Organochlorine Pesticides Residue in Cocoa Beans (Theobroma Cacao) and Soils of Cocoa Plantationsin
The study investigated the levels of organochlorine pesticide residues in both cocoa beans and soils of cocoa plantations in selected farms in Ondo State. Soil samples and cocoa pods were collected from four major farms in the State. The pesticide residues were extracted, cleaned up and analysed using Gas Chromatography-Electron Capture Detector (GC-ECD). In the analysed cocoa samples, the ranges of the mean concentrations of the organochlorine pesticides were: α-HCH (ND-0.094 mg/kg), β-HCH (ND-0.371 mg/kg), γ-HCH (ND-0.032 mg/kg), δ-HCH (ND-0.032 mg/kg), heptachlor (ND-0.272 mg/kg), heptachlor-epoxide (0.040-0.185 mg/kg), aldrin (ND-0.117 mg/kg), dieldrin (0.052-1.110 mg/kg), endrin (0.297-1.516 mg/kg), endosulfan I (1.719-10.689 mg/kg), endosulfan II (0.028-0.570 mg/kg), endosulfan sulphate (ND-3.865 mg/kg), p,p’ DDT (ND-0.100 mg/kg), cis-permethrin (0.078-0.662 mg/kg), trans-permethrin (0.085-0.927 mg/kg). However, the levels of aldrin, dieldrin, endrin and endosulfan in the cocoa samples analysed were found to be high and above Maximum Residual Limits (MRLs) established by WHO/FAO (HCH isomers, heptachlor, heptachlor-epoxide, aldrin, endrin and dieldrin (0.020 mg/kg) and endosulfan I, II and sulphate (0.100 mg/kg)) and European Union (α-HCH, β-HCH and δ-HCH isomers, heptachlor, heptachlor-epoxide, and dieldrin (0.020 mg/kg), γ-HCH (1.000 mg/kg), p,p’-DDT, aldrin (0.050 mg/kg) and endosulfan I, II, cis- and trans-permethrin (0.100 mg/kg)). In the soil samples analysed, the ranges of the mean concentrations of the organochlorine pesticides were: α-HCH (ND-0.064 mg/kg), heptachlor-epoxide (0.059-1.384 mg/kg), aldrin (ND-0.450 mg/kg), dieldrin (0.041-0.066 mg/kg), endrin (0.136-0.567 mg/kg), endosulfan I (0.319-1.451 mg/kg), endosulfan II (0.033-0.113 mg/kg), endosulfan sulphate (0.764-1.711 mg/kg), cis-permethrin (0.077-0.259 mg/kg), trans-permethrin (0.079-0.151 mg/kg) The mean concentration of aldrin, dieldrin, endrin, endosulfan (I and II) in the soil sample analysed were above the MRLs of the analytes established by Netherlands ldrin(0.0025mg/kg), dieldrin(0.0005mg/kg), endrin(0.001mg/kg), endosulfanI(0.050mg/kg), endosulfanII(0.050mg/kg). p, p’ DDT was below detection limit (10-4 mg/kg) in 50% of the analysed cocoa and all the soil samples. Similarly, HCH isomers and p,p’ DDT were below detection limit (10-4 mg/kg) in the soil samples analysed except Oluji-1 where α-HCH was detected. The results of the bioaccumulation factors showed that endosulfan, dieldrin, endrin heptachlor, heptachlor-epoxide, cis- and trans-permethrin were bioaccumulated in the cocoa samples from the selected farms. The high bioaccumulation factors of endosulfan I (7.367 in Oluji-1, 3.084 in Oluji-2 and 14.525 in idanre), Dieldrin (27.073 in Oluji-2, 7.477 in Owena), and cis- and trans-permethrin (1.8 and 11.734 in Owena, 8.597 and 8.429 in Idanre respectively) give cause for concern considering the adverse health hazards pose by high accumulation of these pesticides on man. This indicated recent use of these pesticides despite the ban imposed on their use. The results of ANOVA showed that there was no significant difference between the mean concentrations of the pesticide residues in all the cocoa samples (p<0.05). Similarly, no significant difference was observed between the mean concentrations of the analytes in all the soil (p<0.05).
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