Assessment of organochorine, organophosphate and synthetic pyrethroid pesticides residues on cocoa beans produced in the Sefwi-Wiawso District of the Western Region of Ghana

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MAY, 2015.
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To protect food and cash crops from pests and increase yield, pesticides are being used indiscriminately especially on cocoa farms in Ghana. This practice leaves high levels of pesticides residues in cocoa beans often above the Maximum Residue Levels (MRLs) and thus reduces the value of cocoa beans. This study assessed some pesticide residue levels in cocoa beans from five selected cocoa farming communities in the Sefwi-Wiawso District of the Western Region, Ghana. The results showed that 66 percent of cocoa farmers use bifenthrin, thiamethoxam and imidacloprid which are approved pesticides by the Ghana Cocoa Board. However, 34 percent of farmers use unapproved pesticides (diazinon, dithofencarb, fenvelerate, chlorpyrifos, actamiprid, fenitrothion, malathion and dimethoate). The organophosphates: ethoprophos, phorate, diazinon, fenophos, parathion, chlorfenvinphos and profenofos were not detected in cocoa bean samples from all the five communities. However methamidophos was detected in cocoa beans from all the communities except Nsawora although the level of methamidophos was below the EU MRL in all the four communities. Dimethoate was also detected in cocoa beans from Nsawora and Penakrom while pirimiphos-methyl was detected in Tanoso and Asawinso communities but the levels were below the EU MRLs. Malathion and fenithrothion were detected in Penakrom and Tanoso respectively but their levels were below the EU MRLs. Of the organochlorines only aldrin and chlorpyrifos were detected. Among the five communities, aldrin was detected in only the Nsawora community. Chlorpyrifos was however-, detected in Nsawora, Tanoso and Penakrom communities and the levels were below the EU MRLs. Some traces of banned pesticides (eg. aldrin) were detected in some cocoa bean samples but were below the EU MRLs.  
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A thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements Master of Science degree in Environmental Science.
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