DETERMINATION OF HEAVY METAL CONCENTRATIONS IN VEGETABLES IRRIGATED WITH MIXTURES OF WASTEWATER AND SEWAGE SLUDGE IN ARUSHA MUNICIPALITY: IMPLICATIONS FOR HUMAN HEALTH

The present study was conducted to assess the heavy metals (Cu, Cd, Pb, and Cr) concentrations in wastewater used by vegetable small-scale farmers for irrigation. The concentration of heavy metal from soil and vegetables (Amaranths sp and Ipomoea sp) as a result of wastewater irrigation around Arusha Municipal wastewater stabilization pond were determined using Flame Atomic Absorption Spectrophotometer (FAAS). The results obtained from the edible parts of sampled vegetables (Amaranths sp and Ipomoea sp) in this study, showed concentrations of heavy metals (Cr, Cd, Pb, and Cu) was (1.40, 4.21), (309.87, 152.60), (0.50, 0.48), (281.69, 248.54)(mg /Kg) respectively. This result reflected the risk associated with exposure for the period of life expectancy considered, and the inhabitants are highly exposed to health risks associated to these metals in the order Cd was 225.121and 457.132, Cu was 9.17 and 10.39; Pb were 0.7081 and 0.7081 and Cr was 0.0014 and 0.0041, for Amaranths sp and Ipomoea sp respectively. The THQ in Cd and Cu is greater than one while other metals are less than 1 in all the vegetables species.  Therefore, Cd and Cu pose a health risk to consumers, while other metals do not pose serious health risk concern. However, vegetable consumption was just one part of food consumption, the potential health risks for residents might actually be higher than in this study when other routes of heavy metals intake are considered.