-
Mutation Research. Genetic Toxicology... Dec 2019A committee was constituted within the International Workshop on Genetic Toxicology Testing (IWGT) to evaluate the current criteria for a valid Ames test and to provide...
A committee was constituted within the International Workshop on Genetic Toxicology Testing (IWGT) to evaluate the current criteria for a valid Ames test and to provide recommendations for interpretation of test results. Currently, determination of a positive vs. a negative result is made by applying various data evaluation procedures for comparing dosed plates with the concurrent solvent control plates. These evaluation procedures include a requirement for a specific fold increase (2- or 3-fold, specific to the bacterial strain), formal statistical procedures, or subjective (expert judgment) evaluation. After extensive discussion, the workgroup was not able to reach consensus recommendations in favor of any of these procedures. There was a consensus that combining additional evaluation criteria to the comparison between dosed plates and the concurrent solvent control plates improves test interpretation. The workgroup recommended using these additional criteria because the induction of mutations is a continuum of responses and there is no biological relevance to a strict dividing line between a positive (mutagenic) and not-positive (nonmutagenic) response. The most useful additional criteria identified were a concentration-response relationship and consideration of a possible increase above the concurrent control in the context of the laboratory's historical solvent control values for the particular tester strain. The workgroup also emphasized the need for additional testing to resolve weak or inconclusive responses, usually with altered experimental conditions chosen based on the initial results. Use of these multiple criteria allowed the workgroup to reach consensus on definitions of "clear positive" and "clear negative" responses which would not require a repeat test for clarification. The workgroup also reached consensus on recommendations to compare the responses of concurrent positive and negative controls to historical control distributions for assay acceptability, and the use of control charts to determine the validity of the individual test.
Topics: Animals; Evaluation Studies as Topic; Humans; Mutagenicity Tests; Salmonella typhimurium
PubMed: 31708073
DOI: 10.1016/j.mrgentox.2019.07.004 -
Environmental and Molecular Mutagenesis Jan 20233-Chloroallyl alcohol (3-CAA) can be found in the environment following the application of plant protection products. 3-CAA is formed in groundwater following the...
3-Chloroallyl alcohol (3-CAA) can be found in the environment following the application of plant protection products. 3-CAA is formed in groundwater following the injection of 1,3-dichloropropene, a fumigant used to control nematodes. 3-CAA is also formed, in leafy crops, as a glycoside conjugate following application of the herbicide, clethodim. Human exposure may occur from groundwater used as drinking water or through dietary consumption. To characterize 3-CAA's potential to cause genotoxicity in mammals, in vitro and in vivo studies were conducted. 3-CAA was negative in an Ames test and positive in a mouse lymphoma forward mutation assay. 3-CAA was negative in an acute in vivo CD-1 mouse bone marrow micronucleus assay when administered up to a dose level of 125 mg/kg/day for two consecutive days. In a combined gene mutation assay and erythrocyte micronucleus assay, using transgenic Big Blue® Fischer 344 rats, 3-CAA was administered via drinking water at targeted dose levels of 0, 10, 30, and 100 mg/kg/day for 29 days. Peripheral blood samples, collected at the end of treatment, were analyzed for micronucleus induction in reticulocytes using flow cytometry. Liver and bone marrow samples, collected 2 days after the termination of the treatment, were analyzed for the induction of mutations at the cII locus. 3-CAA did not induce an increase in mutant frequency or micronuclei under the experimental conditions. In conclusion, the mutagenic response observed in the in vitro mouse lymphoma assay is not confirmed in the whole animal. 3-CAA is not considered to pose a mutagenic risk.
Topics: Rats; Mice; Humans; Animals; Drinking Water; Mutagens; Micronucleus Tests; DNA Damage; Rats, Inbred F344; Lymphoma; Mutagenicity Tests; Mammals
PubMed: 36314072
DOI: 10.1002/em.22515 -
Toxicology Aug 20202-Methoxy-4-nitroaniline (MNA), an intermediate in the synthesis of azo dyes used in textiles and paints, is structurally similar to carcinogenic anilines. Human...
2-Methoxy-4-nitroaniline (MNA), an intermediate in the synthesis of azo dyes used in textiles and paints, is structurally similar to carcinogenic anilines. Human exposure occurs primarily in the occupational setting through handling of dye dust, and through use and disposal of MNA-containing products. MNA has been reported to induce contact hypersensitivity in a human, myocardial necrosis in rats, and bacterial mutagenicity. This study assessed the subacute toxicity, genotoxicity, contact hypersensitivity, and reproductive toxicity of MNA in rodents in an effort to more fully characterize its toxicological profile. B6C3F1/N mice were exposed to 0, 650, 1250, 2500, 5000, or 10,000 ppm MNA by dosed feed for 14-days to evaluate subacute toxicity and histopathological endpoints. In female mice, decreased body weight (13.5 %) and absolute kidney weight (14.8 %), compared to control, were observed at 10,000 ppm MNA; increased relative liver weight (10-12 %), compared to control, occurred at 5,000-10,000 ppm MNA. In male mice, absolute (15 %) and relative liver weights (9-13 %) were increased at 2,500-5,000 ppm and 1250-10,000 ppm MNA, compared to control, respectively. In both sexes of mice, minimal elevations of hemosiderin pigmentation (a breakdown product of erythrocytes), relative to control, were observed in the liver (10,000 ppm); minimal to moderate elevations of hemosiderin pigmentation (5,000-10,000 ppm) and minimal increases in hematopoietic cell proliferation occurred in the spleen (≥ 1250 ppm). In a reproductive toxicity study, timed-mated female Harlan Sprague Dawley rats were exposed to 0-10,000 ppm MNA by dosed feed from gestation day 6 through postnatal day (PND) 21. Decreases in mean litter weights were observed at 5000 ppm MNA, compared to control, beginning at PND1. To evaluate potential contact hypersensitivity, MNA (2.5-50 %, in dimethylformamide) was applied to the dorsa of both ears of female Balb/c mice once daily for three days. The increase observed in lymph node cell proliferation (10-50 % increase in thymidine uptake compared to control) did not reproducibly achieve the Sensitization Index (SI) 3 level, and there was no ear swelling evident following sensitization with 10-50 % MNA and challenge with 25 % MNA in the mouse ear swelling test. In bacterial mutagenicity assays, MNA (250-1000 μg/plate) induced significant increases, compared to control, in mutant colonies with and without metabolic activation enzymes in Salmonella typhimurium strains TA100 and TA98. These data indicate that MNA is genotoxic, and may induce erythrocyte damage and reactive phagocytosis by macrophages in the liver and spleen.
Topics: Aniline Compounds; Animals; Body Weight; Comet Assay; Dermatitis, Contact; Dose-Response Relationship, Drug; Female; Liver; Lymph Nodes; Male; Mice; Mice, Inbred BALB C; Micronucleus Tests; Mutagenicity Tests; Nitro Compounds; Organ Size; Rats; Rats, Sprague-Dawley; Reproduction
PubMed: 32380031
DOI: 10.1016/j.tox.2020.152474 -
Food and Chemical Toxicology : An... Dec 2016p-Mentha-1,8-dien-7-al is a naturally occurring cyclic alpha,beta-unsaturated aldehyde that is used as a flavoring substance throughout the world. Due to the chemical... (Review)
Review
p-Mentha-1,8-dien-7-al is a naturally occurring cyclic alpha,beta-unsaturated aldehyde that is used as a flavoring substance throughout the world. Due to the chemical structure and the potential DNA reactivity of the alpha,beta-unsaturated carbonyl moiety, a battery of genotoxicity assays was requested by the European Food Safety Authority. Previous genotoxicity studies on the substance gave mixed results, but both positive and negative results were hampered by not always being performed to any standard guideline. The new test battery data indicated some evidence of mutagenicity in vitro, but an in vivo comet/micronucleus combination assay performed in rats was concluded by the study directors to not result in any biologically relevant positive responses. However, EFSA concluded that the in vivo assay gave evidence that p-mentha-1,8-dien-7-al was of potential genotoxic concern. The Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) has reviewed the newly available data and considered its interpretation relative to standard guidelines such as that established by the Organization for Economic Cooperation and Development, and has concluded that the results in the comet/micronucleus combination assay are consistent with the interpretation by the study directors; namely, that p-mentha-1,8-dien-7-al does not appear to have any in vivo genotoxic potential.
Topics: Animals; DNA Damage; Legislation, Food; Micronucleus Tests; Monoterpenes; Mutagenicity Tests; Perilla; Rats
PubMed: 27773699
DOI: 10.1016/j.fct.2016.10.020 -
Nutrients May 2022In this study, the physicochemical properties, fatty acid composition, antioxidant activities, and in vitro as well as in vivo toxicological safety of emu oil were...
In this study, the physicochemical properties, fatty acid composition, antioxidant activities, and in vitro as well as in vivo toxicological safety of emu oil were investigated. Emu oil was shown to have a low acid and peroxide value, low amounts of carotenoid and phenolic compounds, and high doses of oleic acid and linoleic acid. Furthermore, in a bacterial reverse mutation assay, emu oil demonstrated no change in the amount of revertant colonies for all strains. In a chromosomal assay, no aberrations occurred in any of the emu oil treatment groups (1.25, 2.5, and 5 μg/mL). In the bone marrow micronucleus test, emu oil up to 20 mL/kg showed no significant increase in the incidence of micronucleated polychromatic erythrocytes. Moreover, emu oil up to 19.3 mg/kg body weight did not affect body weight in an acute oral toxicity study. These results are crucial for the adoption of emu oil as an alternative source of edible oil.
Topics: Body Weight; Humans; Micronucleus Tests; Mutagenicity Tests; Oils; Salmonella typhimurium
PubMed: 35684037
DOI: 10.3390/nu14112238 -
Archives of Toxicology Sep 2023Genotoxicity data are mainly interpreted in a qualitative way, which typically results in a binary classification of chemical entities. For more than a decade, there has... (Review)
Review
Genotoxicity data are mainly interpreted in a qualitative way, which typically results in a binary classification of chemical entities. For more than a decade, there has been a discussion about the need for a paradigm shift in this regard. Here, we review current opportunities, challenges and perspectives for a more quantitative approach to genotoxicity assessment. Currently discussed opportunities mainly include the determination of a reference point (e.g., a benchmark dose) from genetic toxicity dose-response data, followed by calculation of a margin of exposure (MOE) or derivation of a health-based guidance value (HBGV). In addition to new opportunities, major challenges emerge with the quantitative interpretation of genotoxicity data. These are mainly rooted in the limited capability of standard in vivo genotoxicity testing methods to detect different types of genetic damage in multiple target tissues and the unknown quantitative relationships between measurable genotoxic effects and the probability of experiencing an adverse health outcome. In addition, with respect to DNA-reactive mutagens, the question arises whether the widely accepted assumption of a non-threshold dose-response relationship is at all compatible with the derivation of a HBGV. Therefore, at present, any quantitative genotoxicity assessment approach remains to be evaluated case-by-case. The quantitative interpretation of in vivo genotoxicity data for prioritization purposes, e.g., in connection with the MOE approach, could be seen as a promising opportunity for routine application. However, additional research is needed to assess whether it is possible to define a genotoxicity-derived MOE that can be considered indicative of a low level of concern. To further advance quantitative genotoxicity assessment, priority should be given to the development of new experimental methods to provide a deeper mechanistic understanding and a more comprehensive basis for the analysis of dose-response relationships.
Topics: Mutagens; DNA Damage; DNA; Risk Assessment; Mutagenicity Tests
PubMed: 37402810
DOI: 10.1007/s00204-023-03553-w -
Mutagenesis May 2022The classical in vitro genotoxicity test battery is known to be sensitive for indicating genotoxicity. However, a high rate of 'misleading positives' was reported when...
The classical in vitro genotoxicity test battery is known to be sensitive for indicating genotoxicity. However, a high rate of 'misleading positives' was reported when three assays were combined as required by several legislations. Despite the recent optimisations of the standard in vitro tests, two gaps could hardly be addressed with assays based on 2D monolayer cell cultures: the route of exposure and a relevant intrinsic metabolic capacity to transform pro-mutagens into reactive metabolites. Following these considerations, fertilised chicken eggs have been introduced into genotoxicity testing and were combined with a classical read-out parameter, the micronucleus frequency in circulating erythrocytes, to develop the hen's egg test for micronucleus induction (HET-MN). As a major advantage, the test mirrors the systemic availability of compounds after oral exposure by reflecting certain steps of Absorption, Distribution, Metabolism, Excretion (ADME) without being considered as an animal experiment. The assay is supposed to add to a toolbox of assays to follow up on positive findings from initial testing with classical in vitro assays. We here report on a validation exercise, in which >30 chemicals were tested double-blinded in three laboratories. The specificity and sensitivity of the HET-MN were calculated to be 98 and 84%, respectively, corresponding to an overall accuracy of 91%. A detailed protocol, which includes a picture atlas detailing the cell and micronuclei analysis, is published in parallel (Maul et al. Validation of the hen's egg test for micronucleus induction (HET-MN): detailed protocol including scoring atlas, historical control data and statistical analysis).
Topics: Animals; Female; Chickens; DNA Damage; Micronucleus Tests; Mutagenicity Tests; Mutagens
PubMed: 34080017
DOI: 10.1093/mutage/geab016 -
Scandinavian Journal of Work,... 1985For certain organic solvents, such as benzene, vinyl chloride, styrene, technical grade trichloroethylene, and acrylonitrile, the available studies provide convincing... (Review)
Review
For certain organic solvents, such as benzene, vinyl chloride, styrene, technical grade trichloroethylene, and acrylonitrile, the available studies provide convincing evidence to demonstrate activity in short-term genetic assays. For a few solvents, such as phenol, vinyl toluene, ethanol, and tetrachloroethylene, the evidence is limited to a certain test system and/or test organism. For most of the solvents reviewed, studies are either lacking or they are so inadequate that no final evaluation on the mutagenic activity of the solvents can be made.
Topics: Animals; Benzene; Chromosome Aberrations; Ethanol; Genes; Humans; Mutagenicity Tests; Mutagens; Sister Chromatid Exchange; Solvents; Vinyl Compounds
PubMed: 3906872
DOI: No ID Found -
Journal of Ethnopharmacology May 2021Syagrus coronata, popularly known as licuri, is a palm native to caatingas. The fixed oil extract of licuri nuts is used by the population of Northeast Brazil for...
ETHNOPHARMACOLOGICAL RELEVANCE
Syagrus coronata, popularly known as licuri, is a palm native to caatingas. The fixed oil extract of licuri nuts is used by the population of Northeast Brazil for therapeutic purposes, including as an antifungal, anti-inflammatory, and a cicatrizant agent. However, there is no scientific information on the possible harmful health effects of the oil and hence its medicinal usability is unknown.
AIM OF THE STUDY
We aimed to analyze the biological safety and possible antioxidant activity of fixed S. Coronata oil.
MATERIALS AND METHODS
Chemical analysis of the oil was performed using gas chromatography with flame ionization detection (CG-FID). The cytotoxicity of varying concentrations of the oil (12.5, 25, 50, 100, and 200 μg/mL) was evaluated using the tetrazolium reduction assay in three cell lines: HEK-293 kidney embryonic cells, J774.A1 macrophages, and the tumor line Sarcoma-180 (S-180). Oral toxicity, genotoxicity, and mutagenicity tests were performed in mice which were administered a single dose of 2000 mg/kg of fixed licuri oil, by gavage. For acute toxicity tests, changes in blood and biochemical parameters, behavior, and weight were analyzed; histomorphometric analyses of the liver, kidney, and spleen were also performed. The comet assay and micronucleus (MN) test were performed to analyze genotoxicity. The antioxidant potential was assessed by the total antioxidant capacity (AAT) and DPPH elimination activity.
RESULTS
Licuri oil consists predominantly of saturated fatty acids, and lauric acid is the major compound. The highest concentrations of the oil showed low levels of cytotoxicity; however, LC50 was not reached in any of the tests. The acute toxicity study did not reveal any evidence of adverse effects in animals treated with oil; biochemical investigation of blood showed a decrease in blood concentration of total proteins and uric acid. The kidneys, spleen, and liver showed no morphological changes indicative of a pathological process. Genotoxic or mutagenic activity was not detected through both the comet assay and MN test. In addition, the oil showed low antioxidant activity in both methods.
CONCLUSION
Licuri oil from the stem of S. coronata did not present significant toxic effects as well as absence of genetic damage when administered orally. Future studies are needed to investigate its pharmacological potential.
Topics: Administration, Oral; Animals; Antioxidants; Arecaceae; Cell Line; Cell Survival; Comet Assay; DNA Damage; Fatty Acids; Humans; Kidney; Liver; Male; Mice; Micronucleus Tests; Mutagenicity Tests; Palm Oil; Spleen; Toxicity Tests, Acute
PubMed: 33610703
DOI: 10.1016/j.jep.2021.113941 -
Environmental Health Perspectives Nov 1987A series of observations and comments are made with respect to several areas of toxicology: these are briefly discussed. Some innovative areas receive discussion as... (Review)
Review
A series of observations and comments are made with respect to several areas of toxicology: these are briefly discussed. Some innovative areas receive discussion as representing substantial progress made in the field of toxicology in recent years. Topics included raise a number of questions: what agents should we test, and how should we go about selecting them; what is the importance of allowing for genetic diversity in carrying out tests that are meaningful for humans; and what is the relevance of studies in pharmacokinetics in the laboratory to humans. Human studies, because of ethical considerations, must be indirect, through access to available autopsy and surgical human tissues. Also, drug trials and clinical studies must be exploited. Cancer testing and evaluation is briefly commented on. Systemic toxicity is considered in respect to possible improved ways of determining the "NOEL," that is, the no-observed-effect level. Suggestions for improving study of mixtures of chemicals are considered. The rapid advances in molecular biology have significantly strengthened our ability to trace the action of chemicals in the body from exposure to disease. It is very important that training in toxicology be based on a sound disciplinary training in one of the classic fields of the biomedical sciences, such as biochemistry, pharmacology, molecular biology. It is concluded that advances in the past decade have made the practice of toxicology a much more scientific endeavor, especially in its use of the latest developments in basic biomedical sciences.
Topics: Animals; Drug Evaluation, Preclinical; Humans; Mutagenicity Tests; Toxicology
PubMed: 3319572
DOI: 10.1289/ehp.877597