Assessment of organochlorine pesticide residues in soils and drinking water sources from cocoa farms in Ghana

Residues of organochlorine pesticides were determined in soils and drinking water sources in cocoa growing areas in Ghana. Soil samples analysed showed the presence of four organochlorine pesticide residues namely lindane (0.005-0.05 mg/kg), beta-HCH (<0.01-0.05 mg/kg), dieldrin (0.005-0.02 mg/kg), and p,p'-DDT (0.005-0.04 mg/kg), with dieldrin occurring most frequently. Similarly, organochlorine pesticide residues detected in the water samples were lindane (0.01-0.03 µg/l), alpha-endosulfan (0.01-0.03 µg/l), endosulfan-sulphate (0.01-0.04 µg/l), dieldrin (0.01-0.03 µg/l) and p,p'-DDT (0.01-0.04 µg/l), with heptachlor occurring most frequently. The concentrations of the detected organochlorine residues in the soil samples were below their respective US maximum residues limits (MRLs) for agricultural soils, except for lindane recorded at Kwakuanya (S4) and beta-HCH recorded at Krakrom (S3) and Kwakuanya (S4). Similarly, the organochlorine pesticide residues recorded in the water samples were below and within their respective WHO MRLs for drinking water except for alpha-endosulfan at Diabaa (S2) and Kwakuanya (S4) at distance 0-15 m and Kwakuanya (S4) at distance 16-30 m, endosulfan-sulfate at Nkrankwanta (S1) and Diabaa (S2) at distance 0-15 m and heptachlor at Krakrom (S3) at distance 16-30 m which were above their WHO MRLs. The presence of the banned organochlorine pesticide residues in soil and water samples from the study area indicates that these chemicals are still being used, illegally, on some cocoa farms. Routine monitoring of pesticide residues in the study area is necessary for the prevention, control and reduction of environmental pollution to minimize health risks.