Institute of Development Studies
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Item Heavy metals accumulation in vegetables grown along the Msimbazi River in Dar es Salaam, Tanzania(African Journals Online (AJOL), 2010) Kihampa, C; Mwegoha, William J. S.Concentrations of cadmium, copper, chromium and lead was determined in four different edible vegetables namely Amaranthus blitum, A. gangeticus, Ipomea batata and Cucurbita maxima grown at four different sites along the contaminated Msimbazi River, Dar es Salaam, Tanzania. Analyses of these heavy metals were conducted using Atomic Absorption Spectrophotometry. Results obtained indicate that the concentrations of heavy metals range from below detection limit to 0.53, 0.14 to 29.08, 0.76 to 17.69, and below detection limit to 39.69 mg/100 g for cadmium, chromium, copper and lead, respectively. With exception to Ipomea batata, other vegetables contained at least two types of heavy metals with high concentrations beyond the permissible values recommended by FAO and WHO for human consumption. Concentrations of cadmium were within the acceptable limits for human consumption in all the vegetables investigated. This work, thus, seeks to provide information on levels of toxic heavy metals in leaves of edible vegetables irrigated with water contaminated by industrial and other anthropogenic effluents, and grown in contaminated soils along the Msimbazi River. The information can be used for monitoring processes to prevent excessive build-up in the food chain.Item Heavy metals concentrations in vegetables grown in the vicinity of the closed dumpsite(International Journal of Environmental Sciences, 2011) Kihampa, Charles; Mwegoha, William J. S.; Shemdoe, Riziki S.Levels of heavy metals cadmium, lead, chromium, zinc and copper in five different edible vegetables, Amaranthus blitum, Vigna unguiculata, Ipomea batata, Solanum nigrum and Cucurbita maxima grown along the slopes of the closed dumpsite were determined using atomic absorption spectrophotometry. The extraction of heavy metals from the vegetables was done by dry ashing methods and data were analysed using Statistical Programme for Social Sciences (SPSS) and Excel computer packages. Results obtained for five heavy metals in vegetables ranged between 0.28 and 1.50 mg/kg dw for cadmium; 0.49 and 20.65 mg/kg dw for lead; 1.15 and 29.39 mg/kg dw for chromium; 18.61 and 122.88 mg/kg dw for zinc and 3.96 and 22.47 mg/kg dw for copper. The levels of Zn, Cr, Pb and Cd were above the permissible levels of heavy metals in food as per FAO/WHO guidelines and Tanzania Bureau of Standards (TBS) standards. This implies that vegetables grown along the closed Mtoni dumpsite are not suitable for human consumption. This study highlights the potential risks involved in the cultivation and consumption of vegetables on plots along the dumpsites and irrigated with water contaminated with leachates effluents, a practice which may place at risk the health of the urban population who consume these vegetables.