Determination of Pesticide Residuals in Soil and Tomato Fruits from Two Tomato Production Areas in northern Ghana

Tomato fruit (Lycopersicon esculentum Mill) is an important vegetable commodity in Ghana, as it is consumed daily in many households either heat-treated or without any form of heat treatments. Tomato production is a major source of income for many smallholder producers in Northern Ghana especially through dry season farming when the major supply of tomatoes from Southern Ghana is exhausted. Research conducted for the past decade confirmed the presence of pesticide residues in fruits and vegetables such as cabbage, onion, cucumber, lettuce, tomatoes, okra and pepper. The objective of this study was to identify and estimate pesticide residual levels in the soil and tomato fruits in comparison with the maximum allowable residual limits. The research was carried out in two production communities namely Doba where the “Burkina” variety is mostly grown in the Kassena Nankana East District of the Upper East Region and Bunglung where the “Wosowoso” variety is cultivated in the Savelugu/Nanton Municipality of Northern Region. Soil samples were collected for residue determination before transplanting of tomato seedlings. Matured and ripe tomato fruits were also collected for the determination of the presence and amount of pesticide residues. All soil and plant samples were analysed using high performance liquid chromatography to determine the presence of twenty-four organochlorines and thirteen organophosphate pesticide residues. From the analysis, pesticide residues were present in different variations which ranged from 0.002 – 0.033 and 0.003 – 0.022 (soils) and 0.330 – 1.187 and 0.002 – 0.088 (fruits) for organochlorines and organophosphates respectively for both communities. Levels of pesticide residues were generally above the acceptable maximum residue limits as farmer practices produced fruits with more pesticide residues since the land areas could have been predisposed with residues from previous seasons for other food crops, which could be translocated into the tomato plant and through into the fruits. The presence of pesticide residues could also be attributed to the influence of run-off and drift from other cultivated lands. For effective determination of pesticides residues in the tomato plants, it is essential to use uncontaminated soil and water to facilitate the efficient estimation of pesticide residues in tomatoes and plants in general.