Pyrethroid Residues Research Articles

Bacillus cereus GW-01 inoculation reduces pyrethroid residues and improves quality of Sichuan Paocai by changing the metabolic profile of fermentation

Pyrethroid residues in vegetables pose a challenge for household food processing. This study introduced Bacillus cereus GW-01, a pyrethroid-degrading bacterium, into Sichuan Paocai (SCP) fermentation. The study investigated the reduction of β-cypermethrin (β-CY), fenpropathrin (FNP), and λ-cyhalothrin (LCT) residues, alterations in metabolic profiles, and shifts in bacterial communities. Over fermentation, concentrations of β-CY, FNP, and LCT decreased. Notably, compared to the control, GW-01 proliferated in SCP, and the sample with GW-01 exhibited an enhanced degradation of β-CY, FNP, and LCT by 26.14%, 36.32%, and 33.70%, respectively. GW-01 presence lead to significant increases in volatile flavor components (VFC), organic acids (OA) including tartaric acid and succinic acid, and free amino acids (FAA) including Asn, Glu, Lys, and Pro after 7 days. The relative abundance of Bacillus in the group inoculated with GW-01 was higher than control, and the probiotics including Leuconostoc, Latilactobacillus, Brochothrix, Weissella, Lactobacillus, and Lactococcus, experienced a remarkable upsurge, reaching their zenith on the 7th day. Compared to CK, intriguing pathways such as bacterial chemotaxis, benzoic acid family, and mineral adsorption were additionally enriched in groups exposed to GW-01 and pyrethroids. The study's aim is to provide insights for reducing pesticide residues and enhancing fermented food quality.

Organochlorine and pyrethroid residue in fish and sediment of Lake Singkarak, a tropical deep lake

Agricultural activities still involve the use of synthetic pesticides to support the increase of their products. On the other hand, the use of synthetic pesticides such as organochlorines and pyrethroids may contribute to the decline of aquatic ecosystem health due to the accumulation of their residues in sediments and organisms. The current study aimed to assess the levels of organochlorine and pyrethroids pesticide residue in endemic fish and sediment from Lake Singkarak. Bilih fish and sediment samples were taken in June 2021 at ten (10) sampling sites in Lake Singkarak. The samples were extracted and analyzed by gas chromatography. Seven organochlorine compounds were measured, including aldrin, endrin, dieldrin, DDT, heptachlor, lindan, and endosulfan. Meanwhile, three compounds chosen from the pyrethroid group, cypermethrin, permethrin, and α-cypermethrin, were also measured. Four organochlorine compounds, aldrin, dieldrin, DDT, and endrin, were detected in bilih fish in three different sites. Dieldrin had the highest concentration at nd-0.007 mg/kg, followed by DDT, endrin, and aldrin. Meanwhile, in the sediments, no organochlorine compounds were detected from all observed sites. Pyrethroid compounds were detected in bilih fish at six sites. The compound with the highest concentration was permethrin (nd-0.02 mg/kg), followed by cypermethrin and α-cypermethrin. The surface sediment from three sites contained two pyrethroid residues, permethrin and α-cypermethrin, at nd-0.002 and nd-0.001 mg/kg, respectively. Our findings show that the residual levels of organochlorine and pyrethroid in bilih fish still meet the standards set by the Codex Alimentarius Commission (CAC). Nevertheless, Bilih fish accumulate more pesticide than surface sediment, so it is essential to be aware of their potential accumulation in the human body as the final consumer. Restriction on synthetic pesticide application is necessary to reduce its residue input into the lake waters for ecological and human health.

Перспективы применения энтомопатогенных грибов для борьбы с постельными клопами

A literature review on the effectiveness of the use of entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana for the destruction of bed bugs is given. Bed bug resistance to pyrethroids does not result in cross-resistance to infection with B. bassiana spores. Insect mortality is highly dependent on the concentration of fungal conidia, which is critical to induce horizontal transfer capable of increasing insect population mortality without the need for direct contact between bed bugs and the inoculated substrate. Pyrethroid residues on treated surfaces significantly reduce the germination of B. bassiana spores. At present, resistance of insects to mycoinsecticides in the field has not been revealed, however, it has been shown that in laboratory conditions its occurrence is possible. Keywords: entomopathogenic fungi, Metarhizium, Beauveria, biopesticides, bed bug, resistance.

Estimation of some Metal Pollutants and Pesticide Residues in Coffee Products Available in the Local Markets of Baghdad

Food contamination has significant effects on consumers? health. The present study aimed to estimate some heavy elements (copper, manganese, nickel, lead, cadmium, chromium, zinc, and iron) and quantify the residuals of pyrethroid pesticides such as cypermethrin, deltamethrin, permethrin, and bifenthrin in coffee products in the markets of Baghdad city. Coffee available in the market was from Brazil, Ethiopia, India, Kenya, Uganda, Indonesia, Guatemala, and Colombia, and 24 different samples were used for the study. The concentrations of heavy metals were estimated using the atomic absorption technique, while the pesticide residues were calculated using the LC-MS technique. The results showed that the copper, manganese, nickel, and zinc concentrations for all coffee samples were within acceptable limits. As for the concentrations of chromium and iron, some samples exceeded the permissible limits, such as the highest concentration of chromium was 1.137 mg/kg, and that iron was 57.089 mg/kg. The pyrethroid residues were high, and cypermethrin, deltamethrin, permethrin, and bifenthrin were on the higher side than the permissible levels and were recorded as 0.437, 0.833, 1.063, and 0.753 mg/kg, respectively, exceeding the maximum limits set by international standards.. KEYWORDS :Atomic absorption technique, Coffee, Metal pollutants, Pesticide residues, Pyrethroids

Study on establishment of residual analysis methods and residue degradation regulation of natural pyrethrin in barley plants and soil on Qinghai Plateau

The purpose of this study is to develop an accurate and efficient assay for the detection of pyrethroid residues and degradation in barley and soil in the Qinghai Plateau region. A sensitive and selective method was developed for the determination of pyrethrin residues in highland barley (kernel, stem, and root) and soil in the Qinghai Plateau by liquid chromatography (LC-MS/MS). Multi-residue analysis of pyrethrin in samples involves simple extraction with acetonitrile, salt-out with NaCl, MgSO4 absorption of water, cleaning with GCB and PSA, respectively, followed by separation with XR-ODS II column, and multi-reaction detection mode detection using a positive mode electrospray ionization source (ESI + ). The results showed that the 6 different components of pyrethrin had a good detection effect in the concentration range of 0.01 ∼ 1.0 mg/L, and the correlation coefficient was greater than 0.9990. The limits of quantitation of each component on each substrate were 0.01 ∼ 0.05 mg/kg, the average daily recoveries were 87.58 ∼ 95.44 %, and the relative standard deviations were 0.4 ∼ 3.8 %. The half-life of pyrethrin in barley grains, stems and soil was 0.77 ∼ 2.57 d. In soil and highland barley, the maximum dose of pyrethrin and twice the maximum dose of pyrethrin were applied, and the final residue 7 days after treatment was less than 0.2 mg/kg. The degradation behavior of pyrethrin in soil at three test sites showed that organic carbon and pH were important factors affecting the degradation of pyrethrin, and the effect of pH on the degradation of six pyrethrin components was greater than that of organic carbon. These studies provide theoretical basis for environmental safety evaluation caused by pyrethrin use in the Qinghai Plateau.

Effect of clarifying agent type and dose on the reduction of pyrethroid residues in apple juice

The widespread usage of pyrethroids in agriculture poses the risk of contamination in juice products. To easily mitigate this contamination, the common clarification process using clarifying agents was employed. In this study, the effects of clarifying agent types (bentonite, casein, gelatin, and polyvinylpolypyrrolidone (PVPP)) and doses (50, 150, 250, 500, and 750 mg/L) on pyrethroid removal from apple juice were investigated. The pyrethroid residues were quantified using magnetic solid-phase extraction and HPLC-PDA analysis. The order of increasing adsorbent effectiveness on pyrethroid reduction was: casein (0.33−51.44%) < bentonite (6.38−69.24%) < PVPP (17.74−73.78%) < gelatin (43.03−93.79%). Each clarifying agent has its optimum condition, and the optimal dose of gelatin at 500 mg/L was identified as the best treatment for removing pyrethroid residues from apple juice. The adsorption mechanisms of gelatin-pyrethroids were proposed based on the removal results and their structures. Furthermore, the effectiveness of all treatments was not influenced by single or mixed pyrethroid solutions, indicating no antagonistic or synergistic effects. This study provided practical and effective treatments for mitigating pyrethroid contamination in apple juice, which reduce the consumer's health risk from exposure to pyrethroids through food consumption.

HEALTH RISK ASSESSMENT OF PYRETHROID PESTICIDE RESIDUES IN PRODUCES AND SOILS IN A FARMLAND FROM ABEOKUTA, OGUN STATE, NIGERIA

Despite being useful in pest control, pyrethroids have been found to bioaccumulate in aquatic organisms and in human breast milk and research has shown that pyrethroids are neurotoxic, affect reproductive health and have ability to interfere with the immunological and endocrine systems, they also function as cancer precursors. This study sought to determine the amounts of pyrethroid residue in the soils and some of the most popular food crops, yam and cassava, in order to evaluate food safety using Gas chromatography Mass spectrometry (GC-MS). Cyfluthrin, alpha cypermethrin and beta cypermethrin are pyrethroids found in all the yams and cassava and soils analysed in this study and their values ranged from 9.98mg/kg to 14.45mg/kg in yam farm soil, 8.1mg/kg to 18.46mg/kg in yam samples, 10.25mg/kg to 14.94mg/kg in cassava samples and 6.13mg/kg to 30.6mg/kg in cassava farm soils. The pyrethroid with the highest residue levels in all the samples taken was beta cypermethrin. The health risk was assessed by calculating bioaccumulation factor and comparing Acceptable Daily Intake (ADI) with Food and Agricultural Organization (FAO) recommendations. Bioaccumulation factor of the foods analysed ranged from 0.49 (beta cypermethrin) to 1.68 (alpha cypermethrin) in cassava and 0.56 (cyfluthrin) and 1.07 (alpha cypermethrin) in yams. The pyrethroid residues discovered in the foods in this study exceeded the ADI of pesticides established by FAO, 0.02mg/kg per day; a significant health risk indication. Care should therefore be taken when using these pesticides and consumption of food exposed to pesticides should be discouraged.

A novel cold-adapted pyrethroid-degrading esterase from Bacillus subtilis J6 and its application for pyrethroid-residual alleviation in food matrix

Prolonged and widespread use of pyrethroid pesticides a significant concern for human health. The initial step in pyrethroid bioremediation involves the hydrolysis of ester-bond. In the present study, the esterase genes est10 and est13, derived from Bacillus subtilis, were successfully cloned and expressed in Escherichia coli. Recombinant Est10 and Est13 were classified within esterase families VII and XIII, respectively, both of which exhibited conserved G-X-G-X-G motifs. These enzymes demonstrated the capability to degrade pyrethroids, with Est13 exhibiting superior efficiency, and thus was selected for further investigation. The degradation products of β-cypermethrin by Est13 were identified as 3-phenoxybenzoic acid, 3-phenoxybenzaldehyde, and 3-(2,2-Dichloroethenyl)− 2,2-dimethyl-cyclopropanecarboxylate, with key catalytic triads comprising Ser93, Asp192, and His222. Notably, Est13 exhibited the highest β-cypermethrin-hydrolytic activity at 25 °C and a pH of 7.0, showing robust stability in low and medium temperature environment and a broad range of pH levels. Furthermore, Est13 displayed notable resistance to organic solvents and NaCl, coupled with wide substrate specificity. Moreover, Est13 exhibited substantial efficiency in removing β-cypermethrin residues from various food items such as milk, meat, vegetables, and fruits. These findings underscore the potential of Est13 for application in the bioremediation of pyrethroid-contaminated environments and reduction of pyrethroid residues in food products.

Residues of pyrethroids and triazoles pesticides in water and sediment of certain Egyptian watercourses: assessing their influence on fungal diversity

Contamination of water and sediment with pyrethroids and triazoles residues can affect fungal diversity, and hence the aquatic system functioning. The aim of the present study is to investigate the effect of water and sediment contamination with pyrethroids and triazoles on fungal diversity. Water and sediment samples were seasonally collected along 2019 from water bodies representing Gharbeya and Qualubeya governorates. Concentrations of pyrethroids and triazoles were determined, and fungal species in water and sediment samples were molecularly identified. The results indicated that temperature and pH varied according to the season. Permethrin, deltamethrin, lambda-cyhalothrin and esfenvalerate showed the highest pyrethroids concentrations, whereas tetraconazole, tebuconazole and difenconazole were of the highest triazoles concentrations. Aspergillus niger was one of the most frequent species, in addition to Trichoderma capillare, Fusarium oxysporum, Penicillium commune and Penicillium polonicum. Principal component analysis indicated a positive correlation between temperature and different Aspergillus spp., and between pH and each of pyrethroids and triazoles. Moreover, a negative correlation was observed between triazoles and Trichoderma asperellum, Penicillium griseofulvum and Aspergillus fumigatus. In conclusion, contamination of water with pesticides affected fungal diversity. This disturbance in fungal assemblages might result in a reduction of some key organisms, or an increase and emergence of new pathogens.

Magnetic effervescence-assisted switchable solvent dispersive liquid-liquid microextraction for the determination of pyrethroids in edible fungi

A simple, rapid, effective, and environmental friendly analytical procedure for determining three pyrethroids (tetramethrin, lambda-cyhalothrin and fenvalerate) in edible fungi was developed by high-performance liquid chromatography-diode array detection after magnetic effervescence-assisted switchable solvent dispersive liquid-liquid microextraction (MEA-SHS-DLLME). In the extraction procedure, hexanoic acid and carbon dioxide were used as the extraction and dispersion solvents. The magnetic Fe3O4 @ graphene with large specific surface area were used to adsorb the extraction solvent and the target analytes. The optimized conditions were as follows: sodium hexanoate 45 mg, citric acid 90 mg, sodium bicarbonate 60 mg, Fe3O4 @ graphene mixing ratio 1:6, and dosage of Fe3O4 @ graphene 25 mg. Under these conditions, accuracy and precision were demonstrated at the concentration range of 1.25-125 mg/kg, and the correlation coefficients were between 0.9903-0.9998. The limits of detection and quantification were 0.0067-0.0329 mg/kg and 0.0224-0.1096 mg/kg, and the extraction recovery was 81.0-97.4% with relative standard deviations < 5.1%. The technique had been successfully proven to be valuable for the ultrasensitive detection of tetramethrin, lambda-cyhalothrin and fenvalerate in 5 kinds of edible fungi, and only magnetic effervescent tablets containing switchable solvent were needed without dispersing solvent, centrifugation, and complex instruments. Moreover, the extraction recovery was better than other reported methods. This novel approach has a favorable potential to be applied for detection of pyrethroid residues in other samples.

Molecular imprinted polymer capped luminescent metal -organic framework for the determination of pyrethroids and its metabolite

Monitoring the pyrethroids and its metabolite is of importance to estimate the potential risk of human exposure. Herein, a lanthanide luminescent metal of framework (Ln-MOF) was employed to construct fluorescent molecular imprinted polymer probe for the detection of pyrethroids metabolite, 3-phenoxybenzaldehyde (3-PBALD). Through a typical sol–gel imprinting process, the imprinted layer capped Ln-MOFs exhibited specific fluorescence quenching at 615 nm upon adding 3-PBALD. Under the optimum condition, a linear relationship was obtained in the range from 0.01 to 5 μg mL−1 and the limit of detection was 8 ng mL−1, which is superior to bare Ln-MOFs. In addition, the obtained probe showed good stability and repeatability as well as anti-interference. Furthermore, coupling with esterase hydrolysis strategy, the proposed fluorescent probe can be extended for the determination of various synthetic pyrethroids. In spiked apple and spinach samples, the recoveries ranged from 80.2% ∼116.7% and 80.8% ∼113.2%, respectively. Therefore, this fluorescent molecular imprinted polymer probe has potential for a broad-spectrum pyrethroids residue screening.

Urinary Cypermethrin Metabolites among Conventional and Organic Farmers in Thailand.

Cypermethrin, a pyrethroid insecticide, is frequently spread on agricultural farmlands and is also used in households in Thailand. Conventional pesticide-using farmers (n = 209) were recruited from the Phitsanulok and Nakornsawan provinces. Certified organic farmers (n = 224) were also recruited in the Yasothorn province. The farmers were interviewed via a questionnaire and the urine from their first morning void was collected. The urine samples were analyzed for 3-phenoxybenzoic acid (3-PBA), cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA), and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA). The results showed no significant difference in the urinary cypermethrin metabolites between the conventional farmers and the organic farmers, for whom the usage of cypermethrin was not accounted for. However, when conventional farmers who used cypermethrin on the farm and in the home were compared with conventional farmers who did not use any cypermethrin or with organic farmers, a significant difference was noted for all metabolites except for trans-DCCA. These findings show that the most significant exposures to cypermethrin are among conventional farmers who use the insecticide on their farms or in their homes. However, measurable levels of all metabolites were found among both conventional and organic farmers who only used cypermethrin in the home or not at all, suggesting that the at-home use of pyrethroids and other possible exposures from pyrethroid residues on market-bought food may contribute to urinary levels of pyrethroids that exceed those of the general population in the US and Canada.

Pyrethroid residues in Indonesian river Citarum: A simple analytical method applied for an ecological and human health risk assessment

Pyrethroid residues in the Citarum River, Indonesia, was first investigated based on their occurrences, water assimilative capacity, and risk assessment. In this paper, first, a relatively simple and efficient method was built and validated for analysis of seven pyrethroids in a river water matrix: bifenthrin, fenpropathrin, permethrin, β-cyfluthrin, cypermethrin, fenvalerate, and deltamethrin. Next, the validated method was used to analyze pyrethroids in the Citarum River. Three pyrethroids, β-cyfluthrin, cypermethrin, and deltamethrin, were detected in some sampling points with concentration up to 0.01 mg/L. Water assimilative capacity evaluation shows that β-cyfluthrin and deltamethrin pollution exceed the Citarum river water capacity. However, due to hydrophobicity properties of pyrethroids, removal through binding to sediments are expected. Ecotoxicity risk assessment shows that β-cyfluthrin, cypermethrin and deltamethrin pose risks to the aquatic organisms in the Citarum River and its tributaries through bioaccumulation in food chain. Based on bioconcentration factors of the detected pyrethroids, β-cyfluthrin poses the highest adverse effect to humans while cypermethrin is the safest. Human risk assessment based on hazard index suggests that acute non-carcinogenic risk associated to consuming fish from the study location polluted with β-cyfluthrin, cypermethrin and deltamethrin is unlikely. However, hazard quotient shows that chronic non-carcinogenic risk associated to consuming fish from the study location polluted with β-cyfluthrin is likely. However, since the risk assessment was performed separately for each pyrethroid, further assessment on the impact of mixture pyrethroid to aquatic organisms and humans should be performed to explore the real impact of pyrethroids to the river system.

Heterosis and reselection for pyrethroid resistance trait maintenance in the lady beetle Eriopis connexa (Germar)

AbstractExposure of Eriopis connexa (Germar) to pyrethroid residues in agroecosystems has resulted in selection for resistance (R). Pyrethroid resistance allows E. connexa to survive lambda‐cyhalothrin applications. Following a field release of E. connexa, development of resistance in an incipient population may depend on three major factors such as the maintenance of: (i) selection pressure, (ii) frequency of mating with susceptible phenotypes (S) and (iii) differential reproductive performance due to the fitness costs associated with resistance. To investigate the potential effects of these three factors on the development of pyrethroid resistance by progeny of field released E. connexa, our experiments included panmictic mating between R and S phenotypes, followed by descendant rearing with and without insecticide selection pressure, reselection and determination of resistance levels. In addition, we measured the reproductive performance of the parental R and S phenotypes and their descendants to assess the cost of resistance after crossing and reselection. Survival of R × S descendants exposed to lambda‐cyhalothrin was reduced across successive generations in the absence of selection pressure, but still enhanced after four generations indicating the persistent presence of resistant phenotypes in the population. Under selection pressure with exposure to lambda‐cyhalothrin applied at label rates, descendant survival was &gt;50%. Fecundity and survival were higher in the first‐generation of crossed R × S females, but higher fecundity was not sustained after reselection. Adults of the R population exhibited a fitness cost, reduced longevity, when compared to S phenotypes and R × S crossed populations. Therefore, resistance maintenance in E. connexa after release will depend on selection pressures imposed by insecticide exposure. In the absence of selection pressure, the phenotype for resistance was reduced, but not completely lost. Further, resistant phenotypes can be reselected following insecticide exposure and this can explain, in part, the high frequency of field‐evolved resistance to lambda‐cyhalothrin in E. connexa.

Multiscale Deepspectra Network: Detection of Pyrethroid Pesticide Residues on the Hami Melon.

The problem of pyrethroid residues has become a topical issue, posing a potential food safety concern. Pyrethroid pesticides are widely used to prevent and combat pests in Hami melon cultivation. Due to its high sensitivity and accuracy, gas chromatography (GC) is used most frequently for detecting pyrethroid pesticide residues. However, GC has a high cost and complex operation. This study proposed a deep-learning approach based on the one-dimensional convolutional neural network (1D-CNN), named Deepspectra network, to detect pesticide residues on the Hami melon based on visible/near-infrared (380-1140 nm) spectroscopy. Three combinations of convolution kernels were compared in the single-scale Deepspectra network. The convolution group of "5 × 1" and "3 × 1" kernels obtained a better overall performance. The multiscale Deepspectra network was compared to three single-scale Deepspectra networks on the preprocessing spectral data and obtained better results. The coefficient of determination (R2) for lambda-cyhalothrin and beta-cypermethrin was 0.758 and 0.835, respectively. The residual predictive deviation (RPD) for lambda-cyhalothrin and beta-cypermethrin was 2.033 and 2.460, respectively. The Deepspectra networks were compared with two conventional regression models: partial least square regression (PLSR) and support vector regression (SVR). The results showed that the multiscale Deepspectra network outperformed the other models. It was found that the multiscale Deepspectra network could be a novel approach for the quantitative estimation of pyrethroid pesticide residues on the Hami melon. These findings can also provide an effective strategy for spectral analysis.

Enhancement degradation efficiency of pyrethroid-degrading esterase (Est816) through rational design and its application in bioremediation

The pervasive use of pyrethroids is seriously hazardous to the environment and even human health. Enzymatic bioremediation is potentially a rapid and environmentally friendly technology to combat the pollution of pyrethroid pesticides. The hydrolysis of ester linkages is the initial and critical enzymatic step in microbial degradation pathways. Here, the versatile and thermostable esterase Est816 was cloned and its new function, pyrethroid-hydrolysis activity, was expanded. To further improve its pyrethroid-hydrolysis ability, Est816 was modified by rational design. After two rounds of mutation, the best-performing mutant, Est816A216V/K238N/M97V, was obtained, which could completely degrade 1 mg/L λ-cyhalothrin, cypermethrin, and deltamethrin within 20 min, and efficiently degrade fenvalerate, reaching over 80% conversion. Degradation activity analyses showed that three substitutions (A216V, K238 N and M97V) were beneficial for enhancing the activity of Est816. Enzymatic characterization showed that Est816A216V/K238N/M97V inherited broad substrate specificity and possessed excellent stability and adaptability over wide ranges of temperature and pH, which is essential for bioremediation in frequently changing conditions. Furthermore, Est816A216V/K238N/M97V had the best degradation effect on all four pyrethroid residues in Panax notoginseng root, with more than 87% conversion after 24 h. Pyrethroid residues in tea, cucumber, and soil were reduced by more than 76%, 80%, and 76%, respectively. Taken together, these findings highlight the great potential of Est816A216V/K238N/M97V in the bioremediation of pyrethroid-contaminated soil and agricultural products.

Cyclodextrin-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplets coupled with HPLC for the determination of pyrethroid residues in cereals

AbstractA simple, rapid, and environmentally friendly sample preparation method for pyrethroids determination in cereals using cyclodextrin-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplets coupled with high-performance liquid chromatography was established. The cereal samples were extracted with acetonitrile, cleaned up, and concentrated by green extractant menthol via γ-cyclodextrin assisted extraction process. The extractant menthol dispersed as fine droplets in the cyclodextrin solution and then solidified at room temperature for efficient extraction and convenient collection. The optimized method provided good linearity in the range of 0.01–10 mg kg−1 with limits of detection of 3.5–9.5 μg kg−1. The fortified recoveries of three pyrethroids (i.e., lambda-cyhalothrin, deltamethrin, and bifenthrin) in four cereals (i.e., rice, wheat, maize, and millet) at three levels were in the range of 77.6–101.6% with relative standard deviations of 0.6–6.6%. Overall, the proposed method can be successfully applied for the determination of pyrethroids in cereals.

Organophosphate Pesticides and Pyrethroids in Farmland of the Pearl River Delta, China: Regional Residue, Distributions and Risks.

A regional-scale survey was conducted to assess the occurrence, distribution, and risk of two extensively used pesticides (organophosphate pesticides and pyrethroids) in agricultural soils from the Pearl River Delta (PRD), South China. All target organophosphate pesticides (OPPs) and pyrethroids (PYs) were detected in the soil samples and both with a detection rate of 100%. The residues of the sum of six OPPs and the sum of four PYs were in the range of LOD-991 ng/g and 8.76-2810 ng/g, respectively. Dimethoate was the dominant OPPs, and fenpropathrin was the predominant PYs in the soils of the PRD region. With intensive agricultural activities, higher residues of OPPs and PYs in soils were detected closer to the seaside, among which Zhuhai city and Huizhou city suffered more serious combined pesticide pollution. The vertical compositional profiles showed that dimethoate could be detected through each soil layer in the PRD region's nine cities. The human exposure estimation of OPPs showed insignificant risks to the local population. In contrast, cypermethrin and fenpropathrin showed a potential ecological risk of 2.5% and 3.75% of the sampling sites, respectively. These results can facilitate those commonly used pesticide controls and promote sustainable soil management.

Expression, characterization, and immobilization of a novel SGNH esterase Est882 and its potential for pyrethroid degradation.

The widely-used pyrethroid pesticides have attracted public attention because of their potentials to cause environmental pollution and toxic effects on non-target organisms. Esterase is a kind of hydrolytic enzyme that can catalyze the cleavage or formation of ester bonds. it plays a pivotal role in the decomposition of pyrethroids and esters containing industrial pollutants through the hydrolysis of ester bonds. Here, a new esterase gene est882 was successfully screened, which encodes Est882, a SGNH family esterase composed of 294 amino acids. It was heterogeneously expressed, identified and immobilized. Multiple sequence alignment showed that Est882 had a typical GDS(X) conserved motif and a catalytic triad composed of Ser79, Asp269 and His275. Phylogenetic analysis showed that Est882 shall belong to a new esterase family. Biochemical characterization demonstrated that the optimum condition was 40°C and pH 9.0. Est882 immobilization was studied with mesoporous silica SBA-15 as the carrier and found to significantly improve the tolerance and stability of Est882. Its optimum pH increased to 10.0 and stabilized within pH 8.0-11.0. Free Est882 can effectively degrade various pyrethroids within 30 min, with a degradation rate above 80%. The immobilized Est882 yet degraded more than 70% of pyrethroids within 30 min. The present study indicated that Est882 has outstanding potential in bioremediation of a pyrethroid-polluted environment. These characteristics endow Est882 with potential values in various industrial applications and hydrolysis of pyrethroid residues.

Pyrethroids contamination and health risk assessment in seafood collected from the coast of Shandong, China

This study provides the first data on pyrethroid residues of seafood in China. A total of 192 seafood samples were randomly selected from four coastal cities of Shandong Province in 2020. The residues of fenpropathrin, cypermethrin and deltamethrin in seafood by GC–MS were ND to 26.82 μg/kg, ND to 19.18 μg/kg and ND to 15.56 μg/kg, respectively. The cumulative risk to general population of different age groups was assessed by the hazard quotient (HQ) and hazard index (HI) approaches, and showed that the maximum value of both HQ (1.81 × 10−3) and HI (2.9 × 10−3) were below the threshold 1. The present results indicated that the three main pyrethroids from the consumption of seafood is unlikely to pose a health risk to general populations in Shandong. The uncertainty analysis indicated that the monitoring study of pyrethroid residues in seafood is worthy of continuous attention to ensure food safety.