HUMAN HEALTH RISK ASSESSMENT OF HEAVY METALS IN CASSAVA TUBERS FROM QUARRY SITES IN OLD NETIM, AKAMKPA LGA, CROSS RIVER STATE, NIGERIA

This study investigated the human health risk assessment of heavy metals in cassava tubers cultivated within three quarry sites in Old Netim, Akamkpa LGA, Cross River State, Nigeria. Soil and Cassava tubers were obtained from three (3) quarry sites of 4.5km apart and 20km from the Control at Oban Okoroba. Composite of soil samples from 0km, 0km, 0.3km, 0.6km and 0.9km were obtained at a depth of 15cm using soil auger while the cassava samples were obtained using a spade. The concentration of heavy metals was determined by Atomic Absorption Spectrophotometry (AAS). Results showed Lead (Pb), Cadmium (Cd), Copper (Cu), Arsenic (As) and Manganese (Mn) had relative abundance in the order Mn > Cu > Pb > As > Cd across all locations and samples. Maximum levels of Mn and Cu were present in cassava tubers obtained from quarry site C (78.651 ± 10.048 mgkg-1 and 7.138 ± 3.203 mgkg-1), while that of Pb, As, and Cd were present in cassava tubers obtained from quarry site D (2.018 ± 1.251 mgkg-1, 0.195 ± 0.205 mgkg-1, and 0.167 ± 0.116 mgkg-1 respectively). Bioaccumulation Factor (BF) of heavy metals from soil to cassava tubers revealed high accumulation of Mn with BF > 1 in tubers across all quarry sites. Estimated daily intake (EDI), Target Hazard Quotient (THQ), and Life Carcinogenic Risk (LCR) showed consumption of cassava tubers cultivated within quarries in Old Netim is safe and free of non-carcinogenic and carcinogenic hazards. However, THI revealed the possible emergence of a non-carcinogenic threat with continuous consumption of these local tubers.