Levels of organochlorine pesticide residues in vegetables, soil, and water from selected agricultural fields in Kumasi

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The levels of organochlorine pesticides residue in cabbage, lettuce, onion, soil around cabbage, soil around lettuce, soil around onion, and irrigation water from five farms at Ayigya, Nsenie, Gyenyase, Kentinkrono were determined to assess the potential health risk associated with exposure to the pesticide residues from vegetables consumption. Sample collection and preparation were conducted using standard procedures. The concentrations of organochlorine pesticide (OCP) residues in the samples were determined using gas chromatograph (Varian CP-3800) equipped with electron capture detector (ECD). A total of fifteen different OCP residues were detected. The residue concentration in vegetables, soil, and irrigation water ranged from <0.01 to 184.10±12.11 µg/kg, <0.01 to 165.20±31.11 µg/kg, and <0.01 to 8.87±0.34 µg/L respectively. Methoxychlor recorded the highest mean concentration of 184.10±12.11 µg/kg in cabbage from Ayigya and beta-HCH recorded the lowest mean concentration of 0.20±0.00 µg/kg also in cabbage from Ayigya. Most of the organochlorine residues detected were below the maximum residue limits (MRLs). Bioconcentration in the fatty tissues of consumers could result in chronic health effects. The differences in residual concentrations of pesticides could be due to different agricultural practices adopted by farmers and also accessibility of the pesticides. Health risk estimation revealed that aldrin in lettuce could pose potential toxicity to the children. The combined risk index showed significant health risk to children. The overall risk index for combined pesticides due to consumption of all the vegetables was higher than 1, which signifies potential health risk to consumers. The carcinogenic risk of the OCP residues in vegetables was of little concern since their carcinogenic rates were below the acceptable risk level
A thesis submitted to the Department of Chemistry,in partial fulfillment of the requirements for the award of Master of Philosophy (MPHIL) in Analytical Chemistry.