ORGANOCHLORINE PESTICIDE RESIDUES IN AGRICULTURAL SOILS FROM RÉGION DES PLATEAUX IN TOGO

Resumen

Région des Plateaux in Togo is the highest producer of cash crops (coffee, cocoa, cotton) as well as vegetables. This region is the area with the supreme use of chemical pesticides to enhance agricultural production in Togo (west Africa). As effective as these chemicals may be in achieving this goal, the incidence of their residues on the environment, together with the associated adverse effects, have been of serious concerns. The objective of this study is to assess soils contamination by organochlorine pesticides in vegetable production areas within this region. Fifty-four soil samples were randomly collected from selected farmers’ plots within six villages. The analytical methods included solvent extraction of pesticide residues and their subsequent quantification using gas chromatography – electron capture detector (GC-ECD). Twenty one different organochlorine pesticides were analyzed. The analytical results showed that only aldrin, endosulfan (α-, β- and sulfate), and hexachlorocyclohexanes (HCH) isomers, including α-HCH, β-HCH, δ-HCH and γ-HCH were detected in various concentrations. The residuals of aldrin varied from detection limit (DL) (< 0.001 μg/kg)
to 0.93 ± 0.03 μg/kg, the concentrations of α-endosulfan from DL to 1.88 ± 0.41 μg/kg,
β-endosulfan from DL to 0.4 ± 0.01 μg/kg and endosulfan sulfate from DL to 3.87 ± 0.19 μg/kg. On the other hand the concentration of each isomer of HCH ranged from DL to 0.89 ± 0.07 μg/kg (α-HCH), 14.6 ± 0.12 μg/kg (β-HCH), 4.27 ± 0.61 μg/kg (γ-HCH) and 2.92 ± 0.05 μg/kg (δ-HCH). The pesticide residue concentrations found in the studied soils were highly below maximum residue limits varying from 100 to 8000 μg/kg set by Food and Agriculture Organization of the United Nations (FAO). The detected pesticide residues reflected the type of pesticides that have been used in the study areas. The differences in the concentrations of these pesticide residues in the soil samples are likely the result of substantial inter-farm variation in intensive use of pesticide as well as the variation in their degradation dynamics. The findings of this study provide information on residue levels of organochlorine pesticides in soils from “Région des Plateaux” in Togo. Routine monitoring of pesticide residues in these study areas is necessary for the prevention, control and reduction of environmental pollution, leading to minimize health risks.