Assessment of water quality for suitability and human health risk: a study of the Owan River, Edo State, Nigeria

Suitability assessment of water bodies for human consumption and its implication on human health is critical to water resources utilisation and sustainable development. This study investigated the water quality of the Owan River and the potential health risk to users. Examined physico-chemical parameters were within the Nigerian National Environmental Standards and Regulation Enforcement Agency permissible limits, except for the lead concentration. Water quality index values (Water Quality Index: 84.50–316.20) indicated that surface water from the sampling locations were of poor quality and unsuitable for drinking (Water Quality Index: > 50). The comprehensive pollution index values (Comprehensive Pollution Index: 0.31–0.57) indicate the water is sub–clean to slightly polluted. Evaluated non–carcinogenic risk to human health showed that children in the receptor population were predisposed to risk from heavy metals through oral ingestion (Oral Hazard Index: > 1), while the water was safe for dermal contact (Dermal Hazard Index: < 1) for adults and children. Integrated carcinogenic risk values classified the surface water as Grade IV (Medium risk), with cadmium having the highest carcinogenic risk. Cadmium accounted for approximately 94% of the total carcinogenic risk and hence a concern for public health. Natural runoff and anthropogenic activities were identified as sources of pollutants within the watershed. The study has provided data for water resource quality monitoring and public health management.