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Background Ames test is used worldwide for detecting the bacterial mutagenicity of chemicals. In silico analyses of bacterial mutagenicity have recently gained acceptance by regulatory agencies; however, current in silico models for prediction remain to be improved. The Japan Pharmaceutical Manufacturers Association (JPMA) organized a task force in 2017 in which eight Japanese pharmaceutical companies had participated. The purpose of this task force was to disclose a piece of pharmaceutical companies’ proprietary Ames test data. Results Ames test data for 99 chemicals of various chemical classes were collected for disclosure in this study. These chemicals are related to the manufacturing process of pharmaceutical drugs, including reagents, synthetic intermediates, and drug substances. The structure-activity (mutagenicity) relationships are discussed in relation to structural alerts for each chemical class. In addition, in silico analyses of these chemicals were conducted using a knowledge-based model of Derek Nexus (Derek) and a statistics-based model (GT1_BMUT module) of CASE Ultra. To calculate the effectiveness of these models, 89 chemicals for Derek and 54 chemicals for CASE Ultra were selected; major exclusions were the salt form of four chemicals that were tested both in the salt and free forms for both models, and 35 chemicals called “known” positives or negatives for CASE Ultra. For Derek, the sensitivity, specificity, and accuracy were 65% (15/23), 71% (47/66), and 70% (62/89), respectively. The sensitivity, specificity, and accuracy were 50% (6/12), 60% (25/42), and 57% (31/54) for CASE Ultra, respectively. The ratio of overall disagreement between the CASE Ultra “known” positives/negatives and the actual test results was 11% (4/35). In this study, 19 out of 28 mutagens (68%) were detected with TA100 and/or TA98, and 9 out of 28 mutagens (32%) were detected with either TA1535, TA1537, WP2uvrA, or their combination. Conclusion The Ames test data presented here will help avoid duplicated Ames testing in some cases, support duplicate testing in other cases, improve in silico models, and enhance our understanding of the mechanisms of mutagenesis.

Safety is a main reason for drug failures, and therefore, the detection of compound toxicity and potential adverse effects in the early stage of drug development is highly desirable. However, accurate prediction of many toxicity endpoints is extremely challenging due to low accessibility of sufficient and reliable toxicity data, as well as complicated and diversified mechanisms related to toxicity. In this study, we proposed the novel multitask graph attention (MGA) framework to learn the regression and classification tasks simultaneously. MGA has shown excellent predictive power on 33 toxicity data sets and has the capability to extract general toxicity features and generate customized toxicity fingerprints. In addition, MGA provides a new way to detect structural alerts and discover the relationship between different toxicity tasks, which will be quite helpful to mine toxicity information from large amounts of toxicity data.

Radiographic examinations combined with clinical and histological tests play an important role in diagnosing changes in the craniofacial region. Considering that X-radiation is a form of ionizing energy capable of damaging the DNA of individuals, it has been the object of studies since its introduction. The micronucleus test is used to quantify this damage, assessing whether or not chromosomal breakage occurs. Objective: To evaluate, through a systematic review (SR) with meta-analysis, the occurrence of genotoxic effects in the oral epithelium after the exposure of patients to panoramic radiographs. Methods: An SR was performed with the PICOS (Population, Intervention, Comparison, Outcome, and Study design) strategy, aiming to answer the following question: “Can panoramic radiographs induce genotoxic effects on the oral epithelium?” The study was registered in the PROSPERO (International prospective register of systematic reviews) platform. A systematic search was performed in the following electronic databases: PubMed (including MedLine), Scopus, Embase, LILACS, Medline EbscoHost, and Google Scholar. Treatment effects were defined as standardized mean difference (SMD), and 95% confidence intervals (CI) were established. The Joanna Briggs Institute questionnaire for observational studies was applied to assess the risk of bias. The GRADE tool was used to assess the quality of evidence of the SR. Results: A total of 251 potentially relevant studies were selected through the search strategy. After screening titles and abstracts, 11 full-text manuscripts were assessed for eligibility and nine observational studies were included in the meta-analysis. The present study showed an increase in micronuclei after the exposure (SMD = 0.21, 95% CI, 0.03 to 0.28, p = 0.02), with a Tau2index = 0.00, Chi2 = 2.35, and p-value = 0.97. Therefore, the articles selected were considered homogeneous and the I² of 0% indicated low heterogeneity. Conclusion: According to the studies analysed, although the quality of evidence was considered low, panoramic radiographs can cause genotoxic damage in the oral epithelium but with a small effect size.

Resumo O agrotóxico malathion vem sendo amplamente utilizado no mundo em programas de controle de arboviroses e em 2015 foi classificado pela Agência Internacional para Pesquisas em Câncer (IARC) como provável agente carcinogênico para seres humanos. Este trabalho objetivou a sistematização das evidências dos efeitos carcinogênicos e mutagênicos associados à exposição do malathion e seus análogos, malaoxon e isomalathion. A busca foi realizada nas bases de dados TOXLINE, PUBMED e SCOPUS por artigos originais publicados de 1983 a 2015. Do total de 273 artigos elegíveis, foram selecionados 73. Os resultados dos estudos in vitro e in vivo evidenciaram danos genéticos e cromossômicos provocados pelo malathion; os estudos epidemiológicos evidenciaram associações significativamente positivas para cânceres de tireóide, de mama, e ovariano em mulheres na menopausa. Estas evidências do efeito carcinogênico do malathion devem ser considerados diante de sua utilização em programas de controle de arboviroses. Abstract Malathion has been widely used worldwide in arbovirus control programs. In 2015, it was classified by the International Agency for Research on Cancer (IARC) as a probable carcinogen to humans. This work aimed to systematize the evidence of the carcinogenic and mutagenic effects associated with the exposure of malathion and its analogs, malaoxon and isomalathion. The search was carried out in Toxline, PubMed and Scopus databases for original papers published from 1983 to 2015. In all, 73 papers were selected from a total of 273 eligible papers. The results of in vitro and in vivo studies showed mainly genetic and chromosomal damages caused by malathion. The epidemiological studies evidenced significant positive associations for thyroid, breast, and ovarian cancers in menopausal women. This evidence of the carcinogenic effect of malathion should be considered before its use in arbovirus control programs.

Objective. Inosine 5’-monophosphate dehydrogenase (IMPDH) activity in cancer cells is increased. Tiazofurin selectively inhibits the activity of IMPDH, and it has been granted for the treatment of different cancers and new viral diseases. Its widespread use was limited because exposure to tiazofurin under certain circumstances was found to have a higher frequency of severe non-hematologic toxicity. Therefore, the objective of this study was to examine genotoxic action and inducement of DNA damage of tiazofurin using the comet assay. Methods. The ability of tiazofurin to induce DNA damage was evaluated using single-cell gel electrophoresis (SCGE) technique/comet assay. Human whole blood cells were exposed to three final concentrations of tiazofurin (1 µM/mL, 2 µM/mL, and 5 µM/mL) for 30 min in vitro. Results. Our results indicate that tiazofurin produced a significant level of DNA damage on whole blood cells after 30 min of exposure vs. control. All tested concentrations were significantly comet-forming, in a concentration-dependent manner. Conclusion. Our investigation on the tiazofurin-treated cells and their relationship to the formation of DNA damage demonstrated that the genotoxic effect was induced after exposure to tiazofurin under described conditions. Cilj. Aktivnost inozin 5'-monofosfat dehidrogenaze (IMPDH) povec'ana je u c'elijama karcinoma. Tiazofurin selektivno inhibira aktivnost IMPDH i odobren je za lečenje različitih karcinoma i novih virusnih bolesti. Njegova široko rasprostranjena upotreba bila je ograničena jer je utvrđeno da je izloženost tiazofurinu pod određenim okolnostima imala vec'u incidencu ozbiljne nehematološke toksičnosti. Stoga je cilj ove studije bio da se pomoc'u komet testa ispita genotoksično delovanje i izazivanje DNK oštec'enja tiazofurinom. Metode. Sposobnost tiazofurina da izazove DNK oštec'enje procenjena je primenom elektroforeze DNK pojedinačnih ćelija (SCGE) / komet testa. Ćelije pune krvi su bile izložene trima konačnim koncentracijama tiazofurina (1 µM/mL, 2 µM/mL, and 5 µM/mL) tokom 30 minuta in vitro. Rezultati. Naši rezultati ukazuju na to da je tiazofurin proizveo značajan nivo DNK oštec'enja na c'elijama pune krvi nakon 30 minuta izlaganja u odnosu na kontrolu. Sve ispitivane koncentracije su dovele do značajnog nastanka kometa, pri čemu je nivo oštećenja rastao s koncentracijom. Zaključak. Naše istraživanje c'elija tretiranih tiazofurinom i njihova reakcija na izazivanje DNK oštec'enja pokazalo je da je tiazofurin ispoljio genotoksični efekat pod opisanim uslovima.

Damage to DNA is a central mechanism to the initiation of carcinogenesis. As a consequence, precise DNA damage detection is essential for an effective risk assessment of xenobiotics and constitutes a powerful tool for human biomonitoring and early stage cancer risk assessment. Here we highlight four innovative approaches for determining genotoxicity in a reliable and in the future high-throughput manner. In this context, we discuss and evaluate recent improvements to well-established methods and present promising new techniques.

Effect-based analyses are being recognized as excellent tools to a comprehensive and reliable water quality evaluation to complement physical and chemical parameters. The Salmonella/microsome mutagenicity test was introduced in the São Paulo State water quality-monitoring program in 1999 and waters from 104 sites used to the production of drinking water were analyzed. Samples were tested after organic extraction, using the microsuspension version of the Salmonella/microsome assay with strains TA98 and TA100 with and without S9-mammalian metabolic system. Of the 1720 water samples analyzed in 20 years, 20% were positive; TA98 was the most sensitive strain, detecting alone 99%. Results were presented in hazard categories to facilitate water managers' understanding and general public communication. Hot spots of mutagenicity were identified, and pollution sources investigated. A flow scheme with instructions of how to proceed in case of mutagenic samples was developed and implemented in the monitoring program. Enforcement actions were taken to reduce exposure of humans and aquatic biota to mutagenic compounds. The results presented provide scientific basis for the incorporation of the Salmonella/microsome assay in a regulatory framework, and to guide water-quality managers. The inclusion of a mutagenicity assay using standardized conditions proved to be an opportunity to improve the quality of water, and the strategy presented here could be applied by any environmental agency around the world. Environ. Mol. Mutagen. 61:200-211, 2020. © 2019 Wiley Periodicals, Inc.

En los últimos quince años se ha registrado un alto grado de deterioro en el río Balsas, México, debido a los asentamientos humanos e industriales. El objetivo de este estudio fue evaluar la condición actual del río y establecer la relación entre los parámetros de la legislación vigente y las pruebas de toxicidad y mutagenicidad. Se determinaron parámetros de campo (color, olor, temperatura, CE, pH, OD), fisicoquímicos (SST, SDT, SSe, DBO5, DQO y GyA, Ntotal, Norg, Ptotal, Porg, ortofosfatos), metales pesados (As, Cd, Cu, Cr, Cr+6, Hg, Ni, Pb, Zn, Al, Fe, Mn), microbiológicos (coliformes fecales) con base en los límites máximos permisibles (LMP) en la NOM-001-ECOL-1996 y en los CE-CCA-001/89, análisis de toxicidad (Vibrio fischeri, Daphnia magna) y mutagenicidad (prueba de Ames con microsomas/Salmonella typhimurium), en época de sequía en nueve estaciones a lo largo de 85km. Los valores para OD, DBO5 y DQO fueron de 2-6, 11-270 y 22-1841mg·l-1, respectivamente. Los metales fueron detectados por debajo de los LMP en todas las estaciones, excepto en la estación 5 (0,002mg·l-1 de Hg) y la 8 (0,13mg·l-1 de Cr+6). Los coliformes fecales rebasaron los LMP en todas las estaciones. Los valores para Vibrio fischeri, Daphnia magna se encuentran en 2-28 y 1-4UT, y para la prueba de Ames entre 5 y 63RM, indicando toxicidad y mutagenicidad desde la estación 3 a la 9. Se registró contaminación alta según la legislación vigente y un riesgo para la salud pública de acuerdo a los parámetros toxicológicos y mutagénicos.

The bacterial strains and mutagenicity test procedure developed by Bruce Ames, and published in 1973, greatly enhanced the ability of laboratories to test chemicals for mutagenicity. The test that became known as the "Ames Test" was simple to perform, took only two days, was relatively inexpensive, and was easily transferrable to other laboratories. Their demonstration that the test was effective at identifying potentially carcinogenic chemicals led its immediate adoption, and requirement, by regulatory authorities world-wide. Despite the development of other microbial and mammalian cell tests to measure mutation or other genetic damage, the Ames test still retains a primary role in the testing of chemicals for commercial use.

Genistein is one of the several known isoflavonic phytoestrogens found in a number of plants, with soybeans and soy products being the primary food source. The aim of the study is to evaluate if genistein is able to exert antineoplastic action in primary human papillary thyroid cancer (PTC) cells. Thyroid tissues were treated with genistein (1-10-50-100 µM). Cell viability, proliferation, DNA primary damage and chromosomal damage were evaluated. An antiproliferative effect was induced by the highest doses of genistein, and such an effect was synergistically enhanced by the cotreatment with the antineoplastic drug sorafenib. Comet assay did not show any genotoxic effect in terms of primary DNA damage at all the times (4 and 24 h) and tested doses. A reduction of hydrogen peroxide-induced DNA primary damage in primary thyrocytes from PTC cells pretreated with genistein was observed. Data suggest that genistein exerts antineoplastic action, does not induce genotoxic effects while reduces oxidative-induced DNA damage in primary thyrocytes from PTC cells, supporting its possible use in therapeutic intervention.

The microalgae Chlorella vulgaris is usually commercialized as nutraceutical although it has potential application in the pharmaceutical and cosmetic industries. Therefore, our objective in this research is to evaluate the mutagenic and antimutagenic action of the aqueous extract of C. vulgaris through the Allium cepa assay. Three concentrations of the aqueous extract of C. vulgaris were tested: 0.075, 0.15 and 0.30mg/mL. In the mutagenicity analysis, A. cepa meristematic cells were cultured in the presence of the aqueous extract of C. vulgaris with distilled water as negative control and copper sulfate as positive control. For antimutagenicity, pre-treatment, simple simultaneous and post-treatment protocols were used. 400 cells/treatment were analyzed under optical microscopy (40x). Data were analyzed by ANOVA (one-way) and Tukey tests, considering p

espanolIntroduccion. El formaldehido es una sustancia ampliamente usada a nivel industrial; sin embargo, es considerada un agente mutagenico y carcinogeno para los humanos. Para determinar el grado de riesgo de los trabajadores ocupacionalmente expuestos (TOE) al formaldehido, debe hacerse un seguimiento de sus niveles de concentracion ambiental y de los biomarcadores que permiten identificar su dano potencial para la salud. En Colombia, lamentablemente, no existen lineamientos respecto a la exposicion ocupacional a esta sustancia. Objetivo. Revisar estudios recientes sobre exposicion ocupacional a formaldehido para disenar una estrategia de seguimiento y vigilancia de los TOE a esta sustancia en Colombia. Materiales y metodos. Se realizo una revision de la literatura en PubMed, MedLine, ScienceDirect y Embase mediante la siguiente estrategia de busqueda: articulos sobre exposicion ocupacional a formaldehido publicados en ingles o espanol entre 2013 y 2017. Los terminos de busqueda fueron “occupational exposure”, “formaldehyde” “mutagenicity test” y “DNA adducts” y sus equivalentes en espanol. Resultados. La busqueda inicial arrojo 103 registros, sin embargo solo 36 articulos cumplieron los criterios de inclusion establecidos. Conclusiones. La gestion adecuada del riesgo derivado de la exposicion ocupacional a formaldehido, asi como el seguimiento medico apropiado de estos trabajadores, requiere la implementacion de una serie de acciones interdisciplinarias que permitan la creacion de un sistema de vigilancia ocupacional integral de los TOE a esta sustancia. EnglishIntroduction: Formaldehyde is a substance widely used in the industry; however, it is classified as mutagenic and carcinogenic to humans. In order to determine the risk of workers who are occupationally exposed to formaldehyde, it is necessary to monitor its environmental concentration levels and the biomarkers that allow identifying its potential health effects. Unfortunately, in Colombia there are not guidelines on occupational exposure to this substance. Objective: To review recent studies on occupational exposure to formaldehyde to design a monitoring and surveillance strategy for Colombian workers exposed to this substance. Materials and methods: A literature review was conducted in PubMed, MedLine, Science- Direct and Embase using the following search strategy: articles on occupational exposure to formaldehyde published in English or Spanish between 2013 and 2017. The following search terms were used: “occupational exposure”, “formaldehyde” “mutagenicity test” y “DNA adducts” and their Spanish equivalents. Results: The initial search yielded 103 articles, of which only 36 met the inclusion criteria. Conclusions: Proper management of the risk derived from occupational exposure to formaldehyde, as well as the appropriate medical follow-up of these workers, requires the implementation of a series of interdisciplinary actions that allow the creation of a comprehensive occupational health surveillance system for workers exposed to this substance.

Modern life implies a constant exposure of living organisms to electromagnetic fields generated by human made technology. The question of whether or not electromagnetic fields in the non-ionizing frequency range can affect cellular functions, increasing the risk of cancer or another pathologies is currently a subject of interest for scientific community of several disciplines of physics, biology, chemistry and medicine. The first part of this short review presents briefly the possible mechanism of interaction of electromagnetic fields in cellular level based in theoretical models and experimental results. The second part refers to experimental observations published by several authors about the potential cytotoxic and genotoxic effects of electromagnetic fields. Results of researches are no yet conclusive enough to accept or reject the genotoxic, carcinogenic or cytotoxic potential of these fields. Up to date the International Agency for Research on Cancer (IARC) has classified the X, gamma and ultraviolet radiation as carcinogenic and the fields generated by radio frequencies as possibly carcinogenic.

Objective: To assess, with a systematic review (SR) with meta-analysis, the occurrence of genotoxic effects on the oral epithelium after exposure to tooth bleaching agents. Material and methods: This review was performed according to the PRISMA protocols. To identify relevant studies, a systematic search was performed in the following electronic databases: PubMed, Scopus, Embase, LILACS, and Google Scholar. The research question was "Can tooth bleaching agents cause genotoxicity in the oral epithelium?”. The treatment effects were defined as the standardized mean difference (SMD) and 95% confidence intervals (CI) were established. Results: 154 studies were selected and, after screening titles and abstracts, seven full-text manuscripts were assessed for eligibility, of which four studies were included in the meta-analysis. There were no statistically significant differences in the frequency of micronuclei before and after exposure (SMD= -0.14, 95% CI, 0.98 to 0.60, p=0.74), with a Tau2 index = 1.00; Chi2 = 70.20; p-value

As part of the hazard and risk assessment of chemicals in man, it is important to assess the ability of a chemical to induce mutations in vivo. Because of the commonalities in the molecular initiating event, mutagenicity in vitro can correlate well to the in vivo endpoint for certain compound classes; however, the difficulty lies in identifying when this correlation holds true. In silico alerts for in vitro mutagenicity may therefore be used as the basis for alerts for mutagenicity in vivo where an expert assessment is carried out to establish the relevance of the correlation. Taking this into account, a data set of publicly available transgenic rodent gene mutation assay data, provided by the National Institute of Health Sciences of Japan, was processed in the expert system Derek Nexus against the in vitro mutagenicity endpoint. The resulting predictivity was expertly reviewed to assess the validity of the observed correlations in activity and mechanism of action between the two endpoints to identify suitable in vitro alerts for extension to the in vivo endpoint. In total, 20 alerts were extended to predict in vivo mutagenicity, which has significantly improved the coverage of this endpoint in Derek Nexus against the data set provided. Updating the Derek Nexus knowledge base in this way led to an increase in sensitivity for this data set against this endpoint from 9% to 66% while maintaining a good specificity of 89%.

Traditional herbal medicines have been part of human healthcare systems since ancient times. The studies on herbal medicines have mainly focused on their beneficial aspects and hence their harmful effects have been usually overlooked. Throughout Middle East and South Asia, Rhazya stricta Decne. and Thymus vulgaris L. are used as traditional medicines for various diseases. We evaluated R. stricta and T. vulgaris aqueous extracts for their genotoxicity and mutagenicity through comet assay and Ames Salmonella mutagenicity test respectively. An overall treatment effect (p

Fischer-Tropsch (FT) Synthetic Paraffinic Kerosene (SPK) jet fuel is a synthetic organic mixture intended to augment petroleum-derived JP-8 jet fuel use by the U.S. armed forces. The FT SPK testing program goal was to develop a comparative toxicity database with petroleum-derived jet fuels that may be used to calculate an occupational exposure limit (OEL). Toxicity investigations included the dermal irritation test (FT vs. JP-8 vs. 50:50 blend), 2 in vitro genotoxicity tests, acute inhalation study, short-term (2-week) inhalation range finder study with measurement of bone marrow micronuclei, 90-day inhalation toxicity, and sensory irritation assay. Dermal irritation was slight to moderate. All genotoxicity studies were negative. An acute inhalation study with F344 rats exposed at 2000 mg/m

Rice is an economically important plant as well as a model organism. The rice genome consists of 35% retrotransposons. Although most of the retrotransposons are inactivated through evolutionary processes, they can be activated under various biotic and abiotic stress conditions. The main objective of this study was to explore the effects of herbicides on retrotransposon activities and the usage of retrotransposons in short-term mutagenicity tests. In this study, bentazone and an MCPA (2-methyl-4-chlorophenoxyacetic acid)-containing herbicide was used. Plant samples were grouped into three classes: control (untreated), 1% and 2% herbicide treatment. Retrotransposon activities were investigated by using the inter-retrotransposon amplified polymorphism (IRAP) marker technique. IRAP analyses were performed for Houba (Tos5/Osr13) retrotransposon. Polymorphism ratios were calculated with the Jaccard similarity index, and the significance of polymorphism was evaluated by one-way analysis of variance (ANOVA). We observed that the polymorphism ratios ranged from 8%–90% for Houba among plant samples. ANOVA showed that these variable ratios were statistically significant. Bentazone and the MCPA-containing herbicide increased the retrotransposon activities, and they might be responsible for DNA mutations. This study indicated valuable data for establishing retrotransposon-based short-term mutagenicity test in rice with suitable retrotransposons such as Houba.

Objectives Despite an asbestos ban in the European Union, exposure to asbestos still represents an occupational risk. Biomarkers of DNA damage and genomic instability in groups exposed to asbestos may contribute to the identification of subgroups/subjects at higher risk. Methods A cross-sectional study was conducted on 468 male individuals (80 working in occupational settings with potential exposure to asbestos fibers, 202 retired workers with past exposure, and 186 non-exposed controls) to compare genomic instability, cell proliferation and differentiation level using the non-invasive micronucleus buccal cytome assay. Data on demographic variables, lifestyle, and occupational history were collected with a standardized questionnaire. Micronuclei (MN) and other biomarkers of DNA damage and genomic instability were scored in a minimum of 2000/1000 cells per individual, respectively. Results Univariate and multivariate analysis showed opposite associations of MN frequency with current and former exposure. Compared to unexposed controls, workers with current potential exposure to asbestos had 55% lower MN frequency [95% confidence interval (CI) 71–29%, P

The Salmonella/microsome assay (Ames test) is the most widely used mutagenicity test for the evaluation of pure chemicals and environmental samples. There are several versions of protocols available in the literature, including those that reduce the amount of sample needed for testing with liquid and agar media. The microsuspension version of the Salmonella/microsome assay is more sensitive than the standard protocol. It is performed using 5-times concentrated bacteria and less sample and S9 mixture, but still uses conventional Petri dishes (90 × 15 mm). It has been extensively used for environmental sample testing, including in effect-directed analysis (EDA). The objective of this study was to miniaturize the microsuspension assay using 12-well microplates instead of the conventional plates. For validation of this miniaturization, thirteen mutagenic compounds were tested using three Salmonella strains that were selected based on their different spontaneous reversion frequencies (low, medium, and high). The conditions of the miniaturized procedure were made as similar as possible to the microsuspension protocol, using the same testing design, metabolic activation, and data interpretation, and the tests were conducted in parallel. The miniaturized plate assay (MPA) and microsuspension procedures provided similar sensitivities although MPA is less laborious and require less sample and reagents, thereby reducing overall costs. We conclude that the MPA is a promising tool and can be particularly suitable for environmental studies such as EDA or monitoring programs. Environ. Mol. Mutagen. 59:488-501, 2018. © 2018 Wiley Periodicals, Inc.

In this study, the concentrations of 16 Polycyclic Aromatic Hydrocarbon (PAH), considered priority by US EPA (US Environmental Protection Agency), in fine particulate matter (PM2.5), were determined in a forest reserve and in an urban area in the city of Rio de Janeiro. The PM2.5 samples were collected in the Tijuca Forest (TF) and on the Maracana campus of the State University of Rio de Janeiro (UERJ), using PM2.5 high-volume air samplers, from November 2015 to April 2016. The organic matter was extracted, separated by liquid chromatography, and analyzed by gas chromatography-mass spectrometry (GC-MS). The mean total PAH (excluding naphthalene, acenaphthene, and acenaphthylene) concentrations were 0.46 ± 0.61 ng m−3 and 1.12 ± 0.71 ng m−3 in PM2.5 collected at TF and UERJ, respectively. The diagnostic ratios suggested vehicular sources for both sites with no clear distinction between light and heavy vehicular sources. Cluster and principal component analyses were also used to clarify the possible PAH sources. Simulations of air mass trajectories confirmed the transport of pollutants from the city to the forest. Mutagenicity tests revealed that the PM collected in the UERJ presented mutagenic positive activity, likely for nitro-PAH and amino-PAH, which may be related to vehicular emissions. For the TF, although the forest was impacted by the pollutants, no positive activity was detected. Correlation and cluster analyses showed different PAH distributions for the TF and UERJ sites, which indicates that the TF receives the air masses from the city but is also impacted by local emissions.

The Salmonella reversion based Ames test is the most widely used method for mutagenicity testing. For rapid toxicity assessment of e.g. water samples and for effect-directed analysis, however, the Ames test suffers from lack of throughput and is regarded as a laborious, time consuming method. To achieve faster analysis, with increased throughput, a (downscaled) luminescent derivative of the Ames Salmonella/microsome fluctuation test has been developed through expression of the Photorhabdus luminescens luciferase in the Salmonella TA98 and TA100 strains. The applicability of this test is demonstrated by analysis of environmentally relevant compounds, a suspended particulate matter extract and an industrial effluent sample. Use of the luminescent reporter reduced the required detection time from 48 to 28 h with a specificity of 84% for responses reported in the literature to a set of 14 mutagens as compared to 72% in the unmodified fluctuation test. Testing of the same compounds in a downscaled luminescent format resulted in an 88% similarity with the response found in the regular luminescent format. The increase in throughput, faster analysis and potential for real-time bacterial quantification that luminescence provides, allows future application in the high-throughput screening of large numbers of samples or sample fractions, as required in effect-directed analysis in order to accelerate the identification of (novel) mutagens.

This study is aimed at determining the mutagenic and anti-mutagenic properties of silver nanoparticles (AgNPs) biosynthesised from Streptomyces griseorubens AU2. To the authors' knowledge, this is the first study about the investigation of these properties for biogenic AgNPs bacterially synthesised. The mutagenic and anti-mutagenic potencies were determined by the Ames Salmonella/microsome mutagenicity test using Salmonella typhimurium TA98 and TA100 strains. After determining the cytotoxic dose of green synthesised AgNPs against S. typhimurium TA98 and TA100 strains, subcytotoxic doses (250, 100 and 50 mu g/plate) were used in the assays. Biogenic AgNPs at the tested concentrations exhibited no mutagenic effects in the mutagenicity test conducted with the test strains. Moderate anti-mutagenic effects were observed at high test concentrations. The concentration of 250 mu g/plate showed the strongest anti-mutagenic activity on S. typhimurium TA98. The results did not indicate any mutagenic effect against either of the strains used for screening the mutagenicity of the biogenic AgNPs as they were found to be genotoxically safe. It can be concluded that biogenic AgNPs showed great anti-mutagenic attributes, standing as a significant factor with respect to medical, pharmaceutical and cosmetic industries.