Water Quality Index and Health Risk Assessment of Groundwater Resources Around the Markets’ Sanitation Facilities in Abeokuta Metropolis, Southwestern Nigeria

Abstract

Groundwater is a sustainable resource that provides potable water for millions of people. Contamination of this resource may, therefore, pose serious health threats to consumers. This study aimed at assessing the water quality index and health risk of groundwater resources around the vicinity of markets’ sanitation facilities in Abeokuta metropolis, southwestern Nigeria. Fifty hand-dug wells of the varying distance of 10 – 81 m to the sanitation waste containers from ten markets in the Abeokuta metropolis were seasonally monitored at wet and dry seasons. Five hand-dug wells from a community with no waste disposal facility were sampled to serve as a control. Groundwater samples were collected and analysed for physical and chemical parameters using the standard method. Data were subjected to descriptive and inferential statistics. Water quality index and health risk assessment (non-carcinogenic hazard quotient [HQ], and cancer risk [CR]) were estimated in groundwater. Significantly higher levels of total dissolved solids, electrical conductivity, dissolved oxygen, biological oxygen demands, and heavy metals were observed in groundwater from the market area than in the control site. Furthermore, the WQIs of groundwater from the market areas were higher than 300, indicating unfit water for drinking. The health risk assessment showed high HQs greater than the acceptable limit of 1.0 for Mn and Pb, establishing non-carcinogenic adverse health effects. Co also indicated carcinogenic effects in the market area groundwater with a CR value greater than the permissible limit of 1.0 x 10-4. This study established the detrimental effects of market wastes on the surrounding groundwater.

Keywords: waste disposal, groundwater quality, health risk, regression model