Bioaccumulation of heavy metals and assessment of the human health risk of consumption of Clarias gariepinus and Parachanna obscura from the Owan River, Edo State, Nigeria

  • Ijeoma Patience Oboh
  • Benjamin Chima Okpara
Keywords: Heavy metals, bioaccumulation, health risks, hazard index


Consumption of fish is a primary route of exposure to heavy metals that could be detrimental to human health due to the tendency of bioaccumulation and biomagnification along the food chain. The aim of this study was to evaluate the accumulation of heavy metals (Ni, Zn, Pb, Fe, and Cr) in two commercially available fishes, Clarias gariepinus and Parachanna obscura, and to estimate the health risks they pose to humans through consumption. Twenty-four (24) fish samples (triplicates for each month for the two species) were collected between July and October 2017. Heavy metals were identified using the atomic absorption spectrophotometer and the health risk to consumers was evaluated using Estimated Daily Intake (EDI), the Target Hazard Quotient (THQ), and the Hazard Index (HI). The THQ for the individual metals in C. gariepinus and P. obscura occurred in the decreasing order of Cr > Pb > Ni and Cr > Pb > Ni > Fe with risk values of 0.015, 0.004, and 0.001, and 0.014, 0.010, 0.002, and 0.001, respectively. The hazard index for C. gariepinus and P. obscura were 0.021 and 0.027, respectively. The values of the hazard index values of the two fish species were below the threshold value of 1, an indication of no potential health risk to consumers of the fishes. However, with the occurrence of bioaccumulation of metals in the studied fishes, regular monitoring of the river is recommended.