Assessment of health hazards of selected heavy metals in surface water from contaminated river in Aleto Eleme, Southern Nigeria

This study investigated the levels of some heavy metals (HMs) in surface water samples from River Aleto, located in Aleto-Eleme, Southern Nigeria. The possible health hazards associated with exposure to the selected heavy metals were evaluated. Experimental surface water samples were collected from River Aleto at upstream and downstream locations while midstream surface water samples from Ogharefe River served as Control sample. Surface water samples were analyzed for the concentrations of Cadmium (Cd), Nickel (Ni), Copper (Cu), Arsenic (As), Chromium (Cr), Lead (Pb), Iron (Fe) and Vanadium (V) using atomic absorption spectrophotometry (AAS). Mean concentration of the selected heavy metals in the surface water samples analyzed was in the order: Fe>Pb>Ni>Cd>Cu>Cr>As>V and Fe>Ni>Cd>Cu>Pb>Cr>As>V for upstream and downstream surface water samples respectively. Results obtained for Cd, Ni, As, Pb and Fe in the analyzed water samples from the different sampling locations were above WHO permissible limits for these heavy metals in water samples. Comparatively, downstream surface water samples had higher concentrations of Cd (0.56±0.00 mg/dl), Ni (0.62±0.00 mg/dl), Cu (0.44±0.00 mg/dl) and Fe (5.23±0.00 mg/dl) than upstream surface water samples. Health risk evaluation was performed using Average Daily Dose (ADD), Target Hazard Quotient (THQ), Hazard Index (HI), Life Cancer Risk (LCR) and Total Life Cancer Risk (TLCR), and indicated that the levels of Cd, Ni, Cr, Pb and Fe in surface water from Aleto River poses potential health and carcinogenic risk, via ingestion and dermal contact exposure routes, in adult and children populations. These findings demonstrate that residents of Aleto Eleme are exposed to health risks associated with consumption of heavy metal contaminants in water.