Multivariate Assessment of Water Quality and Associated Health Risks: Integrating Indices to Uncover Pollution Patterns and Sources Around Dass Metropolitan Bauchi, Nigeria

This study assesses groundwater quality and associated health risks in Dass Metropolitan, Bauchi State, Nigeria, using hydro-chemical analysis, multivariate statistics, and health risk models. A total of fifty (50) groundwater samples were collected and analyzed for physicochemical parameters. Thirty (30) samples were analyzed for heavy metal concentrations (Cd, Cr, Hg, Pb, As), from which seventeen (17) representative samples with complete heavy metal data were selected for detailed evaluation using pollution indices and health risk assessment. Water Quality Index results indicate varying degrees of deterioration, with several locations classified as poor to unsuitable for drinking. Heavy metal concentrations, particularly Cd, Hg, and Pb, exceeded WHO guideline limits in multiple samples. Non-carcinogenic health risk assessment revealed hazard indices greater than one in several locations, indicating potential health concerns for local populations. Carcinogenic risk values were in the order of 10<sup>-3</sup> under conservative assumptions (total chromium treated as hexavalent chromium), exceeding acceptable risk thresholds by two orders of magnitude. Principal Component Analysis extracted three components explaining 78.94% of total variance. The first component accounting for 41.80% represents anthropogenic salinity and nutrient enrichment from agricultural and domestic sources. The second component accounting for 24.80% reflects geogenic metal mobilization influenced by pH conditions. The third component accounting for 12.34% indicates lithology-controlled fluoride enrichment from basement rock weathering. The findings demonstrate combined anthropogenic and geogenic controls on groundwater quality and underscore the urgent need for regular monitoring and targeted mitigation strategies to protect public health.