Concentrations of organochlorine insecticide residues in selected vegetables in the Sunyani West District of the Brong Ahafo Region of Ghana

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A major practice in agriculture over the last decade is the use of pesticides to protect crops from insects and other pests that negatively affect crop quality and yield. That notwithstanding, these pesticides are often harmful to more than just their target species. Many of the most widely used pesticides have been classified as Persistent Organic Pollutants (POPs). They are applied directly to the crops and some may still be present as residues in or on vegetables and fruits after their harvest, especially where there is abuse, misuse and overuse of the pesticides. The present study was undertaken to determine the concentrations of organochlorine insecticide residues in selected vegetables (carrots, cabbage and green pepper) from three farming communities in Sunyani, in the Brong Ahafo Region of Ghana. Sixty eight farmers were interviewed on insecticide use practices. The field survey revealed the use of some banned insecticides and approximately 38.2% of the respondents mixed two or more insecticides without considering the health implications on humans, animals and the environment. A total of 120 pieces of all three vegetables were obtained from farmers’ fields for analysis. Samples were subjected to extraction, clean-up and analysis by Gas Chromatograph Electronic Capture Detector for organochlorine insecticide residues. Laboratory analysis confirmed the presence of organochlorine insecticide residues in some of the samples analyzed. Overall, percent insecticide residues in carrot, lettuce and cabbage samples were 38%, 28% and 34%, respectively, levels which were below the limits set by the EU, except for heptachlor and mirex which exceeded the limits in some cases. Therefore, vegetables from these farming communities are considered safe for consumption but there is the need for constant monitoring since there could be bioaccumulation of residues in the food chain when vegetables are consumed over a long period.
A Thesis Submitted to the Department of Theoretical and Applied Biology, College of Science Kwame Nkrumah University of Science and Technology, in Partial Fulfilment of the Requirements for the Award of Master of Science (Environmental Science),