Use Of Organophosphate Pesticides Research Articles

Preferential Door for Ligand Binding and Unbinding Pathways in Inhibited Human Acetylcholinesterase.

Rising global population and increased food demands have resulted in the increased use of organophosphate pesticides (OPs), leading to toxin accumulation and transmission to humans. Pralidoxime (2-PAM), an FDA-approved drug, serves as an antidote for OP therapy. However, the atomic-level detoxification mechanisms regarding the design of novel antidotes remain unclear. This is the first study to examine the binding and unbinding pathways of 2-PAM to human acetylcholinesterase (HuAChE) through three identified doors using an enhanced sampling method called ligand-binding parallel cascade selection molecular dynamics (LB-PaCS-MD). Remarkably, LB-PaCS-MD could identify a predominant in-line binding mechanism through the acyl door at 63.79% ± 6.83%, also implicating it in a potential unbinding route (90.14% ± 4.22%). Interestingly, crucial conformational shifts in key residues, W86, Y341, and Y449, and the Ω loop significantly affect door dynamics and ligand binding modes. The LB-PaCS-MD technique can study ligand-binding pathways, thereby contributing to the design of antidotes and covalent drugs.

Acetylcholinesterase Inhibition in Rats and Humans Following Acute Fenitrothion Exposure Predicted by Physiologically Based Kinetic Modeling-Facilitated Quantitative In Vitro to In Vivo Extrapolation.

Worldwide use of organophosphate pesticides as agricultural chemicals aims to maintain a stable food supply, while their toxicity remains a major public health concern. A common mechanism of acute neurotoxicity following organophosphate pesticide exposure is the inhibition of acetylcholinesterase (AChE). To support Next Generation Risk Assessment for public health upon acute neurotoxicity induced by organophosphate pesticides, physiologically based kinetic (PBK) modeling-facilitated quantitative in vitro to in vivo extrapolation (QIVIVE) approach was employed in this study, with fenitrothion (FNT) as an exemplary organophosphate pesticide. Rat and human PBK models were parametrized with data derived from in silico predictions and in vitro incubations. Then, PBK model-based QIVIVE was performed to convert species-specific concentration-dependent AChE inhibition obtained from in vitro blood assays to corresponding in vivo dose-response curves, from which points of departure (PODs) were derived. The obtained values for rats and humans were comparable with reported no-observed-adverse-effect levels (NOAELs). Humans were found to be more susceptible than rats toward erythrocyte AChE inhibition induced by acute FNT exposure due to interspecies differences in toxicokinetics and toxicodynamics. The described approach adequately predicts toxicokinetics and acute toxicity of FNT, providing a proof-of-principle for applying this approach in a 3R-based chemical risk assessment paradigm.

Assessing soil bacterial community response to organophosphate pesticides in agricultural field of Yogyakarta, Java, Indonesia

Soil contamination by pesticides is one of the world’s most pressing environmental issues. The widespread use of Organophosphate pesticides (OPPs) in agriculture has led to biological diversity changes. The indigenous bacterial community played significant roles in the remediation of soil contaminated with OPPs. This study examines the overall bacterial community composition of three agricultural fields in Yogyakarta, Java, Indonesia, that were exposed to OPPs. The agricultural field was divided into zones near the beach, residential, and mountainous. Sequencing 16S rRNA amplicon fragments used to analyze the soil bacterial community. It was discovered that Proteobacteria, Actinobacteria, and Firmicutes comprised the majority of the bacterial community. In addition, the samples contain a high relative abundance of Bacillus, Bradyrhizobium, Chryseobacterium, Cystobacter, Microvirga, and Burkholderia. The high alpha diversity indexes suggest that the agricultural soil microbiome provides important ecological services and may harbor a wide variety of bacteria and genes with biotechnological applications. The physicochemical soil characteristics are also correlated with the bacterial community structure. The findings can be used to develop bioremediation strategies that employ native microbes to clean and restore agricultural soil contaminated with OPPs.

English

Regular use of organophosphate pesticides (OPPs) such as chlorpyrolifos in agriculture results in a variety of environmental issues, including groundwater contamination, surface water pollution, enhanced floral and faunal resistance, soil acidity, reduced soil fertility, and nitrate leaching. The objective of the current study was to identify and isolate bacterial strains from native soil that could degrade chlorpyrifos and had high pesticide resistance. A total of 60 distinct microbial strains were isolated from the soil samples and subsequently evaluated for their capacity to degrade chlorpyrifos. Serratia liquefaciens, one of the strains, was discovered to be the most effective among them for degrading chlorpyrifos. It was subsequently examined for the biodegradation of chlorpyrifos under various environmental conditions and was then identified using 16S rRNA sequencing. The strain S. liquefaciens degraded more than 90% of 50 mg L-1 of chlorpyrifos. The strain performed better when urea and sucrose were used as nitrogen and carbon sources, respectively. At a temperature of 35 °C and a basic pH range, the strain functioned exceptionally well. The finding demonstrated that the bacterial strain S. liquefaciens, which was isolated from agricultural soil, is a top contender for cleaning up OPP-contaminated soil.

Degradation effects on dichlorvos by a biocontrol strain, Trichoderma atroviride T23

Excessive use of organophosphate pesticides (OP), such as dichlorvos, in farming system poses a threat to human health through potential contamination of environment. To date, biodegradation has been prospected most promising approach to eliminate environmental OP residues. Trichoderma species as a biological control microorganism is often exposed to the chemical pesticides applied in environments, so it is necessary to understand the mechanism of degradation of dichlorvos by Trichoderma. In this study, dichlorvos significantly inhibited the growth, sporulation and pigmentation of T. atroviride T23, and the dichlorvos degradation activity of T23 required the initial induction effect of dichlorvos and the culture conditions, including the nutrient and pH values of the medium. Various changed primary and secondary metabolites released from T23 in the presence of dichlorvos were speculated as the energy and antioxidants for the strain itself to tolerate dichlorvos stress. The results showed that T23 could produce a series of enzymes, especially the intracellular enzymes, to degrade dichlorvos. The activities of the intracellular enzyme generated by T23 were differentially changed along time course and especially relied on initial dichlorvos concentration, ammonium sulfate and phosphate added in the medium. In conclusion, some dichlorvos-induced chemical degradation related enzymes of T23 were proved to be involved in the degradation of dichlorvos.

POTENTIAL OF SEAWEED (Eucheuma cottonii) EXTRACT AS A HEPATOPROTECTOR IN RABBIT (Oryctolagus cuniculus) INDUCED ORGANOPHOSPHATE PESTICIDES

The use of organophosphate pesticides in developing countries is already widespread and can contaminate animal feed or human food ingredients which has an impact on liver damage and other organs. The use of seaweed containing polyphenols as a hepatoprotector for organophosphate poisoning has not been widely used by the public. The purpose of this study was to determine the potential of seaweed extract as a hepatoprotector in organophosphate-induced rabbits as seen from serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) levels. This study used a complete randomized design with 20 male rabbits as experimental animals which were divided into 4 treatments with 5 repetitions, namely: P0 was the control group which was only given distilled water, P1 was the group given seaweed extract at a dose of 200 mg/Kg BW, P2 is the group given seaweed extract at a dose of 400 mg/KgBB and P3 is the positive control group which is not given seaweed extract and distilled water. On the 15th day the P1, P2, and P3 groups were given profenofos pesticide at a dose of 50 mg/kg BW. The results showed a very significant difference (p-value = 0.02, α = 0.05) in SGOT levels between the P0 control group (135.4 ± 67.00 U/L) and the P1 treatment group (41.8 ± 17.45 U/L), P2 (25.8 ± 8.75 U/L), and the positive control group P3 (70 ± 29.04). The results of the study also found that there was no significant difference in SGPT levels in the P0 control group and the P1, P2, and P3 control groups. Giving seaweed extract with different doses provides a hepatoprotector effect by reducing the release of SGOT into the blood.

Biodegradation pathway of the organophosphate pesticides chlorpyrifos, methyl parathion and profenofos by the marine-derived fungus Aspergillus sydowii CBMAI 935 and its potential for methylation reactions of phenolic compounds

The indiscriminate use of organophosphate pesticides causes serious environmental and human health problems. This study aims the biodegradation of chlorpyrifos, methyl parathion and profenofos with the proposal of new biodegradation pathways employing marine-derived fungi as biocatalysts. Firstly, a growth screening was carried out with seven fungi strains and Aspergillus sydowii CBMAI 935 was selected. For chlorpyrifos, 32% biodegradation was observed and the metabolites tetraethyl dithiodiphosphate, 3,5,6-trichloropyridin-2-ol, 2,3,5-trichloro-6-methoxypyridine, and 3,5,6-trichloro-1-methylpyridin-2(1H)-one were identified. Whereas 80% methyl parathion was biodegraded with the identification of isoparathion, methyl paraoxon, trimethyl phosphate, O,O,O-trimethyl phosphorothioate, O,O,S-trimethyl phosphorothioate, 1-methoxy-4-nitrobenzene, and 4-nitrophenol. For profenofos, 52% biodegradation was determined and the identified metabolites were 4-bromo-2-chlorophenol, 4-bromo-2-chloro-1-methoxybenzene and O,O-diethyl S-propylphosphorothioate. Moreover, A. sydowii CBMAI 935 methylated different phenolic substrates (phenol, 2-chlorophenol, 6-chloropyridin-3-ol, and pentachlorophenol). Therefore, the knowledge about the fate of these compounds in the sea was expanded, and the marine-derived fungus A. sydowii CBMAI 935 showed potential for biotransformation reactions.

Industrial method of decontamination of dimethoate containing wastewater

The problem of wastewater disposal affects not only third countries, but also world giants such as China or the United States of America. The European Union and the Commonwealth of Independent States are no exception. The increasing use of organophosphate pesticides requires the search for new, more efficient and cheaper ways to dispose of their residual amounts. The existing methods of disposal of toxic waste are costly, ineffective, and environmentally hazardous. The optimal solution can be a chemical system for decontamination of wastewater directly at the place of their origin, for example, at the production of pesticide formulations and agro-industrial facilities. This article presents the results of studying the effectiveness of the chemical system for the destruction of organophosphorus compounds based on hydrogen peroxide and potassium hydroxide in relation to dimethoate. The results of the scaling of the decontamination process are presented and an installation for the technological process of wastewater disposal is proposed. The research results show a high reactivity of the system under study and a high efficiency level of the described technological process.

Dynamics of organochlorine and organophosphate pesticide residues in soil, water, and sediment from the Rufiji River Delta, Tanzania

The Rufiji River Delta (RRD) in Tanzania is an internationally important wetland. Subsistence mangrove rice farming (MRF) uses pesticides to combat crabs and herbicides to combat weeds. We undertook the first investigation of the dynamics of pesticide residues and hazard in farm soil, water, and sediment, during and following application. Twenty-one organochlorine and organophosphate insecticides, and the herbicide thiobencarb occurred at quantifiable concentrations. The residue profile indicated past use of organochlorine pesticides and current use of organophosphate pesticides (OPP). Residues of ΣHCH4, ΣDDT4, ΣOPP5, and all residues combined (ΣAll21) in soils and sediments decreased significantly following application, but not for ΣCyclodienes7. ΣDDT4 and ΣCyclodienes7 increased significantly in water following application, although this is likely related to legacy effects from upstream and not its use on MRFs. ΣOPP5 made up 61% of ΣAll21 in soils, 38% in sediments, and 45% in river water during application, dropping to 4.2%, 10%, and 19%, respectively, after application. Concentrations of compounds such as dieldrin, DDT, HCH, and OPPs exceeded various safety guidelines in all matrices. There were complicated dynamics of the residues between soils, sediments, and water, reflecting the complex interactions in a tidal riverine delta environment with the chronic presence of legacy pollutants and seasonal fluxes of current use pesticides. Multivariate analyses showed compound class specific differences in dynamics between matrixes and seasons. The predictions of pollutant concentrations and effects in highly biodiverse and productive tropical deltas with increasing human and extraction pressures, overlain with the spectre of climate change will be difficult. What seems certain though is that the stresses caused by chemicals will not lessen unless managed and calls for urgent interventions and further research.

Novel degradation pathways for Chlorpyrifos and 3, 5, 6-Trichloro-2-pyridinol degradation by bacterial strain Bacillus thuringiensis MB497 isolated from agricultural fields of Mianwali, Pakistan

Over use of organophosphate pesticides including Chlorpyrifos (CPF) has led to contamination of soil and water resources, resulting in serious health problems in humans along with other non-target organisms. The current study was aimed to investigate Chlorpyrifos as well as 3, 5, 6-Trichloro-2-pyridinol (TCP) biodegradation tendency of bacterial strain Bacillus thuringiensis MB497 isolated from wheat/cotton fields of Dera Saleemabad, Mianwali, Pakistan, having a history of heavy Organophosphate pesticides application. HPLC analysis revealed almost 99% degradation of the spiked CPF (200 mg L−1) in M-9 broth, soil slurry and soil microcosm by MB497 after 9 days of incubation. Strain MB497 was also able to degrade and transform TCP (28 mg L−1), up to 90.57% after 72 h of incubation in M-9 broth. A novel compound Di-isopropyl methanephosphonate along with known products of 3, 5, 6-Trichloro-2-pyridinol (TCP), Diethyl thiophospsphate and Phosphorothioic acid were detected as metabolites of CPF by GCMS analysis. Three novel metabolites of TCP (p-Propyl phenol, 2-Ethoxy-4, 4, 5, 5-tetramethyloxazoline and 3-(2, 4, 5-Trichlorophenoxy)-1-propyne) were identified after 72 h. Based on these metabolites, new/amended metabolic pathways for CPF and TCP degradation in these bacteria has been suggested.

Chemometrics Assisted QuEChERS Extraction Method for the Residual Analysis of Organophosphate Insecticides: Application to Their Dissipation Kinetics in Open Field Ecosystem

The present study aimed to investigate the dissipation kinetics and residual levels of five organophosphate pesticides in a carrot- and potato-field ecosystem by sensitive and selective liquid chromatography-tandem mass spectrometry method. The optimization of the modified QuEChERS extraction method was carried out using the cost-effective chemometric tool equipped with Plackett-Burman and central composite designs. Based on the response surface methodology the optimized conditions were found to be 56.5 mg of primary secondary amine sorbent, 1.53 g of sodium chloride, and 213 mg of C18. The average recoveries of the method were obtained over the range of 81.6 to 96.0 % with a relative standard deviation < 14.7 %. The detection and quantification limit ranged from 0.7 to 1.0 μg/kg and 1.0 to 5.0 μg/kg, respectively. The data showed that the first-order model was the best fit for the dissipation of five organophosphate pesticides with a regression coefficient of more than 0.99. The half-lives for all the studied pesticides were below 6.6 and 5.1 days for carrot and potato, respectively. The harvesting intervals for pesticides on the carrot and potato fields were within 28 and 21 days, respectively. The study results contribute to establishing the scientific basis of the dosage for organophosphate pesticide use in the vegetable field.

Kontaminasi Residu Pestisida Organofosfat di Dalam Tanaman Holtikultura

Excessive use of organophosphate pesticides is becoming more common these days. This can affect the level of pesticide residues in farmers' crops. Excessive spraying of pesticides can result in environmental pollution both small and large scale. If excessive exposure to these pesticides can cause damage to the ecosystem. The purpose of this study was to determine the level of organophosphate pesticide residues found in horticulture plants. This research method is a systematic review, by analyzing various studies regarding the contamination of organophosphate pesticide residues in horticultural crops. There are 20 studies from within the country. The results obtained in the form of levels of pesticide residues that are still below the threshold of the BMR (Maximum Residue Limit) of pesticides determined by SNI. Two other studies show that no pesticide residue content was detected. Conclusion: This shows that the sample tested is still safe for consumption. Socialization and education about the doses of pesticide use and how to reduce levels of pesticides in horticultural crops are needed to reduce the risk of exposure to pesticides

Association between cholinesterase's inhibition and cognitive impairment: A basis for prevention policies of environmental pollution by organophosphate and carbamate pesticides in Chile

BackgroundIn Chile organophosphate pesticides are widely used in the production of fruits. Pesticides use is regulated for professional practice but there is no regulation regarding exposure to the general population. ObjectiveTo relate exposure to cholinesterase's inhibitor pesticides during the spray season with neuropsychological impairment in occupationally exposed (OE) and environmentally exposed (EE) groups of people. MethodsExposure was assessed through inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity and neuropsychological outcomes were evaluated through a large battery of tests covering general mental status, language, memory, attention, executive function, praxis and psychomotricity. Evaluations were carried out firstly in a period of no/low organophosphate pesticide use and subsequently during the spray season. All parameters were calculated as the relative change from baseline to spray season. ResultsFor this study in total 156 participants were recruited divided equally over participants with environmental exposures (EE) and participants with occupational exposure (OE). In the EE, BChE's enzyme activity inhibition ≥30% showed significant association with 10% or more decreased performance in several tests evaluating six of the eight cognitive areas (excepting psychomotricity and mood status); besides, for AChE inhibition in EE, the association was significant in three tests evaluating attention and one of executive function. Whereas, in OE, the inhibition of the BChE ≥30% was associated with a low performance of one attention test and for AChE the exceedance of the standard was associated with diminished performance in one test of memory and attention, respectively. The association between biomarkers of biological effect and cognitive impairment persisted among the EE group after removing confounders. No association was found between biomarkers of biological acute effect and decreased cognitive performance in the OE group. ConclusionsIncreased exposure to pesticides was confirmed by increased inhibition of cholinesterase's in both exposure groups; which was associated with a diminished neuropsychological performance, mainly in the environmentally exposed study group. [310 words].

Review of Biomarkers and Analytical Methods for Organophosphate Pesticides and Applicability to Nerve Agents.

Recent malicious use of chemical warfare agents (CWAs) is a reminder of their severity and ongoing threat. One of the main categories of CWAs is the organophosphate (OP) nerve agents. Presently, there is an urgent need to identify and evaluate OP nerve agent biomarkers that can facilitate identification of exposed individuals post-CWA incident. While exposures to OP nerve agents may be scenario-specific, the public is commonly exposed to OP compounds through the ubiquitous use of OP pesticides, which are chemically related to nerve agents. Therefore, a systematic literature review and methodological quality assessment were conducted for OP pesticide biomarker studies to serve as a baseline to assess if these approaches may be adapted to OP nerve agent exposures. We conducted a systematic literature review to identify biomarkers of OP pesticide exposures. English language studies of any design that reported primary data on biomarkers for exposures in nonhuman primates or adult human study participants were eligible for inclusion. Using standard criteria for assessing the completeness of reported analytical methods, the quality of study methods was critically evaluated. A total of 1,044 studies of biomarkers of OP pesticide exposure were identified, of which 75 articles satisfied the inclusion and exclusion criteria. These studies described 143 different analyte/sample matrix combinations: 99 host-based biomarkers, 28 metabolites, 12 pesticides, and 4 adducts. The most commonly reported biomarkers were dialkyl phosphate urinary metabolites (22 studies), blood acetylcholinesterase, and plasma butyrylcholinesterase (26 studies each). None of the assessed quality review criteria were fully addressed by all identified studies, with almost all criteria scoring less than 50%. Cholinesterase activity may have utility for identifying individuals with exposures surpassing a given threshold of OP nerve agent, but further investigation of how acetylcholinesterase and butyrylcholinesterase levels correlate with observed patient symptoms may be required to ensure accuracy of results. As CWAs and nerve agents are more readily used, more standardized reporting of biomarker measurements are needed to develop new approaches for OP nerve agent biomarkers.

Ferulago angulata extract ameliorates epididymal sperm toxicity in mice induced by lead and diazinon.

The potential toxicity that results from environmental xenobiotics is not completely known. Increasing levels of heavy metals and the use of organophosphate pesticides (OPs) and their co-existence in the environment could be associated with an increasing incidence of male reproductive system disorders in humans and animals. Ferulago angulata is a dietary source of phenolic compounds with reported health benefits. This study was conducted to investigate whether an extract of Ferulago angulata could protect adult male NMRI mice against reproductive toxicity induced by lead acetate (PbAc), diazinon (DZN), or PbAc+DZN. Adult male NMRI mice were exposed to either 0.5% PbAc in drinking water, DZN (3mg/kg/day, intraperitoneal [i.p.] injection), or PbAc+DZN in the presence or absence of 400mg/kg/day Ferulago angulata hydroalcoholic extract (FAE) that was administered via gavage for 6weeks. Chronic exposure to PbAc, DZN, and PbAc+DZN decreased sperm quality, sperm chromatin maturity and integrity, increased oxidative stress and lipid peroxidation, and could reduce male fertility indices. Co-administration of FAE could reduce these negative effects. The Ferulago angulata extract should be considered as a useful natural extract for the treatment of male infertility, especially in males exposed to conditions which induce reproductive toxicity.

Isolation and partial characterization of organophosphate pesticide degrading bacteria from soil sample of Noakhali, Bangladesh

Extensive use of organophosphate pesticides particularly malathion can result in pollution of soil, surface water and ground water, and thus disrupts ecosystem byexposing non-target species to its toxicity. Bioremediation with indigenous microorganisms having pesticide utilizing abilities is considered to be a viable solution regarding decontamination of organophosphate residues from pesticide contaminated soil. In this study, we isolated five malathion degrading bacter ial strains designated as S-1, S-2, S-3, S-4 and S-5 from paddy fields of Noakhali, Bangladesh by observing visible growth in malathion supplemented mineral salts medium (MSM) agar following selective enrichment technique. The isolates were provisionally identified based on their morphological and biochemical characteristics as Pseudomonas spp. (S-1), Bacillus subtilis (S-2), Staphylococcus aureus (S-3), Pseudomonas aeruginosa (S-4) and Pseudomonas spp. (S-5) respectively. To determine their malathion utilization potential, the isolates were inoculated in MSM containing 50 mg/l malathion as sole source of carbon. When compared with control, the turbidometric growth study with the isolates revealed that all the isolates showed a significant increase of growth, indicating utilization of malathion (conc. 50 mg/l) in MSM at 37oC. The rate of growth varied for all the isolates when this growth study was done using different temperature schemes (25oC, 35oC and 45oC).&#x0D; Bangladesh J Microbiol, Volume 36 Number 1 June 2019, pp 17-22

Correlation between Cholinesterase Levels and Blood Glucose Levels in Farmers Exposed to Organophosphate Pesticide in Desa Sukorambi Kabupaten Jember

The use of organophosphate pesticides by farmers can cause long-term health risks, one of which is an increase in blood glucose levels. This study aims to determine whether there is a relationship between the levels of cholinesterase as an indicator of exposure to organophosphate pesticides and blood glucose of farmers in Sukorambi Village, Jember Regency. Secondary data in the form of general characteristics of the sample were obtained through interviews, while the primary data was obtained from examining the levels of cholinesterase and blood glucose levels of farmers at the Biochemical Laboratory of the Faculty of Medicine, Jember University. The research method is observational-analytic with cross-sectional study design. Based on the results of statistical analysis using the Spearman correlation test (p = 0.05), it was concluded that there was no significant relationship between the two variables (p = 0.0802).

The organophosphate pesticide methamidophos opens the blood-testis barrier and covalently binds to ZO-2 in mice

Methamidophos (MET) is an organophosphate (OP) pesticide widely used in agriculture in developing countries. MET causes adverse effects in male reproductive function in humans and experimental animals, but the underlying mechanisms remain largely unknown. We explored the effect of MET on mice testes (5 mg/kg/day/4 days), finding that this pesticide opens the blood-testis barrier and perturbs spermatogenesis, generating the appearance of immature germ cells in the epididymis. In the seminiferous tubules, MET treatment changed the level of expression or modified the stage-specific localization of tight junction (TJ) proteins ZO-1, ZO-2, occludin, and claudin-3. In contrast, claudin-11 was barely altered. MET also modified the shape of claudin-11, and ZO-2 at the cell border, from a zigzag to a more linear pattern. In addition, MET diminished the expression of ZO-2 in spermatids present in seminiferous tubules, induced the phosphorylation of ZO-2 and occludin in testes and reduced the interaction between these proteins assessed by co-immunoprecipitation. MET formed covalent bonds with ZO-2 in serine, tyrosine and lysine residues. The covalent modifications formed on ZO-2 at putative phosphorylation sites might interfere with ZO-2 interaction with regulatory molecules and other TJ proteins. MET bonds formed at ZO-2 ubiquitination sites likely interfere with ZO-2 degradation and TJ sealing, based on results obtained in cultured epithelial cells transfected with ZO-2 mutated at a MET target lysine residue. Our results shed light on MET male reproductive toxicity and are important to improve regulations regarding the use of OP pesticides and to protect the health of agricultural workers.

Induction of DNA damage in the peripheral blood of zebrafish (Danio rerio) by an agricultural organophosphate pesticide, monocrotophos

The use of organophosphate pesticides (OPs) in agricultural practices in India has gained popularity due to their broad spectrum, low cost and high potency. Monocrotophos (an OP) which is a systemic and contact broad-spectrum cholinesterase inhibitor is being widely used in India. However, its use entails the damage to other non-target organisms such as fish. In the present study, zebrafish (Danio rerio) were exposed to various doses of monocrotophos (0.125, 0.625 and 1.25 μL/L) and genotoxicity studies were carried out employing the comet assay and micronucleus test in the peripheral blood of these fish after 24, 48 and 72 h of exposure. Significant DNA damage in the form of % tail DNA and micronuclei was observed in all the treated fish compared to the control. Both % tail DNA and micronuclei frequency were found to increase significantly as the concentration increased. DNA damage was also observed at all the time intervals for all treatments except in the 0.125 μL/L-treated group. A positive correlation was also observed between the comet assay and micronucleus test. The study thus suggests the use of zebrafish as an experimental model to study the genotoxic effects of agricultural pesticides using the comet assay and micronucleus test.

Environmental monitoring and risk assessment of organophosphate pesticides in aquatic ecosystems of north-west Bangladesh

The use of organophosphate pesticides (OPPs) to protect a variety of crops has increased in Bangladesh. OPPs may contaminate surrounding aquatic environments through several routes including spray drift, surface runoff and groundwater leaching. Since it is unknown how much OPP end ups in aquatic environment in Bangladesh, the objectives of the present study were to quantify the residues of ten most commonly used OPPs in water and sediment of water bodies of north-west Bangladesh and to assess their ecological risks for aquatic organisms. The risks of the pesticides in surface water and sediment were assessed using a first-tier risk quotient (RQ) approach. The higher-tier PERPEST model was used to refine the ecological risks of pesticides when RQ indicated a potential risk. Results showed the most frequently detected pesticides that appeared in high concentrations were chlorpyrifos, diazinon and quinalphos in surface water and sediment. The highest concentration of OPPs measured in water was 9.1 μg chlorpyrifos/L (median of 1.95 μg/L), while this was 51 μg diazinon/kg dw (median of 11 μg/kg dw) for sediment. Furthermore, results showed high acute and/or chronic RQs (RQ > 1) in surface water and sediment for chlorpyrifos, diazinon, quinalphos, malathion and fenitrothion. The higher-tier PERPEST model confirmed risks of chlorpyrifos, diazinon, quinalphos and fenitrothion for aquatic insects, micro- and macro-crustaceans which were previously derived by RQ-based risk assessment for aquatic organisms. Furthermore, the results of the PERPEST model also indicated possible indirect effects of these pesticides on algae and macrophytes, community metabolism, rotifers and other macro-invertebrates.