Chlorpyrifos Residues Research Articles

Characterization of a novel hyper-thermostable and chlorpyrifos-hydrolyzing carboxylesterase EstC: A representative of the new esterase family XIX

Carboxylesterases have widely been used in a series of industrial applications, especially, the detoxification of pesticide residues. In the present study, EstC, a novel carboxylesterase from Streptomyces lividans TK24, was successfully heterogeneously expressed, purified and characterized. Phylogenetic analysis showed that EstC can be assigned as the first member of a novel family XIX. Multiple sequence alignment indicated that EstC has highly conserved structural features, including a catalytic triad formed by Ser155, Asp248 and His278, as well as a canonical Gly-His-Ser-Ala-Gly pentapeptide. Biochemical characterization indicated that EstC exhibited maximal activity at pH 9.0 (Tris-HCl buffer) and 55 °C. It also showed higher activity towards short-chain substrates, with the highest activity for p-nitrophenyl acetate (pNPA2) (Km = 0.31 ± 0.02 mM, kcat/Km = 1923.35 ± 9.62 s−1 mM−1) compared to other pNP esters used in this experiment. Notably, EstC showed hyper-thermostability and good alkali stability. The activity of EstC had no significant changes when it was incubated under 55 °C for 100 h and reached half-life after incubation at 100 °C for 8 h. Beyond that, EstC also showed stability at pH ranging from 6.0 to 11.0 and about 90% residual activity still reserved after treatment at pH 8.0 or 9.0 for 26 h, especially. Furthermore, EstC had outstanding potential for bioremediation of chlorpyrifos-contaminated environment. The recombinant enzyme (0.5 U mL−1) could hydrolyze 79.89% chlorpyrifos (5 mg L−1) at 37 °C within 80 min. These properties will make EstC have a potential application value in various industrial productions and detoxification of chlorpyrifos residues.

Gut bacteria of the silkworm Bombyx mori facilitate host resistance against the toxic effects of organophosphate insecticides

Organophosphate insecticides that are heavily used in agriculture for pest control have caused growing environmental problems and public health concerns worldwide. Ironically, insecticide resistance develops quickly in major lepidopteran pests, partially via their microbial symbionts. To investigate the possible mechanisms by which the microbiota confers insecticide resistance to Lepidoptera, the model organism silkworm Bombyx mori (Lepidoptera: Bombycidae) was fed different antibiotics to induce gut dysbiosis (microbiota imbalance). Larvae treated with polymyxin showed a significantly lower survival rate when exposed to chlorpyrifos. Through high-throughput sequencing, we found that the abundances of Stenotrophomonas and Enterococcus spp. changed substantially after treatment. To assess the roles played by these two groups of bacteria in chlorpyrifos resistance, a germ-free (GF) silkworm rearing protocol was established to avoid the influence of natural microbiota and antibiotics. Monoassociation of GF silkworms with Stenotrophomonas enhanced host resistance to chlorpyrifos, but not in Enterococcus-fed larvae, consistent with larval detoxification activity. GC-μECD detection of chlorpyrifos residues in feces indicated that neither Stenotrophomonas nor Enterococcus degraded chlorpyrifos directly in the gut. However, gut metabolomics analysis revealed a highly species-specific pattern, with higher levels of essential amino acid produced in the gut of silkworm larvae monoassociated with Stenotrophomonas. This critical nutrient provisioning significantly increased host fitness and thereby allowed larvae to circumvent the deleterious effects of these toxic chemicals more efficiently. Altogether, our study not only suggests a new mechanism for insecticide resistance in notorious lepidopteran pests but also provides a useful template for investigating the interplay between host and gut bacteria in complex environmental systems.

Occurrence of heavy metals and pesticide residues in tomato crop: a threat to public health

The presence of heavy metals and pesticide residues in higher concentrations in irrigation water and crops are two major concerns in developing and underdeveloped countries. The assessment and monitoring of these environmental contaminants in fruit and vegetables are vital for effective management and consumers’ health. In the current study, the presence of heavy metals and pesticides in irrigation water (sewage and tube well), soil, and tomato crop (grown on these water sources and sprayed with different pesticides in various locations of Peshawar city) was determined. Sewage water exhibited a significantly (p > 0.05) higher pH, total dissolved solid (TDS), and electrical conductivity (EC) when compared with the optimum limits as recommended by the World Health Organization (WHO). In addition, the concentrations of heavy metals, i.e., Cd, Pb, Ni, Cu, Zn, and Fe, were also significantly (p > 0.05) higher in this source. Furthermore, the analysis of sewage irrigated soil and various parts of tomato plants grown on this soil revealed a higher concentration of heavy metals compared with the standard limit set by WHO. Similarly, the levels of pesticide residues of chlorpyrifos and emamectin were significantly (p > 0.05) higher in tomato fruits and leaves and soil samples when compared with the standard limits set by the European Union. The current study provides first ever insight into the presence and levels of toxic heavy metals and pesticide residues in tomato crops grown on sewage water in Peshawar city for the effective monitoring and management of these health hazards.

Monitoring of the Organophosphate Pesticide Chlorpyrifos in Vegetable Samples from Local Markets in Northern Thailand by Developed Immunoassay.

Chlorpyrifos is an organophosphate pesticide that is wildly used among farmers for crop protection. However, there are concerns regarding its contamination in the environment and food chain. In the present study, an in-house indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) specific for detecting chlorpyrifos is developed and validated against gas chromatography–flame photometric detection (GC-FPD) as the conventional method. The developed ic-ELISA was used for detecting chlorpyrifos residue in vegetable samples. The developed ic-ELISA showed good sensitivity to chlorpyrifos at an IC50 of 0.80 µg/kg, with low cross-reactivity to other organophosphate pesticides. The 160 samples were collected from local markets located in the Chiang Rai, Chiang Mai, and Nan provinces in northern Thailand. The positive rate of chlorpyrifos residues in the vegetable samples was 33.8%, with the highest levels found in cucumbers, coriander, and morning glory, at 275, 145, and 35.3 µg/kg, respectively. The highest median levels of chlorpyrifos found in the detected samples were Chinese cabbage (332 μg/kg), cucumber (146.3 μg/kg) and Chinese Kale (26.95 μg/kg). The developed ic-ELISA is suitable for the rapid quantitation of chlorpyrifos residues.

Three-dimensional mesoporous dendritic fibrous nanosilica as a highly efficient DNA amplification platform for ultrasensitive detection of chlorpyrifos residues

In this paper, a novel amino-functionalized mesoporous dendritic fibrous nanosilica (NH2-DFNS) was used as DNA amplification platforms with DNA generated electrochemical signal as target conversion strategy to establish an electrochemical aptasensor for chlorpyrifos residues. The signal generation was based on the electrochemical reaction between molybdate with phosphate groups on the aptamer molecules, which greatly simplified the signal transduction and preparation steps of aptasensor, so as to improve the sensitivity of the aptasensor. The NH2-DFNS was prepared by a simple microemulsion method and characterized by SEM, TEM, FT-IR, BET, as well as XPS techniques. Importantly, the results showed that such a sphere-shaped nanomaterial with three-dimensional (3D) centerradial channels and hierarchical pores supported abundant DNA to amplify the DNA generated signal in the aptasensor. Furthermore, this aptasensor for detection of chlorpyrifos showed good sensitivity with a linear range of 1.0 fM∼1.0 nM, a detection limit of 0.43 fM. In addition, this sensor also possessed excellent specificity, repeatability, and stability. Moreover, this proposed electrochemical aptasensor was successfully used for the detection of chlorpyrifos residues in several practical samples.

In vitro oxidation promoted by chlorpyrifos residues on myosin and chicken breast proteins

Organophosphate pesticides are frequently used to eliminate or prevent insects in poultry. However, their residues may continue in meat after slaughtering. In this study, proteomics and peptidomics approaches were used to evaluate their oxidative impact on myosin and chicken breast proteins under in vitro conditions. Myosin protein was exposed to diazinon and chlorpyrifos showing an increase in its oxidation by increasing times, especially with chlorpyrifos.Then, chicken breast was contaminated with chlorpyrifos to evaluate carbonylation and the effect of simulated gastrointestinal digestion. Proteins were isolated using size-exclusion-chromatography and identified by mass spectrometry in tandem. Myosin, β-enolase, CK-M-type and actin were identified as main proteins susceptible to oxidation. Also, oxidised peptides obtained before and after simulated gastrointestinal digestion were identified. Collagen peptides the most susceptible to oxidation. These results suggest that the presence of chlorpyrifos residues on meat could have a negative effect on its final quality and nutritional value.

A description of the characteristics of shallot farmers using pesticides

The biggest use of pesticides is in the Brebes Regency, which is an onion farmer. Farmers in Brebes use a mixture of more than 5 types of pesticides. At the onion pest season, farmers can spray pesticides every 2 days. The results of research on pesticide residues in the soil show that the soil in Brebes still contains chlorpyrifos residues from 0.39 to 0.72 mg/kg. On average, farmers spray onions 15-20 times during the planting period, which is about 2 months. The most widely usage of pesticide is in Dursban 200 EC. This study aims to look at the characteristics of sprayers male farmers and the use of pesticides. The population of shallot male farmers are sprayers male farmers who live in the villages of Pamulihan, Larangan, Siandong, Rengaspendawa, and Sitanggal. The control sample is taken randomly while the case sample is taken by purposive sampling. The results obtain that the majority of respondents'’s education is elementary school graduation (40%), have no history of chronic illness (76%), BMI (Body Mass Index) normal (64%), smoking (66.7%), not drinking alcohol (65.3%), the average spraying frequency is ≥ 3 times a week. The use of high dosage of pesticides (> 183.12 cc) was most in the control group at 66.0% compared to case group 44.0%. The agricultural activities that cover all activities from planting to harvest are mostly carried out by the case group at 100% compared to 97.3% of control group. Much personal protective equipment (PPE) is not used when spraying. The storage distance of shallots is ≤ 5 meters from the gathering place of the family. At the time of spraying, the opposite direction when spraying is more in case respondents at 28.0% compared to 26.0% controls. Post-harvest spraying is performed more in cases with 52.0% compared to 40% in controls. The use of spraying clothes that are the same as clothes worn at home was more in the control group which was 72.0%. The behaviour of not handwashing with soap after spraying pesticides is mostly carried out by case group at 92.0%. Information and education related to pesticide usage is still needed.

A sensitive cytometric bead array for chlorpyrifos using magnetic microspheres

Chlorpyrifos is an organophosphorus pesticide widely used in agriculture and known to cause environmental pollution, as well as negatively impact human health. In this study, we reported a cytometric bead array (CBA) method to detect chlorpyrifos. Magnetic microspheres (Fe3O4@SiO2COOH) were prepared and coupled with chlorpyrifos-BSA. Flow cytometry was then used to perform an indirect competitive immunoassay to detect chlorpyrifos residue. CBA is based on the use of three-dimensional magnetic microspheres and allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb), effectively avoiding interfering from the matrix. The results showed that this assay requires only 15 s for a single run. Furthermore, CBA was shown to have a detection limit of 1.09 ng mL−1and an IC50 of 15.95 ng mL−1. This detection limit value is approximately three times lower than that of ELISA, and the working range for chlorpyrifos detection covers three orders of magnitude. This study indicates that CBA method is a promising detection method with widespread utility for food safety and environmental monitoring.

English

This study aimed at investigating the effect of consortia of three types of indigenous bacteria (Corynebacterium sp., Sphingobacterium gobiense and Kocuria flava) and earthworm (at 5 and 10 earthworms/kg soil) and their combination on the percentage removal of chlorpyrifos from chlorpyrifos contaminated soil in Sudan. Silt soil (Gerf soil) samples were mixed with known concentration of chlorpyrifos (450 mgkg-1) and incubated for various exposure periods (3, 7, 15 and 45 days) with the bacterial consortia alone, low and high densities of earth worm and their combinations under laboratory conditions. Remaining chlorpyrifos residues were measured by gas chromatograph equipped with flame ionization detector. Degradation rates and half-lives were found to follow biphasic model with an initial fast rate of disappearance followed by a second phase of slow disappearance. All treatments caused significant (PE‚0.05) effect on the degradation rates of chlorpyrifos compared to the control. The bacterial consortia alone induced the highest effect (73.83%) on the percentage removal of chlorpyrifos, followed by the bacterial consortia plus high density of earth worm (71.22%). Earth worm alone induced the least effect on the rate degradation of chlorpyrifos (64.27 and 66.49% for the high and low concentrations respectively). Based on this finding indigenous bacterial consortia represent a promising bioremediation agent for treatment of chlorpyrifos contaminated soil and therefore may deserve further investigation under different experimental conditions as well as validation of results under real contaminated soil conditions. Key words: Sudan, earthworm, indigenous bacteria, chlorpyrifos.

The Fabrication of an Impedance Immunosensor Based on Interdigitated Array Microelectrodes and Normalized Impedance Changes for Chlorpyrifos Residue Detection

The Fabrication of an Impedance Immunosensor Based on Interdigitated Array Microelectrodes and Normalized Impedance Changes for Chlorpyrifos Residue Detection

Rapid quantitative determination of chlorpyrifos pesticide residues in tomatoes by surface-enhanced Raman spectroscopy

Chlorpyrifos is a type of organophosphate insecticide used extensively in the plantation of tomatoes, a worldwide popular food. However, chlorpyrifos residues on tomatoes bring risks to human health considering the consumption level of tomato is relatively high across many countries. Accurate detection and strict regulation of chlorpyrifos residues are very important in controlling health risks related to chlorpyrifos. Therefore, we developed a rapid, highly sensitive, economical, and nondestructive surface-enhanced Raman spectroscopy (SERS)-based method that can quantitatively determine the content of chlorpyrifos in tomatoes. Silver colloid was optimized and used as the enhance substrate for SERS. Chlorpyrifos residues on tomato surface and in tomato extract were both measured with SERS, and the results acquired under these practical conditions well matched those of chlorpyrifos standard solutions. Linear relationships between chlorpyrifos concentrations and SERS intensities at crucial characteristic peaks under both conditions were established, and the results showed linearity across the entire measured range from 10−3 to 10−9 mol L−1. The detection limit of the proposed method was 10−9 mol L−1, which was much lower than the standards of chlorpyrifos use for China, Japan and EU, and was the lowest reported concentration chlorpyrifos had been measured on any fruit/vegetable surface or in its extract. The proposed method was very promising in the accurate, quantitative detection of pesticide residues, and it may be adapted to a variety of agricultural products and other areas in food science.

Chronic health risk comparison between China and Denmark on dietary exposure to chlorpyrifos

Chlorpyrifos is one of the most heavily used pesticides in domestic and agricultural insect prevention globally. Given the potential neurotoxicity of chlorpyrifos and its high detection rates in food and drinking water, health risks attributable to chlorpyrifos residue in Chinese drinking water and food in both China and Denmark were assessed in this study. Mixed left-censored handling models were used to deal with the non-detected values in chlorpyrifos concentrations. Results show that chronic exposure imputed to chlorpyrifos residue is much lower than the reference dose, and will thus not pose appreciable health risk to the consumer. Compared to the total exposure from chlorpyrifos in drinking water and food sources, chronic exposure from drinking water sources in China accounts for 0–4.4%. Health risk owing to chlorpyrifos in food within China is 6-7-fold higher than in Denmark, and this coincides with the fact that all application of chlorpyrifos is banned in Denmark, in contrast to China. However, the Danish consumers are still exposed from imported food items. The main health risk contributors in China are the food groups of Grains and grain-based products and Vegetable and vegetable products, while the main chronic health risk contributor in Denmark is the food group of imported fruit and fruit products.

Detection of systemic pesticide residues in tea products at trace level based on SERS and verified by GC-MS.

Surface-enhanced Raman spectroscopy (SERS) has the potential to detect pesticide residues in agricultural products. However, some systemic pesticides, such as chlorpyrifos, can enter the plant tissue, and not just stay on the surface. Consequently, many SERS studies halted at practical application because of its complexity. In this work, SERS technology was used to detect chlorpyrifos residues in tea products at the semiquantitative level. A simple pretreatment method effectively avoided interference of other fluorescent substances, and all major peaks could be distinguished on the basis of a novel substrate. A principal component analysis algorithm was applied to form a regression model, and a nanogram detection limit was obtained. Furthermore, chlorpyrifos residues in the same tea products were also measured by gas chromatography-mass spectrometry, and the results show a small range of errors. From the comparative study of the two detection methods, the results suggest the great promise of SERS technology for rapid inspection of agricultural products.

PESTICIDE RESIDUES IN COW MILK AND DAIRY PRODUCTS FROM THE MAJOR MILK PRODUCING AREA OF SRI LANKA

Nuwara Eliya district is the leading fresh milk producing area in Sri Lanka. In the district, pesticides are widely applied for intensive cultivation of vegetables which leads to contamination of water and material used to feed cows. Contamination and health risk hazards of organophosphorus pesticide residues in milk and dairy products originated in the district were studied. Identification and quantification of eleven commonly used pesticides in 50 milk samples and 12 dairy product samples were performed using standard analytical methods and GC-MS technique. Results revealed that fresh milk contained residues of Prothiofos (0.0568±0.037 mg/kg), Diazinon (0.0378±0.009 mg/kg), Chlorpyrifos (0.0264±0.004 mg/kg), Profenofos (0.196±0.099 mg/kg), Fipronil (0.1906±0.188 mg/kg), Phenthoate (0.1012±0.110mgkg), Dimethoate (0.1196±0.201 mg/kg) and Tebuconazole (0.062±0.069 mg/kg) at higher levels than the recommended maximum residue levels (MRLs) of the World Health Organization. Sterilized milk (0.0115±0.000 mg/kg) and fermented milk (0.022±0.004 mg/kg) contained higher levels of Profenofos than the MRLs. Higher levels of Fipronil than MRLs were observed in pasteurized milk (0.086±0 mg/kg) and fermented milk (0.014±0.000 mg/kg) samples. Phenthoate at higher levels than MRL was reported in pasteurized milk (0.3645±0.402 mg/kg), sterilized milk (0.1405±0.197 mg/kg) and milk powder (0.0055±0.000 mg/kg). Moreover, Dimethoate content in fermented milk (0.087±0.012 mg/kg) was higher than the MRL. Routine monitoring of the above pollutants in food items including fresh milk and value added milk products is essential to prevent, control and reduce the pollution and to minimize the health risks to consumers.

EFFECT OF OZONE MICROBUBBLES WITH VARIOUS TEMPERATURES ON THE CHLORPYRIFOS INSECTICIDE REMOVAL IN TANGERINE CV. SAI NAM PHUENG

Chlorpyrifos, a type of organophosphate insecticide, is widely used to destroy pests in the tangerine orchard to reduce the loss and maintain the quality of fruit. Consequently, the application of insecticides during production leads to the insecticide residues problem in tangerine that can be dangerous to human health. This study investigated the effect of ozone microbubbles (OMBs) on the removal of chlorpyrifos residues in the fruit. Tangerines were sprayed with chlorpyrifos solution at a concentration of 10 minutes. Then, they were treated with OMBs at different temperatures (15, 20 and 25 oC) for various exposing times (0, 10, 20, 30, 40, 50 and 60 minutes). Removal percentage of chlorpyrifos residues in tangerines was determined by gas chromatography-flame photometric detector (GC-FPD). The results showed that chlorpyrifos residues in tangerines were decreased at lower water temperature, especially at 15 oC resulting in the removal up to 81% after treating with OMBs for 30 minutes when compared to control (distilled water). After that, the fruits were stored at 25 oC for 7 days to determine quality changes. The percentage of weight loss, total soluble solids (TSS), titratable acidity (TA), disease incidence and ascorbic acid content in all treatments were not affected by OMBs. These results demonstrate that OMBs treatment at 15 oC is the most effective treatment for removing chlorpyrifos residues in tangerine and have no effects on the fruit quality.

Evaluation of pesticide residues in wheat grains and its products from Algeria

ABSTRACTThe presence of pesticide residues in wheat grains and its products produced and imported in Algeria was determined using QuEchERS extraction method and multi-residue analysis by gas chromatography–mass spectrometry. Among the 80 wheat samples analysed, detectable residues were found in 62.5% of samples. The most often pesticide found was pirimiphos methyl in 46 samples (57.5%). A percentage of 5% of samples contained pesticide residues above Maximum Residue Limits (MRLs) due to benalaxyl, chlorpyrifos and metalaxyl residues. Risk assessment for long-term exposure was done for all pesticides detected in wheat grains, the risk of exposure of Algerian consumers to pirimiphos methyl residues through wheat consumption was potentially high (EDI = 78%ADI). This risk was less important in the case of chlorpyrifos (EDI<9% ADI). For the others residues, EDIs were less than 1.5% of ADIs.

Evaluation of chlorpyrifos residue in breast milk and its metabolite in urine of mothers and their infants feeding exclusively by breast milk in north of Iran.

The most common method of combating insects in low-income communities and developing countries, is the use of insecticides. The use of organophosphate insecticides is increasing due to their low prices and availability on the market. Chlorpyrifos is a medium-risk insecticide for human. The widespread use of organophosphorus insecticides, especially chlorpyrifos, in residential homes has undoubtedly created many health concerns. Babies have a high sensitivity to pesticides and environmental contaminants because of their evolutionary status. On the other hand, the main source of infants' exposure who are breast-fed exclusively to environmental pollutants is through breast milk and oral contact with objects that are covered with dust and particles. In this cross-sectional study, the concentration of chlorpyrifos in breast milk and its metabolite in urine samples of mothers and their under six months infants, feeding exclusively by breast milk in north of Iran have been investigated. The demographic data was collected through interviewing with selected mothers and completion of prepared data collecting forms. The data were statistically analyzed to investigate the relationships between exposure of mothers and their infants to chlorpyrifos. The mean concentration of chlorpyrifos and its metabolite in mothers' urine and milk samples and infant's urines were 1.3 ± 0.6, 2.1 ± 1.4 and 1.4 ± 0.7μg/L, respectively. Also, the mean concentration of chlorpyrifos in the dust on the house floors was73.4 ± 49ng/g. There are good correlations between the mean values of chlorpyrifos concentrations and its metabolite in mother's milk and urine (r = 0.872, p = 0.001), and the mother's milk and infant's urine (r = 0.722, p = 0.001). Also, there was a significant correlation between the concentration of chlorpyrifos in floor dust and its metabolites in the infant's urine (r = 0.554, p = 0.001). Our study suggests that the infants are the recipient of concentrated forms of chlorpyrifos residues through breast milk and house dust and it is quite well known that OP pesticides are toxic and have different kinds of adverse health effects. However, further research needs to be done to determine what these chemicals are doing to our children.

Mesoporous structured molecularly imprinted polymer with restricted access function for highly selective extraction of chlorpyrifos from soil

Mesoporous structured molecularly imprinted polymers combined with restricted access materials (RAM-M-MIPs) were synthesized in this work, then RAM-M-MIPs were used as adsorbents in matrix solid phase dispersion (MSPD) to extract chlorpyrifos residues from soil. The RAM-M-MIPs with mesoporous structure increased adsorptive capacity and accelerated adsorption rate. At the same time, the RAM-M-MIPs with restricted access function showed good exclusion effect toward humic acid in the soil. In addition, the characteristics of RAM-M-MIPs were measured and the optimal experimental conditions of MSPD were explored. In MSPD, the extraction and clean-up procedures can be finished simultaneously, which saved the extraction time. The analyte eluted from soil was determined by LC–MS/MS. The recoveries were in the range of 93.5–106.1% and the relative standard deviations were in the range of 2.8–5.7% at the spiked soil levels of 0.10–10.00 ng g−1, the detection limit was 0.015 ng g−1. Based on these analytical validation results, the developed method can be a useful method to determine chlorpyrifos in soil.

Remediation Technology of Chlorpyrifos Residue in Red Chillies Planted on Light-Textured Soils and Heavy-Textured Soils

Remediation Technology of Chlorpyrifos Residue in Red Chillies Planted on Light-Textured Soils and Heavy-Textured Soils

Remediation Technology of Chlorpyrifos Residue in Red Chillies Planted on Light-Textured Soils and Heavy-Textured Soils

Remediation Technology of Chlorpyrifos Residue in Red Chillies Planted on Light-Textured Soils and Heavy-Textured Soils