ABSTRACT

Keywords: contamination; environment; health risk assessment; pesticide residues; vegetables Introduction Pesticides applied to food crops in the field can leave potentially harmful residues. Organochlorine pesticides in particular can persist in foodstuffs for a considerable period. If crops are sprayed shortly prior to harvest without an appropriate waiting period, even organophosphate residues can persist up until the food is in the hands of the consumer (Bull, 1992). In Ghana, the increase in urban population and food demand has catalysed the use of chemical pesticides for food production (Amoah et al., 2006). Vegetables are grown extensively in Ghana, and constitute a large portion of the diet of the average Ghanaian. Vegetables are essential for a healthy and balanced diet, as well as adding variety, interest and flavour to the menu. However, vegetables also attract a wide range of pests and diseases, and can require intensive pest management. About 87% of the farmers who grow vegetables in Ghana use pesticides (Dinham, 2003). Many of these farmers spray the same wide range of pesticides on all vegetables and ignore pre-harvest intervals (Ntow et al., 2006). Sometimes farmers spray pesticides one day before harvest to sell ‘good-looking’ vegetables. This practice, in particular, exposes consumers to pesticides. Though it is sometimes thought that residues are destroyed if food is properly washed and cooked, this is not always the case. Washing and cooking may reduce pesticide residues in food; boiling may remove only 35-60% of organophosphate residues and 20-25% of organochlorines (Bull, 1992). Residues above tolerance limits do occur in cooked food. Consumption of contaminated food is an important route of human exposure to pesticide residues, and may pose a public health risk (MacIntosh et al., 1996).