Health Risk Assessment of Heavy Metal Contamination in Water Sources at Michael Okpara University of Agriculture

Abstract

This study evaluates the concentrations of heavy metals in water sources at Michael Okpara University of Agriculture and their associated health risks using Average Daily Intake (ADI), Hazard Index (HI), and Incremental Life Cancer Risk (ILCR) models. A total of 15 water samples were collected from five different locations within the university using acid-washed polyethylene bottles. The samples were analyzed using Atomic Absorption Spectroscopy (AAS) to determine the concentrations of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni), and lead (Pb). The measured concentrations ranged from 0.015–0.052 mg/L for As, 0.006–0.0173 mg/L for Cd, 0.075–0.127 mg/L for Co, 0.0077–0.015 mg/L for Cr, 0.0142–0.031 mg/L for Ni, and 0.0035–0.006 mg/L for Pb. Compared to regulatory standards, As and Cd concentrations exceeded the WHO limit of 0.01 mg/L and 0.003 mg/L, respectively, in multiple locations, posing significant health concerns. The ADI results showed that As had the highest dermal exposure value (5.43E-08 mg/kg/day), while Cr exhibited the highest ingestion exposure (4.28E-09 mg/kg/day). HI values for Cr (5.22E-03) and As (4.90E-04) suggest potential non-carcinogenic health risks, particularly through dermal absorption. ILCR analysis identified As as the most carcinogenic contaminant (1.04E-07), significantly surpassing the acceptable risk threshold of 1.0E-06. Site 2 exhibited the highest heavy metal contamination levels, aligning with elevated health risk assessments. These findings emphasize the need for water treatment interventions, enhanced regulatory oversight, and community awareness to mitigate contamination risks and safeguard public health.