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Carbofuran is toxic to humans and the environment, and its misuse in agriculture results in the violation of Maximum Residue Limits (MRL) for most crops. The use of carbofuran in Malaysia is to be banned effectively in May 2023. Limited data were published on the uptake and distribution of carbofuran and its metabolites for most crops. Therefore, a study was conducted to assess carbofuran residues in watermelon grown at the Agriculture Research Centre, Semongok. Carbofuran at 17 kg/ha and 34 kg/ha were applied to watermelon planted under the recommended agronomic practices. The plants were sampled at periodic intervals over 63 days after being treated with carbofuran. The carbofuran and their metabolites in the watermelon leaf, stem, and fruits were determined using a liquid chromatography equipped with a triple quadrupole mass spectrometer. The carbofuran residues were observed up to 35 days after application and reached below the quantification level (0.01 mg/kg) at 42 days after application. Residues were concentrated in the roots and stems for both treatments. About 80 to 90% of the carbofuran was metabolized to carbofuran-3-hydroxy in the watermelon leaves, and 50% in the stems. The highest residue level of carbofuran for application at 17 kg/ha was recorded on Day 9 for roots (0.192 mg/kg), Day 21 for leaves (0.057 mg/kg), and Day 5 for stems (0.134 mg/kg). At 34 kg/ha, the highest carbofuran residues concentrations were recorded on Day 5 for root (0.446 mg/kg) and stem (0.151 mg/kg), and Day 3 for leaves at 0.303 mg/kg. Traces of carbofuran residues were detected in the skin and flesh of the fruit. The carbofuran residue levels in watermelon fruit were below the established MRL of 0.01 mg/kg. Our findings suggest that a proper postharvest interval shall be observed. [ABSTRACT FROM AUTHOR]

Carbofuran is an insecticide with a broad spectrum of activity and is relatively cheap. It is banned in many countries in the world; however, it remains widely used in Asia, Australia, and South America. Carbofuran is commonly used in vegetable farming in Malaysia and it is a legally registered pesticide. This study reports the uptake and dissipation of carbofuran and 3-ketocarbofuran in Chinese kale and brinjal under humid tropic field conditions. The residue profile in plants demonstrated an increase to a maximum, followed by a consistent reduction to a level below the limit of determination (<0.01 mg/kg) over the experimental period. The maximum residue concentration was attained on Day 3 for kale (1.16 mg/kg fresh weight) and Day 7 for brinjal (0.06 mg/kg fresh weight) after carbofuran application. In order to comply with the maximum residue level (MRL) of 0.01 mg/kg, the preharvest interval for kale and brinjal were suggested at 23 and 28 days, respectively. The preharvest interval indicates that carbofuran is not recommended for Chinese kale but it is acceptable for brinjal. The average half-life of carbofuran in soil is 1.24 days, shorter than the literature values reported based on temperate condition, indicating accelerated dissipation under tropical climate. The estimated half-life of carbofuran in leaves was shorter than that in fruits with kale leaves reported at 2.54 days whilst brinjal leaves and fruits recorded at 3.22 and 10.33 days, respectively. [ABSTRACT FROM AUTHOR]