Evaluation of oxidative stress and genotoxicity in organophosphorus insecticide formulators

Blood molecular profile to predict genotoxicity from exposure to antineoplastic drugs

Genotoxicity is an important information that should be included in human biomonitoring programmes. However, the usually applied cytogenetic assays are laborious and time-consuming, reason why it is critical to develop rapid and economic new methods. The aim of this study was to evaluate if the molecular profile of frozen whole blood, acquired by Fourier Transform Infrared (FTIR) spectroscopy, allows to assess genotoxicity in occupational exposure to antineoplastic drugs, as obtained by the cytokinesis-block micronucleus assay. For that purpose, 92 samples of peripheral blood were studied: 46 samples from hospital professionals occupationally exposed to antineoplastic drugs and 46 samples from workers in academia without exposure (controls). It was first evaluated the metabolome from frozen whole blood by methanol precipitation of macromolecules as haemoglobin, followed by centrifugation. The metabolome molecular profile resulted in 3 ratios of spectral bands, significantly different between the exposed and non-exposed group (p < 0.01) and a spectral principal component-linear discriminant analysis (PCA-LDA) model enabling to predict genotoxicity from exposure with 73 % accuracy. After optimization of the dilution degree and solution used, it was possible to obtain a higher number of significant ratios of spectral bands, i.e., 10 ratios significantly different (p < 0.001), highlighting the high sensitivity and specificity of the method. Indeed, the PCA-LDA model, based on the molecular profile of whole blood, enabled to predict genotoxicity from the exposure with an accuracy, sensitivity, and specificity of 92 %, 93 % and 91 %, respectively. All these parameters were achieved based on 1 μL of frozen whole blood, in a high-throughput mode, i.e., based on the simultaneous analysis of 92 samples, in a simple and economic mode. In summary, it can be conclude that this method presents a very promising potential for high-dimension screening of exposure to genotoxic substances.

Organophosphate pesticide-induced toxicity through DNA damage and DNA repair mechanisms

Organophosphate pesticides (OPs) are widely used in agriculture, healthcare, and other industries due to their ability to kill pests. However, OPs can also have genotoxic effects on humans who are exposed to them. This review summarizes the research on DNA damage caused by OPs, the mechanisms behind this damage, and the resulting cellular effects. Even at low doses, OPs have been shown to damage DNA and cause cellular dysfunction. Common phenomena seen in cells that are exposed to OPs include the formation of DNA adducts and lesions, single-strand and double-strand DNA breaks, and DNA and protein inter and intra-cross-links. The present review will aid in comprehending the extent of genetic damage and the impact on DNA repair pathways caused by acute or chronic exposure to OPs. Additionally, understanding the mechanisms of the effects of OPs will aid in correlating them with various diseases, including cancer, Alzheimer's, and Parkinson's disease. Overall, knowledge of the potential adverse effects of different OPs will help in monitoring the health complications they may cause.

Pesticides and tremor: An overview of association, mechanisms and confounders

Pesticides are a heterogeneous class of chemicals mainly used for the protection of crops from pests. Because of their very widespread use, acute or/and chronic exposure to these chemicals can lead to a plethora of sequelae inflicting diseases, many of which involve the nervous system. Tremor has been associated with pesticide exposure in human and animal studies. This review is aimed at assessing the studies currently available on the association between the various types of pesticides/insecticides and tremor, while also accounting for potential confounding factors. To our knowledge, this is the first coherent review on the subject. After appraising the available evidence, we call for more intensive research on this topic, as well as intonate the need of implementing future preventive measures to protect the exposed populations and to reduce potential disabilities and social drawbacks.

Intermittent exposure to chlorpyrifos results in cardiac hypertrophy and oxidative stress in rats

Forbidden in some countries due to its proven toxicity to humans, chlorpyrifos (CPF) still stands as an organophosphate pesticide (OP) highly used worldwide. Cardiotoxicity assessment is an unmet need in pesticide regulation and should be deeply studied through different approaches to better inform and generate an appropriate regulatory response to OP use. In the present study, we used our 4-week intermittent OP exposure model in rats to address the CPF effects on cardiac morphology allied with cardiovascular functional and biomolecular evaluation. Rats were intermittently treated with CPF at doses of 7 mg/kg and 10 mg/kg or saline (i.p.) and assessed for cardiac morphology (cardiomyocyte diameter and collagen content), cardiopulmonary Bezold-Jarisch reflex (BJR) function, cardiac autonomic tone, left ventricle (LV) contractility, cardiac expression of NADPH oxidase (Nox2), catalase (CAT), superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2) and cardiac levels of advanced oxidation protein products (AOPP) and thiobarbituric acid reactive substances (TBARS). Plasma butyrylcholinesterase (BuChE) and brainstem acetylcholinesterase (AChE) were also measured. Intermittent exposure to CPF induced cardiac hypertrophy, increasing cardiomyocyte diameter and collagen content. An impairment of cardioinhibitory BJR responses and an increase in cardiac vagal tone were also observed in CPF-treated animals without changes in LV contractility. CPF exposure increased cardiac Nox-2, CAT, SOD1, and TBARS levels and inhibited plasma BuChE and brainstem AChE activities. Our data showed that intermittent exposure to CPF induces cardiac hypertrophy together with cardiovascular reflex impairment, imbalance of autonomic tone and oxidative stress, which may bring significant cardiovascular risk to individuals exposed to OP compounds seasonally.

Protective effect of plant compounds in pesticides toxicity

INTRODUCTION

The relationship between pesticide exposure and the occurrence of many chronic diseases, including cancer, is confirmed by literature data.

METHODS

In this review, through the analysis of more than 70 papers, we explore an increase in oxidative stress level caused by exposure to environmental pollutants and the protective effects of plant-origin antioxidants.

RESULTS AND DISCUSSION

One of the molecular mechanisms, by which pesticides affect living organisms is the induction of oxidative stress. However, recently many plant-based dietary ingredients with antioxidant properties have been considered as a chemopreventive substances due to their ability to remove free radicals. Such a food component must meet several conditions: eliminate free radicals, be easily absorbed and function at an appropriate physiological level. Its main function is to maintain the redox balance and minimize the cellular damage caused by ROS. Therefore, it should be active in aqueous solutions and membrane domains. These properties are characteristic for phenolic compounds and selected plant hormones. Phenolic compounds have proven antioxidant properties, while increasing number of compounds from the group of plant hormones with a very diverse chemical structure turn out to act as antioxidants, being potential food ingredients that can eliminate negative effects of pesticides.

Pesticide impacts on avian species with special reference to farmland birds: a review

For decades, we have observed a major biodiversity crisis impacting all taxa. Avian species have been particularly well monitored over the long term, documenting their declines. In particular, farmland birds are decreasing worldwide, but the contribution of pesticides to their decline remains controversial. Most studies addressing the effects of agrochemicals are limited to their assessment under controlled laboratory conditions, the determination of lethal dose 50 (LD₅₀) values and testing in a few species, most belonging to Galliformes. They often ignore the high interspecies variability in sensitivity, delayed sublethal effects on the physiology, behaviour and life-history traits of individuals and their consequences at the population and community levels. Most importantly, they have entirely neglected to test for the multiple exposure pathways to which individuals are subjected in the field (cocktail effects). The present review aims to provide a comprehensive overview for ecologists, evolutionary ecologists and conservationists. We aimed to compile the literature on the effects of pesticides on bird physiology, behaviour and life-history traits, collecting evidence from model and wild species and from field and lab experiments to highlight the gaps that remain to be filled. We show how subtle nonlethal exposure might be pernicious, with major consequences for bird populations and communities. We finally propose several prospective guidelines for future studies that may be considered to meet urgent needs.

DNA damage in a Chilean population exposed to pesticides and its association with PON1 (Q192R and L55M) susceptibility biomarker

The active ingredients in pesticides are known to be genotoxic that can cause mutations, chromosomal aberrations, or other types of DNA damage. Early detection of genotoxicity reduces the risk of developing diseases such as cancer or suffering from reproductive disorders. In turn, the genotoxic risk depends on the intrinsic capability of the individual to metabolize and eliminate the xenobiotic from the organism. This study aimed to determine if two polymorphisms of paraoxonase-1 (PON1), which is involved in the metabolism of several organophosphate (OP) pesticides, are predictors of susceptibility to DNA damage in agricultural workers and inhabitants of rural areas chronically exposed to pesticides. A cross-sectional study was made considering three groups: agricultural workers (occupational exposure, OE, n = 85), rural inhabitants (environmental exposure, EE, n = 60), and an unexposed group conformed by people living far from agricultural areas (U, n = 33). The level of individual DNA damage was measured using the comet assay, and genotyping was done to determine the PON1 Q192R and L55M polymorphisms. Acetylcholinesterase and butyrilcholinesterase activities were also measured to determine exposure to OP. Individuals belonging to EE and OE groups displayed higher levels of DNA damage compared with U group (p < .001). OP exposure was the main predictor of genotoxicity (β = 16.19; 95% CI: 1.85, 30.52), instead of PON1 polymorphisms (β = -12.20; 95% CI: -27.87, 3.48). These results confirm the genotoxic effects of pesticide exposure and suggest that the catalytic efficiency of PON1 to metabolize OP pesticides becomes negligible in individuals with a history of long-term environmental or occupational exposure to these substances.

Influence of GSTM1, T1 genes polymorphisms on oxidative stress and liver enzymes in rural and urban pesticides-exposed workers

Several studies discussed the relationship between the toxicity of organophosphates (OPs) and carbamates pesticides and oxidative stress which affects human health. This study aimed to evaluate the effects of pesticides on the induction of oxidative stress and hepatotoxicity. It was also focused on glutathione-S-transferase gene polymorphism in the modulation of these effects. In addition, the role of the educational level of exposed workers was studied. Acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), liver enzymes, malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), and glutathione S transferase (GST) were estimated at 100 pesticide-exposed workers (50 urban researchers (UE) and 50 rural sprayers (RE)), and 100 matched controls (50 urban controls (UC)and 50 rural controls (RC)). AChE and BuChE were decreased in RE and UE compared to RC. Aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activity were elevated in UE and UC compared to the RE and RC. Alanine aminotransferase (ALT) was elevated in UE compared to RE. MDA in RE and UE showed elevation compared to RC. There was a significant reduction in the levels of GSH, GST, and GPx in UE compared to RE and RC. The most sensitive pesticide-induced hepatotoxicity group were exposed workers with the GSTT1 genotype. Within these workers, ALT and ALP were significantly correlated with MDA and inversely correlated with AChE and BuChE, while AST was inversely correlated with AChE and BuChE only in UE. Conclusion: GST gene polymorphisms appeared to have a significant role in workers' susceptibility to hepatotoxic effects due to occupational exposure to pesticides; GSTT1 was the most sensitive genotype.

Assessment of the genotoxic potential of tetrachlorvinphos insecticide by cytokinesis-block micronucleus and sister chromatid exchange assays

Tetrachlorvinphos is an organophosphate that is classified as a carcinogen in humans by several authorities. Due to very limited data regarding the genotoxic potential, we aimed to comprehensively investigate in vitro genotoxic potential of tetrachlorvinphos. We performed our study by applying the cytokinesis-block micronucleus cytome and sister chromatid exchange (SCE) assays to human peripheral blood lymphocytes. We evaluated micronucleus (MN) and SCE frequencies and cytokinesis-block proliferation index in both exposed and non-exposed lymphocytes. We also calculated the chromosomal instability level in response to exposure by combining the results of MN and SCE. We found that MN frequency did not increase with exposure to tetrachlorvinphos (0-50 µg/ml). In contrast, we observed that SCE frequencies significantly increased with exposure to ≥5 µg/ml tetrachlorvinphos. Furthermore, exposure to tetrachlorvinphos at concentrations of 50 µg/ml induced a significant increase in chromosomal instability level (p < 0.05). Cytokinesis-block proliferation index level did not significantly decrease in response to tetrachlorvinphos exposure. Our findings reveal that tetrachlorvinphos resulted in different DNA damages that were measured by two assays. Furthermore, our findings suggested that exposure to tetrachlorvinphos increased chromosomal instability that is a hallmark of many malignancies. We conclude that although tetrachlorvinphos does not significantly increase the MN level, the significant increase of both SCE and CIN frequencies indicates the genotoxic potential of tetrachlorvinphos in human peripheral lymphocytes. Additionally, tetrachlorvinphos is not cytotoxic in the range of tested concentrations.

Case-control study in ALS using the National ALS Registry: lead and agricultural chemicals are potential risk factors

Objective: To identify occupational risk factors for ALS using well-characterized participants with ALS (P-ALS), sibling controls (S-controls), and matched population controls (P-controls) within the National ALS Registry. We also compared oxidative stress (OS) biomarkers between groups. Methods: P-ALS were recruited over 4 years. Demographic, socioeconomic, and medical data were ascertained from medical records and structured interviews. P-ALS were followed prospectively for 2 years or until death, whichever came sooner. S-controls and age-, sex-, race/ethnicity-, and residential location-matched P-controls were recruited over 3 years. Occupational exposure to lead and agricultural chemicals (ACs) were assigned by an occupational hygienist, blinded to case status. OS biomarkers in urine were measured. Results: P-ALS (mean age 62.8 years; 63% males) resided across the United States. Demographic and socioeconomic variables did not differ among P-ALS, S-controls, and P-controls. P-ALS were more likely to report occupations with exposure to lead (adjusted OR (aOR)=2.3, 95% CI 1.1, 4.6) and ACs (aOR = 2.4, 95% CI 1.2, 4.6) compared to pooled controls. Among those with occupations with exposure to both lead and ACs, aOR was 7.2 (95% CI 2.0, 26.1). Urinary 8-oxo-dG was significantly elevated among P-ALS (11.07 ± 5.42 ng/mL) compared to S-controls, P-controls, or pooled controls (pooled 7.43 ± 5.42 ng/mL; p < 0.0001) but was not associated with occupational exposure to either lead or ACs. Conclusions: Findings reveal increased risk of ALS diagnosis among those with occupational exposure to lead and ACs and increased OS biomarkers among cases compared to controls. OS may be an important pathogenic mechanism in ALS.

The effect of ethion on erythrocyte deformability

Organophosphates cause increased oxidative susceptibility of erythrocytes and changes in erythrocyte deformability ability. We aim is to investigate the role of ethion (ETH) on erythrocyte deformability and to show whether vinpocetine (VIN) and carnosine (CAR) are protective against these changes. The study was performed on Sprague Dawley rats with an average weight of 220 ± 40 g and 4-5 months old. Six experimental groups were composed of 10 rats per group. Hematological parameters, erythrocyte deformability, % hemolysis, 2.3bisphosphoglycerate, and methemoglobin values were measured in blood samples taken after 10 days of drug application. Erythrocyte count, hemoglobin amount, hematocrit value, serum potassium level, and erythrocyte deformability decreased in the ETH group. Leukocyte, platelet count, methemoglobin amount, and % hemolysis rates increased in the ETH group. The values of the ETH + CAR and ETH + VIN groups were found to be closer to the control group. In organophosphate poisoning such as ETH, the deformability ability of erythrocytes exposed to constant oxidative stress is changing, and therefore their ability to deliver oxygen to tissues is negatively affected. VIN and CAR may have improve on erythrocyte deformability in this type of intoxication.

Correlation Study Between Erythrocyte Acetylcholinesterase Activity, Serum Malondialdehyde and Insulin Sensitivity in Agricultural Workers and Non-agricultural Workers in Nat-Kan Village, Magway Township

Objective

This study determined the correlation between erythrocyte acetylcholinesterase (AChE) activity, serum malondialdehyde (MDA) and insulin sensitivity in agricultural workers and non-agricultural workers.

Methodology

The cross-sectional comparative study was undertaken in 45 agricultural and 45 non-agricultural workers from Nat-Kan Village, Magway Township. Erythrocyte acetylcholinesterase activity and serum malondialdehyde were measured by spectrophotometric method. Insulin sensitivity was calculated by homeostasis model assessment (HOMA-IR).

Results

Mean erythrocyte AChE activity was significantly lower in agricultural (3553.99 IU/L) compared with nonagricultural workers (4432.68 IU/L) (p<0.001). A significant high level of mean serum MDA was observed in agricultural workers (0.74 versus 0.28 μmol/L, p<0.001). Median HOMA-IR value was significantly higher in agricultural (2.74) than that of non-agricultural workers (2.28) (p<0.05). The risk of insulin resistance was 2.8 times greater in agricultural workers than non-agricultural workers (OR 2.8, 95% CI, 1.18 to 6.72). Erythrocyte AChE activity had weak negative correlation with serum MDA level (r=-0.357, p<0.001) and HOMA-IR (ρ= -0.305, p<0.05). There was a significant but weak positive correlation between serum MDA level and HOMA-IR (ρ=0.355, p<0.001).

Conclusion

Organophosphate pesticide exposure lowered erythrocyte AChE activity and increased oxidative stress. Oxidative stress is partly attributed to the development of insulin resistance.

Toxicity and genotoxic evaluations in African catfish Clarias gariepinus (Burchell 1822) exposed to Act Force Gold®, Butaforce®, and Atraforce®

Act Force Gold^®, Butaforce^®, and Atraforce^® are among the most commonly used pesticides in Nigeria. The lethal concentrations and the respective toxic units for the three pesticides were determined. The genotoxic effects of the three pesticides were investigated in the red blood cells of Clarias gariepinus using micronucleus (MN) assay. The 96 h LC₅₀ was 4.75, 4.84, and 54.74 mg L^-1 for Act Force Gold^®, Butaforce^®, and Atraforce^®, respectively. The toxic units in ascending order of toxicity were 1.83, 20.66, and 21.05 for Act Force Gold^®, Butaforce^®, and Atraforce^® respectively. The estimated safe levels based on NAS/NAE varied from 4.75 × 10^-1-4.75 × 10^-5 in Act Force Gold^® through 4.64 × 10^-1-4.85 × 10^-5 in Butaforce^® to 5.74-5.74 × 10^-5 in Atraforce^®. Fish specimens were exposed to the pesticides and sampling was done at regular intervals at days 1, 7, 14, and 21 and after another 7-day recovery period. The results obtained indicated concentration- and duration-dependent increase in % MN formation with maximum values of 3.40 ± 0.25 for Act Force Gold^® on day 14 and 3.05 ± 0.36 and 2.35 ± 0.14 for Butaforce^® and Atraforce^® respectively on day 7 of exposure. The 7-day recovery period could not reverse the trend as the % MN values obtained were significantly different from the control. The results further support the use of MN assay in assessing the toxicity of aquatic pollutants and can be used in the monitoring of aquatic ecosystems.

Diapocynin, an NADPH oxidase inhibitor, counteracts diisopropylfluorophosphate-induced long-term neurotoxicity in the rat model

Organophosphate (OP) nerve agents are a threat to both the military and civilians. OP exposure causes cholinergic crisis and status epilepticus (SE) because of irreversible inhibition of acetylcholinesterase that can be life-threatening if left untreated. OP survivors develop long-term morbidity, such as cognitive impairment and motor dysfunction, because of oxidative stress and progressive neuroinflammation and neurodegeneration, which act as disease promoters. Current medical countermeasures (MCMs) do not mitigate these pathologies. Therefore, our goal was to target these disease promoters using diapocynin (DPO), an NADPH oxidase inhibitor, in addition to MCMs, in a rat diisopropylfluorophosphate (DFP) model. The DFP-intoxicated rats were treated with DPO (300 mg/kg, oral, six doses, 12-h intervals) or vehicle 2 h following behavioral SE termination with diazepam. The DPO treatment significantly rescued DFP-induced motor impairment and attenuated epileptiform spiking during the first 72 h after DFP exposure in severely seizing rats despite no difference in epileptiform spike rate between the vehicle and DPO groups in mild SE rats. DPO significantly reduced DFP-induced reactive astrogliosis, neurodegeneration, GP91phox , glutathiolated protein, serum nitrite, and proinflammatory cytokines and chemokines, such as interleukins (ILs) IL-1α, IL-6, IL-2, IL-17A, leptin, and IP-10, in the hippocampus. Collectively, these data support a neuroprotective role of DPO in an OP-induced neurotoxicity model.

Organophosphate-pesticides induced survival mechanisms and APE1-mediated Nrf2 regulation in non-small-cell lung cancer cells

Epidemiological and molecular studies have indicated that environmental exposure to organophosphate pesticides (OPPs) is associated with increased cancer risk; however, the underlying molecular mechanisms still need to be explained. Increasing cancer incidence is linked to OPPs-induced oxidative stress (OS). Our study evaluates monocrotophos (MCP) and chlorpyrifos (CP)-induced OS responses and apurinic/apyrimidinic endonuclease 1 (APE1) role in human non-small-cell lung cancer (NSCLC) cells. Our prior study has implicated OPPs-induced base excision repair (BER)-pathway dysregulation and APE1-mediated regulation of transcription factor (TF) c-jun in A549 cells. We further investigated the effects of MCP and CP on apoptosis, proliferation, and APE1's redox-regulation of nuclear factor-like 2 (Nrf2). Data demonstrates that MCP and CP at subtoxic concentrations induced reactive oxygen species generation and oxidative DNA base damage 8-oxo-dG lesions in NCI-H1299 cells. CP moderately upregulated the apoptosis-inducing factor (AIF) in A549 cells, however, it did not trigger other pro-apoptotic factors viz. caspase-9 and caspase-3, suggesting early caspase-independent apoptosis. However, dose-dependent AIF-downregulation was observed for MCP treatment. Furthermore, CP and MCP treatments upregulated proliferating cell nuclear antigen levels. Immunofluorescent confocal imaging showed the colocalization of APE1 with Nrf2 in 10 µM CP- and MCP-treated NCI-H1299 cells. Immunoprecipitation confirmed that APE1 and Nrf2 physically interacted, indicating the role of APE1-mediated Nrf2 activation following OPPs treatment. This study suggests that low concentration MCP and CP exposure generates OS along with DNA damage, and modulates apoptosis, and APE1-mediated Nrf2 activation, which might be considered as the possible mechanism promoting lung cancer cell survival, suggesting that APE1 may have the potential to become a therapeutic target for the treatment of NSCLC.

Investigating the Effect of Fresh Frozen Plasma and Albumin on DNA Damage and Oxidative Stress Biomarkers in Poisoning Cases by Organophosphates

The efficacy of albumin and fresh frozen plasma (FFP) and their effects on biomarkers of oxidative stress has been evaluated. In a randomized clinical control trial, 33 poisoned patients by Organophosphate (OP) were enrolled in the research and divided into three groups. The first group underwent conventional treatments by atropine and pralidoxime (control group); the second and third groups, in addition to traditional treatments, received albumin and FFP. Cholinesterase (ChE) enzyme activity, total antioxidant capacity (TAC), serum thiol groups (TTG), malonyl aldehyde (MDA) and DNA damage were measured in all treatment and control groups. Patients were matched in terms of demographic characteristics at the beginning of the study. ChE activity was increased in all three groups during treatment, which was more noticeable in the FFP group and was statistically significant in both albumin and FFP group compared to the control group (p<0.05). TAC increased, and TTG decreased in FFP and albumin groups compared to the control group; no significant difference was observed. MDA decreased in albumin and FFP and was significantly different in the FFP group compared to the control group (p<0.05). The amount of DNA damage in FFP and albumin groups decreased, and there was a significant difference compared to the control group (p<0.05). According to the results of this study, due to the decrease of oxidative damage parameters and the increase of antioxidant parameters in albumin and specially FFP groups, FFP may be considered as an adjunctive treatment for OP poisoning.

Does oxidative stress contribute to toxicity in acute organophosphorus poisoning? - a systematic review of the evidence

Introduction: Organophosphorus (OP) insecticide self-poisoning is a global problem, killing tens of thousands of people every year. Oxidative stress has been proposed to play a pathological role in OP poisoning, but whether it plays a direct toxic role is currently unclear.Objectives: To determine whether there is consistent evidence of oxidative stress in patients with acute OP insecticide self-poisoning, and whether there are animal or human trial data that indicate that treatment of oxidative stress provides clinical benefit, which would suggest a direct toxic effect of oxidative stress.Methods: We conducted a systematic review using the PubMed, EMBASE and MEDLINE databases, and the Cochrane Database of Systematic reviews, based upon the following search terms and keywords: "organophosphate poisoning", "oxidative stress" and "antioxidant". All articles relevant to the aims of the study were included. Articles related to chronic OP poisoning, to use of medicines without antioxidant benefits, or to subjects other than oxidative stress were excluded. The search returned 256 results of which 17 studies were considered relevant and grouped under the following categories: observational human studies (n = 11) and intervention studies in animals (n = 4) and humans (n = 2).Oxidative stress markers in human studies: Oxidative damage to lipids and proteins was reported in all eleven human studies. Eight of nine studies reported variable increases in a weak marker of lipid peroxidation, malondialdehyde. In two case-control studies, erythrocyte membrane malondialdehyde concentrations were 380% and 160% higher in cases than controls, while plasma malondialdehyde concentrations were ∼63% higher in cases than controls in three case-control studies. In a prospective study, plasma malondialdehyde did not increase significantly from baseline in moderate or severely poisoned patients. Five case-control studies measured thiol residues as markers of protein oxidative damage and found variable changes after poisoning. No evidence of oxidative DNA damage was found in the one study that investigated it.Antioxidant intervention studies in animals: After treatment with an antioxidant, all four studies showed an improvement in either markers of oxidative damage or antioxidant activity. One mouse study with a relatively low risk of bias showed that administration of acetylcysteine 200 mg/kg reduced malondialdehyde by 35% and increased survival by more than 60%.Antioxidant intervention studies in humans: We found two small randomised controlled trials reporting the use of acetylcysteine as an adjunct to standard treatment in acute OP poisoning. The trials found that acetylcysteine reduced atropine requirements by 77% and 55%, but did not affect clinically relevant outcomes.Conclusions: Several studies showed evidence of OP insecticide-induced oxidative damage and antioxidant activity, suggesting that endogenous antioxidant defences are triggered in acute OP poisoning. However, the markers of lipid peroxidation used were weak, there was high inter-individual variability between studies in results and quality, and marked variation between the OP insecticides involved. Animal data provide some evidence that antioxidants alleviate adverse effects of acute poisoning, suggesting that oxidative stress may directly cause clinical harm. Acetylcysteine appeared beneficial in animal studies, but this could be mediated via increased synthesis of the endogenous detoxifying agent, glutathione, rather than through a direct antioxidant effect. The two human clinical studies were too small to provide any clear evidence to support the use of acetylcysteine in OP poisoning. Further research into the mechanisms of oxidative stress in acute OP poisoning, combined with large unambiguous clinical trials of antioxidants, are required before they can be used routinely in treatment.

The evaluation of oxidative damage of DNA after poisoning with nerve agents

The potency of three nerve agents (sarin, soman, tabun) to induce oxidative damage of DNA in lymphocytes, liver and brain during lethal or sublethal poisoning was investigated. The single strand breaks or oxidative base DNA damage was evaluated with the help of Comet assay and a specific enzyme able to detect oxidative bases of DNA (endonuclease III). While sarin and soman administered at sublethal doses corresponding to 50% of their LD50 values were not able to induce oxidative damage of DNA, their lethal dose (LD50) induced the significant increase of the number of oxidative bases in DNA of hepatocytes. In addition, tabun administered at lethal dose (LD50) induced significant increase of the number of single strand breaks and oxidative bases of DNA in glial cells isolated from pontomedullar brain region. Thus, some nerve agents were able to induce oxidative damage in the peripheral as well as central compartment but only in the case of severe poisoning caused by lethal doses of nerve agents. This non-cholinergic effect of nerve agents has probably consequences with nerve agents-induced hypoxic status during acute cholinergic crisis and it can contribute to their long-term toxic effects.

Acetylcholinesterases from Leaf-Cutting ant Atta sexdens: Purification, Characterization, and Capillary Reactors for On-Flow Assays

Acetylcholinesterase (AChE) is responsible for catalyzing the hydrolysis of the neurotransmitter acetylcholine (ACh) leading to acetate and choline (Ch) release. The inhibition of AChE produces a generalized synaptic collapse that can lead to insect death. Herein we report for the first time the isolation of two AChEs from Atta sexdens which were purified by sulphate ammonium precipitation followed by ion exchange chromatography. AsAChE-A and AsAChE-B enzymes have optimum pH of 9.5 and 9.0 and higher activities in 30/50°C and 20°C, respectively, using acetylthiocholine (ATCh) as substrate. Immobilized capillary enzyme reactors (ICERs) were obtained for both enzymes (AsAChE-A-ICER and AsAChE-B-ICER) and their activities were measured by LC-MS/MS through hydrolysis product quantification of the natural substrate ACh. The comparison of activities by LC-MS/MS of both AChEs using ACh as substrate showed that AsAChE-B (free or immobilized) had the highest affinity. The inverse result was observed when the colorimetric assay (Elman method) was used for ATCh as substrate. Moreover, by mass spectrometry and phylogenetic studies, AsAChE-A and AsAChE-B were classified as belonging to AChE-2 and AChE-1 classes, respectively.

A longitudinal follow-up study of oxidative stress and DNA damage among farmers exposed to pesticide mixtures

Exposure to pesticides may have increased risk of oxidative stress and genetic damage and hence of development of chronic diseases. The aim of this longitudinal follow-up study is to compare oxidative stress and DNA damage between the pre- and post-pesticide application seasons among 56 male farmers. The study also investigated the factors associated with changes in oxidative stress, DNA damage, and health symptoms during the pesticide application season. The eligibility criteria for the subjects were men aged between 25 and 55 years, applied pesticide mixtures during May and June 2018, and healthy without current illness. Ten milliliters of venous blood samples was collected twice from each subject in the pre- and post-pesticide application seasons for determination of superoxide dismutase (SOD), 8-hydroxy-2'-deoxyguanosine (8-OHdG), comet tail length, and comet tail moment. The remarkable findings included a statistically significant increase in SOD activity during the pesticide application season (P < 0.001). However, there were no statistical differences in 8-OHdG, comet tail length, and comet tail moment. When we analyzed the factors associated with changes in SOD activity during the pesticide application season by using linear regression analysis, working hours on the farm (B ± SE. = 0.790 ± 0.341, P = 0.025) and planting activities (B ± SE. = 1.217 ± 0.504, P = 0.020) were associated with increase in SOD activity. Therefore, increase in SOD may be a consequence of oxidative damage induced by pesticide exposure and this marker may be used as an early warning for pesticide-induced acute and chronic toxicities.

Herbal medicine against genotoxicity of dimethoate, an insecticide, in mammalian somatic cells

In this study, the genotoxic effects of dimethoate (DIM) were investigated with the in vitro micronucleus test in human peripheral lymphocytes. The ethanol extracts of Rosa canina and Salvia lavandulifolia were used to remove possible genotoxic effects of these substances. For this purpose, different concentrations (0.5-1-2 μg/mL) of dimethoate, DIM + RC_eta and DIM + SL_eta (1:1 v/v) application groups were prepared and applied to the blood culture. The obtained data were compared with the negative control group that was prepared with dimethyl sulfoxide (DMSO) as solvent and a well-known genotoxic effects of ethyl methanesulfonate (EMS) as positive control group. It was observed in lymphocyte cells that the frequency of MN considerably increased depending on the increasing dose of DIM whereas the nuclear division index (NBI)decreased according to the control group, especially in the last concentration (2 μg/mL). But, as the MN frequency decreased, NBI values approached to control group with 2μg/mL DIM + RC_eta and 2μg/mL DIM + SL_eta according to DIM application group (P < 0.05). Additionally, RC_eta and SL_eta were analyzed by gas chromotography-mass spectrometry (GC-MS).

Chlorpyrifos disturbs hepatic metabolism associated with oxidative stress and gut microbiota dysbiosis in adult zebrafish

Chlorpyrifos (CPF) is widely used in agriculture and is considered one of the most toxic pesticides to fish. In this study, adult male zebrafish were exposed to CPF at concentrations of 30, 100 and 300 μg/L for 21 days. It was observed that CPF not only induced oxidative stress but also caused gut microbiota dysbiosis in the gut. The malondialdehyde (MDA) levels increased, and the glutathione (GSH) contents decreased in the gut of the CPF-treated group. For the gut microbiota, at the phylum level, the relative abundance of Proteobacteria showed a significant change after CPF exposure. At the genus level, approximately 25 types of bacteria in the gut changed significantly. In addition, based on a gas chromatography combined with mass spectrometry (GC/MS) analysis, we found that 98 metabolites significantly influenced the zebrafish liver, and these changed metabolites were tightly related to several pathways, including glucose and lipid metabolism, the tricarboxylic acid (TCA) cycle, and amino acid metabolism. Furthermore, the transcriptional levels of some genes related to glycolysis and lipid metabolism decreased significantly in the livers of CPF-treated zebrafish. These results indicated that CPF exposure could induce hepatic glucose and lipid metabolism disorders in adult zebrafish. Taken together, our results suggest that CPF exposure causes hepatic lipid metabolism disorders that are associated with gut oxidative stress and microbiota dysbiosis in adult zebrafish.

Micronucleus frequency is correlated with antioxidant enzyme levels in workers occupationally exposed to pesticides

Oxidative stress can cause DNA damage leading to nuclear anomalies such as micronuclei (MN). Antioxidant enzymes involved in protection against intracellular oxidative stress include glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT). Pesticide exposure induces oxidative stress and alters antioxidant defense mechanisms, including detoxification and scavenger enzymes. The aim of this study was to evaluate MN frequency in workers occupationally exposed to pesticides and their relationship with antioxidant enzyme activities. A cross-sectional study was conducted in 201 individuals, some of whom were dedicated to the spraying of pesticides. The cytokinesis-block micronucleus (CBMN) assay was conducted, and the activities of GPx, GR, SOD, and CAT were determined. The geometric mean (GM) of MN was 5.4 (1-26 MN). The GM for the antioxidant enzymes was 198.68 U/mL for GPx, 38.96 U/g Hb for GR, 94.78 U/mL for SOD, and 69.77 U/g Hb for CAT. There was a lower MN frequency in males than that in females, and a higher nuclear index. In addition, age affected MN frequency. There was a negative correlation between MN frequency and GPx activity, but a positive one between MN frequency and GR activity. These findings suggest the involvement of GPx in MN frequency.

Biomarkers of oxidative stress in blood of workers exposed to non-cholinesterase inhibiting pesticides

In occupational settings workers are often exposed to pesticides at relatively high doses compared to environmental exposures. Long-term exposure to pesticides has been associated with numerous adverse health effects in epidemiological studies, and oxidative stress is often claimed as one of the underlying mechanisms. In fact, different pesticides have been reported to induce oxidative stress due to the generation of free radicals and/or alteration in antioxidant defense enzymes. The present study examined greenhouse workers regularly exposed to diverse pesticides under integrated production system, and a group of controls of the same geographic area without any chemical exposure. Two different periods of the same crop season were assessed, one of high exposure (with greater use of pesticides) and other of low exposure (in which a less use of these compounds was made). Non-specific biomarkers of oxidative stress, e.g. thiobarbituric acid reactive substances (TBARS), ferric reducing ability of serum (FRAS), total thiol groups (SHT), gamma-glutamyl transpeptidase (GGT) and paraoxonase-1 (PON1) were measured in serum samples from all study subjects, alongside erythrocyte acetylcholinesterase (AChE). Results are suggestive of a mild increase in oxidative stress associated with pesticide exposure, which was compensated by an adaptive response to raise the antioxidant defenses and thus counter the detrimental effects of sustained oxidative stress. This response led to significantly increased levels of FRAS, SHT and PON1 in greenhouse workers relative to controls. Furthermore, AChE was decreased likely as a result of oxidative stress as workers did not use organophosphate insecticides.

Mechanisms of organophosphorus pesticide toxicity in the context of airway hyperreactivity and asthma

Numerous epidemiologic studies have identified an association between occupational exposures to organophosphorus pesticides (OPs) and asthma or asthmatic symptoms in adults. Emerging epidemiologic data suggest that environmentally relevant levels of OPs may also be linked to respiratory dysfunction in the general population and that in utero and/or early life exposures to environmental OPs may increase risk for childhood asthma. In support of a causal link between OPs and asthma, experimental evidence demonstrates that occupationally and environmentally relevant OP exposures induce bronchospasm and airway hyperreactivity in preclinical models. Mechanistic studies have identified blockade of autoinhibitory M2 muscarinic receptors on parasympathetic nerves that innervate airway smooth muscle as one mechanism by which OPs induce airway hyperreactivity, but significant questions remain regarding the mechanism(s) by which OPs cause neuronal M2 receptor dysfunction and, more generally, how OPs cause persistent asthma, especially after developmental exposures. The goals of this review are to 1) summarize current understanding of OPs in asthma; 2) discuss mechanisms of OP neurotoxicity and immunotoxicity that warrant consideration in the context of OP-induced airway hyperreactivity and asthma, specifically, inflammatory responses, oxidative stress, neural plasticity, and neurogenic inflammation; and 3) identify critical data gaps that need to be addressed in order to better protect adults and children against the harmful respiratory effects of low-level OP exposures.

Effect of Crocus sativus L. stigma (saffron) against subacute effect of diazinon: histopathological, hematological, biochemical and genotoxicity evaluations in rats

Objective

In this study, the effects of saffron stigma against subacute diazinon (DZN) toxicity on enzymes levels, biochemical, hematological, histopathological and genotoxicity indices were studied in rats.

Methods

Vitamin E (200 IU/kg) and the aqueous extract of saffron (50, 100 and 200 mg/kg) were injected intraperitoneally three times per week alone or with DZN (20 mg/kg/day, orally) for 4 weeks. The hematological and biochemical parameters were evaluated at the end of 4 weeks.

Results

Reticulocytes counts, alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine phosphokinase, CPK-MB, gama glutamyl transferase (GGT), uric acid and micronucleus indices were increased significantly but total protein and RBC cholinesterase activity were decreased in the DZN-treated group. Saffron prevented the effect of DZN on GGT (50 mg/kg), LDH, CPK and CPK-MB (100 and 200 mg/kg) levels. An increased uric acid and reduced protein levels by DZN were prevented by vitamin E and some doses of saffron. A significant reduction was observed in platelets, RBC, hemoglobin and hematocrit indices in the DZN group. Saffron and vitamin E prevented this reduction. Vitamin E and saffron did not reduce the effect of DZN on RBC cholinesterase activity. The extract and vitamin E could not prevent DZN genotoxicity in the micronucleus assay. Other biochemical parameters and pathological evaluation did not show any abnormality in tissues of all groups.

Conclusion

This study shows that vitamin E and saffron reduce DZN induced hematological and biochemical toxicity. However, they do not prevent the genotoxicity induced by DZN.

Oxidative stress and pesticide disease: a challenge for toxicology

Introducción. En los últimos decenios, la síntesis de compuestos químicos ha producido un alto número de sustancias utilizadas para proteger los cultivos y las cosechas de las plagas. La mayoría de pesticidas han sido usados en grandes cantidades para fines agrícolas y la exposición tóxica a estos compuestos es un problema de gran envergadura para la toxicología, pues tiene impacto en la salud pública por su importante morbilidad y discapacidad. Así, las intoxicaciones agudas y crónicas pueden ser comunes entre trabajadores agrícolas y población general. Estos compuestos desencadenan mecanismos moleculares relacionados con la peroxidación lipídica, donde las especies reactivas de oxigeno pueden incrementar procesos oxidativos intracelulares.Objetivo. Realizar una revisión de la literatura científica relacionada con enfermedades por estrés oxidativo producido por pesticidas.Materiales y métodos. Revisión de artículos que utilizó las palabras clave Estrés oxidativo; Pesticidas; Peroxidación de lípido; Toxicidad. Se eligieron los artículos relacionados con las enfermedades por estrés oxidativo producido por pesticidas.Resultados. Se encontró que algunas enfermedades hematológicas, neurológicas, metabólicas y genotóxicas pueden estar relacionadas con la peroxidación lipídica que producen los pesticidas.Conclusión. Se presenta una revisión de la literatura científica sobre el estrés oxidativo, la peroxidación lipídica inducida por pesticidas y las diferentes enfermedades que pueden afectar a la población en general.

DNA damage and epigenetic alteration in soybean farmers exposed to complex mixture of pesticides

Exposure to pesticides can trigger genotoxic and mutagenic processes through different pathways. However, epidemiological studies are scarce, and further work is needed to find biomarkers sensitive to the health of exposed populations. Considering that there are few evaluations of soybean farmers, the aim of this study was to assess the effects of human exposure to complex mixtures of pesticides. The alkaline comet assay modified with restriction enzyme (hOGG1: human 8-oxoguanine DNA glycosylase) was used to detect oxidised guanine, and compared with the buccal micronucleus cytome assay, global methylation, haematological parameters, biochemical analyses (serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, gamma-glutamyl-transferase and butyrylcholinesterase), and particle-induced X-ray emission (PIXE) for the analysis of inorganic elements. Farm workers (n = 137) exposed to different types of pesticides were compared with a non-exposed reference group (control; n = 83). Results of the enzyme-modified comet assay suggest oxidation of guanine in DNA generated by pesticides exposure. It was observed that DNA damage (comet assay and micronucleus test) was significantly increased in exposed individuals compared to the unexposed group. The micronucleus test demonstrated elimination of nuclear material by budding, defective cytokinesis and dead cells. Occupationally exposed individuals also showed genomic hypermethylation of DNA, which correlated with micronucleus frequency. No differences were detected regarding the haematological and biochemical parameters. Finally, significantly higher concentrations of Al and P were observed in the urine of the soybean farmers. DNA damage could be a consequence of the ability of the complex mixture, including Al and P, to cause oxidative damage. These data indicate that persistent genetic instability associated with hypermethylation of DNA in soybean workers after long-term exposure to a low-level to pesticides mixtures may be critical for the development of adverse health effects such as cancer.

Adverse effects of organophosphorus pesticides on the liver: a brief summary of four decades of research

Organophosphorus pesticides (OPs) are widely used volatile pesticides that have harmful effects on the liver in acute and chronic exposures. This review article summarises and discusses a wide collection of studies published over the last 40 years reporting on the effects of OPs on the liver, in an attempt to propose general mechanisms of OP hepatotoxicity and possible treatment. Several key biological processes have been reported as involved in OP-induced hepatotoxicity such as disturbances in the antioxidant defence system, oxidative stress, apoptosis, and mitochondrial and microsomal metabolism. Most studies show that antioxidants can attenuate oxidative stress and the consequent changes in liver function. However, few studies have examined the relationship between OP structures and the severity and mechanism of their action. We hope that future in vitro, in vivo, and clinical trials will answer the remaining questions about the mechanisms of OP hepatotoxicity and its management.

Characterization of the interaction between human serum albumin and diazinon via spectroscopic and molecular docking methods

Human serum albumin (HSA) is a soluble blood protein which binds to small molecules (such as drugs and toxins) and transfers them within the blood circulation. In this research, the interaction of diazinon, as a toxic organophosphate, with HSA was investigated. Various biophysical methods such as fluorescence, ultraviolet–visible (UV-vis), Fourier transform infrared spectroscopy, and molecular docking were utilized to characterize the binding properties of diazinon to HSA under physiological-like condition. The UV-vis spectroscopy showed that the absorption increased and the fluorescence intensity of HSA decreased regularly with regard to the gradual increases of the concentrations of diazinon. Due to the binding constant of ( ka = 3.367 × 10+4 M−1), the α-helix structure for the first day and 35 days of incubation were obtained 66.09–55.4% and 59.99–46.48%, respectively, and their amounts in other secondary structures (β-sheet, β-anti, and random (r) coils) were increased. The molecular docking revealed a good binding site in HSA (Trp-214) for diazinon which was related to the considerable alterations in HSA secondary and tertiary structures. There is a close relationship between the secondary structure of protein and its biological activity and after 35 days of incubation, the high toxic concentrations of diazinon can make HSA to be partially unfolded and lose its structure.

Pesticides contaminated dust exposure, risk diagnosis and exposure markers in occupational and residential settings of Lahore, Pakistan

There are few studies documenting the dust loaded with pesticides as a potential non-dietary exposure source for occupational worker and populations living near agricultural farms and pesticides formulation plants. In present study we have evaluated the pesticide concentration in dust from potential sites and relevant health risk from dust ingestion. Furthermore, the effect of currently used pesticides was investigated on blood and urine parameters of subjects: farmer, factory worker, urban resident and rural resident and controlled subjects with presumably different levels of exposure. The urinary metabolites (TCPY and IMPY) were quantified as biomarkers of exposure to chlorpyrifos and diazinon in relation with biomarkers of effect including BuChE, LH, FSH, testosterone and oxidative stress. Results showed that chlorpyrifos and diazinon were present in higher concentration in dust and posed a high health risk to exposed subjects. The mean SOD value was high among the farmer (3048U/g Hb) followed by factory worker (1677.6U/g Hb). The urinary biomarkers - TCPY and IMPY- were found higher in exposed subjects as compared to control. Furthermore, testosterone was found in higher concentration in factory worker than control (12.63ng/ml vs 4.61ng/ml respectively). A decreased BuChE activity was noticed in occupational group and significant differences were observed in control verses exposed subjects. The PCA analysis evidenced the impact of pesticides on exposure biomarkers and male reproductive hormones. The study suggests that dust contaminated with pesticides engenders significant health risk particularly related to the nervous and endocrine system, not only for occupational workers exposed to direct ingestion but also for nearby residential community. Succinctly putting: Pesticides loaded dust in the city of Lahore, being a high priority concern for the government of Pakistan, demands to be addressed.

Genetic Alterations in Pesticide Exposed Bolivian Farmers An evaluation by analysis of chromosomal aberrations and the comet assay

Background

Pesticides are of concern in Bolivia because of increasing use. Frequent intoxications have been demonstrated due to use of very toxic pesticides, insufficient control of distribution and sale and little knowledge among farmers of protective measures and hygienic procedures.

Method

Questionnaires were applied and blood tests taken from 81 volunteers from La Paz County, of whom 48 were pesticide exposed farmers and 33 non-exposed controls. Sixty males and 21 females participated with a mean age of 37.3 years (range 17–76). Data of exposure and possible genetic damage were collected and evaluated by well known statistical methods, controlling for relevant confounders. To measure genetic damage chromosomal aberrations and the comet assay analysis were performed.

Results

Pesticide exposed farmers had a higher degree of genetic damage compared to the control group. The number of chromosomal aberrations increased with the intensity of pesticide exposure. Females had a lower number of chromosomal aberrations than males, and people living at altitudes above 2500 metres seemed to exhibit more DNA damage measured by the comet assay.

Conclusions

Bolivian farmers showed signs of genotoxic damage, probably related to exposure to pesticides. Due to the potentially negative long term health effects of genetic damage on reproduction and the development of cancer, preventive measures are recommended. Effective control with imports and sales, banning of the most toxic pesticides, education and information are possible measures, which could help preventing the negative effects of pesticides on human health and the environment.

The impact of pesticides on oxidative stress level in human organism and their activity as an endocrine disruptor

Pesticides cause serious environmental and health problems both to humans and animals. The aim of this review is to discuss selected herbicides and fungicides regarding their mode of action and their influence on basic oxidative stress parameters and endocrine disruption properties tested in selected cell cultures in vitro. Because of numerous difficulties which animal studies are subject to, cell cultures are an excellent experimental model reflecting human exposure to different pesticides through all relevant routes. This experimental model can be used to monitor aggregate and cumulative pesticide exposures.

An alternative purification method for human serum paraoxonase 1 and its interaction with methidathion

In this study, an alternative purification method for human Paraoxonase 1 (hPON1) enzyme was developed using two-step procedures, namely ammonium sulphate precipitation and Sepharose-4B-L-tyrosine-1-aminoanthracene hydrophobic interaction chromatography. SDS-polyacrylamide gel electrophoresis of the enzyme indicates a single band with an apparent MW of 43 kDa. The enzyme was purified 674-fold with a yield of 16%. Furthermore, we examined the in vitro effect of methidathion on the enzyme activity to understand the better inhibitory properties of the compound. Methidathion is a highly toxic insecticide used to control a broad spectrum of agricultural insect and mite pests. IC₅₀ value was found to be 0.130 mM for the pesticide. Methidathion showed a competitive inhibition with Ki of 0.119 mM for paraoxon.

Oxidative stress and genetic damage among workers exposed primarily to organophosphate and pyrethroid pesticides

The indiscriminate use of pesticides in agriculture and public health campaigns has been associated with an increase of oxidative stress and DNA damage, resulting in health outcomes. Some defense mechanisms against free radical-induced oxidative damage include the antioxidant enzyme systems. The aim of this study was to determine the levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and the relationship of antioxidant enzyme levels with DNA damage among sprayers (workers) occupationally exposed to pesticides. The determinations of MDA and antioxidant enzymes were performed spectrophotometrically. The genotoxic effects were evaluated using the comet assay. The results showed a marginally significant decrease in SOD and CAT activities in the high exposure group compared to the control group. For MDA, statistically significant differences were found among people working long term vs. those working temporarily (P = 0.02) as sprayers. In the moderate exposure group, a positive correlation was observed between MDA levels and GPx activity. In the high exposure group, a negative correlation was observed between GR and CAT activities, and between MDA levels and GPx activities. Furthermore, in the high exposure group, a positive correlation between DNA damage parameters and MDA levels was observed. The results suggest an important role of antioxidant enzymes for the protection of DNA damage caused by occupational exposure to pesticides.

Potential contribution of insecticide exposure and development of obesity and type 2 diabetes

The introduction of insecticides has greatly improved agricultural productivity and human nutrition; however, the wide use of insecticides has also sparked growing concern over their health impacts. Increased rate of cancers, neurodegenerative disorders, reproductive dysfunction, birth defects, respiratory diseases, cardiovascular diseases and aging have been linked with insecticide exposure. Meanwhile, a growing body of evidence is suggesting that exposure to insecticides can also potentiate the risk of obesity and type 2 diabetes. This review summarizes the relationship between insecticide exposure and development of obesity and type 2 diabetes using epidemiological and rodent animal studies, including potential mechanisms. The evidence as a whole suggests that exposure to insecticides is linked to increased risk of obesity and type 2 diabetes.

Impaired antioxidant gene expression by pesticide residues and its relation with other cellular biomarkers in Nile Tilapia (Oreochromis niloticus) from Lake Burullus

Organochlorines and Organophosphorus are the most commonly used pesticides. These pesticides constitute a considerable contaminating threat due to their excessive agricultural usage which in turn contaminates the aquatic system through agricultural drainage. The aim of this study was to evaluate water and tissue residues of both pesticides in O. niloticus obtained from three different sections in Lake Burullus, Egypt. Assessment of relative change in mRNA levels of GST and Vtg (oxidative stress indicator) was done and its relation with other cellular biomarkers including apoptosis, which is assessed by Cellular apoptosis susceptibility transcript level (CAS), comet assay and micronucleus assays (genotoxicity indicator). Pesticide residue levels in water are fluctuating. In fish tissues, most residues were higher than those found in water and were associated with down regulation of hepatic GST gene and Vtg expression. CAS gene involved in apoptosis, its transcript is down regulated in middle and western sections of the lake with higher pesticide residues. Different degrees of DNA damages in O. niloticus' liver cells were demonstrated by comet assay. Significant increase in the micronucleated cells in the three sections of the lake was observed; the western section fish showed the highest number. Persistent exposures of fish to pesticide caused impairment of antioxidant gene expression. This negatively affects apoptosis associated with damaging DNA and chromosome fragments.

Can the age at onset give a clue to the pathogenesis of ALS?

Pathogenesis could play an important role in the mid- to late-life onset of symptoms in amyotrophic lateral sclerosis (ALS). An analysis of the age at onset of ALS among the incident cases occurring in the population in the Health District of Ferrara, Italy, in the period 1064-2009 was carried out. Two subsequent 23-year time intervals (1964-1986 and 1987-2009) were considered. The mean age at onset (MAAO) was estimated in relation to gender, onset type and area of residence (urban or extra-urban) at disease onset among the incident cases which occurred in the two subsequent time intervals. An uneven increase in the MAAO over time was observed as it was significant only among the female cases (from 56.7 95 % CI 51.6-61.7 years to 65.4 95 % CI 61.8-69.0 years), the overall bulbar onset cases (from 58.0 95 % CI 54.0-62.1 years to 69.3 95 % CI 66.2-72.4 years), the overall cases occurring in the extra-urban population (from 54.5 95 % CI 49.0-60.1 years to 65.1 95 % CI 60.4-69.8 years) and the bulbar onset cases occurring in the extra-urban population (from 57.1 95 % CI 53.5-60.7 years to 69.6 95 % CI 66.3-73.7 years). Although the increasing age of the population combined with improvements in ALS diagnosis among the elderly may have played a part, these uneven findings among the incident cases occurring in a well-defined homogeneous population with a stable ALS incidence would seem to suggest the involvement of risk factors associated with the extra-urban environment.

Methamidophos induces cytotoxicity and oxidative stress in human peripheral blood mononuclear cells

Previous studies have shown that organophosphate pesticide (OP) exposure is associated with oxidative stress. Methamidophos (MET) is an OP widely used in agriculture, which is regarded as a highly toxic pesticide and it is a potent inhibitor of acetylcholinesterase. The aim of this study was to evaluate whether MET can induce oxidative stress at low concentrations in primary cultures of human peripheral blood mononuclear cells (PBMCs). PBMCs from healthy individuals were exposed to MET (0-80 mg/L) for 0-72 h. We performed the MTT and neutral-red assays to assess the cytotoxicity. As indicators of oxidative stress, the levels of reactive oxygen species (ROS) were assessed using flow cytometry, and the malondialdehyde (MDA) and reduced glutathione (GSH) levels were determined. MET decreased the viability of PBMCs in a dose-dependent manner. At concentrations of 3, 10, or 20 mg/L for 24 h, MET increased the ROS production significantly compared with the vehicle control. Similarly, MET increased the levels of MDA at the same concentrations that increased ROS (10 and 20 mg/L); however, no changes in GSH levels were observed. These results suggest that MET increased the generation of oxidative stress in PBMCs. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 147-155, 2017.

Hematological, biochemical, and toxicopathic effects of subchronic acetamiprid toxicity in Wistar rats

Acetamiprid is one of the most widely used neonicotinoids. This study investigates toxic effects of repeated oral administration of three doses of acetamiprid (1/20, 1/10, and 1/5 of LD₅₀) during 60 days. For this, male Wistar rats were divided into four different groups. Hematological, biochemical, and toxicopathic effects of acetamiprid were evaluated. According to the results, a significant decrease in the body weight gain at the highest dose 1/5 of LD₅₀ of acetamiprid was noticed. An increase in the relative liver weight was also observed at this dose level. The hematological constituents were affected. A significant decrease in RBC, HGB, and HCT in rats treated with higher doses of acetamiprid (1/10 and 1/5 of LD₅₀) was noted. However, a significant increase in WBC and PLT were observed at the same doses. Furthermore, acetamiprid induced liver toxicity measured by the increased activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphates (ALPs), and lactate dehydrogenase (LDH) which may be due to the loss of hepatic membrane architecture and hepatocellular damage. In addition, exposure to acetamiprid resulted in a significant decrease in the levels of superoxide dismutase and catalase activities (p ≤ 0.01) with concomitant increase in lipid peroxidation in rat liver. These findings highlight the subchronic hepatotoxicity of acetamiprid.

Pesticides: an update of human exposure and toxicity

Pesticides are a family of compounds which have brought many benefits to mankind in the agricultural, industrial, and health areas, but their toxicities in both humans and animals have always been a concern. Regardless of acute poisonings which are common for some classes of pesticides like organophosphoruses, the association of chronic and sub-lethal exposure to pesticides with a prevalence of some persistent diseases is going to be a phenomenon to which global attention has been attracted. In this review, incidence of various malignant, neurodegenerative, respiratory, reproductive, developmental, and metabolic diseases in relation to different routes of human exposure to pesticides such as occupational, environmental, residential, parental, maternal, and paternal has been systematically criticized in different categories of pesticide toxicities like carcinogenicity, neurotoxicity, pulmonotoxicity, reproductive toxicity, developmental toxicity, and metabolic toxicity. A huge body of evidence exists on the possible role of pesticide exposures in the elevated incidence of human diseases such as cancers, Alzheimer, Parkinson, amyotrophic lateral sclerosis, asthma, bronchitis, infertility, birth defects, attention deficit hyperactivity disorder, autism, diabetes, and obesity. Most of the disorders are induced by insecticides and herbicides most notably organophosphorus, organochlorines, phenoxyacetic acids, and triazine compounds.

The level of DNA damage in adult grasshoppers Chorthippus biguttulus (Orthoptera, Acrididae) following dimethoate exposure is dependent on the insects' habitat

The comet assay was used to study the DNA damage that was induced by dimethoate in the hemocyte cells of adult Chorthippus biguttulus grasshoppers (Insecta: Orthoptera) that originated from two sites with varying levels of pollution. The primary focus of the study was to examine whether continuous exposure to environmental stress can modify the effect of pesticides on genome stability. After three days of acclimation to laboratory conditions, the level of DNA damage in the hemocytes of Bow-winged grasshoppers was within a similar range in the insects from both areas. However, the level of DNA damage following dimethoate treatment was significantly higher in the insects from the reference area (Pogoria) than in the individuals from the heavily polluted location (Szopienice). Four hours after pesticide treatment, the Tail DNA (TDNA) in the hemocytes of the male and female specimens from Pogoria was as high as 75% and 50% respectively, whereas the values in males and females from Szopienice only reached 30% and 20%, respectively. A rapid decrease in DNA damage was observed in both populations 24 h after the pesticide application. The habitat of an insect (site), the administration of the dimethoate (treatment), and the period following the application of the pesticide (time), all significantly influenced the levels of DNA damage. No interactions related to TDNA were observed between the variables 'sex' and 'treatment'. Similarly, the variable 'sex', when analyzed alongside 'treatment' and 'site' (the area from which the insects were collected), or 'treatment' and 'time' had no influence on TL. Exposure to dimethoate undoubtedly contributed to the formation of DNA damage in the hemocytes of adult C. biguttulus. However, the level of damage was clearly dependent on the place where the insects were captured.

The role of oxidative stress in organophosphate and nerve agent toxicity

Organophosphate (OP) nerve agents exert their toxicity through inhibition of acetylcholinesterase. The excessive stimulation of cholinergic receptors rapidly causes neuronal damage, seizures, death, and long-term neurological impairment in those that survive. Owing to the lethality of organophosphorus agents and the growing risk they pose, medical interventions that prevent OP toxicity and the delayed injury response are much needed. Studies have shown that oxidative stress occurs in models of subacute, acute, and chronic exposure to OP agents. Key findings of these studies include alterations in mitochondrial function and increased free radical-mediated injury, such as lipid peroxidation. This review focuses on the role of reactive oxygen species in OP neurotoxicity and its dependence on seizure activity. Understanding the sources, mechanisms, and pathological consequences of OP-induced oxidative stress can lead to the development of rational therapies for treating toxic exposures.

A simplified acute physiology score in the prediction of acute organophosphate poisoning outcome in an intensive care unit

Organophosphate poisoning (OPP) occurs frequently and accounts for a large number of intoxication cases treated in intensive care units (ICU). Poisoning by these agents is a serious public health problem. Among pesticides, OPs are the main cause of poisoning and death in Loghman-Hakim Poison Center of Tehran, Iran. The aim of this study was to determine the impact of the Simplified Acute Physiology Score (SAPS II) in the prediction of mortality in patients with acute OPP requiring admission to the ICU of Loghman-Hakim Hospital Poison Center over a period of 12 months. This study was a prospective, case-control of records of patients with acute OPP admitted to the ICU between January 2006 and December 2006. The Demographic data were collected and SAPS II score was recorded. During the study period, 24 subjects were admitted to the ICU with acute OPP. All 24 patients (15 male) required endotracheal intubation and mechanical ventilation in addition to gastric decontamination and standard therapy with atropine and oximes and adequate hydration. Of these, 24 patients, eight (five male) died. SAPS II score was significantly higher in the non-survival group than the survival group. Mortality following acute OPP remains high despite adequate intensive care and specific therapy with atropine and oximes. One-third of the subjects needing intensive care die within the hospitalization period. SAPS II scores calculated within the first 24 hours were recognized as good prognostic indicator among patients with acute OPP that required ICU admission. It is concluded that SAPS II score above 11 within the first 24 hours is a predictor of poor outcome in patients with acute OPP requiring ICU admission. Human & Experimental Toxicology (2007) 26, 623—627

Alteration of hepatic cells glucose metabolism as a non-cholinergic detoxication mechanism in counteracting diazinon-induced oxidative stress

The aim of this study was to evaluate effects of acute exposure to various doses of diazinon, a widely used synthetic organophosphorus (OP) insecticide on plasma glucose, hepatic cells key enzymes of glycogenolysis and gluconeogenesis, and oxidative stress in rats. Diazinon was administered by gavage at doses of 15, 30 and 60 mg/kg. The liver was perfused and removed under anaesthesia. The activities of glycogen phosphorylase (GP), phosphoenolpyruvate carboxykinase (PEPCK), thiobarbituric acid reactive substances (TBARS) and total antioxidant capacity (TAC) were analysed in liver homogenate. Administration of diazinon (15, 30 and 60 mg/kg) increased plasma glucose concentrations by 101.43% (P=0.001), 103.68% (P=0.000) and 160.65% (P=0.000) of control, respectively. Diazinon (15, 30 and 60 mg/kg) increased hepatic GP activity by 43.5% (P=0.05), 70.3% (P=0.00) and 117.2% (P=0.02) of control, respectively. In addition, diazinon (30 and 60 mg/kg) increased hepatic PEPCK by 77.3% (P=0.000) and 93.5% (P=0.000) of control, respectively. Diazinon (30 and 60 mg/kg) decreased liver TAC by 38% (P=0.046) and 48% (P=0.000) of control, respectively. Also diazinon (30 and 60 mg/kg) increased hepatic cell liver lipid peroxidation by 77% (P=0.05) and 280% (P=0.000) of control. The correlations between plasma glucose and hepatic cells TBARS (r2=0.537, P=0.02), between plasma glucose and ChE activity (r2=0.81, P=0.049) and between plasma glucose and hepatic cells GP activity (r2=0.833, P=0.04) were significant. It is concluded that the liver cells are a site of toxic action of diazinon. Diazinon increases glucose release from liver into blood through activation of glycogenolysis and gluconeogenesis as a detoxication non-cholinergic mechanism to overwhelm diazinon-induced toxic stress. The results are in accordance with the hypothesis that OPs are a predisposing factor of diabetes.

A systematic review on human exposure to organophosphorus pesticides in Iran

Human exposure to organophosphorus (OP) pesticides is a serious health challenge. We conducted a systematic review by searching international and national databases for published literature on any human exposure to OPs in Iran from 1990 to March 2015. Qualified papers were in two categories including studies in which biomarkers of exposure were assessed (n = 13; total no. of subjects = 759) and studies that had reported prevalence of OPs-induced poisoning (OPP) and mortality (n = 26; total no. of subjects = 5428). The mean level of activity of acetyl-cholinesterase and butyryl-cholinesterase were 68.65% and 74.2%, respectively. Overall proportion (%) of OPP was estimated (16; 95% CI, 14 to 19).