Landfill Site's Impact on Surface and Ground Water Qualities and Health Risk Assessment at Aba Eku Area, Ona Ara Local Government, Ibadan, Oyo State, Nigeria

Landfilling remains the most common solid waste management method in developing countries due to its economic feasibility. However, poorly engineered landfills pose serious risks to surface and groundwater quality. This study assessed the physicochemical characteristics and heavy metal contamination of water resources around the Aba Eku landfill site in Ona Ara Local Government, Ibadan, Nigeria, and evaluated the potential health risks to nearby residents. Water samples were collected for six consecutive months from three hand-dug wells and surface water sources proximal to the landfill. Standard methods were employed for physicochemical analysis, and metal concentrations were determined using Atomic Absorption Spectrophotometry (AAS). Human health risk assessments for both carcinogenic and non-carcinogenic effects were conducted using United States Environmental Protection Agency (USEPA) models. Results revealed that several parameters including pH, biological oxygen demand (BOD), total hardness, dissolved oxygen (DO), alkalinity, and turbidity exceeded World Health Organization (WHO) permissible limits in both surface and groundwater samples. Heavy metal analysis indicated elevated levels of Fe, Cd, Cr, and Pb in most locations, suggesting leachate migration and pollutant infiltration from the landfill. The calculated Hazard Quotient (HQ) and Hazard Index (HI) values for Cd and Cr exceeded unity (>1), indicating potential non-carcinogenic health risks, while the cancer risk indices (CRI) for Cd and Cr in both adults and children surpassed the acceptable USEPA range (10⁻⁶–10⁻⁴). Children were found to be at greater risk than adults.This study highlights the urgent need for improved landfill management, groundwater monitoring, and community awareness to mitigate contamination and protect public health

Water, Heavy Metals, Physicochemical analysis, Atomic Absorption Spectrophotometer

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