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BACKGROUND: Tolfenpyrad and dinotefuran are two representative pesticides used for pest control in tea gardens. Their application may bring about a potential risk to the health of consumers. Therefore, it is essential to investigate the residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and metabolites from tea garden to teacup. RESULTS: An effective analytical method was established and validated to simultaneously determine tolfenpyrad, dinotefuran and its metabolites (DN and UF) in tea. The average recoveries of tolfenpyrad, dinotefuran, DN and UF were in the range 72.1–106.3%, with relative standard deviations lower than 11.8%. On the basis of the proposed method, the dissipation of tolfenpyrad and dinotefuran in fresh tea leaves followed first‐order kinetics models with half‐lives of 4.30–7.33 days and 4.65–5.50 days, respectively. With application amounts of 112.5–168.75 g a.i. ha–1 once or twice, the terminal residues of tolfenpyrad and total dinotefuran in green tea were lower than 19.6 and 7.13 mg kg−1, respectively, and below their corresponding maximum residue limits. The leaching rates of tolfenpyrad and total dinotefuran during the tea brewing were in the ranges 1.4–2.3% and 93.7–98.1%, respectively. CONCLUSION: Tolfenpyrad and dinotefuran in tea were easily degraded. The RQc and RQa values for tolfenpyrad were 37.6% and 5.4%, which were much higher than for dinotefuran at 24.7% and 0.84%, respectively. The data indicated that there was no significant health risk in tea for consumers at the recommended dosages. The results provide scientific data regarding the reasonable use of tolfenpyrad and dinotefuran aiming to ensure safe tea consuption. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND Propiconazole is widely used to control fungal diseases in field crops, including celery and onion. The potential risk to the environment and human health has aroused much public concern. Therefore, it is significant to investigate the degradation behaviour, residue distribution, and dietary risk assessment of propiconazole in celery and onion. RESULTS: A sensitive analytical method for determination of propiconazole residue in celery and onion was established and validated through high‐performance liquid chromatography tandem mass spectrometry. The average recovery rate of propiconazole ranged from 85.7% to 101.8%, with a relative standard deviation of 2.1–6.3%. For the dissipation kinetics, the data showed that propiconazole in celery and onion was degraded, with half‐lives of 6.1–6.2 days and 8.7–8.8 days respectively. In the terminal residue experiments, the residues of propiconazole were below 4.66 mg kg−1 in celery after application two or three times and were below 0.029 mg kg−1 in onion after application of three or four times with an interval of 14 days under the designed dosages. The chronic and acute dietary exposure assessments for propiconazole were valued by risk quotient, with all values being lower than 100%. CONCLUSION: Propiconazole in celery and onion was rapidly degraded following first‐order kinetics models. The dietary risk of propiconazole through celery or onion was negligible to consumers. The study not only offers a valuable reference for reasonable usage of propiconazole on celery and onion, but also facilitates the establishment of maximum residue limits in China. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Tebuconazole is an effective but potentially carcinogenic fungicide. Tebuconazole residues in loquat and sugarcane were investigated, together with an analysis of their dietary risk. Solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry showed fortified recoveries of 87% to 98%, with standard deviations ≤ 6.4%. The tebuconazole residues were below 6.34 mg kg−1 for whole loquat and 0.80 mg kg−1 for sugarcane. Based on the final residue test, the chronic hazard index was 90.74% in whole loquat and sugarcane, while the acute hazard index ranged from 66.32% to 109.49% for loquat and 33.37% to 76.93% for sugarcane. The assessment of potential dietary risk showed that while loquats may represent an acute risk to human health, whereas sugarcane consumption was safe. A 21-day pre-harvest interval is proposed to comply with maximum residue limit regulations and the observed risks when using 430 g/L tebuconazole for treating sugarcane. These findings offer guidance for tebuconazole formulation and use. [ABSTRACT FROM AUTHOR]

• The inhibition risk of shikonin on UGT enzymes was firstly investigated. • Shikonin significantly inhibited UGT1A1, UGT1A3, UGT1A9/PROG, and UGT2B7/AZTG activities in human and rat liver microsomes. • Shikonin exhibited no time-dependent inhibition on UGT activities. • Shikonin displayed competitive inhibition on UGT isoforms. Shikonin, a natural red colorant, is widely used for food garnishment and cosmetic ingredient in the world. Shikonin also possesses a variety of pharmacological actions, including anti-inflammation and anti-cancer activities. However, little is known about its effects on the UDP-glucuronosyltransferases (UGT) activity. Therefore, the aim of this study was to evaluate the effect of shikonin on the UGT1A1, UGT1A3, UGT1A6, UGT1A9 and UGT2B7 activities via the human and rat liver microsomal assay and cocktail approach. The results showed shikonin inhibited human and rat liver microsomal UGT activity only in a dose-dependent manner. The further enzyme kinetic studies demonstrated that shikonin was not only a competitive inhibitor of human UGT1A1, UGT1A9, and UGT2B7, but also presented competitive inhibition on rat UGT1A1 and AZTG reactions. In conclusion, shikonin as a reversible inhibitor of UGT enzyme has a high-risk potential to cause the possible toxicity, especially drug-drug or food-drug interactions. [ABSTRACT FROM AUTHOR]

The dissipation and residue levels of thiacloprid, spirotetramat and its four metabolites residues in cowpeas were investigated under field conditions. The QuEChERS technique with high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) was used to detect thiacloprid, spirotetramat and its four metabolites residues content in cowpeas. The recoveries were 81.3–95.1% at a spike level of 0.005–0.5 mg/kg, the relative standard deviations (RSDs) were 2.1–9.5%. The dissipation kinetics data showed that thiacloprid and spirotetramat in cowpeas were degraded with the half-lives of 1.14–1.54 days and 1.25–2.79 days. The terminal residues of thiacloprid and spirotetramat were 0.0255–0.4570 mg kg−1 and 0.0314–0.3070 mg kg−1 after application 2 times with a pre-harvest interval (PHI) of 3 days under the designed dosages. The chronic and acute dietary exposure assessment risk quotient (RQ) values of thiacloprid in cowpeas for different consumers were 2.44–4.41% and 8.72–15.78%, respectively, and those of spirotetramat were 1.03–1.87% and 0.18–0.32%, respectively, all of the RQ values were lower than 100%. The dietary risk of thiacloprid through cowpeas to consumers was higher than spirotetramat. The results from this study are important reference for Chinese governments to develop criteria for the safe and rational use of thiacloprid and spirotetramat, setting maximum residue levels (MRLs), monitoring the quality safety of agricultural products and protecting consumer health. [ABSTRACT FROM AUTHOR]

Dissipation, residues and risk assessment of lufenuron during kumquat growing and kumquat processing were investigated under field and household conditions. The QuEChERS technique with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was used to detect lufenuron residues content in kumquats and its processed products. The recoveries were 82.3–102.8% at a spike level of 0.005–0.5 mg kg−1, the relative standard deviations (RSDs) were 1.1–9.4%. The dissipation kinetics data showed that lufenuron in kumquats were degraded with the half-lives of 9.12–12.60 days. The terminal residues of lufenuron in kumquats were 0.064–0.107 mg kg−1 after application one times with a pre-harvest interval (PHI) of 14 days under the designed dosages. The juicing process can significantly reduce the residues of lufenuron in kumquats juice, and the processing factor (PF) value of juicing process was 0.15. The chronic dietary exposure assessment risk quotient (RQ) values of lufenuron in kumquats fruit and juice for different consumers were 0.71–2.13% and 0.37–0.86%, all of the RQ values were lower than 100%. The results from this study are important reference for Chinese governments to develop criteria for the safe and rational use of lufenuron on kumquats and monitor the quality safety of agricultural products and protecting consumer health. • Residue behaviorof lufenuron in kumquats during growing and processing is reported for the first time. • The degradation half-life of lufenuron showed that lufenuron degrades relatively slowly. • The juicing process can significantly reduce the residues of lufenuron in kumquats juice. • Dietary exposure risks associated with lufenuron in kumquats fruit and juice in China are all not a health concern. [ABSTRACT FROM AUTHOR]