Sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary (CHO-K1) cells treated with the insecticide pirimicarb

Cytotoxic and genotoxic profiles of the pyrethroid insecticide lambda-cyhalothrin and its microformulation Karate® in CHO-K1 cells

Lambda-cyhalothrin (LCT) and its microformulation Karate® (25 % a.i.) were analysed for its genotoxicity and cytotoxicity on Chinese hamster ovary (CHO-K1) cells. Cytokinesis-block micronucleus cytome (CBMN-cyt) and alkaline single-cell gel electrophoresis (SCGE) bioassays were selected to test genotoxicity. Neutral red uptake (NRU), succinic dehydrogenase activity (MTT) and apoptogenic induction were employed for estimating cytotoxicity. Both compounds were analysed within a concentration range of 0.1-100 µg/mL. Only LCT produced a significant augment in the frequency of micronuclei (MNs) when the cultures were exposed to highest concentrations of 10 and 100 µg LCT/mL. A noticeable decrease in NDI was observed for cultures treated with LCT at 10 and 100 µg/mL. Karate® induced the inhibition of both the proportion of viable cells and succinic dehydrogenase activity and triggered apoptosis 24 h of exposition. Whilst an increased GDI in CHO-K1 cells was observed in the treatments with 1-100 µg Karate®/mL, the GDI was not modified in the treatments employing LCT at equivalent doses. SCGE showed that Karate® was more prone to induce genotoxic effects than LCT. Only 50 µg/mL of Karate® was able to increase apoptosis. Our results demonstrate the genomic instability and cytotoxic effects induced by this pyrethroid insecticide, confirming that LCT exposure can result in a severe drawback for the ecological equilibrium of the environment.

Do environmentally relevant concentrations of the neonicotinoid insecticide imidacloprid induce DNA damage and oxidative stress on Cnesterodon decemmaculatus (Jenyns, 1842)?

Lethal and sublethal effects of imidacloprid (IMI) were assessed on Cnesterodon decemmaculatus (Pisces: Poeciliidae) by acute exposure to environmentally relevant concentrations of the commercial formulation Punto 35® (Gleba S.A.) under laboratory conditions. Specimens were exposed for 96 h to 1, 10, 20, 25, 35, 75, 100, 125, 150 and 175 mg IMI L^-1 from which an LC₅₀ 96 h value of 35.59 mg IMI L^-1 was calculated. Moreover, sublethal concentrations 0.175, 0.35 and 1 mg IMI L^-1 for 96 h were employed for the evaluation of the comet assay and the variation of activities of catalase (CAT) and glutathione content (GSH). Result demonstrated an increased genetic damage index and activity of CAT was observed. Conversely, no significant variation was observed in GSH activity. Total protein content decreased in treated organisms. These results represent the first report of acute effects induced by IMI on C. decemmaculatus exposed under laboratory conditions.

Conserved Metabolic and Evolutionary Themes in Microbial Degradation of Carbamate Pesticides

Carbamate pesticides are widely used as insecticides, nematicides, acaricides, herbicides and fungicides in the agriculture, food and public health sector. However, only a minor fraction of the applied quantity reaches the target organisms. The majority of it persists in the environment, impacting the non-target biota, leading to ecological disturbance. The toxicity of these compounds to biota is mediated through cholinergic and non-cholinergic routes, thereby making their clean-up cardinal. Microbes, specifically bacteria, have adapted to the presence of these compounds by evolving degradation pathways and thus play a major role in their removal from the biosphere. Over the past few decades, various genetic, metabolic and biochemical analyses exploring carbamate degradation in bacteria have revealed certain conserved themes in metabolic pathways like the enzymatic hydrolysis of the carbamate ester or amide linkage, funnelling of aryl carbamates into respective dihydroxy aromatic intermediates, C1 metabolism and nitrogen assimilation. Further, genomic and functional analyses have provided insights on mechanisms like horizontal gene transfer and enzyme promiscuity, which drive the evolution of degradation phenotype. Compartmentalisation of metabolic pathway enzymes serves as an additional strategy that further aids in optimising the degradation efficiency. This review highlights and discusses the conclusions drawn from various analyses over the past few decades; and provides a comprehensive view of the environmental fate, toxicity, metabolic routes, related genes and enzymes as well as evolutionary mechanisms associated with the degradation of widely employed carbamate pesticides. Additionally, various strategies like application of consortia for efficient degradation, metabolic engineering and adaptive laboratory evolution, which aid in improvising remediation efficiency and overcoming the challenges associated with in situ bioremediation are discussed.

A critical review on genotoxicity potential of low dimensional nanomaterials

Low dimensional nanomaterials (LDNMs) have earned attention among researchers as they exhibit a larger surface area to volume and quantum confinement effect compared to high dimensional nanomaterials. LDNMs, including 0-D and 1-D, possess several beneficial biomedical properties such as bioimaging, sensor, cosmetic, drug delivery, and cancer tumors ablation. However, they threaten human beings with the adverse effects of cytotoxicity, carcinogenicity, and genotoxicity when exposed for a prolonged time in industry or laboratory. Among different toxicities, genotoxicity must be taken into consideration with utmost importance as they inherit DNA related disorders causing congenital disabilities and malignancy to human beings. Many researchers have performed NMs' genotoxicity using various cell lines and animal models and reported the effect on various physicochemical and biological factors. In the present work, we have compiled a comparative study on the genotoxicity of the same or different kinds of NMs. Notwithstanding, we have included the classification of genotoxicity, mechanism, assessment, and affecting factors. Further, we have highlighted the importance of studying the genotoxicity of LDNMs and signified the perceptions, future challenges, and possible directives in the field.

Visible-Light Driven Photocatalytic Degradation of Pirimicarb by Pt-Doped AgInS2 Nanoparticles

This study describes the synthesis and characterization of Pt-doped AgInS2 nanoparticles and reports their prospective application as visible-light catalysts for photodegradation of frequently used pirimicarb insecticides, which pose serious health and environmental concerns. The nanomaterials were characterized by XRD, SEM, TEM, XPS, photoluminescence (PL), and UV–vis diffuse reflectance spectra (DRS). The presented photocatalytic method for water treatment from pirimicarb has the advantages of using visible light source without any costly additive such as H2O2 needed in other employed methods. The Pt-doped AgInS2 exhibited higher photocatalytic activities for pirimicarb degradation than undoped AgInS2. The 1.0 wt% Pt/AgInS2 photocatalyst exhibited the highest photodegradation rate, showing enhancement of 56% in comparison to the pure AgInS2 photocatalyst. The photodegradation rate was found to increase with increasing the catalyst dosage until reaching the optimal dosage of 1.0 g L−1. The pirimicarb degradation was significantly more efficient under acidic conditions, and the rates drastically dropped upon increasing the pH. The photocatalytic mechanism of Pt/AgInS2 composites and the main active species involved in the process were investigated. The mechanism of pirimicarb degradation was proposed via two different pathways, N-dealkylation and decarbamoylation. Lastly, the photocatalysts demonstrated remarkable stability and were reusable in three successive catalytic tests without compromising catalytic activities. The Pt/AgInS2 photocatalyst also exhibited efficiency and feasibility in pirimicarb removal from environmental lake and river water samples.

Toxicity to Rhinella arenarum tadpoles (Anura, Bufonidae) of herbicide mixtures commonly used to treat fallow containing resistant weeds: glyphosate-dicamba and glyphosate-flurochloridone

Glyphosate (GLY)-dicamba (DIC) and GLY-flurochloridone (FLC) are herbicide mixtures which are widely used for treating fallow containing glyphosate resistant weeds. The aim of this study was to evaluate the acute toxic effects and the prevailing interactions on stage 36 tadpoles of the anuran species Rhinella arenarum when exposed to equitoxic and non-equitoxic combinations of these herbicide combinations. Experiments were realized using the following combinations of commercial formulations: 48% GLY-based Credit® + 57.71% DIC-based Banvel® and 48% GLY-based Credit® + 25% FLC-based Twin Pack Gold®. GLY-DIC and GLY-FLC equitoxic mixtures were assayed mixing each constituent with an equivalent individual toxicity able to induce the same lethality effect. After 96 h of exposure, GLY-DIC and GLY-FLC equitoxic mixtures presented toxic unit 50 values (TU50 96h) of 1.74 (confidence interval: 1.58-1.92) and 1.54 (confidence interval: 1.46-1.62) respectively, indicating the presence of a weak antagonistic interaction as TU values were greater than 1. For their part, most non-equitoxic combinations of GLY-DIC and GLY-FLC tested did not significantly differ from additivity, the only exception being when DIC and FLC were fixed at 0.33 TUs, where a weak antagonism was observed. Overall, results indicate that the toxicity of both GLY-DIC and GLY-FLC mixtures to R. arenarum tadpoles vary from additive to slightly antagonistic, depending on the proportion of constituting herbicide formulations present in the mixture.

Cytotoxic and genotoxic assessments of 2,4-dichlorophenoxyacetic acid (2,4-D) in in vitro mammalian cells

A combined approach employing alkaline single cell gel electrophoresis (SCGE) and cytokinesis-blocked micronucleus (MNs) cytome bioassays was adopted to assess the deleterious properties of the auxinic 2,4-dichlorophenoxyacetic acid (2,4-D) and its microparticulated low volatility product Dedalo Elite (30% a.i.) on Chinese hamster ovary (CHO-K1) cells. Cytotoxicity was estimated by neutral red uptake (NRU), succinic dehydrogenase activity (MTT) and apoptosis assessment. Both compounds were assayed at 0.1-10 μg/ml concentration range. Whereas exposed CHO-K1 cells revealed a statistically significant enhancement of MNs when 10 μg 2,4-D/ml was assayed, MNs were only achieved in cells treated with 2 μg Dedalo Elite/ml. A diminution in the nuclear division index was only achieved after exposure to Dedalo Elite within the 1-10 μg/ml concentration range. Whereas increased genetic damage index was achieved when 6 and 10 μg 2,4-D/ml were assayed, GDI induction was observed in treatments employing 4 μg Dedalo Elite/ml. Both compounds induced cytotoxicity by inhibition of both lysosomal and MTT activities by enhancing the frequencies of early and late apoptotic cells. Our results not only indicate the genotoxic and cytotoxic potential of 2,4-D and its microparticulated marketplace formulation, but also highlight the risk of these agrochemicals present towards the biota and human health.

Auxinic herbicides induce oxidative stress on Cnesterodon decemmaculatus (Pisces: Poeciliidae)

Pesticides might increase the production of reactive oxygen species (ROS). Dicamba (DIC) and 2,4-dichlorophenoxyacetic acid (2,4-D) are auxinic herbicides commonly applied in agroecosystems to control unwanted weeds. We analysed the oxidative damage exerted on the fish Cnesterodon decemmaculatus by an acute exposure to DIC- and 2,4-D-based herbicides formulations Banvel® and DMA®, respectively. The Endo III- and Fpg-modified alkaline comet assay was employed for detecting DNA damage caused by oxidative stress, whereas enzymatic and non-enzymatic biomarkers such as the activities of catalase (CAT), glutathione-S-transferase (GST), acetylcholinesterase (AChE), and glutathione content (GSH) were used to assess antioxidant response to these two herbicides. At the DNA level, results demonstrate that both auxinic herbicides induce oxidative damage at purines level. An increase on CAT and GST activities were detected in 48 h- and 96 h-treated specimens with both auxinics. GSH content decreased in fish exposed to DIC during 48 h and to 2,4-D after 96 h of exposure. Additionally, a diminished AChE activity in specimens treated with DIC and 2,4-D was observed only after 96 h. Total protein content decreased in fish exposed to both auxinics during 96 h. These results represent the first evaluation of oxidative damage related to DIC and 2,4-D exposure on a fish species as the Neotropical freshwater teleost C. decemmaculatus.

DNA damage exerted by mixtures of commercial formulations of glyphosate and imazethapyr herbicides in Rhinella arenarum (Anura, Bufonidae) tadpoles

Glyphosate (GLY) and imazethapyr (IMZT) are two herbicides commonly used worldwide, either alone or in mixtures. They represent key pesticides in modern agricultural management. The toxicity that results when employed as mixtures has not been characterized so far. Acute toxicity of the 48% GLY-based herbicide (GBH) Credit® and the 10.59% IMZT-based herbicide (IBH) Pivot® H alone and their binary combinations was analyzed in Rhinella arenarum tadpoles exposed in a semi-static renewal test. Lethal effects were determined using mortality as the end-point, whereas sublethal effects were determined employing the single-cell gel electrophoresis (SCGE) bioassay. Based on mortality experiments, results revealed LC5096 h values of 78.18 mg/L GBH and 0.99 mg/L IBH for Credit® and Pivot® H, respectively. An increase in the genetic damage index (GDI) was found after exposure to Credit® or Pivot® H at 5 and 10% of LC5096 h values. The combinations of 5% Credit®-5% Pivot® H LC5096 h and 10% Credit®-10% Pivot® H LC5096 h concentrations significantly enhanced the GDI in comparison with tadpoles exposed only to Credit® or Pivot® H. Thus, the effect of interaction between GBH and IBH inducing DNA damage in R. arenarum blood cells can be considered to be synergistic.

Synergism of mixtures of dicamba and 2,4-dichlorophenoxyacetic acid herbicide formulations on the neotropical fish Cnesterodon decemmaculatus (Pisces, Poeciliidae)

Dicamba (DIC) and 2,4-dichlorophenoxyacetic acid (2,4-D) are two of the most applied auxinic herbicides worldwide, both individually and as part of a mixture. However, the toxicity and interactions achieved when applied as a mixture have not yet been characterised. The equitoxic and non-equitoxic acute toxicity exerted by binary mixtures of Banvel^® (57.71% DIC) and DMA^® (58.4% 2,4-D) on the Neotropical fish Cnesterodon decemmaculatus were evaluated. Results revealed mean values of 1.02 (range, 0.96-1.08) for the toxic unit (TU) that induced 50% mortality (TU_{50 96 h}) to the fish exposed to binary equitoxic mixtures of the commercial formulations Banvel^®-DMA^®. These results suggest that the mixture is nearly concentration additive. Furthermore, results demonstrated the occurrence of synergistic interaction when non-equitoxic combinations of Banvel^®-or DMA^®-formulated herbicides were assayed. In this context and regardless of their concentrations, either Banvel^®- or DMA^®-induced toxicity were synergised by the presence of the counterpart within mixtures. The present study represents the first evidence of the lethality exerted by mixtures of two auxinic herbicides-namely, DIC and 2,4-D-reported to date for fish and other biotic matrices. When C. decemmaculatus is used as the target organism, a synergistic pattern is observed following exposure to a mixture of both herbicides.

Lethal and sublethal effects of the pirimicarb-based formulation Aficida® on Boana pulchella (Duméril and Bibron, 1841) tadpoles (Anura, Hylidae)

Acute lethal and sublethal toxicity of the pirimicarb-based commercial formulation Aficida^® were evaluated on Boana pulchella tadpoles. Whereas mortality was used as end point for lethality, frequency of micronuclei and other nuclear abnormalities as well as alterations in the frequency of erythroblasts in circulating blood as biomarkers for genotoxicity and cytotoxicity, respectively. Swimming, growth, developmental and morphological abnormalities were also employed as sublethal end points. Results show that the species is within the 13th percentile of the distribution of acute sensitivity of species to pirimicarb for aquatic vertebrates. Results revealed values of 23.78 and 101.45mg/L pirimicarb as LC50_96h for GS25 and GS36 tadpoles, respectively. The most evident effects were related with the swimming activity with NOEC and LOEC values within the 0.005-0.39mg/L pirimicarb concentration range. Aficida^® induced DNA damage at the chromosomal level by increasing micronuclei frequency and other nuclear abnormalities, i.e., lobbed and notched nuclei and binucleated cells. Cellular cytotoxicity was found after Aficida^® treatment. The presence of abdominal oedemas in exposed organisms and thus flotation response of organisms could be proposed as a new sensitive exposure parameter. The multiple end point assessment approach used allowed a complete understanding the multi level of effects occurring by exposure to pirimicarb, at least in B. pulchella.

Assessment of genotoxicity of Lannate-90® and its plant and animal metabolites in human lymphocyte cultures

This study evaluated direct and metabolic genotoxic effects caused by Lannate-90®, a methomyl-based formulation (90 % active ingredient), in human lymphocyte cultures using sister chromatid exchange assay (SCE). Two processes were used for the plant promutagens evaluation: in vivo activation, applying the insecticide systemically in plants for 4 h and subsequently adding plant metabolites containing extracts to lymphocyte cultures; and in vitro activation, where the insecticide was incubated with Vicia faba S10 mix plus human lymphocyte culture. Direct treatment with the insecticide significantly increased SCE frequency in human lymphocytes (250-750 mgL-1), with cellular death observed at 1000 mgL-1 concentration. Using the extracts of Vicia faba treated with Lannate-90® to treat human lymphocytes, a dose-response relationship was observed. In lymphocyte cultures treated directly with the insecticide for 2 h, a negative response was obtained. When S10 mix was added, SCE frequency did not change significantly. Meanwhile, a mixture of S9 mammalian metabolic mix and Lannate-90® increased the SCE frequency, with an observed concentration-dependent response. Although Lannate-90® induced cellular death at the highest concentrations, it did not cause a delay in cell proliferation in any of the treatments, confirming its genotoxic action. This study is one of the first to evaluate and compare the direct effect of Lannate-90® in two bioassays, animal and vegetal, and the effect of plant and animal metabolism on its genotoxic potential.

Evaluation of potential genotoxic/cytotoxic effects induced by epoxiconazole and fenpropimorph-based fungicide in bovine lymphocytes in vitro

Potential genotoxic/cytotoxic effects of the epoxiconazole/fenpropimorph-based fungicide were investigated using single cell gel electrophoresis and cytogenetic assays: chromosomal aberrations, sister chromatid exchanges, micronuclei and fluorescence in situ hybridization in cultured bovine lymphocytes. No statistically significant elevations of DNA damage and increases in cytogenetic endpoints were seen. However, evident cytotoxic effect presented as a decrease in mitotic and proliferation indices were recorded after exposure of bovine lymphocytes to the fungicide for 24 and 48 h at concentrations ranging from 3 to 15 µg mL(-1) (P < 0.05, P < 0.01, P < 0.001). Similarly, for 24 h an inhibition in the cytokinesis block proliferation index (CBPI) was obtained after exposure to the fungicide at concentrations ranging from 1.5 to 15 µg mL(-1) (P < 0.01, P < 0.001) in each donor.

Genotoxic effect of a binary mixture of dicamba- and glyphosate-based commercial herbicide formulations on Rhinella arenarum (Hensel, 1867) (Anura, Bufonidae) late-stage larvae

The acute toxicity of two herbicide formulations, namely, the 57.71 % dicamba (DIC)-based Banvel(®) and the 48 % glyphosate (GLY)-based Credit(®), alone as well as the binary mixture of these herbicides was evaluated on late-stage Rhinella arenarum larvae (stage 36) exposed under laboratory conditions. Mortality was used as an endpoint for determining acute lethal effects, whereas the single-cell gel electrophoresis (SCGE) assay was employed as genotoxic endpoint to study sublethal effects. Lethality studies revealed LC5096 h values of 358.44 and 78.18 mg L(-1) DIC and GLY for Banvel(®) and Credit(®), respectively. SCGE assay revealed, after exposure for 96 h to either 5 and 10 % of the Banvel(®) LC5096 h concentration or 5 and 10 % of the Credit(®) LC5096 h concentration, an equal significant increase of the genetic damage index (GDI) regardless of the concentration of the herbicide assayed. The binary mixtures of 5 % Banvel(®) plus 5 % Credit(®) LC5096 h concentrations and 10 % Banvel(®) plus 10 % Credit(®) LC5096 h concentrations induced equivalent significant increases in the GDI in regard to GDI values from late-stage larvae exposed only to Banvel(®) or Credit(®). This study represents the first experimental evidence of acute lethal and sublethal effects exerted by DIC on the species, as well as the induction of primary DNA breaks by this herbicide in amphibians. Finally, a synergistic effect of the mixture of GLY and DIC on the induction of primary DNA breaks on circulating blood cells of R. arenarum late-stage larvae could be demonstrated.

Cytotoxic and genotoxic effects of abamectin, chlorfenapyr, and imidacloprid on CHOK1 cells

The cytotoxicity and genotoxicity of abamectin, chlorfenapyr, and imidacloprid have been evaluated on the Chinese hamster ovary (CHOK1) cells. Neutral red incorporation (NRI), total cellular protein content (TCP), and methyl tetrazolium (MTT) assays were followed to estimate the mid-point cytotoxicity values, NRI50, TCP50, and MTT50, respectively. The effects of the sublethal concentration (NRI25) on glutathione S-transferase (GST), glutathione reductase (GRD), glutathione peroxidase (GPX), and total glutathione content have been evaluated in the presence and absence of reduced glutathione (GSH), vitamin C, and vitamin E. The genotoxicity was evaluated using chromosomal aberrations (CA), micronucleus (MN) formation, and DNA fragmentation techniques in the presence and absence of the metabolic activation system, S9 mix. Abamectin was the most cytotoxic pesticide followed by chlorfenapyr, while imidacloprid was the least cytotoxic one. The glutathione redox cycle components were altered by the tested pesticides in the absence and presence of the tested antioxidants. The results of genotoxicity indicate that abamectin, chlorfenapyr, and imidacloprid have potential genotoxic effects on CHOK1 cells under the experimental conditions.

Analysis of the genotoxic potential of low concentrations of Malathion on the Allium cepa cells and rat hepatoma tissue culture

Based on the concentration of Malathion used in the field, we evaluated the genotoxic potential of low concentrations of this insecticide on meristematic and F1 cells of Allium cepa and on rat hepatoma tissue culture (HTC cells). In the A. cepa, chromosomal aberrations (CAs), micronuclei (MN), and mitotic index (MI) were evaluated by exposing the cells at 1.5, 0.75, 0.37, and 0.18mg/mL of Malathion for 24 and 48hr of exposure and 48hr of recovery time. The results showed that all concentrations were genotoxic to A. cepa cells. However, the analysis of the MI has showed non-relevant effects. Chromosomal bridges were the CA more frequently induced, indicating the clastogenic action of Malathion. After the recovery period, the higher concentrations continued to induce genotoxic effects, unlike the observed for the lowest concentrations tested. In HTC cells, the genotoxicity of Malathion was evaluated by the MN test and the comet assay by exposing the cells at 0.09, 0.009, and 0.0009mg/5mL culture medium, for 24hr of exposure. In the comet assay, all the concentrations induced genotoxicity in the HTC cells. In the MN test, no significant induction of MN was observed. The genotoxicity induced by the low concentrations of Malathion presented in this work highlights the importance of studying the effects of low concentrations of this pesticide and demonstrates the efficiency of these two test systems for the detection of genetic damage promoted by Malathion.

Toxic and genotoxic effects of the imazethapyr-based herbicide formulation Pivot H® on montevideo tree frog Hypsiboas pulchellus tadpoles (Anura, Hylidae)

Acute lethal and sublethal toxicity of the imidazolinone imazethapyr (IMZT)-based commercial formulation herbicide Pivot H® (10.59% IMZT) was evaluated on Hypsiboas pulchellus tadpoles. Whereas mortality was used as the end point for lethality, frequency of micronuclei (MNs) and other nuclear abnormalities as well as DNA single-strand breaks evaluated by the single cell gel electrophoresis assay were employed to test genotoxicity. Behavioral, growth, developmental, and morphological abnormalities were also employed as sublethal end points. Mortality studies revealed equivalent LC50 (96h) values of 1.49mg/L (confidence limit, 1.09-1.63) and 1.55mg/L (confidence limit, 1.51-1.60) IMZT for Gosner stage (GS) 25 and GS36, respectively. Behavioral changes, i.e., irregular swimming and immobility, as well as a decreased frequency of keratodonts were observed. The herbicide increased the frequency of MNs in circulating erythrocytes of tadpoles exposed for 48h to the highest concentration assayed (1.17mg/L). However, regardless of the concentration of the herbicide assayed, an enhanced frequency of MNs was observed in tadpoles exposed for 96h. The herbicide was able to induce other nuclear abnormalities, i.e., blebbed and notched nuclei, only when tadpoles were exposed for 96h. In addition, we observed that exposure to IMZT within the 0.39-1.17mg/L range increased the genetic damage index in treatments lasting for both 48 and 96h. This study represents the first evidence of acute lethal and sublethal effects exerted by IMZT on amphibians. Finally, our findings highlight the properties of this herbicide that jeopardize nontarget living species exposed to IMZT.

Carbamates: A study on genotoxic, cytotoxic, and apoptotic effects induced in Chinese hamster ovary (CHO-K1) cells

In vitro effects of the carbamates pirimicarb and zineb and their formulations Aficida® (50% pirimicarb) and Azzurro® (70% zineb), respectively, were evaluated in Chinese hamster ovary (CHO-K1) cells. Whereas the cytokinesis-blocked micronucleus cytome assay was employed to test for genotoxicity, MTT, neutral red (NR), and apoptosis evaluation were used as tests for estimating cell viability and succinic dehydrogenase activity, respectively. Concentrations tested were 10-300 μg/ml for pirimicarb and Aficida®, and 1-50 μg/ml for zineb and Azzurro®. All compounds were able to increase the frequency of micronuclei. A marked reduction in the nuclear division index was observed after treatment with 5 μg/ml of zineb and Azzurro® and 10 μg/ml of Azzurro®. Alterations in the cellular morphology not allowing the recognition of binucleated cells exposed to 300 μg/ml pirimicarb and Aficida® as well as 10-50 μg/ml zineb and Azzurro®. All four compounds induced inhibition of both cell viability and succinic dehydrogenase activity and trigger apoptosis in CHO-K1 cells, at least when exposed for 24 h. The data herein demonstrate the genotoxic and cytotoxic effects exerted by these carbamates and reveal the potential risk factor of these pesticides, still extensively used worldwide, for both human health and the environment.

Chlorpyrifos-based insecticides induced genotoxic and cytotoxic effects in the ten spotted live-bearer fish, Cnesterodon decemmaculatus (Jenyns, 1842)

Mortality, genotoxicity, and cytotoxicity of the 48% chlorpyrifos (CPF)-based formulations Lorsban* 48E(®) and CPF Zamba(®) were evaluated on Cnesterodon decemmaculatus (Jenyns, 1842) (Pisces, Poeciliidae) under laboratory conditions. Induction of micronucleus (MN) and alterations in the erythrocyte/erythroblast frequencies were employed as end points for genotoxicity and cytotoxicity, respectively. For Lorsban* 48E(®) , mean values of 0.13 and 0.03 mg/L were determined for LC50 at 24 and 96 h, respectively, and these concentrations reached mean values of 0.40 and 0.21 mg/L for CPF Zamba(®) . Mortality values increased as a positive linear function of the CPF Zamba(®) concentrations, but not for Lorsban* 48E(®) concentrations. There was no significant relationship between mortality and exposure time within the 0-96 h period for both formulations. LC50 values indicated that the fish were seven fold more sensitive to Lorsban* 48E(®) than to CPF Zamba(®) . Lorsban* 48E(®) within the concentration range of 0.008-0.025 mg/L increased MN frequency at both 48 and 96 h of treatment. Similar results were also observed when fish were exposed to 0.052-0.155 mg/L of CPF Zamba(®) , regardless of the exposure time. Cellular cytotoxicity was found after Lorsban* 48E(®) and CPF Zamba(®) treatments for all concentrations and time exposures, estimated by a decrease in the frequency of mature erythrocytes and a concomitant enhanced frequency of erythroblasts in circulating blood. Furthermore, our results demonstrated that Lorsban* 48E(®) and CPF Zamba(®) should be considered as CPF-based commercial formulations with marked genotoxic and cytotoxic properties.

Assessment of cytotoxic and genotoxic potential of pyracarbolid by Allium test and micronucleus assay

The present study evaluates the cytotoxic and genotoxic potential of pyracarbolid using both micronuleus (MN) assay, in human lymphocytes, and Allium cepa assay, in the root meristem cells. In Allium test, EC50 value was determined in order to selecting the test concentrations for the assay and the root tips were treated with 25 ppm (EC50/2), 50 ppm (EC50) and 100 ppm (EC50 × 2) concentrations of pyracarbolid. One percent of dimethyl sulphoxide (DMSO) and methyl methane sulfonate (MMS) were used as negative and positive controls, respectively. In the micronucleus assay, the cultures were treated with four concentrations (250, 500, 750 and 1000 µg/ml) of pyracarbolid for 24 and 48 h, negative and positive controls were also used in the experiment parallely. The results showed that mitotic index (MI) significantly reduced with increasing the pyracarbolid concentration at each exposure time. It was also obtained that prophase and metaphase index decreased significantly in all concentration at each exposure time. Anaphase index decreased as well and results were found to be statistically significant, except 24 h. A significant increase was observed in MN frequency in all concentrations and both treatment periods when compared with the controls. Pyracarbolid also caused a significant reduction in the cytokinesis block proliferation index (CBPI) in all concentration and both exposure time.

Comparative evaluation in vitro of the herbicide flurochloridone by cytokinesis-block micronucleus cytome and comet assays

The in-vitro effects of flurochloridone and its formulations Twin Pack Gold® (25% a.i.) and Rainbow® (25% a.i.) were evaluated in Chinese Hamster Ovary K1 (CHO-K1) cells. The cytokinesis-block micronucleus cytome (CBMN-cyt) and single-cell gel electrophoresis (SCGE) assays were used. The activities were tested within the range of final concentrations of 0.25-15 μg flurochloridone/mL. The results demonstrated that both the flurochloridone and Rainbow® were not able to induce micronuclei (MN). On the other hand, Twin Pack Gold® only increased the frequency of MN at 5 μg/mL. Furthermore, 10 and 15 μg/mL of both formulations resulted in a cellular cytotoxicity demonstrated by alterations in the nuclear division index and cellular death. SCGE assay appeared to be a more sensitive bioassay for detecting primary DNA strand breaks at lower concentrations of flurochloridone than MN did. A marked increase in the genetic damage index was observed when 5 and 15 μg/mL of both flurochloridone and Rainbow® but only when 15 μg/mL of Twin Pack Gold® were used. This is the first report demonstrating that flurochloridone and its two commercial formulations are able to induce single-strand DNA breaks in vitro on mammalian cells.

Micronucleus assay in human lymphocytes after exposure to alloxydim sodium herbicide in vitro

This study evaluates the cytotoxic and genotoxic potential of alloxydim sodium using micronucleus (MN) assay, in human peripheral lymphocytes. MN assay was used to investigate the genotoxic effects of alloxydim sodium in human peripheral lymphocytes treated with 250, 500, 750, 1,000 µg/ml concentrations of alloxydim sodium for 24 and 48 h. Solvent, negative and positive controls were also used in the experiments in parallel. The obtained results were evaluated in statistical analyses by using Dunnett-t test (two sided) and p < 0.05 was accepted as significant. Alloxydim sodium significantly increased the MN formation compared with the negative control, at both 750 and 1,000 µg/ml concentrations and treatment periods. We also evaluated the nuclear division index (NDI) for cytotoxicity of this pesticide in the experiment, and finally observed a significant decrease of the NDI values at all concentrations of alloxydim sodium and at both treatment periods.

The genotoxic effects of the imidacloprid-based insecticide formulation Glacoxan Imida on Montevideo tree frog Hypsiboas pulchellus tadpoles (Anura, Hylidae)

The neonicotinoid insecticide imidacloprid (IMI) affects the insect central nervous system and is successfully applied to control pests for a variety of agricultural crops. In the current study, acute toxicity and genotoxicity of the IMI-containing commercial formulation insecticide Glacoxan Imida (35 percent IMI) was evaluated on Hypsiboas pulchellus (Anura: Hylidae) tadpoles exposed under laboratory conditions. A lethal effect was evaluated as the end point for lethality, whereas micronucleus (MN) frequency and DNA single-strand breaks evaluated by the single cell gel electrophoresis (SCGE) assay were employed as end points for genotoxicity. Sublethal end points were assayed within the 12.5-37.5mg/L IMI concentration range. Experiments were performed on tadpoles at stage 36 (range, 35-37) according to the classification proposed by Gosner. Lethality studies revealed an LC50 96h value of 52.622mg/L IMI. Increased frequency of MNs was only observed when 25.0mg/L was assayed for 96h, whereas no other nuclear abnormalities were induced. Increase of the genetic damage index was observed at 48h of treatment within the 12.5-37.5mg/L concentration range, whereas an increased frequency of DNA damage was observed only in tadpoles treated with 37.5mg/L IMI for 96h. This study represents the first evidence of the acute lethal and genotoxic effects exerted by IMI on tadpoles of an amphibian species native to Argentina under laboratory conditions.

Flurochloridone-based herbicides induced genotoxicity effects on Rhinella arenarum tadpoles (Anura: Bufonidae)

Acute toxicity and genotoxicity of the flurochloridone (FLC)-containing commercial formulation herbicides Twin Pack Gold(®) (25 percent a.i.) and Rainbow(®) (25 percent a.i.) were evaluated on Rhinella arenarum (Anura: Bufonidae) tadpoles exposed under laboratory conditions. Lethal effect was evaluated as end point for lethality, whereas frequency of micronuclei (MN) and single cell gel electrophoresis (SCGE) were employed as end points for genotoxicity. Lethality studies revealed equivalent LC-5096 h values of 2.96 and 2.85 mg/L for Twin Pack Gold(®) and Rainbow(®), respectively. Twin Pack Gold(®) did not induce DNA damage at the chromosomal level, whereas Rainbow(®) increased the frequency of MN only when the lowest concentration (0.71 mg/L) was used. However, all concentrations of Twin Pack Gold(®) and Rainbow(®) increased the frequencies of primary DNA lesions estimated by alkaline SCGE. This study represents the first evidence of the acute toxic and genotoxic effects exerted by two FLC-based commercial formulations, Twin Pack Gold(®) and Rainbow(®), on tadpoles of an amphibian species native to Argentina under laboratory conditions. Finally, our findings highlight the importance of minimizing the impacts on nontarget living species exposed to agrochemicals.

Comparative study of cytotoxic and genotoxic effects induced by herbicide S-metolachlor and its commercial formulation Twin Pack Gold® in human hepatoma (HepG2) cells

The in vitro effects of S-metolachlor and its formulation Twin Pack Gold(®) (96% a.i.) were evaluated in human hepatoma (HepG2) cells. Cytokinesis-blocked micronucleus cytome (CBMN-cyt) and MTT assays as well as Neutral Red uptake were employed for genotoxicity and cytotoxicity evaluation. Activities were tested within the concentration range of 0.25-15 μg/ml S-metolachlor for 24h of exposure. Both compounds rendered a minor reduction in the NDI although not reaching statistical significance. Results demonstrated that the S-metolachlor was not able to induce MNs. On the other hand, 0.5-6 μg/ml Twin Pack Gold(®) increased the frequency of MNs. When cytotoxicity was estimated, S-metolachlor was not able to induce either a reduction of lysosomal or mitochondrial activity. Contrarily, whereas 1-15 μg/ml Twin Pack Gold(®) induced a significant reduction of mitochondrial activity, all tested concentrations of the formulated product induced a significant decrease of lysosomal performance as a function of the concentration of the S-metolachlor-based formulation titrated into cultures. Genotoxicity and cytotoxicity differences obtained with pure S-metolachlor and the commercial S-metolachlor-based formulation indicate that the latter may contain additional unsafe xenobiotics and support the concept of the importance of evaluating not only the active principle but also the commercial formulation when estimating the real hazard from agrochemicals.

Assessment of cytogenetic damage in bovine peripheral lymphocytes exposed to in vitro tebuconazole-based fungicide

The tebuconazole-based fungicide was tested in vitro for its potential genotoxic and cytotoxic effects on cultured bovine peripheral lymphocytes. Following 24h and 48 h of incubation, several cytogenetic endpoints were investigated such as: Chromosome Aberrations (CAs); Sister Chromatid Exchanges (SCEs); Micronuclei (MN); Mitotic Index (MI); Proliferation Index (PI); and Cytokinesis Block Proliferation Index (CBPI). The cultured lymphocytes were exposed to the fungicide formulation at concentrations of 3, 6, 15, 30 and 60 μg mL(-1). Statistical significant increases were seen in the CA assays at concentrations ranging from 6 to 30 μg mL(-1) for 24h. The higher doses caused a decrease or total inhibition of chromosome damages in comparison to the last active dose, or the control values. The Fluorescence in situ Hybridisation (FISH) technique was also used for the study of stable/unstable structural chromosomal aberrations and numerical aberrations of aneuploidy/polyploidy at the concentrations of 6 and 15 μg mL(-1). Under conditions of our study, no reciprocal translocations were detected. The more frequent types of aberrations were trisomies and monosomies; both have been identified in association with either bovine chromosome 5 or 7. No statistical significant value was seen in the induced MN; but, the clear, evident reduction of the CBPI was observed. Significant elevations of SCE were observed after the applications of the fungicide formulation at doses from 15 to 60 μg mL(-1) in each donor for 24h. The highest concentrations also caused a statistical significant decrease in the PI. The treatment for 48 h failed to exhibit any genotoxic activity of the fungicide.

Pirimicarb-based formulation-induced genotoxicity and cytotoxicity in the freshwater fish Cnesterodon decemmaculatus (Jenyns, 1842) (Pisces, Poeciliidae)

We analyzed the aspects of lethality, genotoxicity, and cytotoxicity in the ten spotted live-bearer exposed under laboratory conditions to the pirimicarb-based formulation Patton Flow® (50% active ingredient (a.i.)). Acute effects were evaluated using different end points for lethality, genotoxicity, and cytotoxicity. Median lethal concentration (LC50) estimation was employed as a bioassay for lethality, whereas micronucleus (MN) induction and alterations in erythrocyte/erythroblast frequency were used as end points for genotoxicity and cytotoxicity, respectively. Results demonstrated an LC5096h value of 88 mg/L. Patton Flow® increased the MN frequency in fish erythrocytes after 48 h of exposure at a concentration of 66 mg/L, whereas a concentration range of 22–66 mg/L was able to exert the same genotoxic effect at 96 h of treatment. Furthermore, cytotoxicity was also observed by alterations in erythrocyte/erythroblast frequencies within the concentration range of 22–66 mg/L, regardless of the exposure time. Our current observations provide evidence that Patton Flow® (50% a.i.) should be considered a clear lethal, cytotoxic, and genotoxic agent on Cnesterodon decemmaculatus. Thus, repeated applications of this carbamic insecticide can enter the aquatic environment and exert deleterious effects on aquatic organisms other than the evaluated species C. decemmaculatus.

Evaluation of the genotoxic and cytotoxic effects of glyphosate-based herbicides in the ten spotted live-bearer fish Cnesterodon decemmaculatus (Jenyns, 1842)

Mortality, genotoxicity, and cytotoxicity of the 48% glyphosate-based formulations Panzer and Credit(®) were evaluated on Cnesterodon decemmaculatus (Jenyns, 1842) (Pisces, Poeciliidae) under laboratory conditions. Induction of micronuclei (MN) and alterations in the erythrocytes:erythroblasts ratio were employed as end points for genotoxicity and cytotoxicity, respectively. For Panzer(®), mean values of 16.70 and 15.68 mg/L were determined for LC(50) at 24 and 96 h, respectively, and these concentrations reached mean values of 98.50 and 91.73 mg/L for Credit(®). LC(50) values decreased as a negative linear function of Panzer(®) exposure time within the 0-96 h period, but not for Credit(®). LC(50) values indicated that the fish were more sensitive to Panzer(®) than to Credit(®). Both 3.9 and 7.8 mg/L of Panzer(®) increased MN frequency at 48 and 96 h of treatment. When fish were exposed to Credit(®), an increased frequency of MN over control values was found after 96 h for all concentrations assayed, but not after 48 h. No cellular cytotoxicity was found after Panzer(®) and Credit(®) treatment, regardless of both the concentration and the sampling time. Furthermore, our results demonstrated that Panzer(®) and Credit(®) should be considered as glyphosate-based commercial formulations with genotoxic but not cytotoxic effect properties.

Nanobiosensors based on chemically modified AFM probes: a useful tool for metsulfuron-methyl detection

The use of agrochemicals has increased considerably in recent years, and consequently, there has been increased exposure of ecosystems and human populations to these highly toxic compounds. The study and development of methodologies to detect these substances with greater sensitivity has become extremely relevant. This article describes, for the first time, the use of atomic force spectroscopy (AFS) in the detection of enzyme-inhibiting herbicides. A nanobiosensor based on an atomic force microscopy (AFM) tip functionalised with the acetolactate synthase (ALS) enzyme was developed and characterised. The herbicide metsulfuron-methyl, an ALS inhibitor, was successfully detected through the acquisition of force curves using this biosensor. The adhesion force values were considerably higher when the biosensor was used. An increase of ~250% was achieved relative to the adhesion force using an unfunctionalised AFM tip. This considerable increase was the result of a specific interaction between the enzyme and the herbicide, which was primarily responsible for the efficiency of the nanobiosensor. These results indicate that this methodology is promising for the detection of herbicides, pesticides, and other environmental contaminants.

Genotoxic and cytotoxic evaluation of the herbicide flurochloridone on Chinese hamster ovary (CHO-K1) cells

The in vitro effects of flurochloridone (FLC) and its formulations Twin Gold Pack® (25% a.i.) and Rainbow® (25% a.i.) were evaluated on Chinese hamster ovary (CHO-K1) cells by genotoxicity [sister chromatid exchange (SCE)] and cytotoxicity [cell-cycle progression, proliferative rate index (PRI), mitotic index (MI), MTT, and neutral red] end points. Cells were treated for 24h within the 0.25-15μg/ml concentration range. FLC and Twin Pack Gold® induced a significant and equivalent increase in SCEs regardless of the concentration. Rainbow®-induced SCEs at concentrations higher than 2.5μg/ml; however, the increases were always lower than those induced by FLC and Twin Pack Gold®. For all compounds, the PRI decreased as a function of the concentration titrated into cultures. Whereas only the highest FLC and Twin Pack Gold® concentrations induced a significant reduction of the MI, all tested Rainbow® concentrations induced MI inhibition. Overall, the results demonstrated that although all compounds were not able to reduce the lysosomal activity, the mitochondrial activity was diminished when the highest concentrations were employed. These observations represent the first study analyzing the genotoxic and cytotoxic effects exerted by FLC and two formulated products on mammalian cells in vitro, at least on CHO-K1 cells.

Spectroscopic studies of the interaction between pirimicarb and calf thymus DNA

The interaction between pirimicarb and calf thymus DNA in physiological buffer (pH 7.4) was investigated with the use of Neutral Red (NR) dye as a spectral probe by UV-vis absorption, fluorescence and circular dichroism (CD) spectroscopy, as well as viscosity measurements and DNA melting techniques. The results revealed that an intercalation binding should be the interaction mode of pirimicarb to DNA. CD spectra indicated that pirimicarb induced conformational changes of DNA. The binding constants of pirimicarb with DNA were obtained by the fluorescence quenching method. The thermodynamic parameters, enthalpy change (ΔHθ) and entropy change (ΔSθ) were calculated to be -52.13±2.04 kJ mol(-1) and -108.8±6.72 J mol(-1) K(-1) according to the van't Hoff equation, which suggested that hydrogen bonds and van der Waals forces might play a major role in the binding of pirimicarb to DNA. Further, the alternative least squares (ALS) method was applied to resolve a complex two-way array of the absorption spectra data, which provided simultaneously the concentration information for the three reaction components, pirimicarb, NR and DNA-NR. This ALS analysis indicated that the intercalation of pirimicarb into the DNA by substituting for NR in the DNA-NR complex.

Impact of EMS outreach: successful developments in Latin America

This collection of articles was inspired by the long-standing relationship between the Environmental Mutagen Society and Latin American scientists, and by the program for the 39th Environmental Mutagen Society meeting in Puerto Rico in 2008, which included a symposium featuring "South of the border" scientists. This collection, compiled by Graciela Spivak and Ofelia Olivero, both originally from Argentina, highlights scientists who work in or were trained in Latin American countries and in Puerto Rico in a variety of scientific specialties related to DNA repair and cancer susceptibility, genomic organization and stability, genetic diversity, and environmental contaminants.