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Calabrese EJ, Selby PB. Comet assay and hormesis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 341:122929. [PMID: 37979647 DOI: 10.1016/j.envpol.2023.122929] [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: 09/08/2023] [Revised: 11/06/2023] [Accepted: 11/11/2023] [Indexed: 11/20/2023]
Abstract
The paper provides the first assessment of the occurrence of hormetic dose responses using the Comet assay, a genotoxic assay. Using a priori evaluative criteria based on the Hormetic Database on peer-reviewed comet assay experimental findings, numerous examples of hormetic dose responses were obtained. These responses occurred in a large and diverse range of cell types and for agents from a broad range of chemical classes. Limited attempts were made to estimate the frequency of hormesis within comet assay experimental studies using a priori entry and evaluative criteria, with results suggesting a frequency in the 40% range. These findings are important as they show that a wide range of genotoxic chemicals display evidence that is strongly suggestive of hormetic dose responses. These findings have significant implications for study design issues, including the number of doses selected, dose range and spacing. Likewise, the widespread occurrence of hormetic dose responses in this genotoxic assay has important risk assessment implications.
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Affiliation(s)
- Edward J Calabrese
- Department of Environmental Health Sciences, Morrill I, N344, University of Massachusetts, Amherst, MA, 01003, USA.
| | - Paul B Selby
- Retired from Oak Ridge National Laboratory at Oak Ridge, TN. Home Address: 4088 Nottinghill Gate Road, Upper Arlington, OH, 43220, USA.
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Azqueta A, Stopper H, Zegura B, Dusinska M, Møller P. Do cytotoxicity and cell death cause false positive results in the in vitro comet assay? MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 881:503520. [PMID: 36031332 DOI: 10.1016/j.mrgentox.2022.503520] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 06/10/2022] [Accepted: 06/21/2022] [Indexed: 10/17/2022]
Abstract
The comet assay is used to measure DNA damage induced by chemical and physical agents. High concentrations of test agents may cause cytotoxicity or cell death, which may give rise to false positive results in the comet assay. Systematic studies on genotoxins and cytotoxins (i.e. non-genotoxic poisons) have attempted to establish a threshold of cytotoxicity or cell death by which DNA damage results measured by the comet assay could be regarded as a false positive result. Thresholds of cytotoxicity/cell death range from 20% to 50% in various publications. Curiously, a survey of the latest literature on comet assay results from cell culture studies suggests that one-third of publications did not assess cytotoxicity or cell death. We recommend that it should be mandatory to include results from at least one type of assay on cytotoxicity, cell death or cell proliferation in publications on comet assay results. A combination of cytotoxicity (or cell death) and proliferation (or colony forming efficiency assay) is preferable in actively proliferating cells because it covers more mechanisms of action. Applying a general threshold of cytotoxicity/cell death to all types of agents may not be applicable; however, 25% compared to the concurrent negative control seems to be a good starting value to avoid false positive comet assay results. Further research is needed to establish a threshold value to distinguish between true and potentially false positive genotoxic effects detected by the comet assay.
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Affiliation(s)
- Amaya Azqueta
- Department of Pharmacology and Toxicology, University of Navarra, C/Irunlarrea 1, 31009 Pamplona, Spain and IdiSNA, Navarra Institute for Health Research, Pamplona, Spain.
| | - Helga Stopper
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078 Würzburg, Germany
| | - Bojana Zegura
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Maria Dusinska
- Health Effects Laboratory, Department of Environmental Chemistry, NILU-Norwegian Institute for Air Research, Instituttveien 18, 2002 Kjeller, Norway
| | - Peter Møller
- Department of Public Health, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen, Denmark
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3
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Silver bionanoparticles toxicity in trophoblast is mediated by nitric oxide and glutathione pathways. Toxicology 2021; 454:152741. [PMID: 33662506 DOI: 10.1016/j.tox.2021.152741] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 01/30/2021] [Accepted: 02/28/2021] [Indexed: 12/26/2022]
Abstract
Silver bionanoparticles (AgNPs) biosynthesized by Pseudomonas aeruginosa culture supernatant have an important antibacterial activity mediated by ROS increase; however their toxicity in human cells is not known. Due to the high susceptibility of the developing tissues to xenobiotics, the aim of this study was to investigate the AgNPs effect on first trimester human trophoblasts. The HTR8/SVneo cell line was treated with AgNPs (0.3-1.5 pM), for 6 and 24 h. Cell viability, reactive nitrogen and oxygen species (RNS and ROS) production, nitric oxide synthase expression, antioxidant defenses and biomolecule damage were evaluated. The exposure to AgNPs produced changes in HTR8/SVneo cell morphology and decreased cell viability. Alterations in redox balance were observed, with an increase in ROS and RNS levels, and NOS2 protein expression. Superoxide dismutase and catalase augmented their activity accompanied with a decreased in glutathione content and glutathione S-transferase activity. Protein oxidation and genotoxic damage were observed at concentrations greater than 0.6 pM. The pre-incubation with l-NMMA, NAC, mannitol and peroxidase demonstrated that AgNPs-induced cytotoxicity was not mediated by HO and H2O2, but nitric oxide and glutathione pathways were implicated in cell death. Since reported AgNPs microbicidal mechanism is mediated by increasing ROS (mainly HO and H2O2) without an increase in RNS, this work indicates an interesting difference in the reactive species and oxidative pathways involved in AgNPs toxicity in eukaryotic and prokaryotic cells. Highlighting the importance of toxicity evaluation to determine the safety of AgNPs with pharmaceutical potential uses.
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Abstract
The aim of the present study was to investigate the antiproliferative and proapoptotic actions of N-(5-benzyl-1,3-thiazol-2-yl)-3,5-dimethyl-1-benzofuran-2-carboxamide derivative (compound 5) in glioma cells in comparison with the actions of temozolomide (TMZ) and doxorubicin (Dox), used as positive controls. The antiproliferative activity of the compound 5, TMZ, and Dox on human glioblastoma U251 and human glioblastoma multiform T98G cells was measured using the MTT test. Western blot analysis, fluorescent microscopy, agarose gel retardation assay, flow cytometric analysis, and the DNA comet assay under alkaline conditions were carried out to study the effect of compound 5 on U251 cells. This compound showed ~20 times higher cytotoxicity toward U251 and T98G cells compared with the effects of TMZ and approximately two times higher activity than that of the Dox. Compound 5 induced apoptosis in U251 cells by PARP1 and caspase 3 cleavage mechanisms, also inducing an increase in the level of Bax and Bim proapoptotic proteins and a decrease in the level of phosho-ERK1/2 kinase. The cytotoxicity of compound 5 was associated with an increase in the production of the hydrogen peroxide and the formation of DNA single-strand breaks. This compound 5 did not intercalate into a DNA molecule. Thus, the novel thiazole derivative (compound 5) proved to be a potential antiglioma drug that showed much higher cytotoxic action on human glioma cells compared with the effects of TMZ and Dox. Its cytotoxicity is associated with apoptosis induction, production of the reactive oxygen species, and formation of DNA single-strand breaks without significant DNA intercalation.
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5
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Al-Saleh I, Elkhatib R, Al-Rajoudi T, Al-Qudaihi G, Manogarannogaran P, Eltabache C, Alotaibi A, Mummer AB, Almugbel S. Cytotoxic and genotoxic effects of e-liquids and their potential associations with nicotine, menthol and phthalate esters. CHEMOSPHERE 2020; 249:126153. [PMID: 32058129 DOI: 10.1016/j.chemosphere.2020.126153] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/15/2020] [Accepted: 02/06/2020] [Indexed: 05/06/2023]
Abstract
In this study, we determined DNA damage and chromosome breakage (indicators of genotoxicity) and cell viability (an indicator of cytotoxicity) in human lymphoblastoid TK6 and Chinese hamster ovary (CHO) cells treated with 33 e-liquids using in vitro single cell gel (comet), micronucleus (MN), and trypan blue assays, respectively. We also measured the contents of nicotine, five phthalate esters, and DL-menthol in the e-liquids to examine their effects on DNA damage, chromosome breakage, and cell viability. Our chemical analyses showed that: (1) six e-liquids had nicotine ≥2-fold higher than the manufacture's label claim (2-3.5 mg); (2) both dimethyl- and dibutyl-phthalate levels were >0.1 μg/g, i.e., their threshold limits as additives in cosmetics; and (3) the DL-menthol contents ranged from 0.0003 to 85757.2 μg/g, with those of two e-liquids being >1 mg/g, the threshold limit for trigging sensory irritation. Though all the e-liquids induced DNA damage in TK6 cells, 20 resulted in cell viabilities ≤75%, indicating cytotoxicity, yet the inverse relationship between cell viability and DNA damage (r = -0.628, p = 0.003) might reflect their role as pro-apoptotic and DNA damage inducers. Fifteen e-liquids induced MN% in TK6 cells ≥3-fold that of untreated cells. Some of the increase in %MN might be false due to high cytotoxicity, yet six brands showed acceptable cell viabilities (59-71%), indicating chromosome damage. DNA damage and %MN increased when the TK6 cells were exposed to metabolic activation. The CHO cells were less sensitive to the genotoxic effects of the e-liquids than the TK6 cells. DL-menthol was found to be associated with decreased cell viability and increased DNA damage, even at low levels. We cannot dismiss the presence of other ingredients in e-liquids with cytotoxic/genotoxic properties since out of the 63 different flavors, 47 induced DNA damage (≥3-folds), and 26 reduced cell viability (≤75%) in TK6 cells.
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Affiliation(s)
| | | | | | | | | | | | - Aminah Alotaibi
- National Center for Biotechnology and Genomic Research, King Abdulaziz City for Science and Technology, Saudi Arabia
| | - Abdulrahman Bin Mummer
- Biostatistics, Epidemiology & Scientific Computing Department, King Faisal Specialist Hospital & Research Centre, Saudi Arabia
| | - Saad Almugbel
- College of Medicine, Al-Imam Muhammed Ibn Saud Islamic University, Riyadh, Saudi Arabia
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Cohen SM, Eisenbrand G, Fukushima S, Gooderham NJ, Guengerich FP, Hecht SS, Rietjens IMCM, Bastaki M, Davidsen JM, Harman CL, McGowen MM, Taylor SV. FEMA GRAS assessment of natural flavor complexes: Mint, buchu, dill and caraway derived flavoring ingredients. Food Chem Toxicol 2019; 135:110870. [PMID: 31604112 DOI: 10.1016/j.fct.2019.110870] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 09/18/2019] [Accepted: 10/02/2019] [Indexed: 02/08/2023]
Abstract
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. NFC flavor materials include a variety of essential oils and botanical extracts. The re-evaluation of NFCs is conducted based on a constituent-based procedure outlined in 2005 and updated in 2018 that evaluates the safety of NFCs for their intended use as flavor ingredients. This procedure is applied in the re-evaluation of the generally recognized as safe (GRAS) status of NFCs with constituent profiles that are dominated by alicyclic ketones such as menthone and carvone, secondary alcohols such as menthol and carveol, and related compounds. The FEMA Expert Panel affirmed the GRAS status of Peppermint Oil (FEMA 2848), Spearmint Oil (FEMA 3032), Spearmint Extract (FEMA 3031), Cornmint Oil (FEMA 4219), Erospicata Oil (FEMA 4777), Curly Mint Oil (FEMA 4778), Pennyroyal Oil (FEMA 2839), Buchu Leaves Oil (FEMA 2169), Caraway Oil (FEMA 2238) and Dill Oil (FEMA 2383) and determined FEMA GRAS status for Buchu Leaves Extract (FEMA 4923), Peppermint Oil, Terpeneless (FEMA 4924) and Spearmint Oil, Terpeneless (FEMA 4925).
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Affiliation(s)
- Samuel M Cohen
- Havlik-Wall Professor of Oncology, Dept. of Pathology and Microbiology, University of Nebraska Medical Center, 983135 Nebraska Medical Center, Omaha, NE, 68198-3135, USA
| | - Gerhard Eisenbrand
- Food Chemistry & Toxicology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Shoji Fukushima
- Japan Bioassay Research Center, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan
| | - Nigel J Gooderham
- Dept. of Metabolism, Digestion, and Reproduction, Imperial College London, Sir Alexander Fleming Building, London, SW7 2AZ, United Kingdom
| | - F Peter Guengerich
- Dept. of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232-0146, USA
| | - Stephen S Hecht
- Masonic Cancer Center and Dept. of Laboratory Medicine and Pathology, University of Minnesota, MMC 806, 420 Delaware St., S.E., Minneapolis, MN, 55455, USA
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE, Wageningen, the Netherlands
| | - Maria Bastaki
- Flavor and Extract Manufacturers Association, 1101 17th Street NW, Suite 700, Washington, DC, 20036, USA
| | - Jeanne M Davidsen
- Flavor and Extract Manufacturers Association, 1101 17th Street NW, Suite 700, Washington, DC, 20036, USA
| | - Christie L Harman
- Flavor and Extract Manufacturers Association, 1101 17th Street NW, Suite 700, Washington, DC, 20036, USA
| | - Margaret M McGowen
- Flavor and Extract Manufacturers Association, 1101 17th Street NW, Suite 700, Washington, DC, 20036, USA
| | - Sean V Taylor
- Flavor and Extract Manufacturers Association, 1101 17th Street NW, Suite 700, Washington, DC, 20036, USA.
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Malekmohammad K, Rafieian-Kopaei M, Sardari S, Sewell RDE. Toxicological effects ofMentha x piperita(peppermint): a review. TOXIN REV 2019. [DOI: 10.1080/15569543.2019.1647545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Khojasteh Malekmohammad
- Department of Animal Sciences, Faculty of Basic Sciences, Shahrekord University, Shahrekord, Iran
| | - Mahmoud Rafieian-Kopaei
- Medical Plants Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Samira Sardari
- Department of Pathobiology, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran
| | - Robert D. E. Sewell
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, UK
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8
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Sykora P, Witt KL, Revanna P, Smith-Roe SL, Dismukes J, Lloyd DG, Engelward BP, Sobol RW. Next generation high throughput DNA damage detection platform for genotoxic compound screening. Sci Rep 2018; 8:2771. [PMID: 29426857 PMCID: PMC5807538 DOI: 10.1038/s41598-018-20995-w] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/29/2018] [Indexed: 11/23/2022] Open
Abstract
Methods for quantifying DNA damage, as well as repair of that damage, in a high-throughput format are lacking. Single cell gel electrophoresis (SCGE; comet assay) is a widely-used method due to its technical simplicity and sensitivity, but the standard comet assay has limitations in reproducibility and throughput. We have advanced the SCGE assay by creating a 96-well hardware platform coupled with dedicated data processing software (CometChip Platform). Based on the original cometchip approach, the CometChip Platform increases capacity ~200 times over the traditional slide-based SCGE protocol, with excellent reproducibility. We tested this platform in several applications, demonstrating a broad range of potential uses including the routine identification of DNA damaging agents, using a 74-compound library provided by the National Toxicology Program. Additionally, we demonstrated how this tool can be used to evaluate human populations by analysis of peripheral blood mononuclear cells to characterize susceptibility to genotoxic exposures, with implications for epidemiological studies. In summary, we demonstrated a high level of reproducibility and quantitative capacity for the CometChip Platform, making it suitable for high-throughput screening to identify and characterize genotoxic agents in large compound libraries, as well as for human epidemiological studies of genetic diversity relating to DNA damage and repair.
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Affiliation(s)
- Peter Sykora
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL, 36604, USA
| | - Kristine L Witt
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Pooja Revanna
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL, 36604, USA
| | - Stephanie L Smith-Roe
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Jonathan Dismukes
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL, 36604, USA
| | | | - Bevin P Engelward
- Department of Biological Engineering, MIT, Cambridge, MA, 02139, USA
| | - Robert W Sobol
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL, 36604, USA.
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9
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Manasfi T, De Méo M, Di Giorgio C, Coulomb B, Boudenne JL. Assessing the genotoxicity of two commonly occurring byproducts of water disinfection: Chloral hydrate and bromal hydrate. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2017; 813:37-44. [DOI: 10.1016/j.mrgentox.2016.11.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 12/21/2022]
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DNA damage induced by hydroquinone can be prevented by fungal detoxification. Toxicol Rep 2014; 1:1096-1105. [PMID: 28962321 PMCID: PMC5598254 DOI: 10.1016/j.toxrep.2014.10.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 10/25/2014] [Accepted: 10/28/2014] [Indexed: 01/03/2023] Open
Abstract
Hydroquinone is a benzene metabolite with a wide range of industrial applications, which has potential for widespread human exposure; however, the toxicity of hydroquinone on human cells remains unclear. The aims of this study are to investigate the cytotoxicity and genotoxicity of hydroquinone in human primary fibroblasts and human colon cancer cells (HCT116). Low doses of hydroquinone (227-454 μM) reduce the viability of fibroblasts and HCT116 cells, determined by resazurin conversion, and induce genotoxic damage (DNA strand breaks), as assessed by alkaline comet assays. Bioremediation may provide an excellent alternative to promote the degradation of hydroquinone, however few microorganisms are known that efficiently degrade it. Here we also investigate the capacity of a halotolerant fungus, Penicillium chrysogenum var. halophenolicum, to remove hydroquinone toxicity under hypersaline condition. The fungus is able to tolerate high concentrations of hydroquinone and can reverse these noxious effects via degradation of hydroquinone to completion, even when the initial concentration of this compound is as high as 7265 μM. Our findings reveal that P. chrysogenum var. halophenolicum efficiently degrade hydroquinone under hypersaline conditions, placing this fungus among the best candidates for the detoxification of habitats contaminated with this aromatic compound.
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11
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Genotoxicity of hydroquinone in A549 cells. Cell Biol Toxicol 2013; 29:213-27. [DOI: 10.1007/s10565-013-9247-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/20/2013] [Indexed: 11/25/2022]
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12
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Kier LD, Kirkland DJ. Review of genotoxicity studies of glyphosate and glyphosate-based formulations. Crit Rev Toxicol 2013; 43:283-315. [PMID: 23480780 DOI: 10.3109/10408444.2013.770820] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
An earlier review of the toxicity of glyphosate and the original Roundup™-branded formulation concluded that neither glyphosate nor the formulation poses a risk for the production of heritable/somatic mutations in humans. The present review of subsequent genotoxicity publications and regulatory studies of glyphosate and glyphosate-based formulations (GBFs) incorporates all of the findings into a weight of evidence for genotoxicity. An overwhelming preponderance of negative results in well-conducted bacterial reversion and in vivo mammalian micronucleus and chromosomal aberration assays indicates that glyphosate and typical GBFs are not genotoxic in these core assays. Negative results for in vitro gene mutation and a majority of negative results for chromosomal effect assays in mammalian cells add to the weight of evidence that glyphosate is not typically genotoxic for these endpoints in mammalian systems. Mixed results were observed for micronucleus assays of GBFs in non-mammalian systems. Reports of positive results for DNA damage endpoints indicate that glyphosate and GBFs tend to elicit DNA damage effects at high or toxic dose levels, but the data suggest that this is due to cytotoxicity rather than DNA interaction with GBF activity perhaps associated with the surfactants present in many GBFs. Glyphosate and typical GBFs do not appear to present significant genotoxic risk under normal conditions of human or environmental exposures.
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Zhang L, Xu L, Zeng Q, Zhang SH, Xie H, Liu AL, Lu WQ. Comparison of DNA damage in human-derived hepatoma line (HepG2) exposed to the fifteen drinking water disinfection byproducts using the single cell gel electrophoresis assay. Mutat Res 2012; 741:89-94. [PMID: 22108252 DOI: 10.1016/j.mrgentox.2011.11.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 10/10/2011] [Accepted: 11/03/2011] [Indexed: 05/15/2023]
Abstract
Disinfection of drinking water reduces pathogenic infection, but generates disinfection by-products (DBPs) in drinking water. In this study, the effect of fifteen DBPs on DNA damage in human-derived hepatoma line (HepG2) was investigated by the single cell gel electrophoresis (SCGE) assay. These fifteen DBPs are: four trihalomethanes (THMs), six haloacetic acides (HAAs), three haloacetonitriles (HANs), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), and chloral hydrate (CH). Based on the minimal effective concentration (MEC) at which DBPs induced significant increase in olive tail moment (OTM), the rank order of DNA-damaging potency is: bromodichloromethane (BDCM)>dibromochloromethane (DBCM)>tribromomethane (TBM)>trichloromethane (TCM) of the four THMs; iodoacetic acid (IA)>bromoacetic acid (BA)>dibromoacetic acid (DBA)>dichloracetic acid (DCA)>trichloroacetic acid (TCA) of the five HAAs; dibromoacetonitrile (DBN)approximately dichloroacetonitrile (DCN)>trichloroacetonitrile (TCN) of the three HANs. The DNA damaging potency of MX and CH is similar to TCA and DCA, respectively. IA is the most genotoxic DBP in the fifteen DBPs, followed by BA. Chloroacetic acid (CA) is not genotoxic in this assay. Our findings indicated that HepG2/SCGE is a sensitive tool to evaluate the genotoxicity of DBPs and iodinated DBPs are more genotoxic than brominated DBPs, but chlorinated DBPs are less genotoxic than brominated DBPs.
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Affiliation(s)
- Li Zhang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, PR China
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14
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Speit G, Rothfuss A. The comet assay: a sensitive genotoxicity test for the detection of DNA damage and repair. Methods Mol Biol 2012; 920:79-90. [PMID: 22941597 DOI: 10.1007/978-1-61779-998-3_6] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The comet assay (single-cell gel electrophoresis) is a simple and sensitive method for studying DNA damage and repair. In this microgel electrophoresis technique, a small number of cells suspended in a thin agarose gel on a microscope slide is lysed, electrophoresed, and stained with a fluorescent DNA-binding dye. Cells with increased DNA damage display increased migration of chromosomal DNA from the nucleus towards the anode, which resembles the shape of a comet. The assay has manifold applications in fundamental research for DNA damage and repair, in genotoxicity testing of novel chemicals and pharmaceuticals, environmental biomonitoring, and human population monitoring. This chapter describes a standard protocol of the alkaline comet assay and points to some useful modifications.
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Affiliation(s)
- Günter Speit
- Institut für Humangenetik, Universität Ulm, Ulm, Germany.
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15
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Liviac D, Creus A, Marcos R. Mutagenic analysis of six disinfection by-products in the Tk gene of mouse lymphoma cells. JOURNAL OF HAZARDOUS MATERIALS 2011; 190:1045-1052. [PMID: 21561708 DOI: 10.1016/j.jhazmat.2011.04.062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 03/14/2011] [Accepted: 04/13/2011] [Indexed: 05/30/2023]
Abstract
Drinking water must be disinfected prior to its distribution for human consumption. This water treatment process generates disinfection by-products (DBPs), formed by the interaction of the disinfectant with organic matter, anthropogenic contaminants and inorganic (bromide/iodide) matter naturally present in source water. Due to the potential genotoxic/carcinogenic risk of these DBPs, we have investigated the mutagenic potential of six of such compounds on the thymidine kinase (Tk) gene in the well-validated mouse lymphoma assay (MLA). The MLA quantifies a wide range of genetic alterations affecting the expression of this gene in L5178Y/Tk(+/-)-3.7.2C cells. In this study we selected six emerging DBPs, corresponding to three different chemical classes: halonitromethanes (bromonitromethane and trichloronitromethane), halogenated acetaldehydes (tribromoacetaldehyde and chloral hydrate) and hydroxyfuranones (mucobromic and mucochloric acids), each class including one chlorinated and one brominated form. The results showed that after 4h of treatment, only mucobromic acid increased the frequency of mutant colonies, with a higher proportion of small colonies, which would indicate a clastogenic potential. This is the first study reporting mutagenicity data in mammalian cells for the six selected DBPs.
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Affiliation(s)
- Danae Liviac
- Grup de Mutagènesi, Departament de Genètica i de Microbiologia, Facultat de Biociències, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Cerdanyola del Vallès, Spain
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16
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Frikke-Schmidt H, Roursgaard M, Lykkesfeldt J, Loft S, Nøjgaard JK, Møller P. Effect of vitamin C and iron chelation on diesel exhaust particle and carbon black induced oxidative damage and cell adhesion molecule expression in human endothelial cells. Toxicol Lett 2011; 203:181-9. [PMID: 21421028 DOI: 10.1016/j.toxlet.2011.03.011] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 03/04/2011] [Accepted: 03/07/2011] [Indexed: 01/07/2023]
Abstract
Exposure to particulate matter is associated with oxidative stress and risk of cardiovascular diseases. We investigated if vitamin C and desferrioxamine (iron chelator) altered the levels of oxidative stress and expression of cell adhesion molecules upon exposure to diesel exhaust particles (DEP) and carbon black in cultured human umbilical vein endothelial cells (HUVECs). We found that the particles were only slightly cytotoxic in the high concentration ranges. Particle-induced intracellular reactive oxygen species (ROS) production was attenuated by vitamin C administration or iron chelation and particularly when combined (p<0.001). Only desferrioxamine protected the DNA from oxidative damage in terms of strand breaks and formamidopyrimidine DNA glycosylase sensitive sites induced by carbon black (p<0.01). Carbon black and small sized DEP generated from an Euro4 engine increased the surface expression of VCAM-1 and ICAM-1, whereas DEP from an engine representing an old combustion type engine (SRM2975) with larger particles did not affect the expression of cell adhesion molecules. These effects were also attenuated by desferrioxamine but not vitamin C. The study shows that exposure to carbon black and DEP in HUVECs can generate both oxidative stress and expression of cell surface adhesion molecules and that these effects can in part be attenuated by vitamin C and desferrioxamine.
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Affiliation(s)
- Henriette Frikke-Schmidt
- Section of Biomedicine, Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Denmark
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Liviac D, Creus A, Marcos R. DNA damage induction by two halogenated acetaldehydes, byproducts of water disinfection. WATER RESEARCH 2010; 44:2638-2646. [PMID: 20189624 DOI: 10.1016/j.watres.2010.01.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 01/20/2010] [Accepted: 01/25/2010] [Indexed: 05/28/2023]
Abstract
Drinking water contains disinfection byproducts, generated by the interaction of chlorine (or other disinfecting chemicals) with organic matter, anthropogenic contaminants, and bromide/iodide naturally present in most source waters. One class of these chemicals is the halogenated acetaldehydes (HAs), identified in high quantities when ozone is used as primary or secondary disinfectant. In this study, an analysis of the genotoxic potential of two HAs, namely tribromoacetaldehyde (TBA) and chloral hydrate (CH) has been conducted in human cells (TK6 cultured cells and peripheral blood lymphocytes). The comet assay was used to 1) measure the induction of single and double-strand DNA breaks, 2) evaluate the capacity of inducing oxidative DNA damage, and 3) determine the DNA repair kinetics of the induced primary genetic damage. In addition, chromosome damage, as a measure of fixed damage, was evaluated by means of the micronucleus test. The results of the comet assay show that both compounds are clearly genotoxic, inducing high levels of DNA breaks, TBA being more effective than CH. According to the comet results, both HAs produce high levels of oxidized bases, and the induced DNA damage is rapidly repaired over time. Contrarily, the results obtained in the micronucleus test, which measures the capacity of genotoxic agents to induce clastogenic and aneugenic effects, are negative for the two HAs tested, either using TK6 cells or human peripheral blood lymphocytes. This would indicate that the primary damage induced by the two HAs is not fixed as chromosome damage, possibly due to an efficient repair or the death of damaged cells, which is an important point in terms of risk assessment of DBPs exposure.
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Affiliation(s)
- Danae Liviac
- Grup de Mutagènesi, Departament de Genètica i de Microbiologia, Facultat de Biociències, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Cerdanyola del Vallès, Spain
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18
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Hartmann A, Speit G. Comet Assay – Protocols and Testing Strategies. THE COMET ASSAY IN TOXICOLOGY 2009. [DOI: 10.1039/9781847559746-00373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Andreas Hartmann
- Novartis Pharma AG Preclinical Safety WKL105.4. 09 CH-4002 Basel Switzerland
| | - Günter Speit
- Universität Ulm Institut für Humangenetik D-89069 Ulm Germany
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The comet assay: A sensitive method for detecting DNA damage in individual cells. Methods 2009; 48:46-53. [DOI: 10.1016/j.ymeth.2009.02.016] [Citation(s) in RCA: 222] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 02/25/2009] [Indexed: 01/13/2023] Open
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21
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Belsito D, Bickers D, Bruze M, Calow P, Greim H, Hanifin JM, Rogers AE, Saurat JH, Sipes IG, Tagami H. A toxicologic and dermatologic assessment of cyclic and non-cyclic terpene alcohols when used as fragrance ingredients. Food Chem Toxicol 2008; 46 Suppl 11:S1-S71. [PMID: 18655821 DOI: 10.1016/j.fct.2008.06.085] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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22
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Burlinson B, Tice RR, Speit G, Agurell E, Brendler-Schwaab SY, Collins AR, Escobar P, Honma M, Kumaravel TS, Nakajima M, Sasaki YF, Thybaud V, Uno Y, Vasquez M, Hartmann A. Fourth International Workgroup on Genotoxicity testing: Results of the in vivo Comet assay workgroup. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 627:31-5. [PMID: 17118697 DOI: 10.1016/j.mrgentox.2006.08.011] [Citation(s) in RCA: 369] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 07/31/2006] [Accepted: 08/14/2006] [Indexed: 11/29/2022]
Abstract
As part of the Fourth International Workshop on Genotoxicity Testing (IWGT), held 9-10 September 2005 in San Francisco, California, an expert working group on the Comet assay was convened to review and discuss some of the procedures and methods recommended in previous documents. Particular attention was directed at the in vivo rodent, alkaline (pH >13) version of the assay. The aim was to review those protocol areas which were unclear or which required more detail in order to produce a standardized protocol with maximum acceptability by international regulatory agencies. The areas covered were: number of dose levels required, cell isolation techniques, measures of cytotoxicity, scoring of comets (i.e., manually or by image analysis), and the need for historical negative/positive control data. It was decided that a single limit dose was not sufficient although the required number of dose levels was not stipulated. The method of isolating cells was thought not to have a qualitative effect on the assay but more data were needed before a conclusion could be drawn. Concurrent measures of cytotoxicity were required with histopathological examination of tissues for necrosis or apoptosis as the "Gold Standard". As for analysing the comets, the consensus was that image analysis was preferred but not required. Finally, the minimal number of studies required to generate a historical positive or negative control database was not defined; rather the emphasis was placed on demonstrating the stability of the negative/positive control data. It was also agreed that a minimum reporting standard would be developed which would be consistent with OECD in vivo genotoxicity test method guidelines.
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Affiliation(s)
- Brian Burlinson
- Huntingdon Life Sciences, Cellular & Molecular Toxicology, Woolley Road, Alconbury, Huntington, Cambs PE28 4HS, UK.
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23
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Calabrese EJ. Cancer biology and hormesis: human tumor cell lines commonly display hormetic (biphasic) dose responses. Crit Rev Toxicol 2006; 35:463-582. [PMID: 16422392 DOI: 10.1080/10408440591034502] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This article assesses the nature of the dose-response relationship of human tumor cell lines with a wide range of agents including antineoplastics, toxic substances (i.e., environmental pollutants), nonneoplastic drugs, endogenous agonists, and phyto-compounds. Hormetic-like biphasic dose responses were commonly reported and demonstrated in 136 tumor cell lines from over 30 tissue types for over 120 different agents. Quantitative features of these hormetic dose responses were similar, regardless of tumor cell line or agent tested. That is, the magnitude of the responses was generally modest, with maximum stimulatory responses typically not greater than twice the control, while the width of the stimulatory concentration range was usually less than 100-fold. Particular attention was directed to possible molecular mechanisms of the biphasic nature of the dose response, as well as clinical implications in which a low concentration of chemotherapeutic agent may stimulate tumor cell proliferation. Finally, these findings further support the conclusion that hormetic dose responses are broadly generalizable, being independent of biological model, endpoint measured, and stressor agent, and represent a basic feature of biological responsiveness to chemical and physical stressors.
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Affiliation(s)
- Edward J Calabrese
- Environmental Health Sciences, University of Massachusetts, Amherst 01003, USA.
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Romero-Jiménez M, Campos-Sánchez J, Analla M, Muñoz-Serrano A, Alonso-Moraga A. Genotoxicity and anti-genotoxicity of some traditional medicinal herbs. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2005; 585:147-55. [PMID: 16005256 DOI: 10.1016/j.mrgentox.2005.05.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 04/22/2005] [Accepted: 05/03/2005] [Indexed: 10/25/2022]
Abstract
Six herbal infusions used worldwide (Matricaria chamomilla, Tilia cordata, Mentha piperita, Mentha pulegium, Uncaria tomentosa and Valeriana officinalis) were assayed for anti-genotoxicity using the Somatic Mutation And Recombination Test (SMART) in Drosophila melanogaster. All these infusions are traditionally used for various medical purposes, including anti-inflammatory processes. Hydrogen peroxide was used as an oxidative genotoxicant to test the anti-genotoxic potency of the medicinal infusions. None of these infusions showed a significant genotoxicity, quite the reverse they were able to behave as desmutagens, detoxifying the mutagen hydrogen peroxide. The phenolic content of such herbal infusions is argued to be the possible scavenger of reactive oxygen radicals produced by the hydrogen peroxide.
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Affiliation(s)
- Magdalena Romero-Jiménez
- University of Cordoba, Department of Genetics, Campus Universitario Rabanales, Edificio Gregor Mendel, C-5, 14071 Cordoba, Spain
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Brendler-Schwaab S, Hartmann A, Pfuhler S, Speit G. The in vivo comet assay: use and status in genotoxicity testing. Mutagenesis 2005; 20:245-54. [PMID: 15899933 DOI: 10.1093/mutage/gei033] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The in vivo comet assay (single cell gel electrophoresis assay) in its alkaline version (pH >13) is being increasingly used in genotoxicity testing of substances such as industrial chemicals, biocides, agrochemicals, food additives and pharmaceuticals. Recommendations for an appropriate performance of the test using OECD guidelines for other in vivo genotoxicity tests have been published. In this review, we critically discuss the biological significance of comet assay effects in general and the status of the test in current strategies for genotoxicity testing. Examples for practical applications of the in vivo comet assay and potential consequences of positive and negative test results are given. The significance of comet assay results for hazard identification and risk assessment is discussed. In accordance with international guidelines for genotoxicity testing the in vivo comet assay is recommended for follow-up testing of positive in vitro findings. It is particularly useful as a tool for the evaluation of local genotoxicity, especially for organs/cell types which cannot easily be evaluated with other standard tests. A positive result in an appropriately performed in vivo comet assay indicates genotoxicity of the test compound in the tissue tested and gains particular significance when a mutagenic potential of the test compound has already been demonstrated in vitro. Such findings will have practical consequences in the risk assessment processes and further development of substances.
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Abstract
The common preservative thimerosal is one of the most important organic mercury compounds human populations are exposed to. It has toxic effect on several cell lines, and it also induces programmed cell death in in vitro experiments. Association is suggested between application of thimerosal-containing vaccines and the occurrence of neurodevelopmental disorders, like autism. While specific recommendations were made to eliminate thimerosal from vaccines, consistent evidence is still lacking for an association of exposure and disease. Unfortunately, it is very hard to study the molecular background of complex human diseases directly; however, investigations on more simple model organisms may lead to a better understanding of thimerosal as a possible disease inducing factor.
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Affiliation(s)
- A Mádi
- Signalling and Apoptosis Research Group of the Hungarian Academy of Sciences, University of Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary.
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Calabrese EJ. Hormesis: from marginalization to mainstream. Toxicol Appl Pharmacol 2004; 197:125-36. [PMID: 15163548 DOI: 10.1016/j.taap.2004.02.007] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2004] [Accepted: 02/17/2004] [Indexed: 10/26/2022]
Abstract
The paper provides an account of how the hormetic dose response has emerged in recent years as a serious dose-response model in toxicology and risk assessment after decades of extreme marginalization. In addition to providing the toxicological basis of this dose-response revival, the paper reexamines the concept of a default dose model in toxicology and risk assessment and makes the argument that the hormetic model satisfies criteria (e.g., generalizability, frequency, application to risk assessment endpoints, false positive/negative potential, requirements for hazard assessment, reliability of estimating risks, capacity for validation of risk estimates, public health implications of risk estimates) for such a default model better than its chief competitors, the threshold and linear at low dose models. The selection of the hormetic model as the default model in risk assessment for noncarcinogens and specifically for carcinogens would have a profound impact on the practice of risk assessment and its societal implications.
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Affiliation(s)
- Edward J Calabrese
- Environmental Health Sciences, University of Massachusetts, Morrill I, N344, Amherst, MA 01003, USA.
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