Dissipation and Risk Assessment of Propaquizafop in Ginseng under Field Conditions.

Propaquizafop is a highly efficient aryloxy phenoxy propionate chiral herbicide. However, the use of propaquizafop, including its safe use methods, residue patterns, dietary risk assessment, and maximum residue limits, for ginseng, a traditional Chinese medicinal plant, has not been studied. An analytical method was established for the simultaneous determination of propaquizafop and its four metabolites in ginseng soil, fresh ginseng, ginseng plant, and dried ginseng using HPLC-MS/MS. This approach showed good linearity (R2 ranging from 0.9827 to 0.9999) and limit of quantification ranging from 0.01 to 0.05 mg/kg. The intra- and interday recovery rates of this method ranged from 71.6 to 107.1% with relative standard deviation ranging from 1.3 to 23.2%. The method was applied to detect residual samples in the field, and it was found that the degradation of propaquizafop in ginseng plants and soil followed a first-order kinetic equation. R2 was between 0.8913 and 0.9666, and the half-life (t1/2) ranged from 5.04 to 8.05 days, indicating that it was an easily degradable pesticide (T1/2 < 30 days). The final propaquizafop residues in ginseng soil, plants, fresh ginseng, and dried ginseng ranged from 0.017 to 0.691 mg/kg. A dietary risk assessment was conducted on the final propaquizafop residue in fresh and dried ginseng. The results showed that the chronic exposure risk quotient values were less than 100% for fresh and dried ginseng (1.15% for fresh ginseng and 1.13% for dried ginseng). This illustrates that the dietary risk associated with the use of 10% propaquizafop emulsifiable concentrate in ginseng is very low. Thus, applying 750 mL/ha of propaquizafop on ginseng could not pose an unacceptable risk to public health. The results of the present study support the registration of propaquizafop in ginseng.

Degradation and residues of mandipropamid in soil and ginseng and dietary risk assessment in Chinese culture.

Mandipropamid, a new fungicide for oomycete disease, has a strong effect on the blight of many crops and has been registered for the treatment of ginseng blight in China. However, no maximum residue limit (MRL) of mandipropamid has been identified for ginseng, and there have been few related studies. We established and verified the analysis method of mandipropamid in ginseng using high-performance liquid chromatography-tandem mass spectrometry. The method has good linearity and accuracy in the range of 0.002-0.5 mg/kg. The average recovery of mandipropamid was 87.4-101.6%, and the standard deviation was 1.1-4.0. Mandipropamid in ginseng plants and soil rapidly degraded following first-order kinetics models. The degradation dynamics showed that the half-life of mandipropamid in ginseng plant and soil was 13.8-28.0 and 9.8-27.4 d, respectively. After the recommended dose of mandipropamid was applied once, the residual content of mandipropamid in fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil was < 0.01-0.185, < 0.01-0.265, 0.085-1.544, 0.075-4.800, and < 0.01-0.014 mg/kg, respectively. The dietary risk assessment of mandipropamid on ginseng showed that the risk quotient value was far less than 100%, indicating that the recommended dose of mandipropamid does not cause unacceptable risks to humans. After the recommended dose of mandipropamid was applied once, it did not cause unacceptable risks to humans. This study not only provides a reasonable spray dosage of mandipropamid to ginseng but also offers a reference for the establishment of MRLs in China.

Dissipation and Dietary Risk Assessment of Pydiflumetofen Residues in Soybean.

In this study, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, combined with high-performance liquid chromatography−tandem mass spectrometry, was chosen for detecting pydiflumetofen residues in soybean plants, soybeans and soil, and assessing the risk of short- and long-term dietary intake. Pydiflumetofen concentrations ranging from 0.001−0.5 mg/L exhibited good linearity (r > 0.997). At varying doses, the average pydiflumetofen recovery rates and relative standard deviations among soybean plants, soybeans, and soil ranged from 83.9 ± 1.1% to 99.5 ± 3.3% and from 0.77 to 7.77%, respectively. The sensitivity, accuracy, and precision of the chosen methodology met the requirements of pesticide residue analysis. The results of the degradation dynamics test showed that the half-life of pydiflumetofen (t1/2) in soybean plants and in soil were 3.6 to 5.7 and from 7.9 to 25.7 d, respectively. Assessment of the concentration of pydiflumetofen residues in soybeans revealed acute and chronic dietary exposure risks of 0.06 and 7.54%, respectively. As these values are very low, pydiflumetofen residues in soybeans present an acceptable risk to public health. The results of this study will help to guide the practical application of pydiflumetofen and minimize the environmental risks associated with its use.

Dissipation, Processing Factors and Dietary Risk Assessment for Flupyradifurone Residues in Ginseng.

The massive use of pesticides has brought great risks to food and environmental safety. It is necessary to develop reliable analytical methods and evaluate risks through monitoring studies. Here, a method was used for the simultaneous determination of flupyradifurone (FPF) and its two metabolites in fresh ginseng, dried ginseng, ginseng plants, and soil. The method exhibited good accuracy (recoveries of 72.8-97.5%) and precision (relative standard deviations of 1.1-8.5%). The field experiments demonstrated that FPF had half-lives of 4.5-7.9 d and 10.0-16.9 d in ginseng plants and soil, respectively. The concentrations of total terminal residues in soil, ginseng plants, dried ginseng, and ginseng were less than 0.516, 2.623, 2.363, and 0.641 mg/kg, respectively. Based on these results, the soil environmental risk assessment shows that the environmental risk of FPF to soil organisms is acceptable. The processing factors for FPF residues in ginseng were 3.82-4.59, indicating that the concentration of residues increased in ginseng after drying. A dietary risk assessment showed that the risk of FPF residues from long-term and short-term dietary exposures to global consumers were 0.1-0.4% and 12.07-13.16%, respectively, indicating that the application of FPF to ginseng at the recommended dose does not pose a significant risk to consumers.

Degradation of anthranilic diamide insecticide tetrachlorantraniliprole in water: Kinetics, degradation pathways, product identification and toxicity assessment.

In the present study, aqueous behavior and fate of diamide insecticide tetrachlorantraniliprole (TCTP) were investigated under laboratory-controlled conditions. Half-lives of TCTP photolysis in natural water and pH buffers were 1.4-2.8 h, comparing with those of 1.2-231 d for hydrolysis. Both processes were highly influenced by pH with respect to degradation kinetics and routes. The hydrolysis rate of TCTP was accelerated by elevated temperatures. The presence of nitrate enhanced TCTP photolysis while fulvic acid exhibited suppression, with the extent of both effects as a function of concentration. Four degradation products were identified using a variety of spectroscopic approaches. Key reactions involved in the degradation pathways include intramolecular substitution and cyclization. There was a reduction in the acute toxicity of all four products to Daphnia magna by comparison with TCTP, whereas they were still classified as category 1 or 2 hazardous substances to the aquatic environment according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) standards.

Residue Behavior and Risk Assessment of Rimsulfuron and Quizalofop-P-ethyl in Potato Under Field Conditions.

A method for simultaneous quantitation of rimsulfuron, quizalofop-P-ethyl and quizalofop-P in potato plant, soil and potato tuber samples was established. The mean recoveries of rimsulfuron, quizalofop-P-ethyl and quizalofop-P in different matrices spiked with them were 81.4%-101.1%, 76.1%-99.0% and 77.4%-106.4% with relative standard deviations (RSDs) of 2.7%-13.3%, 0.9%-5.5%, 1.7%-11.3%, respectively. The open-field trials in China were conducted in potato cultivation system of Changchun and Jinan. The results indicated that the half-lives of rimsulfuron and quizalofop-P-ethyl were 0.04-13.1 days. The residues of quizalofop-P during the harvest time in Jinan soil were < 0.01-0.044 mg kg-1, while there was no residue of target herbicides detected in all other samples. The risk assessment results demonstrated that the risk quotients (RQs) of rimsulfuron and quizalofop-P-ethyl were 7.857 × 10-5 and 8.730 × 10-3, respectively, which exhibited an acceptable dietary risk to Chinese consumers.