Health risk assessment of heavy metals in Tympanotonus fuscatus along Oron water channel, Cross River Estuary, South Eastern Nigeria

Health risk associated with the consumption of contaminated seafood has become of global concern. The study evaluated potential human health risk associated with heavy metal contamination of Tympanotonus fuscatus along Oron water channel Cross River Estuary. The following metals: chromium (Cr), cadmium (Cd), nickel (Ni), lead (Pb) and zinc (Zn) were analyzed using standard procedure. The target hazard quotient (THQ) and cancer risk (TCR) were estimated using USEPA guidelines. Results showed significant differences (p<0.05) in Ni across the sampling period. The principal component analysis (PCA) had 71.2% of the total variance (with PC 1 represented by Ni and Pb and PC 2 dominated by Cd and Zn). The results for THQ and hazard index (HI) were: Cr = 0.95 mg/kg; Ni = 0.12 mg/kg; Zn = 0.16 mg/kg; Cd = 0.06 mg/kg and Pb = 0.69 mg/kg. These values were below the WHO limit of 1.0 mg/kg. This indicated no adverse health effects associated with the consumption of T. fuscatus from the estuary. A high value of TCR (2.15 x 10-3 mg/kg) was recorded for Ni which showed potential ability to induce moderate cancer risk in human over 70 years of consumption. The health risk associated with accumulated metal in tissues of T. fuscatus underscores the need for periodic biomonitoring of the Cross River Estuary. Keywords: Molluscs, Heavy Metal, Risk assessment, Pollution, Cross River Estuary