nvestigation of Levels of Selected Heavy Metals and Associated Health Risks In Tomato (Lycopersicon esculentum Mill) Fruit Produced With Irrigation Water and The Supporting Soil Sample Around Lake Ziway, Ethiopia

Abstract

Tomato (Lycopersicon esculentum Mill.) is one of the most important vegetable worldwide. Tomato fruit is rich in minerals and vitamin and it contribute to a healthy, well-balanced human diet. Today, heavy metals contamination of vegetable including tomato fruits is becoming a human health concern worldwide. The contamination through different food chains is the major pathway of heavy metal exposure for humans and may pose a risk to human health. The aim of this study was to determine the levels of some selected heavy metals in tomato fruit produced with irrigation water and in supporting soil using ICP-OES and to evaluate possible health risks of the metals due to the consumptions of the vegetable. Wet digestion procedure was employed in order to extract the metals from the sample matrix. Method validations were performed by estimating percent recovery (% R), percent relative standard deviation (% RSD), Method Detection Limit (MDL), Method quantification Limit (MQL) values and linearity. The measured % R values are in the range of 80.7 – 123.8% for the tomato and in the range of 93.8 - 121.8 % for the soil samples. The MDL and MQL for the studied heavy metals in tomato sample was falls in the interval of 0.0033 – 0.149 and 0.0063 – 0.156 mg/kg, respectively. Similarly, the MDL and MQL for the studied heavy metals in soil sample was falls in the interval of 0.006 – 0.807 and 0.01 – 1.247mg/kg, respectively. The results of the study showed that the measured mean concentration of heavy metals in tomato samples collected from Adami Tulu Jido Kombolcha (ATJK) and Dugda districts were in range of 79.48 -96.03, 12.47-13.14, 17.16-206.34, 4.25-5.11, 2.97- 15.33, 0.18, < MQL ,1.67-1.78 and 1.99- 8.55 mg/kg for Fe, Mn, Zn, Cu, Cr, Cd , Pb, C o and Ni, respectively. Furthermore, the mean heavy metals concentration measured in soil samples collected from ATJK and Dugda were in range of 10983.62-18713.12, 595.85-1053.21, 50.92-62.07, 11.88-15.79, 9.33-16.84, 1.69-2.70, 141.43- 158.31, 17.81-35.65 and 8.28-15.440 mg/kg for Fe, Mn, Zn, Cu, Cr, Cd, Pb, C o and Ni, respectively. The non-carcinogenic human health risk assessment results have indicated that the measured mean concentration level of chromium cause risk to the health of consumers. Moreover, the estimated results of hazard index (HI) indicated the human health risk due to mixture of the heavy metals. Carcinogenic risk assessment results have showed that there is cancer risk of Cr and Ni due to consumption of tomato collected from districts.