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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/9795

Title: Pesticide and Pathogen Contamination of Vegetables in Ghana’s Urban Markets
Authors: Amoah, P.
Drechsel, P.
Abaidoo, R. C.
Ntow, W. J.
Issue Date: 2006
Publisher: Arch. Environ. Contam. Toxicol.
Citation: Arch. Environ. Contam. Toxicol. 50, 1–6 (2006) DOI: 10.1007/s00244-004-0054-8
Abstract: The objective of the study was to determine and compare the current level of exposure of the Ghanaian urban population to hazardous pesticide and fecal coliform contamination through the consumption of fresh vegetables produced in intensive urban and periurban smallholder agriculture with informal wastewater irrigation. A total of 180 vegetable samples (lettuce, cabbage, and spring onion) were randomly collected under normal purchase conditions from 9 major markets and 12 specialized selling points in 3 major Ghanaian cities: Accra, Kumasi and Tamale. The samples were analyzed for pesticide residue on lettuce leaves, total and fecal coliforms, and helminth egg counts on all three vegetables. Chlopyrifos (Dursban) was detected on 78% of the lettuce, lindane (Gamalin 20) on 31%, endosulfan (Thiodan) on 36%, lambdacyhalothrin (Karate) on 11%, and dichloro-diphenyl-trichloroethane on 33%. Most of the residues recorded exceeded the maximum residue limit for consumption. Vegetables from all 3 cities were fecally contaminated and carried fecal coliform populations with geometric mean values ranging from 4.0 · 103 to 9.3 · 108 g–1 wet weight and exceeded recommended standards. Lettuce, cabbage, and spring onion also carried an average of 1.1, 0.4, and 2.7 helminth eggs g–1, respectively. The eggs were identified as those of Ascaris lumbricoides, Ancylostoma duodenale, Schistosoma heamatobium, and Trichuris trichiura. Because many vegetables are consumed fresh or only slightly cooked, the study shows that intensive vegetable production, common in Ghana and its neighboring countries, threatens public health from the microbiologic and pesticide dimensions. Standard recommendations to address this situation (better legislations, law enforcement, or integrated pest management) often do not match the capabilities of farmers and authorities. The most appropriate entry point for risk decrease that also addresses postharvest contamination is washing vegetables before food preparation at the household or ‘‘chop’’ bar (street restaurant). Sub-Saharan Africa is one of the regions most affected by urbanization. It has an annual growth rate of 2.8% in the total population and 5.8% in the urban population (World Bank 2000). In Ghana, the urban population is growing at an estimated annual rate of 4.2% compared with the overall population growth of 2.7% (Ghana Statistical Service 2002). The increase in urban population and food demand has catalyzed the use of urban open spaces for food production (‘‘urban agriculture’’). A typical expression of urban agriculture is the production of perishable high-value crops such as most exotic and some traditional vegetables. Because the demand for these vegetables is not seasonal, farmers attempt yearround production wherever irrigation water is available. This takes place closest to the urban markets on unused spaces in the urban environment. The production is input and output intensive with several harvests per year and depending heavily on irrigation, manure, and pesticide application. The use of potable water for vegetable production is constrained because > 40% of city dwellers in Ghana are still without good drinking water. Therefore, the irrigation water used by these farmers is derived from different urban sources including drains, which are often highly polluted because no or little option exists for water treatment (Keraita et al. 2002). Another potential health risk derives from the use of pesticides, although this is beneficial in decreasing crop loss both before and after harvest (Clarke et al. 1997). Despite the recognition of urban agriculture as a source of urban food security, concern has been growing among city authorities. Efforts have been made toward safer cultivation of vegetables in Ghana (Sonou 2001) although few data exist on the actual gravity of the problem for guidance of appropriate interventions or policy formulation. Therefore, to assess the public health implications, this investigation went beyond water analysis and aimed to assess the hygienic quality of irrigated vegetables produced and sold in major cities of Ghana. The objective was to determine the current level of exposure of the Ghanaian local population to fecal microorganisms and hazardous pesticides. The study is part of a larger investigation cofunded by the International Water Management Institute (IWMI) and International Development Research Centre (IDRC-AGROPOLIS), both of which target contamination at farm gates and markets as well as develop strategies to decrease health risks at different entry points (e.g., water source, farm, markets, households).
Description: An article published by Arch. Environ. Contam. Toxicol. 50, 1–6 (2006) DOI: 10.1007/s00244-004-0054-8
URI: http://hdl.handle.net/123456789/9795
Appears in Collections:College of Science

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