Uptake and Dissipation of Carbofuran and Its Metabolite in Chinese Kale and Brinjal Cultivated under Humid Tropic Climate

Abstract

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.