Contamination and pesticide multiresidue analysis in cotton production systems in Benin

Abstract

High quantity of chemical pesticides spraying in conventional cotton production systems may affect negatively natural ecosystems components. This study examined the contamination levels of soil in Benin's cotton production system in West Africa by residues of pesticides used in cotton farming. One hundred and fourteen soil samples from six conventional and organic cotton production systems were collected and analysed. Multi-class pesticide residues were extracted from the soil samples, and analysed using respectively modified QuEChERS extraction and LC–MS/MS chromatography methods. Results showed an overall soil contamination to emamectin benzoate (18.5 μg/kg), imidacloprid (116.3 μg/kg), profenofos (12.7 μg/kg), acetamiprid (10.8 μg/kg), triasophos (12.6 μg/kg), abamectin (14.3 μg/kg), and deltamethrin (10.4 μg/kg). Especially, emamectin benzoate was detected with a high contamination in Banikoara district (18.5 μg/kg). Nevertheless, these contaminations were not deemed threatening from a toxicological perspective. Soils in conventional cotton cultivation displayed lower organic matter levels but higher concentrations of pesticides, whereas soils in organic cotton cultivation were less degraded and contaminated. Consequently, it is imperative to conduct environmental risk assessments and monitor key pesticide metabolites to establish sustainable cotton production systems in Benin.