Levels of Organochlorine Insecticide Residues in Fresh Tomatoes from some Selected Farming Communities in Navrongo, Ghana

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The concentrations of organochlorine insecticides residues in five tomato varieties from three farming communities in Navrongo (Bonia, Korania and Nangalkenia) were determined using gas chromatography in January and February 2011. A total of nineteen different organochlorine insecticides were detected, with at least five different residues in each sample. The residues were detected in the range of 0.0038 to 15.9007μg/kg. Beta HCH recorded the highest mean concentration (15.9007 μg/kg) at Korania and Cis-chlordane recorded the lowest mean concentration of 0.0038 μg/kg at Nangalkenia. The mean concentrations of heptachlor, delta HCH, gamma HCH (Lindane), beta HCH and p, p-DDT were relatively higher than the other organochlorine pesticides detected. Cis-heptachlor epoxide, oxychlordane, Cis-chlordane, hexachlorobenzene, and Cis-Nonachlor were not detected in most of the samples. Two of the organochlorine insecticide residues detected (beta HCH and delta HCH) exceeded the UK/EC Maximum Residue Limits (MRLs). Although, almost all the organochlorine residues detected were below the UK/ EC MRLs, bioconcentration in the fatty tissues of consumers could result in chronic health effects. A pair-wise comparison among concentrations of the organochlorine insecticides in the varieties indicated no statistically significant differences in concentrations. Questionnaire survey indicated that most tomato farmers do not experience any health problems that can be associated with pesticide use. In view of the damaging effects on human health and the environment, regular monitoring and analysis of organochlorine residues in the study area is recommended.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the Degree of Master of Science in Environmental Science