Heavy Metal Pollution in the Ona River and Its Potential Human Health Consequences

Abstract

Aims: This study investigates the levels, sources, and ecological implications of heavy metal contamination in River Ona within its residential catchment area. Methodology: Water and sediment samples were analyzed for Fe, Cu, Ni, Zn, Mg, Mn, and As using standard analytical procedures. The degree of contamination was evaluated using multiple indices, including the Geo-accumulation Index (IGEO), Contamination Factor (CF), Enrichment Factor (EF), Pollution Load Index (PLI), and Ecological Risk Index (ERI). Results: Results revealed moderate to high pollution levels, with arsenic and manganese posing the greatest ecological risks. Health risk assessment showed that the non-carcinogenic Hazard Index (HI) exceeded the safe threshold at all sites, primarily due to magnesium, arsenic, and manganese. The carcinogenic risk (CR) was dominated by arsenic, with total cancer risk (TCR) values far above the USEPA acceptable range, indicating a significant long-term risk of cancer for exposed populations. Conclusion: The study concludes that the river system is under emerging heavy metal stress primarily from industrial effluents, domestic runoff, and agricultural inputs. Regular environmental surveillance and pollution control measures are essential to prevent further accumulation and protect human and ecological health.