Dissipation, occurrence, and risk assessment of 12 pesticides in Dendrobium officinale Kimura et Migo

Occurrence, dissipation and processing factors of multi-pesticides in goji berry

As medicine and food homology substance, goji berry is consumed worldwide in the form of fresh, dried and juice; however, pesticide residues have become one of the problems that essentially threaten its quality during cultivation and processing. In this study, a total of 75 dried goji berries were sampled from markets across China, and for the determination of 62 analytes, 28 pesticides were identified. Nine pesticides with high detectable rates and residual levels were selected for folia spraying, and their half-lives were found to range from 1.04 to 2.21 d. The processing factors (PFs) of juice were between 0.25 and 1.02, and this was mainly related with their octanol-water partition coefficient (logKow values). Washing could reduce pesticides residues to varying degrees with the removal rates between 17.00% and 74.05%. Sun drying with higher PF values in the range of 0.61-5.91 exhibited more obvious enrichment effect compared to oven drying. Commercial goji berry had cumulative chronic dietary risks with the hazard index (HI) values of 1.61%-4.97%. Its acute risk quotients (HQas) for consumers were 543.32%-585.92% and were mainly due to insecticides. These results provide important references for rationalizing pesticide application during goji berry cultivation and for the improvement of process to ensure food safety.

Occurrence and health risk of pesticide residues in Chinese herbal medicines from Shandong Province, China

Pesticide residue was one of the stress factors affecting quality and safety of Chinese herbal medicines (CHMs). The present study was designed to investigate the occurrence and dietary exposure of 70 pesticide residues in 307 samples of CHMs, including 104 American ginseng, 100 Ganoderma lucidum (G. lucidum), and 103 Dendrobium officinale (D. officinale) in Shandong Province, China. The study revealed that a total of 29 pesticides were detected in the majority (92.5%) of samples, and the pesticide residues of 85 (27.7%) samples exceeded the maximum residue levels (MRLs). Particularly, the maximum concentration of chlorpyrifos was 23.8 mg kg-1, almost 50 times of the MRLs in food in GB 2763-2021, while there's no standard restrictions specified in CHMs in China. The chronic, acute, and cumulative risk assessment results indicated that risk exposure of the three types of CHMs were unlikely to pose a health risk to consumers. However, more attention should be paid to the multiple residues with the presence of four or more pesticides in one sample and high over-standard rate of pesticides. The pesticide users and the government should pay more attention to the pesticides used in CHMs and regularly monitor the presence of these compounds. The study recommended the MRLs of these pesticides in CHMs should be established and perfected by the relevant departments in China.

Natural product osthole can significantly disrupt cell wall integrity and dynamic balance of Fusarium oxysporum

Dendrobium officinale Kimura et Migo is a traditional Chinese herbal medicinal plant. However, the frequent occurrence of soft rot disease (SRD) is one of the most harmful diseases in D. officinale production in recent years, which can seriously affect its yield and quality. In this study, the major pathogenic fungus (SR-1) was isolated from D. officinale with typical symptoms of SRD, and was identified as Fusarium oxysporum through morphological and molecular identification. The biological activities of five natural products were determined against F. oxysporum using a mycelial growth inhibition assay. The results showed that osthole had the highest antifungal activity against F. oxysporum, with an EC50 value of 6.40 mg/L. Scanning electron microscopy (SEM) showed that osthole caused F. oxysporum mycelia to shrink and deform. Transmission electron microscopy (TEM) showed that the organelles were blurred and the cell wall was thickened in the presence of osthole. The sensitivity of F. oxysporum to calcofluor white (CFW) staining was significantly enhanced by osthole. Relative conductivity measurements and propidium iodide (PI) observation revealed that osthole had no significant effect on the cell membrane. Further experiments showed that the activity of chitinase and β-1,3-glucanase were decreased, and expression levels of chitinase and β-1,3-glucanase related genes were significantly down-regulated after treatment with osthole. In conclusion, osthole disrupted the cell wall integrity and dynamic balance of F. oxysporum, thereby inhibiting normal mycelial growth.

Multiple pesticide residues and risk assessment of Dendrobium officinale Kimura et Migo: a three-year investigation

Dendrobium officinale Kimura et Migo (D. officinale) is a traditional Chinese medicine homologous to food, and its safety has attracted considerable attention. Pesticide residues are critical indicators for evaluating the safety of D. officinale. This study investigated the levels of 130 pesticides in 137 stem samples and 82 leaf samples from five main production areas of D. officinale in Zhejiang Province, along with the associated risk of dietary exposure for the population between 2019 and 2021. Forty-five pesticides were detected in 171 samples, of which pyraclostrobin had the highest detection frequency. Multiple residues were detected in 52.56% of the stem samples and 54.88% of the leaf samples, and one stem sample contained up to 18 pesticides. Here, the level of difenoconazole in three samples (two stem samples and one leaf sample) was higher than the maximum residue limit (MRL) in China. Considering the possible health risks related to pesticide residues, a risk assessment of human exposure to pesticides via the intake of D. officinale stems and leaves was evaluated, indicating negligible short-term, long-term, and cumulative risks to human health. However, considering the high detection rate of unregistered pesticides, the supplementation of pesticide registration information on D. officinale should be expedited, and MRLs should be established to ensure food and drug safety.

Dissipation and dietary exposure risk assessment of spinosad, thiocyclam, and its metabolite nereistoxin in cucumber and groundwater for different population groups

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique using ultrahigh-performance liquid chromatography with tandem mass spectrometry for the analysis of spinosad (spinosyn A + spinosyn D), thiocyclam, and nereistoxin in cucumber was developed with mean recoveries of 93-104%, relative standard deviations of ≤9%, and limits of quantification of 0.01 mg/kg. Field trials of spinosad and thiocyclam were performed in 12 representative cultivating areas in China. Field trial results indicate that spinosyn A and spinosyn D easily dissipated in cucumber with half-lives of 2.48-6.24 and <3 days, respectively. Nereistoxin was produced after thiocyclam application and was more persistent than its parent. The terminal residues of spinosad were all below the maximum residue limits (0.2 mg/kg) in China, whereas the terminal concentration of nereistoxin (calculated as the stoichiometric equivalent of thiocyclam), which was much higher than that of thiocyclam, was far beyond the maximum residue limits of thiocyclam in cucumber (0.01 mg/kg) established by the European Union. The predicted no-effect concentrations of spinosyn A, spinosyn D, thiocyclam, and nereistoxin leaching into groundwater were estimated using China-PEARL (Pesticide Emission Assessment at Regional and Local scales) models after application. However, the dietary (food and water) exposure risk quotient for different populations was below 1 with a preharvest interval set at 5 days after the last application, indicating that the application of spinosad and thiocyclam in cucumber was unlikely to pose unacceptable risk for human health. This study provides data for the safe use of spinosad and thiocyclam in cucumber ecosystem.

In vitro assessment of the pesticide bioaccessibility in Dendrobium officinale Kimura et Migo

Bioaccessibility (BA) is a crucial factor for evaluating the absorption of pollutants in the human digestion system, which is of vital importance for risk assessment of pollutants via food intake. Multi-pesticides were detected in Dendrobium officinale Kimura et Migo (D. officinale), a popular dual-use plant with both botanical medicine and food applications. Nevertheless, the BA of pesticides in D. officinale remains unknown, restricting its market size. Herein, the BA of 19 pesticides with varying properties was evaluated by using an in vitro digestion model, showing BA values between 27.4 and 96.8%. The BA was controlled by the hydrophobicity and water solubility of pesticides, since the significant correlation between these two factors and BA values was observed. Moreover, co-ingested food ingredients could influence the BA, wherein the effect was significant for pesticides of logKow values no less than 3. Lipids enhanced the BA by 9-66%, whereas proteins or carbohydrates decreased BA values by 6-28%. In particular, considering the BA, the risk quotient values were reduced by 3-73%. Clearly, this work suggested that traditional risk assessment without considering the BA would seriously overestimate the actual risk of pesticides in food.

Assessment of health risks associated with pesticide and heavy metal contents in Fritillaria thunbergii Miq. (Zhe Beimu)

Fritillaria thunbergii Miq. (Zhe Beimu, F. thunbergii) is widely cultivated in China's Zhejiang province, and pesticides and heavy metals are two major factors affecting its quality and safety. A total of 106 F. thunbergii samples from six main production areas were analyzed for 76 pesticides and four heavy metal content (As, Cd, Hg, and Pb). The pesticide detection rate of the samples was 66.98%; overall, the pesticide residues were very low, and residue levels ranged from 0.010 to 0.231 mg kg^-1. The detection rates of As, Cd, Hg, and Pb were 95.3%, 100%, 76.4%, and 100%, respectively. A risk assessment of human exposure to pesticides and heavy metals via intake of F. thunbergii was performed, and the results revealed that the pesticide residues and heavy metal content detected in F. thunbergii does not pose a potential risk to human health, either in the long or short term. The exposure assessment showed that the levels of pesticides and heavy metals in F. thunbergii were safe for human consumption. These results provide useful information on F. thunbergii consumption.

Simultaneous determination of nine phenolic compounds in imitation wild Dendrobium officinale samples using ultrahigh-performance liquid chromatography-tandem mass spectrometry

Dendrobium officinale Kimura et Migo (D. officinale), one of the nine everlasting types of grass, has gained increasing attention owing to its important roles in alternative medicines and drug discovery. Due to its natural resources being in danger of being extinct, imitation wild planting is becoming increasingly common. To assess the product's quality completely, an efficient ultrahigh performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-QQQ-MS/MS) method was established to simultaneously quantify nine phenolic compounds in D. officinale samples. The extraction parameters, including solvent, solvent concentration, solid-liquid ratio, and extraction time, were systematically optimized with the single-factor test. The results demonstrated that extraction with a 1:200 solid-to-liquid ratio of 80% methanol for 1.5 h was the most efficient condition for the extraction of flavonoids. Satisfactory retention times and resolution of the nine analytes were acquired on the Thermo Scientific Hypersil GOLD column with multiple reaction monitoring in negative ion scanning mode. The method was validated to demonstrate its selectivity, linearity, precision, accuracy, and robustness. Thus, the verified UHPLC-QQQ-MS/MS method was successfully applied to the quantification of phenolic components present in D. officinale samples. The results indicated that the quantity and composition of phenolic components in D. officinale from various provenances were significantly different. This work provides a theoretical foundation for the cultivation and assessment of wild D. officinale quality.

Comparison of Chemiluminescence Enzyme Immunoassay (Cl-ELISA) with Colorimetric Enzyme Immunoassay (Co-ELISA) for Imidacloprid Detection in Vegetables

Imidacloprid is one of the most commonly used insecticides for managing pests, thus, improving the quality and yield of vegetables. The abuse/misuse of imidacloprid contaminates the environment and threatens human health. To reduce the risk, a colorimetric enzyme-linked immunoassay assay (Co-ELISA) and chemiluminescence enzyme-linked immunoassay assay (Cl-ELISA) were established to detect imidacloprid residues in vegetables. The linear range of Co-ELISA ranged between 1.56 μg/L and 200 μg/L with a limit of detection (LOD) of 1.56 μg/L. The values for Cl-ELISA were 0.19 μg/L to 25 μg/L with an LOD of 0.19 μg/L, which are lower than those of Co-ELISA. Fortifying Chinese cabbage, cucumber, and zucchini with imidacloprid at 10, 50, and 100 μg/L yielded recoveries between 81.7 and 117.6% for Co-ELISA and at 5, 10, and 20 µg/L yielded recoveries range from 69.7 to 120.6% for Cl-ELISA. These results indicate that Cl-ELISA has a high sensitivity and a rapid detection time, saving cost (antigen and antibody concentrations) and serving as a more efficient model for the rapid detection of imidacloprid residue.

Mixture effects of imidacloprid and difenconazole on enzymatic activity and gene expression in small yellow croakers (Larimichthys polyactis)

Agrochemicals usually exist as mixtures in aqueous ecosystems and have harmful impacts on the natural environment. Nonetheless, the combined effects and underlying mechanisms of agrochemicals on aqueous organisms remain poorly understood. In the present study, the interactive effects of imidacloprid (IMI) and difenconazole (DIF) on the embryos of small yellow croakers (Larimichthys polyactis) were assessed using various toxicological assays, including acute toxicity, enzymatic activity, and gene expression changes. The results showed that DIF (72-h LC₅₀ value of 0.20 mg L^-1) had higher toxicity than IMI (72-h LC₅₀ value of 12.5 mgL^-1). Simultaneously, combinations of IMI and DIF exerted synergistic acute effects on the embryos of L. polyactis. In addition, the SOD, CAT, GST, and CarE activities were noticeably altered in most single and mixed exposures, relative to the untreated control. The expression of four genes (cyp19a1b, ngln2, klf2a, and socs3a) related to the immune system, endocrine system, and neurodevelopment was also surprisingly altered when the embryos of L. polyactis were subjected to individual and combined exposures relative to the untreated control. Changes in enzymatic activity and gene expression might provide early warning indices for the identification of agrochemical co-exposure. The results of this study provide valuable insights into the comprehensive toxicity of agrochemical mixtures to L. polyactis. Further studies on the long-term effects of agrochemical mixtures on marine fish should be conducted to formulate definitive conclusions concerning hazards.

Dissipation behavior, residue transfer, and safety evaluation of chlorantraniliprole and indoxacarb during tea growing and brewing by ultrahigh-performance liquid chromatography-tandem mass spectrometry

A reliable and simple analytical method was developed and validated to simultaneously determine chlorantraniliprole and indoxacarb in tea using ultrahigh-performance liquid chromatography-tandem mass spectrometry. The average recoveries of chlorantraniliprole were in the range of 86-110%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 1.9 to 8.4% and from 2.4 to 8.8%, respectively. The average recoveries of indoxacarb were in the range 81-105%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 2.0 to 9.8% and from 2.7 to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. The results based on the supervised field trials showed that chlorantraniliprole and indoxacarb in two tea samples followed first-order kinetics models with half-lives of 2.2-4.7 days and 2.5-3.5 days, which could be regarded as a moderately degrading pesticide. The terminal residues of chlorantraniliprole and indoxacarb in made tea were below 6.7 and 4.5 mg/kg, respectively, lower than their corresponding maximum residue limits (MRLs) established by several major countries and organizations (50 and 5 mg/kg). The leaching rates of chlorantraniliprole and indoxacarb during the tea brewing ranged from 4.78 to 12.62% and 4.13 to 10.67%, respectively. The chronic intake risk quotient (RQc) values for chlorantraniliprole and indoxacarb were 0.24% and 35.10%, while the acute dietary risk assessment (RQa) value of indoxacarb was 5.8%, which were all much lower than 100%. The results in the present study indicated that the health risk posed by the chlorantraniliprole and indoxacarb mixture pesticides was negligible in tea for consumers at the recommended dosages.

Residue levels, household processing evolution and risk assessment of chlorothalonil, SDS-3701, metalaxyl and dimethomorph in Dendrobium officinale Kimura et Migo

Dendrobium officinale, a minor crop with medicinal and edible value, is increasingly entering people's diets, but the pesticide residues on it have received little attention. In this work, field trials were conducted under good agricultural practice (GAP) conditions to investigate the residues of chlorothalonil, SDS-3701, metalaxyl and dimethomorph in D. officinale, then the evolution of these pesticides after household processing were studied. The results indicated that chlorothalonil, SDS-3701, metalaxyl and dimethomorph were 2.41-30.12, 0.20-1.23, 0.07-0.80, 0.19-7.90 mg kg^-1 respectively in stems at recommended preharvest interval (PHI, 30 d). Washing and soaking removed the pesticides in fresh stems with the processing factors (PFs) of 0.41-1.14 and 0.12-1.13, respectively. In brewing test, the transfer rates (TRs) of pesticides in dry stems decreased from the first time (4.27-95.40%) to the third time (3.89-15.57%). Intake risk assessments were also conducted and the risk quotients (RQs) were no more than 27.02% for all compounds in different samples, which indicated acceptable risks for consumers. As effective risk-reducing home processing methods, washing, soaking and multiple brewing were suggested in this work, hoping to help consumers with diet safety.

Residue, Dissipation Pattern, and Dietary Risk Assessment of Imidacloprid in Chinese Chives

The demand for Chinese chives is growing as they are also rich in vitamins, fiber, and sulfur nutrients. Chinese chives should be sprayed with imidacloprid to control pests and diseases to safeguard their yield and to meet the demands of East Asian consumers for Chinese chives. Overspraying of imidacloprid can lead to residues in Chinese chives, posing a severe risk to human health. To reduce the harmful effects of imidacloprid residues on humans, we investigated the imidacloprid dissipation pattern and the final residue on Chinese chives using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Good linearity (R²= 0.9988), accuracy (expressed as recovery % of 78.34–91.17%), precision [expressed as relative SDs (RSDs) of 0.48–6.43%], and sensitivity [a limit of quantification (LOQ) ≤ 8.07 × 10⁴ mg/kg] were achieved. The dissipation dynamics were consistent with the first-order kinetics, with a half-life of 2.92 days. The final residual levels on Chinese chives were 0.00923–0.166 mg/kg, which is lower than the maximum residue limits (MRLs) of 1 mg/kg for imidacloprid on Chinese chives. A risk assessment index of <1 indicates that Chinese chives are safe for consumption.

Dissipation of imidacloprid and its metabolites in Chinese prickly ash (Zanthoxylum) and their dietary risk assessment

Dissipation of imidacloprid (IMI) and its metabolites (urea, olefin, 5-hydroxy, guanidine, 6-chloronicotinic acid) in Chinese prickly ash (CPA) was investigated using QuEChERS combined with UPLC-MS/MS. Good linearity (r² ≥0.9963), accuracy (recoveries of 71.8-104.3%), precision (relative standard deviations of 0.9-9.4%), and sensitivity (limit of quantification ≤0.05 mg kg^-1) were obtained. After application of IMI at dosage of 467 mg a.i. L^-1 for three times with interval of 7 d, the dissipation dynamics of IMI in CPA followed first-order kinetics, with half-life of 6.48-7.29 d. IMI was the main compound in CPA, followed by urea and guanidine with small amounts of olefin, 5-hydroxy, and 6-chloronicotinic acid. The terminal residues of total IMI and its metabolites at PHI of 14-21 d were 0.16-7.80 mg kg^-1 in fresh CPA and 0.41-10.44 mg kg^-1 in dried CPA, with the median processing factor of 3.62. Risk assessment showed the acute (RQa) and chronic dietary risk quotients (RQc) of IMI in CPA were 0.020-0.083% and 0.052-0.334%, respectively. Based on the dietary structures of different genders and ages of Chinese people, the whole dietary risk assessment indicated that RQc was less than 100% for the general population except for 2- to 7-year-old children (RQc of 109.9%), implying the long-term risks of IMI were acceptable to common consumers except for children.