Health Risk Assessment of Heavy Metal Contamination of Groundwater Around Nnewi Industrial Area, Anambra State, Nigeria

Abstract

The influence of water quality from boreholes situated around the Nnewi industrial area was evaluated by assessing the heavy metal concentrations and health risks associated with human exposure. Water samples were collected from 16 different boreholes around eight industries at a monthly interval from May – October 2019 and November 2019 – April 2020 to cover the rainy and dry seasons, respectively. Water samples were analyzed for copper (Cu), lead (Pb), iron (Fe), zinc (Zn), chromium (Cr), and arsenic (As) using atomic absorption spectrophotometer (AAS). The results were compared with the World Health Organization (WHO) standards. Data obtained for both seasons indicate Cu had a mean value of (0.268±0.136 mg/L), Pb (0.014±0.013 mg/L), Fe (0.119±0.133 mg/L), Zn (0.572±0.220 mg/L), Cr (0.051±0.011 mg/L), and As (0.013±0.001 mg/L) respectively. All the heavy metal concentrations of the sampled water were within their various WHO permissible limits except As, Cr and Pb. The pollution index of As, Cr and Pb were greater than 1, showing heavy contamination of the water. Carcinogenic risk assessment of water via ingestion and dermal route for Cr and As were above the recommended safe limit of 1×10^-6 which posed a cancer risk. The results show that borehole waters were contaminated with heavy metals in both seasons. It is, therefore, recommended that borehole water from the study areas should be treated before being used for various domestic purposes.