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Asghari M, Sahari MA, Kia SJ, Tavakoli A, Barzegar M. Berberis integerrima bioactive molecules loaded in chitosan-based electrospun nanofibers for soybean oil oxidative protection. Int J Biol Macromol 2024; 268:131692. [PMID: 38702247 DOI: 10.1016/j.ijbiomac.2024.131692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 04/09/2024] [Accepted: 04/17/2024] [Indexed: 05/06/2024]
Abstract
Natural bioactive molecules such as phenolic acids and alkaloids play a crucial role in preserving the quality and safety of food products, particularly oils, by preventing oxidation. Berberis integerrima, a rich source of such antioxidants, has been explored in this study for its potential application in soybean oil preservation. Electrospun nanofibers, composed of polyvinyl alcohol and chitosan, were fabricated and loaded with an alcoholic extract of Berberis integerrima. The antioxidant activity of Berberis integerrima was evaluated, and the phenolic compounds contributing to its efficacy were identified and quantified. The physicochemical properties of the polyvinyl alcohol /chitosan/Berberis integerrima nanofibers, including morphology, crystallinity, functional groups, and thermal stability, were characterized. The results revealed that the polyvinyl alcohol/chitosan/Berberis integerrima nanofibers exhibited high antioxidant capacity and improved the stability of Berberis integerrima, indicating their potential as effective and biodegradable materials for food preservation. This study underscores the potential of harnessing natural antioxidants from Berberis integerrima in nanofibers to enhance the quality and safety of soybean oil.
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Affiliation(s)
- Mohsen Asghari
- Department of Food Technology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Ali Sahari
- Department of Food Technology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
| | - Seyed Jalal Kia
- Department of Polymer Engineering and Color Technology, Amir Kabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Atefeh Tavakoli
- Department of Food Technology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
| | - Mohsen Barzegar
- Department of Food Technology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
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2
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Paustenbach DJ, Brown SE, Heywood JJ, Donnell MT, Eaton DL. Risk characterization of N-nitrosodimethylamine in pharmaceuticals. Food Chem Toxicol 2024; 186:114498. [PMID: 38341171 DOI: 10.1016/j.fct.2024.114498] [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: 09/28/2023] [Revised: 01/23/2024] [Accepted: 01/31/2024] [Indexed: 02/12/2024]
Abstract
Since 2018, N-nitrosodimethylamine (NDMA) has been a reported contaminant in numerous pharmaceutical products. To guide the pharmaceutical industry, FDA identified an acceptable intake (AI) of 96 ng/day NDMA. The approach assumed a linear extrapolation from the Carcinogenic Potency Database (CPDB) harmonic-mean TD50 identified in chronic studies in rats. Although NDMA has been thought to act as a mutagenic carcinogen in experimental animals, it has not been classified as a known human carcinogen by any regulatory agency. Humans are exposed to high daily exogenous and endogenous doses of NDMA. Due to the likelihood of a threshold dose for NDMA-related tumors in animals, we believe that there is ample scientific basis to utilize the threshold-based benchmark dose or point-of-departure (POD) approach when estimating a Permissible Daily Exposure limit (PDE) for NDMA. We estimated that 29,000 ng/kg/day was an appropriate POD for calculating a PDE. Assuming an average bodyweight of 50 kg, we expect that human exposures to NDMA at doses below 5800 ng/day in pharmaceuticals would not result in an increased risk of liver cancer, and that there is little, if any, risk for any other type of cancer, when accounting for the mode-of-action in humans.
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Affiliation(s)
- D J Paustenbach
- Paustenbach and Associates, 970 West Broadway, Suite E, Jackson, WY, USA
| | - S E Brown
- Paustenbach and Associates, 207 Canyon Blvd, Boulder, CO, USA.
| | - J J Heywood
- Paustenbach and Associates, 207 Canyon Blvd, Boulder, CO, USA
| | - M T Donnell
- Valeo Sciences LLC, 333 Corporate Drive, Suite 130, Ladera Ranch, CA, USA
| | - D L Eaton
- Professor Emeritus, Department of Environmental & Occupational Health Sciences, University of Washington, Seattle, WA, USA
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3
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Thiffault C, Freeman EL, Williams GM, Tran NL. Lack of genotoxicity potential and safety assessment of 4-(2-hydroxyethyl) morpholine present as an impurity in pharmaceuticals and nutritional supplements. Food Chem Toxicol 2024; 184:114352. [PMID: 38081535 DOI: 10.1016/j.fct.2023.114352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/06/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023]
Abstract
4-(2-Hydroxyethyl) morpholine (HEM) is widely used as a building block of macromolecules in the manufacture of pharmaceuticals and dietary supplements and could remain as an impurity in the finished products. An evaluation of HEM was conducted to identify endpoints that could be used to determine the point-of-departure (POD) for use in assessing the potential risk from exposure to HEM. No oral repeated dose toxicological studies of appropriate duration were found for HEM. Therefore, suitable analogue(s) were identified. Although oral repeated dose studies were available for the analogues, the studies were not of sufficient duration for use in the assignment of a POD for risk evaluation. Accordingly, the Threshold of Toxicological Concern (TTC) approach, which proposes that a de minimis value can be derived to qualitatively assess risk, was considered for HEM. To determine the appropriate TTC approach (genotoxic or non-genotoxic), the genotoxicity of HEM and its analogues were evaluated. The weight of the evidence indicated that HEM, and the appropriate analogues, are not genotoxic. Considering the chemical structure of HEM, the non-genotoxic Cramer class III TTC value of 1.5 μg/kg bw/day was determined to be appropriate for use in safety assessment of HEM as an impurity in products intended for human consumption.
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Affiliation(s)
- Christine Thiffault
- Exponent Center for Chemical Regulation and Food Safety, Washington, DC, USA.
| | - Elaine L Freeman
- Exponent Center for Chemical Regulation and Food Safety, Washington, DC, USA
| | - Gary M Williams
- Department of Pathology, New York Medical College Valhalla, NY, USA
| | - Nga L Tran
- Exponent Center for Chemical Regulation and Food Safety, Washington, DC, USA
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4
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Kobets T, Hickey C, Johnson G, Duan JD, Etter S, Smith B, Williams GM. Assessment of no-observed-effect-levels for DNA adducts formation by genotoxic carcinogens in fetal turkey livers. Toxicology 2024; 501:153714. [PMID: 38141718 DOI: 10.1016/j.tox.2023.153714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/08/2023] [Accepted: 12/18/2023] [Indexed: 12/25/2023]
Abstract
For genotoxic carcinogens, covalent binding to DNA is a critical initiating event in tumorigenesis. The present research investigated dose-effect relationships of three genotoxic carcinogens representing different structural classes, 2-acetylaminofluorene (2-AAF), benzo[a]pyrene (B[a]P) and quinoline (QUI), to assess the existence of no-observed-effect-levels (NOELs) for the formation of DNA adducts. Carcinogens were administered into the air sac of fertilized turkey eggs over wide dose ranges in three daily injections on days 22 to 24 of incubation. DNA adducts were measured in the fetal turkey livers by the 32P-nucleotide postlabeling (NPL) assay. B[a]P and QUI produced DNA adducts in a dosage-related manner and exhibited NOELs at 0.65 and 0.35 mg/kg bw/day, respectively. In contrast, 2-AAF formed DNA adducts at all tested dosages down to 0.005 mg/kg bw/day. Benchmark dose (BMD) analysis identified the potencies of 2-AAF and QUI to be similar, while B[a]P was the least potent compound. Overall, findings in fetal turkey livers demonstrated that exposure levels to genotoxic compounds that do not result in DNA adducts can exist but are not evident with all carcinogens of this type. The use of mechanistic dose-effect studies for genotoxic endpoints can provide critical information for prioritization of concerns for risk assessment.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA.
| | | | | | - Jian-Dong Duan
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
| | | | - Benjamin Smith
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA
| | - Gary M Williams
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
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Ishii Y, Shi L, Takasu S, Ogawa K, Umemura T. A 13-week comprehensive toxicity study with adductome analysis demonstrates the toxicity, genotoxicity, and carcinogenicity of the natural flavoring agent elemicin. Food Chem Toxicol 2023; 179:113965. [PMID: 37495168 DOI: 10.1016/j.fct.2023.113965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/10/2023] [Accepted: 07/23/2023] [Indexed: 07/28/2023]
Abstract
Elemicin, an alkenylbenzene flavoring, exists naturally in foods, herbs, and spices. Some alkenylbenzenes are hepatotoxic and hepatocarcinogenic in rodents. However, few studies have examined the toxicology of elemicin. In the current study, we comprehensively evaluated the general toxicity, genotoxicity, and carcinogenicity of elemicin using gpt delta rats and DNA adductome analysis. Groups of 10 male F344 gpt delta rats were treated with elemicin by gavage at a dose of 0, 25, 100, or 400 mg/kg bw/day for 13 weeks. Liver weights were significantly increased with histopathological changes in groups receiving 100 mg/kg bw/day or more. Significant increases in serum hepatotoxic parameters were observed in the 400 mg/kg bw/day group. Based on the observed changes in liver weights, 18.6 mg/kg bw was identified as the low benchmark dose. Significant increases in the number and area of glutathione S-transferase placental form-positive foci and gpt mutant frequencies were apparent only in the 400 mg/kg/day group, although elemicin-specific DNA adducts were detected from the lowest dose, suggesting that elemicin exhibited hepatocarcinogenicity in rats only at higher doses. Because elemicin showed no mutagenicity at lower doses, there was an adequate safety margin between the acceptable daily intake and the estimated daily intake of elemicin.
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Affiliation(s)
- Yuji Ishii
- Division of Pathology, National Institute of Health Sciences, Kanagawa, Japan
| | - Liang Shi
- Division of Pathology, National Institute of Health Sciences, Kanagawa, Japan
| | - Shinji Takasu
- Division of Pathology, National Institute of Health Sciences, Kanagawa, Japan
| | - Kumiko Ogawa
- Division of Pathology, National Institute of Health Sciences, Kanagawa, Japan
| | - Takashi Umemura
- Division of Pathology, National Institute of Health Sciences, Kanagawa, Japan; Graduate School of Animal Health Technology, Yamazaki University of Animal Health Technology, Tokyo, Japan.
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Regulska K, Matera-Witkiewicz A, Mikołajczyk A, Stanisz BJ. In silico and in vitro screening for carcinogenic potential of angiotensin-converting enzyme inhibitors and their degradation impurities. Toxicol Appl Pharmacol 2023; 469:116541. [PMID: 37149094 DOI: 10.1016/j.taap.2023.116541] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/24/2023] [Accepted: 05/01/2023] [Indexed: 05/08/2023]
Abstract
According to some clinical observations, the use of angiotensin-converting enzyme inhibitors (ACEI) may be associated with an increased risk of cancer. The aim of the present study was to screen for the potential carcinogenicity, mutagenicity and genotoxicity of these drugs using in silico methodology. Delapril, enalapril, imidapril, lisinopril, moexipril, perindopril, ramipril, trandolapril, spirapril were thereby analyzed. In parallel, the corresponding degradation impurities, the diketopiperazine (DKP) derivatives, were also investigated. (Q)SAR computer software (VEGA-GUI and Lazar), available in the public domain, was employed. The obtained predictions suggested that none of the compounds tested (from the group of ACE-Is and DKPs) was mutagenic. Moreover, none of the ACE-Is was carcinogenic. The reliability of these predictions was high to moderate. In contrast, in the DKP group, ramipril-DKP and trandolapril-DKP were found to be potentially carcinogenic, but the reliability of this prediction was low. As for the genotoxicity screening, all compounds tested (ACE-I and DKP) were predicted to be active and genotoxic, with moexipril, ramipril, spirapril, and all DKP derivatives within the highest risk group. They were prioritized for experimental verification studies to confirm or exclude their toxic activity. On the other hand, the lowest risk of carcinogenicity was assigned to imidapril and its DKP. Then, a follow-up in vitro micronucleus assay for ramipril was performed. It showed that this drug was genotoxic via aneugenic activity, but only at concentrations exceeding real-life levels. At concentrations found in human blood after standard dose, ramipril was not genotoxic in vitro. Therefore, ramipril was considered safe for human use with a standard dosing regimen. The other compounds of concern (spirapril, moexipril and all DKP derivatives) should be subjected to analogous in vitro studies. We also concluded that the adopted in silico software was applicable for ACE-I toxicity prediction.
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Affiliation(s)
- Katarzyna Regulska
- Greater Poland Cancer Centre, Research and Implementation Unit, 15(th) Garbary Street, 61-866 Poznań, Poland; Poznan University of Medical Sciences, Department of Clinical Pharmacy and Biopharmacy, Collegium Pharmaceuticum, 3(rd) Rokietnicka Street, 60-806 Poznań, Poland.
| | - Agnieszka Matera-Witkiewicz
- Screening of Biological Activity Assays and Collection of Biological Material Laboratory, Wroclaw Medical University Biobank, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211 A, 50-556 Wroclaw, Poland
| | - Aleksandra Mikołajczyk
- Screening of Biological Activity Assays and Collection of Biological Material Laboratory, Wroclaw Medical University Biobank, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211 A, 50-556 Wroclaw, Poland
| | - Beata J Stanisz
- Poznan University of Medical Sciences, Chair and Department of Pharmaceutical Chemistry, 6(th) Grunwaldzka Street, 60-780 Poznan, Poland
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Kobets T, Smith BPC, Williams GM. Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk. Foods 2022; 11:foods11182828. [PMID: 36140952 PMCID: PMC9497933 DOI: 10.3390/foods11182828] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
- Correspondence: ; Tel.: +1-914-594-3105; Fax: +1-914-594-4163
| | - Benjamin P. C. Smith
- Future Ready Food Safety Hub, Nanyang Technological University, Singapore 639798, Singapore
| | - Gary M. Williams
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
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Konzept für die Bewertung von krebserzeugenden Stoffen im bevölkerungsbezogenen Human-Biomonitoring – Stellungnahme der Kommission Human-Biomonitoring des Umweltbundesamtes. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2022; 65:951-957. [PMID: 36048212 DOI: 10.1007/s00103-022-03570-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Linear non-threshold (LNT) fails numerous toxicological stress tests: Implications for continued policy use. Chem Biol Interact 2022; 365:110064. [DOI: 10.1016/j.cbi.2022.110064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/24/2022] [Accepted: 07/18/2022] [Indexed: 11/16/2022]
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Concept for the Evaluation of Carcinogenic Substances in Population-Based Human Biomonitoring. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19127235. [PMID: 35742488 PMCID: PMC9223427 DOI: 10.3390/ijerph19127235] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/03/2022] [Accepted: 06/10/2022] [Indexed: 11/17/2022]
Abstract
The Human Biomonitoring (HBM) Commission at the German Environment Agency holds the opinion that for environmental carcinogens for which no exposure levels can be assumed and are harmless to health, health-based guidance values corresponding to the classical definition of the HBM-I or HBM-II value cannot be established. Therefore, only reference values have been derived so far for genotoxic carcinogens from exposure data of the general population or subpopulations. The concept presented here opens up the possibility of performing health risk assessments of carcinogenic substances in human biomonitoring, and thus goes decisively beyond the purely descriptive statistical reference value concept. Using the presented method, quantitative dose descriptors of internal exposure can be derived from those of external exposure, provided that sufficient toxicokinetic information is available. Dose descriptors of internal exposure then allow the simple estimate of additional lifetime cancer risks for measured biomarker concentrations or, conversely, of equivalent concentrations for selected risks, such as those considered as tolerable for the general population. HBM data of chronic exposures to genotoxic carcinogens can thus be used to assess the additional lifetime cancer risk referring to the general population and to justify and prioritize risk management measures.
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11
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Acrylonitrile induction of rodent neoplasia: Potential mechanism of action and relevance to humans. TOXICOLOGY RESEARCH AND APPLICATION 2022. [DOI: 10.1177/23978473211055363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Acrylonitrile, an industrial chemical, is a multisite carcinogen in rats and mice, producing tumors in four tissues with barrier function, that is, brain, forestomach, Zymbal’s gland, and Harderian gland. To assess mechanism(s) of action (MoA) for induction of neoplasia and to evaluate whether the findings in rodents are indicative of human hazard, data on the potential key effects produced by acrylonitrile in the four rodent target tissues of carcinogenicity were evaluated. A notable finding was depletion of glutathione in various organs, including two target tissues, the brain, and forestomach, suggesting that this effect could be a critical initiating event. An additional combination of oxidative DNA damage and cytotoxic effects of acrylonitrile and its metabolites, cyanide, and 2-cyanoethylene oxide, could initiate pro-inflammatory signaling and sustained cell and tissue injury, leading to compensatory cell proliferation and neoplastic development. The in vivo DNA-binding and genotoxicity of acrylonitrile has been studied in several target tissues with no compelling positive results. Thus, while some mutagenic effects were reported in acrylonitrile-exposed rodents, data to determine whether this mutagenicity stems from direct DNA reactivity of acrylonitrile are insufficient. Accordingly, the induction of tumors in rodents is consistent primarily with a non-genotoxic MoA, although a contribution from weak mutagenicity cannot be ruled out. Mechanistic data to support conclusions regarding human hazard from acrylonitrile exposure is weak. Comparison of metabolism of acrylonitrile between rodents and humans provide little support for human hazard. Three of the tissues affected in bioassays (forestomach, Zymbal’s gland, and Harderian gland) are present only in rodents, while the brain is anatomically different between rodents and humans, diminishing relevance of tumor induction in these tissues to human hazard. Extensive epidemiological data has not revealed causation of human cancer by acrylonitrile.
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Hemgesberg M, Stegmüller S, Cartus A, Schrenk D. A Benchmark analysis of acrylamide-derived DNA adducts in rat hepatocytes in culture measured by a new, highly sensitive method. Toxicology 2021; 464:153022. [PMID: 34743026 DOI: 10.1016/j.tox.2021.153022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 10/31/2021] [Accepted: 11/01/2021] [Indexed: 10/19/2022]
Abstract
Acrylamide (AA) is a carcinogen formed during thermal food processing and can cause tumors in rodents while its carcinogenic potency in humans is unclear. Metabolism of AA, preferentially in the liver, leads to glycidamide (GA) forming N7-GA-guanine (N7-GA-Gua) as the major AA-derived DNA adduct in rodents. Here, a novel method allowing high sensitivity by avoidance of major matrix effects was applied to analyze N7-GA-Gua levels in nuclear DNA from rat hepatocytes in primary culture. We could thus for the first time detect a background level of 5-10 adducts/108 nucleosides in untreated hepatocytes. Incubation with AA did not result in a statistically significant increase in adduct levels over background up to a substrate concentration of 500 μM although a trend to slightly higher adduct levels was observed at and above 200 μM AA. At concentrations > 500 μM significant increases in N7-GA-Gua levels were found. When Benchmark concentration (BMC) modeling was applied to the data, non-linear concentration-response curves were obtained suggesting that AA started to cause measurable increases over background of N7-GA-Gua levels above certain concentrations only. Calculation of the composite BMCL10 (Lower Bound of a 95 % confidence interval) of a BMC leading to a 10 % increase of N7-GA-Gua levels over background resulted in a value of 6.35 μM AA after 24 h. A concentration below this value cannot be expected to lead to an increase in N7-GA-Gua of more than 10 % over the background seen in untreated hepatocytes.
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Affiliation(s)
- Melanie Hemgesberg
- Food Chemistry and Toxicology Department, University of Kaiserslautern, D-67663 Kaiserslautern, Germany.
| | - Simone Stegmüller
- Food Chemistry and Toxicology Department, University of Kaiserslautern, D-67663 Kaiserslautern, Germany.
| | - Alexander Cartus
- Food Chemistry and Toxicology Department, University of Kaiserslautern, D-67663 Kaiserslautern, Germany.
| | - Dieter Schrenk
- Food Chemistry and Toxicology Department, University of Kaiserslautern, D-67663 Kaiserslautern, Germany.
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Johnson GE, Dobo K, Gollapudi B, Harvey J, Kenny J, Kenyon M, Lynch A, Minocherhomji S, Nicolette J, Thybaud V, Wheeldon R, Zeller A. Permitted daily exposure limits for noteworthy N-nitrosamines. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2021; 62:293-305. [PMID: 34089278 DOI: 10.1002/em.22446] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
A genotoxic carcinogen, N-nitrosodimethylamine (NDMA), was detected as a synthesis impurity in some valsartan drugs in 2018, and other N-nitrosamines, such as N-nitrosodiethylamine (NDEA), were later detected in other sartan products. N-nitrosamines are pro-mutagens that can react with DNA following metabolism to produce DNA adducts, such as O6 -alkyl-guanine. The adducts can result in DNA replication miscoding errors leading to GC>AT mutations and increased risk of genomic instability and carcinogenesis. Both NDMA and NDEA are known rodent carcinogens in male and female rats. The DNA repair enzyme, methylguanine DNA-methyltransferase can restore DNA integrity via the removal of alkyl groups from guanine in an error-free fashion and this can result in nonlinear dose responses and a point of departure or "practical threshold" for mutation at low doses of exposure. Following International recommendations (ICHM7; ICHQ3C and ICHQ3D), we calculated permissible daily exposures (PDE) for NDMA and NDEA using published rodent cancer bioassay and in vivo mutagenicity data to determine benchmark dose values and define points of departure and adjusted with appropriate uncertainty factors (UFs). PDEs for NDMA were 6.2 and 0.6 μg/person/day for cancer and mutation, respectively, and for NDEA, 2.2 and 0.04 μg/person/day. Both PDEs are higher than the acceptable daily intake values (96 ng for NDMA and 26.5 ng for NDEA) calculated by regulatory authorities using simple linear extrapolation from carcinogenicity data. These PDE calculations using a bench-mark approach provide a more robust assessment of exposure limits compared with simple linear extrapolations and can better inform risk to patients exposed to the contaminated sartans.
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Affiliation(s)
- George E Johnson
- Swansea University Medical School, Swansea University, Swansea, Wales, UK
| | - Krista Dobo
- Genetic Toxicology, Drug Safety Research and Development, Pfizer, Groton, Connecticut, USA
| | - Bhaskar Gollapudi
- Center for Toxicology and Mechanistic Biology, Exponent Consulting, Midland, Michigan, USA
| | | | | | - Michelle Kenyon
- Genetic Toxicology, Drug Safety Research and Development, Pfizer, Groton, Connecticut, USA
| | | | | | - John Nicolette
- Genetic, Environmental and Occupational Toxicology, AbbVie, Chicago, Illinois, USA
| | | | - Ryan Wheeldon
- Swansea University Medical School, Swansea University, Swansea, Wales, UK
| | - Andreas Zeller
- Pharmaceutical Sciences, pRED Innovation Center Basel, Hoffmann-La Roche Ltd, Basel, Switzerland
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14
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Cohen JM, Beck BD, Rhomberg LR. Historical perspective on the role of cell proliferation in carcinogenesis for DNA-reactive and non-DNA-reactive carcinogens: Arsenic as an example. Toxicology 2021; 456:152783. [PMID: 33872731 DOI: 10.1016/j.tox.2021.152783] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/07/2021] [Accepted: 04/11/2021] [Indexed: 10/21/2022]
Abstract
Our understanding of the etiology of cancer has developed significantly over the past fifty years, beginning with a single-hit linear no-threshold (LNT) conceptual model based on early studies conducted in Drosophila. Over the past several decades, multiple lines of evidence have accumulated to support a contemporary model of chemical carcinogenesis: a multi-hit model involving a prolonged stress environment that over time may drive the mutation of multiple cells into an injured state that ultimately could lead to uncontrolled proliferation via clonal expansion of mutation-carrying daughter cells. Arsenic carcinogenicity offers a useful case study for further exploration of advanced conceptual models for chemical carcinogenesis. A threshold for arsenic carcinogenicity is supported by its mode of action, characterized by repeating cycles of cytotoxicity and cellular regeneration. Furthermore, preliminary meta-analyses of epidemiology dose-response data for inorganic arsenic (iAs) and bladder cancer, correlated to dose-response data measured in vitro, support a threshold of effect in humans on the order of 50-100 μg/L in drinking water. In light of recent developments in our understanding of cancer etiology, we urge strong consideration of the existing mode-of-action evidence supporting a threshold of effect for arsenic carcinogenicity, as well as consideration of the potential methodological pitfalls in evaluating epidemiology dose-response data that could potentially bias in the direction of low-dose linearity.
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Bercu JP, Masuda-Herrera M, Johnson G, Czich A, Glowienke S, Kenyon M, Thomas R, Ponting DJ, White A, Cross K, Waechter F, Rodrigues MAC. Use of less-than-lifetime (LTL) durational limits for nitrosamines: Case study of N-Nitrosodiethylamine (NDEA). Regul Toxicol Pharmacol 2021; 123:104926. [PMID: 33862169 DOI: 10.1016/j.yrtph.2021.104926] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 04/02/2021] [Accepted: 04/06/2021] [Indexed: 11/30/2022]
Abstract
The ICH M7(R1) guideline describes a framework to assess the carcinogenic risk of mutagenic and carcinogenic pharmaceutical impurities following less-than-lifetime (LTL) exposures. This LTL framework is important as many pharmaceuticals are not administered for a patient's lifetime and as clinical trials typically involve LTL exposures. While there has been regulatory caution about applying LTL concepts to cohort of concern (COC) impurities such as N-nitrosamines, ICH M7 does not preclude this and indeed literature data suggests that the LTL framework will be protective of patient safety for N-nitrosamines. The goal was to investigate if applying the LTL framework in ICH M7 would control exposure to an acceptable excess cancer risk in humans. Using N-nitrosodiethylamine as a case study, empirical data correlating exposure duration (as a percentage of lifespan) and cancer incidence in rodent bioassays indicate that the LTL acceptable intake (AI) as derived using the ICH M7 framework would not exceed a negligible additional risk of cancer. Therefore, controlling N-nitrosamines to an LTL AI based on the ICH M7 framework is thus demonstrated to be protective for potential carcinogenic risk to patients over the exposure durations typical of clinical trials and many prescribed medicines.
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Affiliation(s)
- Joel P Bercu
- Gilead Sciences, Nonclinical Safety and Pathobiology (NSP), Foster City, CA, USA.
| | | | - George Johnson
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA3 5DE, UK
| | - Andreas Czich
- Sanofi, R&D Preclinical Safety, D-65926, Frankfurt, Germany
| | | | - Michelle Kenyon
- Pfizer Worldwide Research and Development, Genetic Toxicology, Eastern Point Road, Groton, CT, USA
| | - Rob Thomas
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS, UK
| | - David J Ponting
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS, UK
| | - Angela White
- GlaxoSmithKline R&D, Park Road, Ware, Hertfordshire, SG12 0DP, UK
| | - Kevin Cross
- Leadscope Inc. an Instem Company, Columbus, OH, 43215, USA
| | - Fernanda Waechter
- Aché Laboratórios Farmacêuticos S.A., Rodovia Presidente Dutra, km 222,2, Porto da Igreja, 07034-904, Guarulhos, SP, Brazil
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16
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Adamson RH. A speculative discussion of four animal carcinogens endogenously produced in humans and a formula for cancer development. TOXICOLOGY RESEARCH AND APPLICATION 2020. [DOI: 10.1177/2397847320977540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The major factors (macro) which cause human cancer have been elucidated and include tobacco use, diet, infection, reproductive and sexual behavior and, to a lesser extent, alcohol consumption and occupational factors. Several reports have been published about endogenous chemicals made in humans which produce DNA adducts; however, few have linked them to possible carcinogenic activity. This paper discussed four chemicals made in humans (formaldehyde, acetaldehyde, isoprene and ethylene oxide), pathways of their formation, their animal carcinogenicity and questions about these and other endogenous chemicals’ possible role in human cancer. In addition, the author posits a simplified formula for development of cancer and a formula for causing mutations by various agents.
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17
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LeBaron MJ, Hotchkiss JA, Zhang F, Koehler MW, Boverhof DR. Investigation of potential early key events and mode of action for 1,2-dichloroethane-induced mammary tumors in female rats. J Appl Toxicol 2020; 41:362-374. [PMID: 32830330 DOI: 10.1002/jat.4048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/30/2020] [Accepted: 07/28/2020] [Indexed: 01/01/2023]
Abstract
1,2-dichloroethane (DCE or EDC) is a chlorinated hydrocarbon used as a chemical intermediate, including in the synthesis of polyvinyl chloride. Although DCE has induced tumors in both rats and mice, the overall weight-of-evidence suggests a lack of in vivo mutagenicity. The present study was conducted to explore a potential mode of action further for tumor formation in rat mammary tissue. Fischer 344 rats were exposed to target concentrations of 0 or 200 ppm of DCE vapors (6 hours/day, 7 days/week) for at least 28 days; 200 ppm represents a concentration of ~20% higher than that reported to induce mammary tumors. Endpoints examined included DNA damage (via Comet assay), glutathione (reduced, oxidized and conjugated), tissue DNA adducts, cell proliferation and serum prolactin levels. Exposure to DCE did not alter serum prolactin levels with consistent estrous stage, did not cause cell proliferation in mammary epithelial cells, nor result in histopathological alterations in the mammary gland. DNA adducts were identified, including the N7 -guanylethyl glutathione adduct, with higher adduct levels measured in liver (nontumorigenic target) compared with mammary tissue isolated from the same rats; no known mutagenic adducts were identified. DCE did not increase the Comet assay response in mammary epithelial cells, whereas DNA damage in the positive control (N-nitroso-N-methylurea) was significantly increased. Although the result of this study did not identify a specific mode of action for DCE-induced mammary tumors in rats, the lack of any exposure-related genotoxic responses further contributes to the weight-of-evidence suggesting that DCE is a nongenotoxic carcinogen.
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Affiliation(s)
- Matthew J LeBaron
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, Midland, Michigan, USA
| | - Jon A Hotchkiss
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, Midland, Michigan, USA
| | - Fagen Zhang
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, Midland, Michigan, USA
| | - Matthew W Koehler
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, Midland, Michigan, USA
| | - Darrell R Boverhof
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, Midland, Michigan, USA
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18
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Kluxen FM. "New statistics" in regulatory toxicology? Regul Toxicol Pharmacol 2020; 117:104763. [PMID: 32781239 DOI: 10.1016/j.yrtph.2020.104763] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/04/2020] [Accepted: 08/07/2020] [Indexed: 12/28/2022]
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19
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Hartwig A, Arand M, Epe B, Guth S, Jahnke G, Lampen A, Martus HJ, Monien B, Rietjens IMCM, Schmitz-Spanke S, Schriever-Schwemmer G, Steinberg P, Eisenbrand G. Mode of action-based risk assessment of genotoxic carcinogens. Arch Toxicol 2020; 94:1787-1877. [PMID: 32542409 PMCID: PMC7303094 DOI: 10.1007/s00204-020-02733-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as "omics" approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B1, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs.
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Affiliation(s)
- Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany.
| | - Michael Arand
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zurich, Switzerland
| | - Bernd Epe
- Institute of Pharmacy and Biochemistry, University of Mainz, 55099, Mainz, Germany
| | - Sabine Guth
- Department of Toxicology, IfADo-Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund, Ardeystr. 67, 44139, Dortmund, Germany
| | - Gunnar Jahnke
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Alfonso Lampen
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Hans-Jörg Martus
- Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Bernhard Monien
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Simone Schmitz-Spanke
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Henkestr. 9-11, 91054, Erlangen, Germany
| | - Gerlinde Schriever-Schwemmer
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131, Karlsruhe, Germany
| | - Gerhard Eisenbrand
- Retired Senior Professor for Food Chemistry and Toxicology, Kühler Grund 48/1, 69126, Heidelberg, Germany.
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20
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EURL ECVAM Genotoxicity and Carcinogenicity Database of Substances Eliciting Negative Results in the Ames Test: Construction of the Database. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2020; 854-855:503199. [PMID: 32660827 PMCID: PMC7374420 DOI: 10.1016/j.mrgentox.2020.503199] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 01/08/2023]
Abstract
EURL ECVAM Consolidated Genotoxicity and Carcinogenicity Database extended. Negative Ames test results were compiled and reviewed. A database of Ames negative results was constructed. Database chemical space characterization was conducted. OFG representation of carcinogens and non-carcinogens was characterised.
The bacterial reverse mutation test (Ames test) is the most commonly used genotoxicity test; it is a primary component of the chemical safety assessment data required by regulatory agencies worldwide. Within the current accepted in vitro genotoxicity test battery, it is considered capable of revealing DNA reactivity, and identifying substances that can produce gene mutations via different mechanisms. The previously published consolidated EURL ECVAM Genotoxicity and Carcinogenicity Database, which includes substances that elicited a positive response in the Ames test, constitutes a collection of data that serves as a reference for a number of regulatory activities in the area of genotoxicity testing. Consequently, we considered it important to expand the database to include substances that fail to elicit a positive response in the Ames test, i.e., Ames negative substances. Here, we describe a curated collection of 211 Ames negative substances, with a summary of complementary data available for other genotoxicity endpoints in vitro and in vivo, plus available carcinogenicity data. A descriptive analysis of the data is presented. This includes a representation of the chemical space formed by the Ames-negative database with respect to other substances (e.g. REACH registered substances, approved drugs, pesticides, etc.) and a description of the organic functional groups found in the database. We also provide some suggestions on further analyses that could be made.
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21
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Brescia S. Thresholds of adversity and their applicability to endocrine disrupting chemicals. Crit Rev Toxicol 2020; 50:213-218. [PMID: 32228218 DOI: 10.1080/10408444.2020.1740973] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Within the European Union, various legislative acts contain specific provisions on endocrine disruption, requiring the regulation of substances with endocrine disrupting properties via a hazard-based approach. Presumably this is due to an assumed lack of thresholds for the adverse effects of such substances. Conversely, in other jurisdictions, such as USA, Canada, Australia and Japan, endocrine disruptors (EDs) are regulated using a risk-based approach. As a consequence, in recent years there has been increasing controversy on whether thresholds can be inferred for endocrine-mediated effects. There is concern that the endocrine system is too complex to allow estimation of safe levels of exposure to such chemicals. This brief review aims to evaluate the available scientific evidence in this area and offer a sound and robust conclusion supported by this analysis. It is concluded that there is nothing special or unique about endocrine disruption or greater uncertainties in its assessment compared to other non-genotoxic forms of toxicity to justify adopting a non-threshold approach by default. Biology predicts that thresholds of adversity exist and are the rule for all endpoints, including those arising from endocrine disruption. A threshold approach to the risk assessment of endocrine disrupting chemicals is scientifically justified.
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Affiliation(s)
- Susy Brescia
- Health and Safety Executive (HSE), Chemicals Regulation Division (CRD), Merseyside, UK
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22
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Felter SP, Boobis AR, Botham PA, Brousse A, Greim H, Hollnagel HM, Sauer UG. Hazard identification, classification, and risk assessment of carcinogens: too much or too little? - Report of an ECETOC workshop. Crit Rev Toxicol 2020; 50:72-95. [PMID: 32133908 DOI: 10.1080/10408444.2020.1727843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) organized a workshop "Hazard Identification, Classification and Risk Assessment of Carcinogens: Too Much or Too Little?" to explore the scientific limitations of the current binary carcinogenicity classification scheme that classifies substances as either carcinogenic or not. Classification is often based upon the rodent 2-year bioassay, which has scientific limitations and is not necessary to predict whether substances are likely human carcinogens. By contrast, tiered testing strategies founded on new approach methodologies (NAMs) followed by subchronic toxicity testing, as necessary, are useful to determine if a substance is likely carcinogenic, by which mode-of-action effects would occur and, for non-genotoxic carcinogens, the dose levels below which the key events leading to carcinogenicity are not affected. Importantly, the objective is not for NAMs to mimic high-dose effects recorded in vivo, as these are not relevant to human risk assessment. Carcinogenicity testing at the "maximum tolerated dose" does not reflect human exposure conditions, but causes major disturbances of homeostasis, which are very unlikely to occur at relevant human exposure levels. The evaluation of findings should consider biological relevance and not just statistical significance. Using this approach, safe exposures to non-genotoxic substances can be established.
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Affiliation(s)
| | | | | | - Alice Brousse
- European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), Brussels, Belgium
| | | | | | - Ursula G Sauer
- Scientific Consultancy - Animal Welfare, Neubiberg, Germany
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23
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Klapacz J, Gollapudi BB. Considerations for the Use of Mutation as a Regulatory Endpoint in Risk Assessment. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:84-93. [PMID: 31301246 DOI: 10.1002/em.22318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/08/2019] [Accepted: 07/10/2019] [Indexed: 06/10/2023]
Abstract
Assessment of a chemical's potential to cause permanent changes in the genetic code has been a common practice in the industry and regulatory settings for decades. Furthermore, the genetic toxicity battery of tests has typically been employed during the earliest stages of the research and development programs of new product development. A positive outcome from such battery has a major impact on the chemical's utility, industrial hygiene, product stewardship practices, and product life cycle analysis, among many other decisions that need to be taken by the industry, even before the registration of a chemical is undertaken. Under the prevailing regulatory paradigm, the dichotomous (yes/no) evaluation of the chemical's genotoxic potential leads to a conservative, linear no-threshold (LNT) risk assessment, unless compelling and undeniable data to the contrary can be provided to satisfy regulators, typically in a number of different global jurisdictions. With the current advent of predictive methods, new testing paradigms, mode-of-action/adverse outcome pathways, and quantitative risk assessment approaches, various stakeholders are starting to employ these state-of-the-science methodologies to further the conversation on decision making and advance the regulatory paradigm beyond the dominant LNT status quo. This commentary describes these novel methodologies, relevant biological responses, and how these can affect internal and regulatory risk assessment approaches. Environ. Mol. Mutagen. 61:84-93, 2020. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Joanna Klapacz
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan
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24
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Smart DJ, Helbling FR, Verardo M, Huber A, McHugh D, Vanscheeuwijck P. Development of an integrated assay in human TK6 cells to permit comprehensive genotoxicity analysis in vitro. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2020; 849:503129. [DOI: 10.1016/j.mrgentox.2019.503129] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/26/2019] [Accepted: 12/23/2019] [Indexed: 01/24/2023]
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25
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Kobets T, Iatropoulos MJ, Williams GM. Mechanisms of DNA-reactive and epigenetic chemical carcinogens: applications to carcinogenicity testing and risk assessment. Toxicol Res (Camb) 2019; 8:123-145. [PMID: 30997017 PMCID: PMC6417487 DOI: 10.1039/c8tx00250a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 12/18/2018] [Indexed: 01/03/2023] Open
Abstract
Chemicals with carcinogenic activity in either animals or humans produce increases in neoplasia through diverse mechanisms. One mechanism is reaction with nuclear DNA. Other mechanisms consist of epigenetic effects involving either modifications of regulatory macromolecules or perturbation of cellular regulatory processes. The basis for distinguishing between carcinogens that have either DNA reactivity or an epigenetic activity as their primary mechanism of action is detailed in this review. In addition, important applications of information on these mechanisms of action to carcinogenicity testing and human risk assessment are discussed.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology , New York Medical College , Valhalla , NY 10595 , USA . ; ; Tel: +1 914-594-3105
| | - Michael J Iatropoulos
- Department of Pathology , New York Medical College , Valhalla , NY 10595 , USA . ; ; Tel: +1 914-594-3105
| | - Gary M Williams
- Department of Pathology , New York Medical College , Valhalla , NY 10595 , USA . ; ; Tel: +1 914-594-3105
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