Assessment of Organochlorine Pesticide Residue Levels in Watermelon Grown in Ada-West District of Ghana

Abstract

The study which aimed at assessing the levels of organochlorine pesticide (OCP) residues in watermelon was conducted in two parts; a field survey and laboratory work. The field survey involved the use of semi- structured questionnaires administered to 60 farmers in four selected communities in Ada-West district of Ghana. Laboratory work involved the use of Soxhlet Apparatus and CP-3800 Gas Chromatograph eguipped with a 63Ni electron capture detector to investigate the levels of pesticide residues in samples of watermelon. Data was analysed with SPSS version 23 and Microsoft Excel statistical tools. The survey results showed that 15 pesticides with different trade names were used by farmers, of which 66.67 % were insecticides and 33.33 % were fungicides and these chemicals were used in various cocktail forms. Although the survey results showed that many of the farmers did not observe the correct or any pre-harvest interval as exactly 25 % of the farmers harvested the same day after pesticide application, results from the laboratory analysis revealed that the mean levels of the detected pesticide residues in peel, pulp and seeds of watermelon were below residue limits (MRL) set by WHO/FAO and EU. Most of the OCP residues investigated were below the limit of detection of 0.01ng/g. The highest mean level of 2.10 ng/g of p’p-DDE was recorded in seeds of watermelon from Koluedor. The lowest mean level of 0.20 ng/g of dieldrin and p’p-DDE were recorded in peel of watermelon from Sege. As these toxic chemicals have the potential to bioaccumulate, their presence is therefore undesirable and of great concern. It is recommended that regulatory authorities should ensure compliance and enforcement of the laws on the use of banned and restricted pesticides. A constant and regular monitoring programmes through residue level assessment at the sampling sites is recommended due to the changing trends of insecticide usage.