Assessment of pesticide residues in selected field vegetables from different cultivation types: A preliminary comparative study.

Abstract

In Sri Lanka, vegetables are cultivated using three distinct approaches: organic, Good Agriculture Practices (GAP), and conventional cultivation. Each method has its own set of principles, methods, and philosophies. However, it is noteworthy that several studies conducted in other countries have detected pesticide residues in organically grown vegetables. In Sri Lanka, no reports have tested pesticide residues in organically and GAP-grown vegetables. Therefore, the study aimed to assess pesticide residues in field-grown vegetables, comparing small-scale organic, GAP, and conventional cultivation. The study involved a total of 27 random selections of small-scale organic, GAP certified and conventional farmers in the Anuradhapura district, based on recorded data from the Department of Agriculture and the National Institute of Post-harvest Management for sample collection. During the sample collection process from farmers, specific details of pesticide applications were recorded. Three fresh vegetable species, namely brinjal, long bean, and chili were chosen for the study, each with three replicates. The sample preparation and extraction method utilized anhydrous sodium sulfate and ethyl acetate as the aqueous phase, followed by the detection of pesticide residues using Gas Chromatography with Mass Spectrometry. The findings revealed that among the long bean samples grown organically, there was a small peak observed for Acetamide pesticide residues in one of the samples, while the rest of all organic samples were free from pesticides. Among the conventionally grown samples, minor traces of Acetamide, Milbemycin insecticide, and Dithiocarbamate pesticides were noticed in long beans. Chilli had only Acetamide residues. Additionally, Gibberellic acid, a plant growth regulator, was found in both brinjal and long bean samples. Importantly, vegetables from GAP had no detectable pesticide residues. In conclusion, our preliminary study suggests that the applied methodology for the extraction procedure needs further development and quantification of the detected pesticide levels for comparison with the Maximum Residue Levels.