Preliminary study for the determination of pesticides in vegetables marketed in a zone of Michoacán (México)

Abstract

Organophosphates (OP) are widely used in the world for their low cost, high efficiency, and less persistence. These neurotoxic compounds have been detected in biological and environmental matrices in various countries. The use of pesticides implies the risk of accumulation of residues in agricultural products; however, in some regions of Mexico, the monitoring of pesticide residues in food and other matrices is limited. The objective of this work was to determine residues of OP in vegetables commercialized in tianguis (popular market days) of Jiquilpan, Michoacan, Mexico. Samples of pumpkin, cucumber, tomato, onion, strawberry, and apple were collected (n = 30), as well as tomato and organic strawberry (n=6). The samples with ethyl acetate were extracted, and the presence of malathion and chlorpyrifos-ethyl residues was analyzed using high-resolution thin layer chromatography (HPTLC). The organic samples did not show residual malathion and chlorpyrifos-ethyl. Under the conditions of this study, no malathion residues were detected in the vegetable samples. However, the presence of chlorpyrifos-ethyl residues was observed in four onion samples and in one apple sample (20% of the total samples). The HPTLC technique was used as a screening technique. It has been reported that chronic exposure to low concentrations of pesticides can represent a risk to human health, since its effects could be additive and could appear in the medium and long term. Periodic monitoring of pesticides in food and exposed populations is required.