Investigation Of Levels Of Selected Heavy Metals And Associated Human Health Risks In Fish Samples From Gafarsa Reservior Oromia, Ethiopia

Abstract

Aquatic foods (e.g., fish food) is among the priority concern as the pathway through which humans exposed to considerable amount of trace heavy metals and become vulnerable to the metals caused human health risks. Nine heavy metals including Fe, Pb, Zn, Cd, Cu, Cr, Mn Ni, and Co were quantified in different organs of fish (gill, muscle and liver) of fish species (C. carpio) collected from Gafarsa Reservoir, Oromia, Ethiopia. The levels of these heavy metals were quantified by flame atomic absorption spectrometry after preparing the samples using wet digestion method. The fish organs were digested, each of the powder samples was then transferred into a digestion flask where a mixture with HNO3 (65%) and hydrogen peroxide (30%), prepared in a 3:1 (v/v) ratio was added and also HClO4 in polypropylene vial. Hazard quotient (HQ) was calculated to assess risk of the metals to the consumer's health. The mean concentrations measured were 5.95±0.581-40.43±1.778, 2.25±0.687-5.05±0.229, 54.45±3.33- 131.33±5.121, 5.51±0.115-7.00±0.953, 7.93±0.840-18.46±2.814, 4.78±1.674-19.23±12.07, 10.40±1.19-46.90±0.687, 17.75±0.912-55.53±6.915 and 7.46±0.490-18.33±0.981 mg/kg for Fe, Pb, Zn, Cd, Cu, Cr, Mn, Ni, and Co, respectively. The concentration levels of the studied heavy metals generally the highest in the liver followed by gill, but in muscle the lowest mean values of the metals were observed. In all samples the concentration of heavy metals compared to available quality guideline value is higher than permissible limit. THQ of all metals were below 1, except cobalt these results indicated that Co can pose non-carcinogenic human health risk. The carcinogenic risk associated with fish consumption by human was also assessed. The elevated value of target cancer risk (TCR) for Pb (5.9×10−4), Cd (6.2×10−2) Cr (7.03× 10−2) and Ni (8.8×10−2) were higher than the acceptable risk limit (1×10−6) indicated that the inhabitants consuming the fish from Gafarsa Reservior were exposed to Pb, Cd, Cr, and Ni pollution with a lifetime carcinogenic risk. The result of one-way ANOVA analysis each fish sample showed that there are statistically significant differences (p˂0.05) in their heavy metal concentration. Since HQ values was more than one in all organs, therefore there are health effect on humans