Dissipation Pattern, Processing Factors, and Safety Evaluation for Dimethoate and Its Metabolite (Omethoate) in Tea (Camellia Sinensis)

Abstract

Residue levels of dimethoate and its oxon metabolite (omethoate) during tea planting, manufacturing, and brewing were investigated using a modified QuEChERS sample preparation and gas chromatography. Dissipation of dimethoate and its metabolite in tea plantation followed the first-order kinetic with a half-life of 1.08–1.27 d. Tea manufacturing has positive effects on dimethoate dissipation. Processing factors of dimethoate are in the range of 2.11–2.41 and 1.41–1.70 during green tea and black tea manufacturing, respectively. Omethoate underwent generation as well as dissipation during tea manufacturing. Sum of dimethoate and omethoate led to a large portion of 80.5–84.9% transferring into tea infusion. Results of safety evaluation indicated that omethoate could bring higher human health risk than dimethoate due to its higher hazard quotient by drinking tea. These results would provide information for the establishment of maximum residue limit and instruction for the application of dimethoate formulation on tea crop.

Black Tea Source, Production, and Consumption: Assessment of Health Risks of Fluoride Intake in New Zealand

“…Pesticides residues in tea can be transferred into tea infusion and then consumed by humans [310]. As previously noted, it has also been found that coexposure to F and aluminium or pesticides, such as CPF, results in synergistic interactions and enhanced toxicity [275–280].…”

Development of a Data Set of Pesticide Dissipation Rates in/on Various Plant Matrices for the Pesticide Properties Database (PPDB)

“…Dissipation rates also have application in consumer safety. For example, these values are used in calculations for predicting residue concentrations in harvested produce and for determining the time interval needed between crop spraying and harvesting or potential processing/consumption in order to minimise residue concentrations [4,5]. Dissipation rates also have value when considering the potential risk to non-target and beneficial organisms (e.g., pollinators) that may forage or otherwise come in contact with a pesticide treated plant, as well as informing on how long the chemical is likely to offer satisfactory pest control before it decays [6][7][8].…”

Washing fresh tea leaves before picking decreases pesticide residues in tea

“…Evaporation, rain-rinse, photolysis, hydrolysis, metabolism and growth dilution are important degradation processes influencing the fate of pesticides in or on plants. [9][10][11][12] Evaporation, rain-rinse and photolysis mainly occur on the leaf surface. [13][14][15][16] Some AIs can be taken up by the leaf, where they would be subjected to different environmental variables.…”