Heavy metals concentrations in vegetables grown in the vicinity of the closed dumpsite

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.