principles
governing transcriptome changes
upon transition from safe to hazardous drug concentrations or from
tolerated to cytotoxic drug levels are important for the application
of toxicogenomics data in developmental toxicology. Here, we tested
the effect of eight concentrations of valproic acid (VPA; 25–1000
μM) in an assay that recapitulates the development of human
embryonic stem cells to neuroectoderm. Cells were exposed to the drug
during the entire differentiation process, and the number of differentially
regulated genes increased continuously over the concentration range
from zero to about 3000. We identified overrepresented transcription
factor binding sites (TFBS) as well as superordinate cell biological
processes, and we developed a gene ontology (GO) activation profiler,
as well as a two-dimensional teratogenicity index. Analysis of the
transcriptome data set by the above biostatistical and systems biology
approaches yielded the following insights: (i) tolerated (≤25
μM), deregulated/teratogenic (150–550 μM), and
cytotoxic (≥800 μM) concentrations could be differentiated.
(ii) Biological signatures related to the mode of action of VPA, such
as protein acetylation, developmental changes, and cell migration,
emerged from the teratogenic concentrations range. (iii) Cytotoxicity
was not accompanied by signatures of newly emerging canonical cell
death/stress indicators, but by catabolism and decreased expression
of cell cycle associated genes. (iv) Most, but not all of the GO groups
and TFBS seen at the highest concentrations were already overrepresented
at 350–450 μM. (v) The teratogenicity index reflected
this behavior, and thus differed strongly from cytotoxicity. Our findings
suggest the use of the highest noncytotoxic drug concentration for
gene array toxicogenomics studies, as higher concentrations possibly
yield wrong information on the mode of action, and lower drug levels
result in decreased gene expression changes and thus a reduced power
of the study.
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Affiliation(s)
- Tanja Waldmann
- Doerenkamp-Zbinden Chair for in Vitro Toxicology and Biomedicine, University of Konstanz , 78457 Konstanz, Germany
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21
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Budinsky R, Gollapudi B, Albertini RJ, Valentine R, Stavanja M, Teeguarden J, Fensterheim R, Rick D, Lardie T, McFadden L, Green A, Recio L. Nonlinear responses for chromosome and gene level effects induced by vinyl acetate monomer and its metabolite, acetaldehyde in TK6 cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2013; 54:755-768. [PMID: 24038327 DOI: 10.1002/em.21809] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/26/2013] [Accepted: 07/08/2013] [Indexed: 06/02/2023]
Abstract
Vinyl acetate monomer (VAM) produced rat nasal tumors at concentrations in the hundreds of parts per million. However, VAM is weakly genotoxic in vitro and shows no genotoxicity in vivo. A European Union Risk Assessment concluded that VAM's hydrolysis to acetaldehyde (AA), via carboxylesterase, is a critical key event in VAM's carcinogenic potential. In the following study, we observed increases in micronuclei (MN) and thymidine kinase (Tk) mutants that were dependent on the ability of TK6 cell culture conditions to rapidly hydrolyze VAM to AA. Heat-inactivated horse serum demonstrated a high capacity to hydrolyze VAM to AA; this activity was highly correlated with a concomitant increase in MN. In contrast, heat-inactivated fetal bovine serum (FBS) did not hydrolyze VAM and no increase in MN was observed. AA's ability to induce MN was not impacted by either serum since it directly forms Schiff bases with DNA and proteins. Increased mutant frequency at the Tk locus was similarly mitigated when AA formation was not sufficiently rapid, such as incubating VAM in the presence of FBS for 4 hr. Interestingly, neither VAM nor AA induced mutations at the HPRT locus. Finally, cytotoxicity paralleled genotoxicity demonstrating that a small degree of cytotoxicity occurred prior to increases in MN. These results established 0.25 mM as a consistent concentration where genotoxicity first occurred for both VAM and AA provided VAM is hydrolyzed to AA. This information further informs significant key events related to the mode of action of VAM-induced nasal mucosal tumors in rats.
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22
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Albertini RJ. Vinyl acetate monomer (VAM) genotoxicity profile: Relevance for carcinogenicity. Crit Rev Toxicol 2013; 43:671-706. [DOI: 10.3109/10408444.2013.827151] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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23
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A comprehensive review about micronuclei: mechanisms of formation and practical aspects in genotoxicity testing. Arch Toxicol 2011; 85:861-2. [PMID: 21789669 DOI: 10.1007/s00204-011-0738-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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24
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Non-genotoxic mode of action and possible threshold for hepatocarcinogenicity of Kojic acid in F344 rats. Food Chem Toxicol 2011; 49:471-6. [DOI: 10.1016/j.fct.2010.11.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 10/21/2010] [Accepted: 11/20/2010] [Indexed: 11/19/2022]
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25
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Goodman JE, Prueitt RL, Thakali S, Oller AR. The nickel ion bioavailability model of the carcinogenic potential of nickel-containing substances in the lung. Crit Rev Toxicol 2010; 41:142-74. [DOI: 10.3109/10408444.2010.531460] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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26
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Boehme K, Dietz Y, Hewitt P, Mueller SO. Activation of P53 in HepG2 cells as surrogate to detect mutagens and promutagens in vitro. Toxicol Lett 2010; 198:272-81. [PMID: 20655369 DOI: 10.1016/j.toxlet.2010.07.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 07/10/2010] [Accepted: 07/14/2010] [Indexed: 01/03/2023]
Abstract
The current genotoxicity tests of the standard in vitro battery, especially those using mammalian cells, are limited by their low specificity and highlight the importance of new in vitro tools. This study aimed to evaluate the suitability of HepG2 cells for assaying mutagens and promutagens. We determined P53 activity as surrogate genotoxicity endpoint in HepG2 cells. Our results revealed a significant P53-induction by actinomycin D, methyl methanesulfonate and etoposide. Prior to the investigation of promutagens we characterized HepG2 cells by analyzing the expression of 45 genes involved in xenobiotic metabolism and measuring the activity of selected Cytochrome-P450 (CYP) enzymes. We determined a limited metabolic capacity prompting us to employ a co-treatment with rat liver S9 as metabolic activation system (MAS) for promutagens. While cyclophosphamide showed an elevation of activated P53 in the presence of S9, 7,12-dimethylbenz[a]anthracene and aflatoxin B(1) responded without the MAS. Inhibition of cellular CYP3A4 or CYP1A/1B suppressed the aflatoxin B(1)- and dimethylbenz[a]anthracene-mediated P53 response, respectively, indicating that HepG2 cells are capable of metabolizing these compounds in a CYP1A/B/3A4-dependent manner. In summary, our results indicate that P53 activation in HepG2 cells combined with a MAS can be used for the identification of new (pro)genotoxicants.
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Affiliation(s)
- Kathleen Boehme
- Merck KGaA, Merck Serono, Toxicology, 64293 Darmstadt, Germany
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27
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28
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Chemical Carcinogenesis and Mutagenesis. Clin Toxicol (Phila) 2010. [DOI: 10.3109/9781420092264-32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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29
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Lara-Mayorga I, Durán-Hinojosa U, Arana-Cuenca A, Monroy-Hermosillo O, Ramírez-Vives F. Vinyl acetate degradation by Brevibacillus agri isolated from a slightly aerated methanogenic reactor. ENVIRONMENTAL TECHNOLOGY 2010; 31:1-6. [PMID: 20232673 DOI: 10.1080/09593330903260904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In a previous paper, the authors showed that a slight aeration of a methanogenic reactor treating wastewater from the manufacture of polymeric resins could improve its performance, by increasing or allowing the removal of some of its contaminants, including vinyl acetate (VA). This paper reports the isolation under aerobic conditions of a VA-biodegrading axenic culture (strain C1) retrieved from the sludge of a slightly aerated methanogenic reactor at 1 mg L(-1) d(-1) of dissolved oxygen (DO). The axenic culture obtained was phenotypically (morphology, biochemical properties, VA consumption kinetics) and phylogenetically characterized. It formed white colonies with a branched and flat morphology on solid medium. The cell morphology of the isolate was bacillus with round endings and flagellate. The cells could form chains and were stained Gram-negative. The isolate required simple nutritional elements and had a growth rate of 0.024 h(-1). The phylogenetical analysis showed that the aerobic bacterium was identified as Brevibacillus agri, with 99.3% similarity. The VA consumption kinetics in the methanogenic sludge were: volumetric consumption rate (rVA) of 1.74 +/- 0.2 mg L(-1) h(-1), maximum specific consumption rate (qVAmax) of 3.98 mg g(-1) volatile suspended solids (VSS) h(-1) and affinity constant (Ks) of 457.1 mg L(-1). The same parameters in the axenic culture were 1.69 +/- 0.04 mg L(-1) (h-1), 4.09 mg g(-1) dry weight h(-1) and 421.9 mg L(-1), respectively. These results show evidence that the aerobic isolated bacterium, identified as Brevibacillus agri, carried out the VA hydrolysis in the slightly aerated methanogenic sludge, which is the limiting step in the degradation of this compound.
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Affiliation(s)
- I Lara-Mayorga
- Biotechnology Department, Universidad Autnoma Metropolitana-Iztapalapa, D.F., Mexico
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30
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Hernández LG, van Steeg H, Luijten M, van Benthem J. Mechanisms of non-genotoxic carcinogens and importance of a weight of evidence approach. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2009; 682:94-109. [DOI: 10.1016/j.mrrev.2009.07.002] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/29/2009] [Accepted: 07/13/2009] [Indexed: 01/20/2023]
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31
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Lachenmeier DW, Gumbel-Mako S, Sohnius EM, Keck-Wilhelm A, Kratz E, Mildau G. Salivary acetaldehyde increase due to alcohol-containing mouthwash use: a risk factor for oral cancer. Int J Cancer 2009; 125:730-5. [PMID: 19444911 DOI: 10.1002/ijc.24381] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Increasing evidence suggests that acetaldehyde, the first and genotoxic metabolite of ethanol, mediates the carcinogenicity of alcoholic beverages. Ethanol is also contained in a number of ready-to-use mouthwashes typically between 5 and 27% vol. An increased risk of oral cancer has been discussed for users of such mouthwashes; however, epidemiological evidence had remained inconclusive. This study is the first to investigate acetaldehyde levels in saliva after use of alcohol-containing mouthwashes. Ready-to-use mouthwashes and mouthrinses (n = 13) were rinsed in the mouth by healthy, nonsmoking volunteers (n = 4) as intended by the manufacturers (20 ml for 30 sec). Saliva was collected at 0.5, 2, 5 and 10 min after mouthwash use and analyzed using headspace gas chromatography. The acetaldehyde content in the saliva was 41 +/- 15 microM, range 9-85 microM (0.5 min), 52 +/- 14 microM, range 11-105 microM (2 min), 32 +/- 7 microM, range 9-67 microM (5 min) and 15 +/- 7 microM, range 0-37 microM (10 min). The contents were significantly above endogenous levels and corresponding to concentrations normally found after alcoholic beverage consumption. A twice-daily use of alcohol-containing mouthwashes leads to a systemic acetaldehyde exposure of 0.26 microg/kg bodyweight/day on average, which corresponds to a lifetime cancer risk of 3E-6. The margin of exposure was calculated to be 217,604, which would be seen as a low public health concern. However, the local acetaldehyde contents in the saliva are reaching concentrations associated with DNA adduct formation and sister chromatid exchange in vitro, so that concerns for local carcinogenic effects in the oral cavity remain.
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Affiliation(s)
- Dirk W Lachenmeier
- Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Karlsruhe, Germany.
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32
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Pottenger LH, Schisler MR, Zhang F, Bartels MJ, Fontaine DD, McFadden LG, Bhaskar Gollapudi B. Dose-response and operational thresholds/NOAELs for in vitro mutagenic effects from DNA-reactive mutagens, MMS and MNU. Mutat Res 2009; 678:138-47. [PMID: 19616119 DOI: 10.1016/j.mrgentox.2009.07.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 07/08/2009] [Indexed: 11/25/2022]
Abstract
The dose-response relationships for in vitro mutagenicity induced by methylmethanesulfonate (MMS) or methylnitrosourea (MNU) in L5178Y mouse lymphoma (ML) cells were examined. DNA adducts (N7-methylguanine, N7MeG and O(6)-methylguanine, O(6)MeG) were quantified as biomarkers of exposure. Both endpoints were assessed using 5replicates/dose (4-h treatment) with MMS or MNU (0.0069-50muM), or vehicle (1% DMSO). Mutant frequency (MF) (thymidine kinase (TK) locus) was determined using the soft agar cloning methodology and a 2-day expression period; in addition, microwell and Sequester-Express-Select (SES) methods were used for MMS. Isolated DNA was acid-hydrolyzed, and adducts quantified by LC/ESI-MS/MS, using authentic and internal standards. MF dose-responses were analyzed using several statistical approaches, all of which confirmed that a threshold dose-response model provided the best fit. NOAELs for MF were 10muM MMS and 0.69muM MNU, based on ANOVA and Dunnett's test (p<0.05). N7MeG adducts were present in all cell samples, including solvent-control cells, and were increased over control levels in cells treated with >/=10muM MMS or 3.45muM MNU. O(6)MeG levels were only quantifiable at >/=10muM MNU; O(6)MeG was not quantifiable in control or MMS-treated cells at current detection limits. Thus, (1) cells treated with </=0.69muM MNU or </=10muM MMS did not demonstrate increases in TK(-) MF, but did demonstrate quantifiable levels of N7MeG adducts; and (2) the levels of N7MeG adducts did not correlate with induced MF, as MNU-treated cells had fewer N7MeG adducts but higher MF compared with MMS-treated cells, for quasi-equimolar doses. Taken together, these results demonstrate operational thresholds, defined as the highest dose for which the response is not significantly (statistically or biologically) distinguishable from the control/background values, for induction of mutations and N7MeG adducts in ML cells treated with MMS or MNU, and a lack of correlation between induced MF and levels of N7MeG adducts.
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Affiliation(s)
- Lynn H Pottenger
- Toxicology and Environmental Research & Consulting, The Dow Chemical Company, Midland, MI 48674, USA.
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Schreck I, Chudziak D, Schneider S, Seidel A, Platt KL, Oesch F, Weiss C. Influence of aryl hydrocarbon- (Ah) receptor and genotoxins on DNA repair gene expression and cell survival of mouse hepatoma cells. Toxicology 2009; 259:91-6. [DOI: 10.1016/j.tox.2009.02.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 02/13/2009] [Accepted: 02/13/2009] [Indexed: 01/15/2023]
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Epoxide hydrolases are not only a molecular sponge sucking up genotoxic epoxides: new roles in control of blood pressure, inflammation as well as nociception and cell proliferation. Arch Toxicol 2009; 83:289-91. [PMID: 19333580 DOI: 10.1007/s00204-009-0422-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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35
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Acikgöz A, Karim N, Giri S, Schmidt-Heck W, Bader A. Two compartment model of diazepam biotransformation in an organotypical culture of primary human hepatocytes. Toxicol Appl Pharmacol 2009; 234:179-91. [DOI: 10.1016/j.taap.2008.09.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 09/25/2008] [Indexed: 10/21/2022]
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36
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Krishnamurthi K, Saravana Devi S, Hengstler JG, Hermes M, Kumar K, Dutta D, Muhil Vannan S, Subin TS, Yadav RR, Chakrabarti T. Genotoxicity of sludges, wastewater and effluents from three different industries. Arch Toxicol 2008; 82:965-71. [DOI: 10.1007/s00204-008-0380-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 10/15/2008] [Indexed: 11/29/2022]
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37
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Enomoto M, Tierney WJ, Nozaki K. Risk of human health by particulate matter as a source of air pollution--comparison with tobacco smoking. J Toxicol Sci 2008; 33:251-67. [PMID: 18670156 DOI: 10.2131/jts.33.251] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Increased air pollution, containing carcinogenic particulate matter smaller than 2.5 microm (PM(2.5)), has gained particular attention in recent years as a causative factor in the increased incidence of respiratory diseases, including lung cancer. Extensive carcinogenicity studies conducted recently under Good Laboratory Practice conditions by National Toxicology Program in the USA, Ramazzini Foundation in Italy or Contract Research Organizations on numerous chemical compounds have demonstrated the importance of considering dose levels, times and duration of exposure in the safety evaluation of carcinogenic as well as classical toxic agents. Data on exposure levels to chemical carcinogens that produce tumor development have contributed to the evaluation of human carcinogens from extrapolation of animal data. A popular held misconception is that the risk from smoking is the result of inhaling assorted particulate matter and by products from burning tobacco rather than the very low ng levels of carcinogens present in smoke. Consider the fact that a piece of toasted bread contains ng levels of the carcinogen urethane (ethyl carbamate). Yet, no one has considered toast to be a human carcinogen. Future human carcinogenic risk assessment should emphasize consideration of inhalation exposure to higher levels of benzo (a) pyrene and other possible carcinogens and particulate matter present in polluted air derived from automobile exhaust, pitch and coal tar on paved roads and asbestos, in addition to other environmental contaminant exposure via the food and drinking water.
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Bolt HM. International symposium on genotoxic and carcinogenic thresholds. Arch Toxicol 2008; 82:981-2. [DOI: 10.1007/s00204-008-0374-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Accepted: 10/06/2008] [Indexed: 10/21/2022]
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39
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New aspects on mechanisms of chemical carcinogenesis: emphasis on species and gender/sex differences and developmental/aging determinants. Arch Toxicol 2008; 82:875-80. [DOI: 10.1007/s00204-008-0368-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 09/23/2008] [Indexed: 02/07/2023]
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40
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von Mach MA, Hermanns-Clausen M, Koch I, Hengstler JG, Lauterbach M, Kaes J, Weilemann LS. Experiences of a Poison Center Network with Renal Insufficiency in Acetaminophen Overdose: An Analysis of 17 Cases. Clin Toxicol (Phila) 2008; 43:31-7. [PMID: 15732444 DOI: 10.1081/clt-44992] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE Renal insufficiency is less common than liver failure in acetaminophen overdose but renal tubular damage occurs even in the absence of hepatotoxicity. Data published on this topic are rare consisting mostly of case reports or reports in a small number of patients. Presently, a larger number of patients with renal insufficiency associated with acetaminophen overdose should be analyzed using a multicenter approach. STUDY DESIGN Retrospective analysis of patients with acetaminophen-related nephrotoxicity reported to a poison center network from 1995 to 2003. Renal insufficiency was defined as elevated serum creatinine of more than double of the normal range (>2.4 mg/dL [212 micromol/L]). Patients were classified into 4 groups (A: creatinine 2.4-5.0 mg/dL, B: creatinine>5.0 mg/dL requiring no dialysis, C: creatinine>5.0 mg/dL requiring dialysis, D: creatinine>5.0 mg/dL with fatal outcome). RESULTS Seventeen patients were included (8 female, 9 male, average age 31.7 +/- 21.1 yrs) with 6 patients in group A (B: 7, C: 2, D: 2). In 5 patients renal insufficiency occurred without elevation of liver enzymes. Regarding possible risk factors 5 patients concomitantly ingested nephrotoxic substances, 4 presented with dehydration due to vomiting, 4 with chronic excessive dosing (overdose) of acetaminophen, 3 showed pre-existing renal insufficiency, 2 pre-existing liver disease and 2 died with multiple organ failure. CONCLUSIONS Renal insufficiency in acetaminophen overdose mostly resolved without dialysis and occurred isolated without hepatotoxicity in less than one-third of the investigated patients. Conditions which might play a role as influencing factors for renal complications included concomitant ingestion of nephrotoxic drugs, dehydration, chronic excessive dosing (overdose) of acetaminophen, pre-existing renal or liver disease and multiple organ failure. Renal function should be monitored in acetaminophen overdose particularly in patients showing the latter comorbidity.
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Affiliation(s)
- M A von Mach
- Division of Clinical Toxicology and Poison Center, II. Medical Department, University of Mainz, Mainz, Germany.
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Bogen KT. An adjustment factor for mode-of-action uncertainty with dual-mode carcinogens: the case of naphthalene-induced nasal tumors in rats. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2008; 28:1033-1051. [PMID: 18564993 DOI: 10.1111/j.1539-6924.2008.01066.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The U.S. Environmental Protection Agency (USEPA) guidelines for cancer risk assessment recognize that some chemical carcinogens may have a site-specific mode of action (MOA) involving mutation and cell-killing-induced hyperplasia. The guidelines recommend that for such dual MOA (DMOA) carcinogens, judgment should be used to compare and assess results using separate "linear" (genotoxic) versus "nonlinear" (nongenotoxic) approaches to low-level risk extrapolation. Because the guidelines allow this only when evidence supports reliable risk extrapolation using a validated mechanistic model, they effectively prevent addressing MOA uncertainty when data do not fully validate such a model but otherwise clearly support a DMOA. An adjustment-factor approach is proposed to address this gap, analogous to reference-dose procedures used for classic toxicity endpoints. By this method, even when a "nonlinear" toxicokinetic model cannot be fully validated, the effect of DMOA uncertainty on low-dose risk can be addressed. Application of the proposed approach was illustrated for the case of risk extrapolation from bioassay data on rat nasal tumors induced by chronic lifetime exposure to naphthalene. Bioassay data, toxicokinetic data, and pharmacokinetic analyses were determined to indicate that naphthalene is almost certainly a DMOA carcinogen. Plausibility bounds on rat-tumor-type-specific DMOA-related uncertainty were obtained using a mechanistic two-stage cancer risk model adapted to reflect the empirical link between genotoxic and cytotoxic effects of the most potent identified genotoxic naphthalene metabolites, 1,2- and 1,4-naphthoquinone. Bound-specific adjustment factors were then used to reduce naphthalene risk estimated by linear extrapolation (under the default genotoxic MOA assumption), to account for the DMOA exhibited by this compound.
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Affiliation(s)
- Kenneth T Bogen
- Exponent Inc., Health Sciences Group, 500 1th Street, Oakland, CA 94607, USA.
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Cadmium, cobalt and lead cause stress response, cell cycle deregulation and increased steroid as well as xenobiotic metabolism in primary normal human bronchial epithelial cells which is coordinated by at least nine transcription factors. Arch Toxicol 2008; 82:513-24. [DOI: 10.1007/s00204-008-0331-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 06/12/2008] [Indexed: 01/27/2023]
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Application of mode-of-action considerations in human cancer risk assessment. Toxicol Lett 2008; 180:75-80. [PMID: 18588958 DOI: 10.1016/j.toxlet.2008.05.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 05/28/2008] [Accepted: 05/28/2008] [Indexed: 10/22/2022]
Abstract
The distinction between carcinogens with DNA-reactive and epigenetic modes of action and the application of mode-of-action considerations to risk assessment is reviewed. A bioindicator-based risk assessment strategy is described. This approach involves the use of mechanistic data to establish a "toxicologically insignificant daily intake".
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Bolt HM, Hengstler JG. A new series of review articles on drug metabolizing enzymes: nomenclature of isoenzyme families, genetic organization, polymorphisms, substrate specificities, clinical relevance and role in carcinogenesis. Arch Toxicol 2008; 82:413-4. [DOI: 10.1007/s00204-008-0321-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Oxidative stress: from modification of cell-cycle related events, secondary messenger function, dysregulation of small GTPases, protein kinases and phosphatases to redox-sensitive cancer models. Arch Toxicol 2008; 82:271-2. [DOI: 10.1007/s00204-008-0305-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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46
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Loss of DNA damage checkpoint genes: switch from preferential induction of point mutations to chromosomal damage precedes the transition towards an aggressive cancer type. Arch Toxicol 2008; 82:341-2. [DOI: 10.1007/s00204-008-0295-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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47
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Lilienblum W, Dekant W, Foth H, Gebel T, Hengstler JG, Kahl R, Kramer PJ, Schweinfurth H, Wollin KM. Alternative methods to safety studies in experimental animals: role in the risk assessment of chemicals under the new European Chemicals Legislation (REACH). Arch Toxicol 2008; 82:211-36. [DOI: 10.1007/s00204-008-0279-9] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 01/07/2008] [Indexed: 10/22/2022]
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Lovell DP. Experimental Design and Statistical Analysis of Studies to Demonstrate a Threshold in Genetic Toxicology: A Mini-review. Genes Environ 2008. [DOI: 10.3123/jemsge.30.139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Watanabe M. Threshold-like Dose-response Relationships in a Modified Linear-no-threshold Model: Application of Experimental Data and Risk Evaluation. Genes Environ 2008. [DOI: 10.3123/jemsge.30.17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Bolt HM. The Concept of “Practical Thresholds” in the Derivation of Occupational Exposure Limits for Carcinogens by the Scientific Committee on Occupational Exposure Limits (SCOEL) of the European Union. Genes Environ 2008. [DOI: 10.3123/jemsge.30.114] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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