Risk assessment of airborne agricultural pesticide exposure in humans in rural China.

Continuous exposure to airborne pesticides causes their gradual accumulation in the human body, eventually posing a threat to human health. To the best of our knowledge, risk assessment study of pesticide non-occupational exposure to residents in agricultural areas has not been conducted in China. In this study, air samples (gas and dust) were collected from inside and outside residences of seven households and an area near the field in a grain-growing area (wheat and maize rotation) for eight months, and the pesticides present were examined both qualitatively and quantitatively. Using a 95% confidence interval, 9 out of 16 pesticides were detected, namely acetamiprid, acetochlor, atrazine, flucarbazone-sodium, imidacloprid, methyldisulfuron-methyl, nicosulfuron-methyl, pendimethalin, and beta-cyhalothrin, and their safety was subsequently evaluated. The results showed that the inhalation exposure of households to beta-cyhalothrin exceeded the acceptable range in the first residential, and the excess lifetime cancer risk of acetochlor inhalation exposure in six households and area around the field exceeds 1E-6, which highlights the need to strengthen preventive screening for cancer risk.

Risk assessment of human exposure to airborne pesticides in rural greenhouses.

In comparison to an open field, greenhouses utilize much more pesticides. The non-occupational exposure risk caused by pesticide drift is unknown. In this study, within 8 months (from March 2018 to October 2018), air samples were collected from indoor and outdoor houses and public areas near greenhouses in vegetable growing areas (eggplant, leek, garlic, etc.), and qualitative and quantitative analyses of pesticides were carried out. Using a 95% confidence interval, six pesticides (acetamiprid, difenoconazole, thiazophos, isoprocarb, malathion, and pyridaben) were detected. The results of the safety assessment showed that the non-cancer exposure risk of single pesticides for all residents in the agricultural areas was within the acceptable range, and the excess lifetime cancer risk of all residents inhaling difenoconazole exceeded 1E-6, and the agricultural region urgently needs increased cancer regulatory scrutiny. But combined toxicity of six pesticides not evaluated due to lack of suitable data. Comparison with open field scenes, the results show that pesticide levels to airborne are lower in greenhouse regions.

Toward Stable Al Negative Electrodes of Aluminum-Ion Batteries: Kinetic Parameters and Electrode Structure.

Rechargeable aluminum-ion batteries have attracted significant attention as candidates for next-generation energy storage devices owing to their high theoretical capacity, safe performance, and abundance of raw materials. Al metal is the best option as the negative electrode, while its issues such as dendrite growth and corrosion accompanying hydrogen evolution in ionic liquid electrolyte have been seriously overlooked. Understanding the electrochemical mechanism of the surface evolution behavior of Al metal is a vital pathway for solving these issues. Kinetic parameters and electrode structure are the two key parameters that affect the surface evolution behavior of Al negative electrodes. Herein, the qualitative relationship between the kinetic parameters and surface evolution behavior of the Al negative electrode was established through a combination of in-situ optical technology and multi-physical field numerical simulation method. The key kinetic parameters, including ion concentration and transfer coefficient, exhibited different laws of influence on the surface evolution behavior, such as dendrite growth and corrosion. The electrochemical mechanism on the surface evolution was explored to guide the optimization design of Al-ion batteries. Based on the coupling design of the electrode structure and kinetic parameters, a highly stable porous aluminum structure composed of Al powder with a particle size of 100 µm was constructed to obtain highly stable and high-performance aluminum-ion batteries. This method provides new sight into the design of high-performance aluminum-ion batteries.

Influence of the neonicotinoid insecticide thiamethoxam on soil bacterial community composition and metabolic function.

Understanding of neonicotinoid insecticides toxicity on non-target organisms, such as bees, has indirectly promoted their soil treatment use. However, their effect on soil ecosystems haven't fully understood. Here, based on 16S rRNA high-throughput sequencing and metagenomics, the effects of neonicotinoid insecticide thiamethoxam on bacterial communities and metabolic functions in two types of soils were studied. Thiamethoxam treatment significantly affected soil bacterial abundance, reduced microbial diversity, and changed the bacterial community structure in the short term, and the structure soon returned to a stable state. Soil type and time were important factors affecting bacterial community structure. Some plant growth-promoting rhizosphere bacteria (PGPR) including Actinobacteria were found, and their populations were reduced, while pollutant-degrading bacteria including Firmicutes were also found, and their populations were increased. Based on metagenomics analysis, thiamethoxam treatment insignificantly promoted or inhibited multiple metabolic processes, but gene abundance of some key processes significantly changed. Subtypes of 18 biodegradation genes (BDGs) and 5 pesticide degradation genes (PDGs) were identified. Thiamethoxam treatment significantly increased the abundance of BDGs and PDGs, including cytochrome P450. Potential hosts of P450 degradation genes, including the genus Rhodococcus, were discovered. Conclusions of this study will promote safety evaluation and degradation-related research on neonicotinoid insecticides in soil.

Spatial and temporal distribution, degradation, and metabolism of three neonicotinoid insecticides on different parts, especially pests' target feeding parts of apple tree.

BACKGROUND: Neonicotinoid insecticides (NIs) have been recently banned in some countries because of increased pest resistance and deleterious risks to non-target organisms. Recent studies considered all parts of crops as a whole part in plant protection. However, there are few reports focused on the distribution and metabolic trends of NIs on target feeding sites of different pests in apple orchards. RESULTS: The spatial and temporal distribution, absorption, degradation, and metabolism of three NIs, imidacloprid, acetamiprid, and thiamethoxam, on different parts of apple trees were studied under foliar spray and root irrigation treatments. In the spray treatment, the initial average concentration ratios (TCRs) were 31.6% for lower shoots, 23.3% for upper leaves, 23.2% for upper shoots, 21.0% for lower leaves, and 0.5% and 0.4% for upper and lower fruits, respectively. The average half-lives of the three NIs were 2.9 days for shoots, 7.4 days for leaves, and 10.8 days for fruits. The degradation rate of shoots was 2.5 times that of leaves, and 3.6 times that of fruits. Imidacloprid olefin and N-methyl acetamiprid were two of the main metabolites. In the root treatment, both roots and soils had high TCRs during the whole sampling period. Only imidacloprid was transmitted to above-ground parts of the plants, with TCRs of 0.38-50.94%. CONCLUSION: This study found significant differences in spatial and temporal distribution, degradation, metabolism, and trends of NIs on different pest target sites of apple trees. The data obtained may help promote scientific control of target pests and evaluation of safety for non-target species in orchards. © 2020 Society of Chemical Industry.

Isotope-labeled internal standards and grouping scheme for determination of neonicotinoid insecticides and their metabolites in fruits, vegetables and cereals - A compensation of matrix effects.

Neonicotinoid insecticides (NIs) are widely used. However they produce high levels of residues and are toxic to non-target organisms, especially when their metabolites exhibit comparable or elevated toxicities. In this study, we established a multi-residue analytical method for analyzing 20 compounds - 8 NIs and their 11 major toxic metabolites. QuEChERS pretreatment and ultra-high-performance liquid chromatography-tandem mass spectrometry were used to detect residues in fruits, vegetables and cereals. Determination time was shortened to 6 min. Average recoveries of all compounds were in the range of 90.1-105.5%, with relative standard deviations lower than 15.0% and the limit of quantitation being 10 µg kg-1. For the first time, 8 NIs and 11 major toxic metabolites were grouped simultaneously, such that the matrix effect of analytes was satisfactorily corrected using their own isotopically labeled molecules; other NIs and metabolites in the same group were also corrected. This is the first report that simultaneously quantified multiple metabolites of eight NIs in multiple matrices.

Distribution, Dissipation, and Metabolism of Neonicotinoid Insecticides in the Cotton Ecosystem under Foliar Spray and Root Irrigation.

The uptake, distribution, metabolism, and degradation of three neonicotinoid insecticides (NIs)-imidacloprid (IMI), acetamiprid (ACE), and thiamethoxam (THI) in different parts of cotton plants were investigated under field conditions. Insecticides were either applied by foliar spraying or root irrigation. Foliar application resulted in high tissue concentration (average tissue concentration ratio, TCR: 46.78-68.61% for leaves and 12.2-31.40% for flowers). The flowers showed high NI residual. The metabolism and trends of NIs in different parts of cotton were reported here for the first time. Metabolites, toxic to bees, were detected in the flowers. The translocation factor was around 0.004 for the spray treatment and 0.2-0.7 for the root irrigation treatment. The average root concentration factors of IMI, ACE, and THI were 0.838, 8.027, and 1.014, respectively, indicating that the three NIs can be transported from the soil to the plant. The high concentrations of NIs and their metabolites in flowers indicate exposure risk to pollinators, such as bees.

Modeling of the Phytophthora capsici cellulose synthase 3 and its inhibitors activity assay.

BACKGROUND: Phytophthora capsici is a devastating pathogen for crop. Cellulose synthase 3 (CesA3) is a target for many potential fungicides such as valinamide derivatives. However, the 3-dimensional structure (3-DS) of CesA3 in Phytophthora capsici was still unknown. RESULTS: Here CesA3 protein sequence was retrieved from the NCBI protein sequence database We did the 3-DS structural modeling for CesA3 and used molecular dynamics to optimize the model. The model was further validated by the Ramachandran plot in PROCHECK program. Two series of new valinamide compound were synthesized and tested for its biological activity. The docking data obtained by the model perfectly matched with the biometric data, indicating that the model is valid. Moreover, docking study data revealed the mechanism of action of inhibitors on target enzymes. CONCLUSION: The 3-DS structural model was analyzed from the perspective of the biocide receptor, the structure of the target protein and the mechanism of action of the compound. It provides a new perspective for the design of new fungicides. © 2019 Society of Chemical Industry.

Synthesis and bioactivity studies of sex pheromone analogs of the diamond back moth, Plutella xylostella.

BACKGROUND: Diamondback moth, Plutella xylostella L., is a very important pest of cruciferous vegetables causing excessive economic losses worldwide. Bioactivities of halo-, diazo-, and cyclopropane acetates of P. xylostella sex pheromone have been evaluated using electrophysiology and enzyme inhibition assays. RESULTS: A total of 23 sex pheromone analogs of P. xylostella were designed and synthesized and the result shows that (11Z)-hexadec-11-en-1-yl 2,2,2-trifluoroacetate, (11Z)-hexadec-11-en-1-yl 2,2,3,3,3-pentafluoropropanoate, and (11Z)-hexadec-11-en-1-yl trifluoromethanesulfonate elicited potential inhibitory effects at all doses tested in the electrophysiology and enzyme inhibition assays. Interference of locating the sex pheromone source was found strongest when these three analogs were mixed with the sex pheromone at a 10:1 ratio. In addition, field test showed that the rate of mating disruption was over 90% when (11Z)-hexadec-11-en-1-yl 2,2,2-trifluoroacetate or (11Z)-hexadec-11-en-1-yl 2,2,3,3,3-pentafluoropropanoate was mixed with the sex pheromone at a 10:1 ratio. CONCLUSION: Two sex pheromone antagonists were screen out by electrophysiology, enzyme inhibition assays, wind tunnel and field tests. We believe that these antagonists could be used to establish a novel eco-friendly measure to control P. xylostella and provide evidence for clarifying the specific functions and molecular mechanisms of sex pheromone antagonists. © 2018 Society of Chemical Industry.

Effect of spraying direction on the exposure to handlers with hand-pumped knapsack sprayer in maize field.

Only less than one percent applied pesticides reach the target pest, the remainder spread out into the environment, effecting on workers, bystanders, consumers and so on. Handlers with manual knapsack sprayer are completely exposed to the pesticide spray plume when they deal with the pesticides. Those kinds of sprayer are widely used in developing countries, more than 75% of farmers using hand-pumped knapsack sprayer in China, yet rarely systematic studies had been focused on the typical applying scenario. The occupational exposure of pesticide is highly correlated with the pesticide spray plume flying time in the air in this scenario. Our study aimed to compare the estimated exposure level of handlers to chlorpyrifos sprayed at three spraying direction using a lever-operated knapsack in small farms in five agro-climatic zones of China. Experiments were performed by 24 farms in each province with three different crop heights (< 80 cm, spraying downward; 80-130 cm, spraying horizontal; and > 130 cm, spraying upward; eight farms for every direction) under typical field conditions. Each farmer covered a uniform area of 667 m2. The whole body dosimetry method and a personal air sampler were used to monitor the dermal and inhalation exposure. The estimated dermal exposure of the three spraying direction was 629, 1580, and 2140 mg/kg, respectively. The results showed that the total dermal exposure level increased with the spraying direction from downward to upward. Furthermore, appropriate cotton coveralls could reduce more than 90% of the total dermal exposure.

Male-Produced Aggregation Pheromone of Coffee Bean Weevil, Araecerus fasciculatus.

The coffee bean weevil (CBW), Araecerus fasciculatus (De Geer, 1775), is a cosmopolitan stored-product pest, especially in tropical and subtropical areas. Previous reports showed evidence for aggregation behavior of CBW and this study aimed to identify and evaluate the aggregation pheromone of this pest. Whole-body solvent extractions were analyzed by coupled gas chromatography-mass spectrometry and comparison of male and female extracts showed a male-specific compound which was identified as squalene, 2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene. This compound was shown to attract male and female CBW in Y-tube olfactometer and storage trap assays. The longevity of septum lures was also evaluated in a warehouse. Squalene could be useful in monitoring and controlling this pest.

Potential exposure to clothianidin and risk assessment of manual users of treated soil.

BACKGROUND: Treated soil is the second most prevalent application technique for all registered pesticides in China. Some developing countries also adopt this method. However, the safety of this scenario has not been reported in the literature. Experiments were therefore conducted to assess exposure using standard whole-body dosimetry and air sampling methodologies. RESULTS: Dermal deposition was the main route of exposure in this scenario. The total dermal unit exposure (UE) of operators to clothianidin-treated soil was 51.7 mg kg-1 AI handled (SD = 20.59, n = 16), and hands accounted for 36%. Inhalation UE was 0.04 mg kg-1 AI handled (SD = 0.02, n = 4), negligible compared with dermal exposure. Using an NOAEL (no observed adverse effect level) of 10 mg kg-1 day-1 , the margin of exposure was 773, i.e. greater than 100. CONCLUSION: For the first time, the scenario of treated soil exposure was assessed and was found to pose less risk than conventional pesticide application. These results can be used as a reference in pesticide management. © 2017 Society of Chemical Industry.

Attraction of Coffee Bean Weevil, Araecerus fasciculatus, to Volatiles from the Industrial Yeast Kluyveromyces lactis.

The coffee bean weevil (CBW), Araecerus fasciculatus (De Geer, 1775) (Coleoptera: Anthribidae) is an important pest of stored products such as grains, coffee beans, cassava, and traditional Chinese medicine materials. In China, CBW causes large losses of Daqu, a traditional Chinese liquor fermentation starter, and, unfortunately, the use of conventional insecticides against CBW is not suitable in Daqu storage. We found CBW to be highly attracted to fermenting yeast cultures, such as Kluyveromyces lactis. Eight volatile compounds, produced by fermenting cultures and not by sterile samples, were identified by gas chromatography coupled with mass spectrometry. Five of these substances elicited significant responses in Y-tube behavioral bioassays. Field trapping experiments revealed 2-phenylethanol and 2-phenylethyl acetate to be crucial for attraction of CBW. Results show that yeast volatiles play an important role in host location, and that 2-phenylethanol and 2-phenylethyl acetate could be utilized as potential attractants in monitoring and control systems against this important pest.

Synthesis of Isotopically Labeled (13)C3-Simazine and Development of a Simultaneous UPLC-MS/MS Method for the Analysis of Simazine in Soil.

The isotope dilution mass spectrometry (IDMS) is a highly efficient method for tackling the ion suppression in complex matrix by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), but a lack of commercial internal standards is a limiting factor for these analyses. Herein, an economical and efficient strategy for the synthesis of (13)C3-simazine via a three-step procedure was developed. The isotope-labeled internal standard was used for determination of simazine residue in soil samples. The quantitation method has a limit of detection of 0.015 µg/kg and quantitation of 0.08 µg/kg. The inter-day and intra-day precision of the method were below 4.6%. Recovery values were ranged between 92.9% and 99.2%. All the samples obtained from six provinces in China contained from 1 to 62 µg/kg of simazine.

Synthesis and biological activity of novel benzimidazole derivatives as potential antifungal agents.

In the present study, a series of novel benzimidazole derivatives containing chrysanthemum acid moieties was designed and synthesized. Preliminary investigation of biological activity indicated that all of the compounds exhibited lower activity than that of beta-cypermethrin against Plutella xylostella and Lipaphis erysimi; meanwhile, they showed good inhibitory activity against Botrytis cinerea and Sclerotinia sclerotiorum in vitro. The fungicidal activity of compound 8a against B. cinerea was approximately equal to that of thiabendazole and was twice as active against S. sclerotiorum as was thiabendazole. In addition, compound 9e displayed the most potent inhibitory activity against both fungi and was almost twice as potent as thiabendazole.

Measurement of operator exposure to chlorpyrifos.

BACKGROUND: To date, no research has been conducted to establish exposure levels for occupational pesticide operators under typical use scenarios in China. Through surrogate skin techniques (the whole-body method), the authors monitored dermal and inhalation exposure of pesticide applicators in China. In addition, the exposure of pesticide mixers was analysed. RESULTS: The total dermal exposure of inexperienced and experienced applicators was respectively 4037 and 536 mg kg(-1) of active ingredient (AI) handled for application to maize that was <80 cm in height. The exposure level was highest on hands; the closer to the hands, the lower arms and the upper legs, the higher the exposure. The unit exposure of mixers differed according to the formulation; exposure to emulsifiable concentrate (EC) and oil-in-water emulsion (EW) was greater than exposure to wettable powder (WP) or wettable dispersible granules (WG). The unit exposure of mixers via inhalation was significantly greater than that of applicators when chlorpyrifos (48% EC) was used (P < 0.0001). CONCLUSIONS: The main objectives of this study were to provide an indication of the realistic exposure risk of mixers and applicators, and to contribute useful information for risk mitigation and management and epidemiological studies in China.

Synthesis of C-13-labeled atrazine.

Atrazine is a long-lasting herbicide that has been shown to affect hormone levels in amphibians. Using the C-13 labeled atrazine to detect its residue is effective and essential. This study presents three steps for the synthesis of [(13) C3 ]atrazine, which starts from [(13) C]urea, and results in the incorporation of C-13 atoms at the 1, 3 and 5 positions of the S-triazine ring of atrazine. The method prepares the product in an overall yield of 57.6% and chemical purity of 98.6%, for use as an internal standard.

Liquid-phase synthesis of cyanuric acid from urea.

The focus of this paper was to identify a cheaper solvent from among diesel fuel, kerosene, sulfolane or a mixture of sulfolane and cyclohexanol for the preparation of cyanuric acid heterocyclization of urea. To obtain a higher yield, the effects of catalyst (sodium, ammonium, calcium and zinc salts) and temperature (160 degrees C to 220 degrees C) on the trimerization of urea were also carefully studied. We established the optimal reaction conditions and further validated them in our scale-up experiments.

New flavonoid glycosides from Elsholtzia rugulosa Hemsl.

Elsholtzia rugulosa Hemsl. is known in China as a local herbal tea, medicinal herb and honey plant. Chemical examination of E. rugulosa led to the isolation of two new flavonoid glycosides, apigenin 4'-O-alpha-D-glucopyranoside (1) and 5,7,3',4'-tetrahydroxy-5'-C-prenylflavone-7-O-beta-D-glucopyranoside (2), together with nine known flavonoids. Their structures were elucidated on the basis of spectroscopic evidence.