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International Journal of Environmental... Aug 2021Antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) and other viral infections are among the emerging contaminants considered for ecological...
Antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) and other viral infections are among the emerging contaminants considered for ecological risk assessment. These compounds have been reported to be widely distributed in water bodies and other aquatic environments, while data concerning the risk they may pose to unintended non-target species in a different ecosystem (environment) is scanty. In South Africa and other developing countries, lamivudine is one of the common antiretrovirals applied. Despite this, little is known about its environmental impacts as an emerging contaminant. The present study employed a battery of ecotoxicity bioassays to assess the environmental threat lamivudine poses to aquatic fauna and flora. (filter feeders), the Ames bacterial mutagenicity test, (lettuce) germination test, and the root tip assay were conducted, testing lamivudine at two concentrations (10 and 100 µg/L), with environmental relevance. The toxicity test revealed a statistically significant response ( << 0.05) with a mortality rate of 85% on exposure to 100 µg/L lamivudine in freshwater, which increased to 100% at 48-h exposure. At lower concentrations of 10 µg/L lamivudine, 90% and 55% survival rates were observed at 24 h and 48 h, respectively. No potential mutagenic effects were observed from the Ames test at both concentrations of lamivudine. bioassays revealed a noticeable adverse impact on the root lengths on exposure to 100 µg/L lamivudine. This impact was further investigated through microscopic examination, revealing some chromosomal aberration in the exposed root tips. The bioassay showed a slight adverse impact on both the germination rate of the seeds and their respective hypocotyl lengths compared to the control. Overall, this indicates that lamivudine poses an ecological health risk at different trophic levels, to both flora and fauna, at concentrations previously found in the environment.
Topics: Animals; Daphnia; Ecosystem; Humans; Lamivudine; Onions; Toxicity Tests; Water Pollutants, Chemical
PubMed: 34444108
DOI: 10.3390/ijerph18168358 -
Toxicology Feb 2022Molybdenum, lithium, and tungsten are constituents of many products, and exposure to these elements potentially occurs at work. Therefore it is important to determine at... (Review)
Review
Molybdenum, lithium, and tungsten are constituents of many products, and exposure to these elements potentially occurs at work. Therefore it is important to determine at what levels they are toxic, and thus we set out to review their pulmonary toxicity, genotoxicity, and carcinogenicity. After pulmonary exposure, molybdenum and tungsten are increased in multiple tissues; data on the distribution of lithium are limited. Excretion of all three elements is both via faeces and urine. Molybdenum trioxide exerted pulmonary toxicity in a 2-year inhalation study in rats and mice with a lowest-observed-adverse-effect concentration (LOAEC) of 6.6 mg Mo/m. Lithium chloride had a LOAEC of 1.9 mg Li/m after subacute inhalation in rabbits. Tungsten oxide nanoparticles resulted in a no-observed-adverse-effect concentration (NOAEC) of 5 mg/m after inhalation in hamsters. In another study, tungsten blue oxide had a LOAEC of 63 mg W/m in rats. Concerning genotoxicity, for molybdenum, the in vivo genotoxicity after inhalation remains unknown; however, there was some evidence of carcinogenicity of molybdenum trioxide. The data on the genotoxicity of lithium are equivocal, and one carcinogenicity study was negative. Tungsten seems to have a genotoxic potential, but the data on carcinogenicity are equivocal. In conclusion, for all three elements, dose descriptors for inhalation toxicity were identified, and the potential for genotoxicity and carcinogenicity was assessed.
Topics: Animals; Body Burden; Carcinogenicity Tests; Cell Transformation, Neoplastic; Dose-Response Relationship, Drug; Humans; Inhalation Exposure; Lithium Chloride; Lung; Metal Nanoparticles; Molybdenum; Mutagenicity Tests; Neoplasms; Oxides; Risk Assessment; Tungsten
PubMed: 35026344
DOI: 10.1016/j.tox.2022.153098 -
Genes & Genetic Systems Apr 2023Chromosomal damage occurs both endogenously and exogenously and is a crucial factor in the induction of carcinogenesis. Chemically induced chromosomal damage is mainly... (Review)
Review
Chromosomal damage occurs both endogenously and exogenously and is a crucial factor in the induction of carcinogenesis. Chemically induced chromosomal damage is mainly exogenous. The OECD has developed methods to detect chemicals that induce chromosomal damage so as to identify hazardous substances and limit their exposure to humans. The development and improvement of in vitro mammalian cell methods have been the focus of recent research, as these techniques have higher throughput than in vivo animal methods and are cruelty-free. In vitro mammalian cell methods are highly sensitive and widely used. Nevertheless, they have a high frequency of misleading positive test results, causing the wastage of vital raw materials and pharmaceutical agents, and necessitating additional in vivo animal tests. Therefore, the improvement of in vitro mammalian cell methods is required. Novel methodologies have been proposed and developed for robust animal-free evaluation. As they include omics and AI approaches that use big data, they may enable objective, multidirectional interpretation when applied in combination with current in vitro experimental techniques. We review the existing approaches toward improving chromosome damage detection and introduce innovative techniques that facilitate animal-free testing. The current and latest evaluation methods can support the protection of public health as well as the development of promising chemicals that enrich our lives.
Topics: Animals; Humans; Mutagenicity Tests; Public Health; Carcinogenesis; DNA Damage; Chromosomes; Mammals
PubMed: 36754383
DOI: 10.1266/ggs.22-00058 -
International Journal of Molecular... Jun 2021The toxicity of chloroacetamide herbicide in embryo development remains unclear. Acetochlor (AC) is a chloroacetamide that metabolizes into...
The toxicity of chloroacetamide herbicide in embryo development remains unclear. Acetochlor (AC) is a chloroacetamide that metabolizes into 2‑ethyl‑6‑methyl-2-chloroacetanilide (CMEPA) and 6‑ethyl‑o‑toluidine (MEA). The present study determined the potential effect of AC and its metabolites on embryo development. Both HepG2 cells and zebrafish embryos were exposed to AC, CMEPA and MEA in the presence or absence of co‑treatment with anti‑reactive oxygen species (ROS) reagent N‑acetylcysteine. The generation of ROS, levels of superoxide dismutase (SOD) and glutathione (GSH) in HepG2 cells and lactate dehydrogenase (LDH) leakage from HepG2 cells were investigated. The effects of AC, CMEPA and MEA on DNA breakage, MAPK/ERK pathway activity, viability and apoptosis of HepG2 cells were examined by comet assay, western blotting, MTT assay and flow cytometry, respectively. Levels of LDH, SOD and GSH in zebrafish embryos exposed to AC, CMEPA and MEA were measured. The hatching and survival rates of zebrafish embryos exposed to AC, CMEPA and MEA, were determined, and apoptosis of hatched fish was investigated using acridine orange staining. The present data showed AC, CMEPA and MEA induced generation of ROS and decreased levels of SOD and GSH in HepG2 cells, which in turn promoted DNA breakage and LDH leakage from cells, ultimately inhibiting cell viability and inducing apoptosis, as well as phosphorylation of JNK and P38. However, co‑treatment with N‑acetylcysteine alleviated the pro‑apoptosis effect of AC and its metabolites. Moreover, exposure to AC, CMEPA and MEA lead to toxicity of zebrafish embryos with decreased SOD and GSH and increased LDH levels and cell apoptosis, ultimately decreasing the hatching and survival rates of zebrafish, all of which was attenuated by treatment with N‑acetylcysteine. Therefore, AC and its metabolites (CMEPA and MEA) showed cytotoxicity and embryo development toxicity.
Topics: Acetamides; Acetanilides; Animals; Apoptosis; Embryo, Nonmammalian; Glutathione; Hep G2 Cells; Herbicides; Humans; L-Lactate Dehydrogenase; Metabolome; Mutagenicity Tests; Reactive Oxygen Species; Superoxide Dismutase; Survival Analysis; Toluidines; Zebrafish
PubMed: 33907828
DOI: 10.3892/ijmm.2021.4936 -
Regulatory Toxicology and Pharmacology... Oct 2019In silico toxicology (IST) approaches to rapidly assess chemical hazard, and usage of such methods is increasing in all applications but especially for regulatory...
In silico toxicology (IST) approaches to rapidly assess chemical hazard, and usage of such methods is increasing in all applications but especially for regulatory submissions, such as for assessing chemicals under REACH as well as the ICH M7 guideline for drug impurities. There are a number of obstacles to performing an IST assessment, including uncertainty in how such an assessment and associated expert review should be performed or what is fit for purpose, as well as a lack of confidence that the results will be accepted by colleagues, collaborators and regulatory authorities. To address this, a project to develop a series of IST protocols for different hazard endpoints has been initiated and this paper describes the genetic toxicity in silico (GIST) protocol. The protocol outlines a hazard assessment framework including key effects/mechanisms and their relationships to endpoints such as gene mutation and clastogenicity. IST models and data are reviewed that support the assessment of these effects/mechanisms along with defined approaches for combining the information and evaluating the confidence in the assessment. This protocol has been developed through a consortium of toxicologists, computational scientists, and regulatory scientists across several industries to support the implementation and acceptance of in silico approaches.
Topics: Animals; Computer Simulation; Humans; Models, Theoretical; Mutagenicity Tests; Mutagens; Research Design; Risk Assessment; Toxicology
PubMed: 31195068
DOI: 10.1016/j.yrtph.2019.104403 -
Mutation Research. Genetic Toxicology... Nov 2019Chemical safety evaluations require assessment of genetic toxicity. Transgenic rodent (TGR) assays permit enumeration of mutations in chromosomally-integrated targets... (Review)
Review
Chemical safety evaluations require assessment of genetic toxicity. Transgenic rodent (TGR) assays permit enumeration of mutations in chromosomally-integrated targets contained in shuttle vectors. In order to improve in vitro mutagenicity assessment, and to substantially reduce animal use, in vitro assays using transgenic reporters have been developed. These assays are based on cells derived from TGRs, or cells transfected with transgenic shuttle vectors containing a mutation target. As part of the 7th International Workshop on Genotoxicity Testing, an In Vitro Mammalian Cell Gene Mutation Assay working group reviewed all published information pertaining to in vitro transgene mutagenicity assays; the utility, advantages and disadvantages of the assays were evaluated and discussed. The review revealed that over 20 TGR-based in vitro assays have been used to assess the mutagenic activity of over 150 agents. Overall, the Working Group considered in vitro transgene mutagenicity assays pragmatic tools for the safety evaluation of new and existing substances. A formal SWOT (strengths, weaknesses, opportunities, threats) analysis revealed advantages including the use of established scoring protocols, avoidance of laborious clone isolation and enumeration, ability to use metabolically competent primary cells, ability to detect different types of genetic damage, large dynamic range, and complementarity to in vivo TGR endpoints. Disadvantages include lack of validation and little consistency in protocols, the use of specialised reagents, the time and effort required for mutant enumeration, the use of some cell lines that lack metabolic capacity, and the need for multiple assays to cover all mutational mechanisms. Several assays have been partially validated, indicating promising reliability, reproducibility and applicability domain. Once in vitro transgene mutagenicity assays have been more thoroughly validated, they are well placed to augment or replace existing in vitro mammalian cell mutagenicity assays, particularly in cases where the in vivo TGR mutation assay is intended for follow-up.
Topics: Animals; Animals, Genetically Modified; Biotransformation; Cell Division; Cell Line; Escherichia coli Proteins; Genes, Reporter; Genetic Vectors; Humans; In Vitro Techniques; Lac Operon; Mutagenicity Tests; Pentosyltransferases; Reproducibility of Results; Research Design; Rodentia; Transgenes; Validation Studies as Topic
PubMed: 31699347
DOI: 10.1016/j.mrgentox.2019.04.002 -
Mutation Research. Genetic Toxicology... Dec 2019The bacterial reverse mutation test is a mainstay for evaluation of mutagenicity predicting the carcinogenic potential of a test substance and is recommended by...
The bacterial reverse mutation test is a mainstay for evaluation of mutagenicity predicting the carcinogenic potential of a test substance and is recommended by regulatory agencies across the globe. The popularity of the test is due, in part, to the relatively low cost, rapid results and small amount of test material required compared to most other toxicological tests as well as the near universal acceptance of the toxicological significance of a clear positive or negative result. Most laboratories follow the Organization for Economic Cooperation and Development Test Guideline 471 (TG471) or national guidelines based on TG471. Regulatory agencies in most countries are obligated to consider results from tests which meet the recommendations laid out in TG471. Nonetheless, laboratories unfamiliar with the test sometimes have trouble generating reliable, reproducible results. TG471 is a test guideline, not a detailed test protocol. A group of experts from regulatory agencies and laboratories which use the assay has assembled here a set of recommendations which if followed, will allow an inexperienced laboratory to acquire proficiency in assay conduct. These include recommendations for how to create a cell bank for the 5 Salmonella typhimurium/Escherichia coli strains and develop a laboratory protocol to reliably culture each strain to ensure each culture has the characteristics which allow adequate sensitivity for detection of mutagens using the test as described in TG471. By testing compounds on the provided lists of positive and negative test substances, the laboratory will have surmounted many of the problems commonly encountered during routine testing of unknown chemicals and will have gained the experience necessary to prepare the detailed protocol needed for performing the test under Good Laboratory Procedures and the laboratory will have generated the historical positive and negative control databases which are needed for test reports which adhere to TG471.
Topics: Efficiency, Organizational; Escherichia coli; Laboratories; Mutagenicity Tests; Salmonella typhimurium
PubMed: 31708077
DOI: 10.1016/j.mrgentox.2019.07.005 -
Molecules (Basel, Switzerland) Feb 2021(RVS) has been traditionally used as an herbal remedy to support the digestive functions in traditional Korean medicine. Additionally, the pharmacological effects of...
(RVS) has been traditionally used as an herbal remedy to support the digestive functions in traditional Korean medicine. Additionally, the pharmacological effects of RVS, including antioxidative, antimicrobial and anticancer activities, have been well-reported. The genotoxicity of RVS, however, is elusive; thus, we evaluated the genotoxicity of RVS without bark (RVX) for safe application as a resource of functional food or a medical drug. To evaluate the genotoxicity of RVX, we used a bacterial reverse mutation test, chromosomal aberration test and comet assay, according to the "Organization for Economic Co-operation and Development" (OECD) guidelines. Briefly, for the reverse mutation test, samples (5000, 1667, 556, 185, 62 and 0 μg/plate of RVX or the positive control) were treated with a precultured strain (TA98, TA100, TA1535, TA1537 or WP2µvrA) with or without the S9 mix, in which RVX partially induced a reverse mutation in four bacterial strains. From the chromosomal aberration test and comet assay, the RVX samples (556, 185, 62, 20 and 0 μg/mL of RVX or the positive control) were treated in a Chinese hamster ovary cell line (CHO-K1 cells) in the conditions of the S9 mix absent or S9 mix present and in Chang liver cells and C2C12 myoblasts, respectively. No chromosomal aberrations in CHO-K1 or DNA damage in Chang liver cells and C2C12 myoblasts was observed. In conclusion, our results suggest the non-genotoxicity of RVX, which would be helpful as a reference for the safe application of bark-removed as functional raw materials in the food, cosmetics or pharmaceutical fields.
Topics: Animals; CHO Cells; Cricetulus; Dose-Response Relationship, Drug; Humans; Mice; Mutagenicity Tests; Plant Bark; Plant Extracts; Rhus; Water
PubMed: 33567750
DOI: 10.3390/molecules26040896 -
Food and Chemical Toxicology : An... Jun 2021β-Carotene oxidation products have newly discovered bioactivity in plants and animals. Synthetic fully oxidized β-carotene (OxBC) has application in supporting...
β-Carotene oxidation products have newly discovered bioactivity in plants and animals. Synthetic fully oxidized β-carotene (OxBC) has application in supporting livestock health, with potential human applications. The safety of synthetic OxBC has been evaluated. An Ames test showed weak-to-moderate mutagenicity in only one cell line at high concentrations. A mouse micronucleus assay established a non-toxic dose of 1800 mg/kg body weight, and no bone marrow micronuclei were induced. Plant sources of β-carotene inevitably contain varying levels of natural OxBC. Vegetable powders and dried forages can be especially rich. Intakes of natural OxBC for humans and livestock alike have been estimated. The exposure range for humans (1-22 mg/serving) is comparable to the safe intake of β-carotene (<15 mg/d). In livestock, OxBC in alfalfa can contribute ~550-850 mg/head/d for dairy cattle but in forage-deficient poultry feed much less (~1 ppm). Livestock intake of supplemental synthetic OxBC is comparable to OxBC potentially available from traditional plant sources. Human intake of synthetic OxBC in meat from livestock fed OxBC is similar to a single serving of food made with carrot powder. It is concluded that consumption of synthetic OxBC at levels comparable to natural OxBC is safe for humans and animals.
Topics: Animals; Cats; Cattle; Dietary Exposure; Dogs; Escherichia coli; Humans; Mice; Micronucleus Tests; Oxidation-Reduction; Poultry; Salmonella typhimurium; Swine; beta Carotene
PubMed: 33891992
DOI: 10.1016/j.fct.2021.112207 -
Regulatory Toxicology and Pharmacology... Dec 2020Currently the only methods for non-genotoxic carcinogenic hazard assessment accepted by most regulatory authorities are lifetime carcinogenicity studies. However, these... (Review)
Review
Currently the only methods for non-genotoxic carcinogenic hazard assessment accepted by most regulatory authorities are lifetime carcinogenicity studies. However, these involve the use of large numbers of animals and the relevance of their predictive power and results has been scientifically challenged. With increased availability of innovative test methods and enhanced understanding of carcinogenic processes, it is believed that tumour formation can now be better predicted using mechanistic information. A workshop organised by the European Partnership on Alternative Approaches to Animal Testing brought together experts to discuss an alternative, mechanism-based approach for cancer risk assessment of agrochemicals. Data from a toolbox of test methods for detecting modes of action (MOAs) underlying non-genotoxic carcinogenicity are combined with information from subchronic toxicity studies in a weight-of-evidence approach to identify carcinogenic potential of a test substance. The workshop included interactive sessions to discuss the approach using case studies. These showed that fine-tuning is needed, to build confidence in the proposed approach, to ensure scientific correctness, and to address different regulatory needs. This novel approach was considered realistic, and its regulatory acceptance and implementation can be facilitated in the coming years through continued dialogue between all stakeholders and building confidence in alternative approaches.
Topics: Agrochemicals; Animal Testing Alternatives; Animals; Carcinogenicity Tests; Cell Transformation, Neoplastic; Congresses as Topic; Humans; Mutagenicity Tests; Neoplasms; Risk Assessment; Toxicity Tests, Subchronic; Toxicokinetics
PubMed: 33035627
DOI: 10.1016/j.yrtph.2020.104789