Carcinogenic and Non-carcinogenic Health Risk Assessment of Heavy Metals in Njaba River, Imo State, Nigeria

Abstract

Daily exposure to potentially toxic elements (heavy metals) through the oral ingestion of water has been a major concern to human health due to its detrimental effects. Studies focusing on health risk assessment of potentially toxic elements in surface and ground waters have been conducted, but none has been reported in Njaba River. Few studies conducted have focused only on the assessment of its water quality. Therefore, this study assessed the carcinogenic and non-carcinogenic effects of the potentially toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) in Njaba River. Overall, a total of 135 water samples was collected for this study and were analyzed using Agilent FS240AA AAS. The potentially toxic elements concentrations were: As (0.015±0.001 to 0.021±0.001 mg L-1), Cd (0.006±0.002 to 0.018±0.002 mg L-1), Cr (0.027±0.001 to 0.074±0.001 mg L-1), Cu (0.016±0.002 to 0.033±0.001 mg L-1), Ni (0.031±0.001 to 0.053±0.002 mg L-1), Pb (0.050±0.002 to 0.092±0.001 mg L-1), and Zn (0.061±0.002 to 0.097±0.002 mg L-1). As, Ni and Pb recorded concentrations above their respective maximum permissible limits. Physicochemical parameters were appraised using the American Public Health Association standard method (APHA). The evaluation of the carcinogenic and non-carcinogenic health risks of the analyzed elements was carried out based on the guidelines of the USEPA. The hazard index values for children via upstream, midstream and downstream sample points were 0.0000128, 0.00000895 and 0.0513 respectively, while the hazard index values for adults via upstream, midstream and downstream sample points were 0.00000551, 0.00000395 and 0.00000581 respectively. The health risk estimation showed that the hazard quotients were within acceptable limits. The total cancer risks of potentially toxic elements were generally within the range of tolerable risk for adults and above the range of tolerable risk for children.