Exposure hazards of physicochemical water pollutants in rivers of oil-rich communities of Anambra State, Nigeria

This study examines the exposure hazards posed by physicochemical and heavy metal pollutants in river water from ten rivers across seven oil-rich communities in Anambra State, Nigeria. Standard methods were employed to assess water quality parameters, including total dissolved solids (TDS), electrical conductivity (EC), pH, total alkalinity (TA), total hardness (TH), dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD). At the same time, heavy metals were quantified using Atomic Absorption Spectrophotometry. The results showed that TDS (6.10–268 mg/L), EC (50–167 µS/cm), TA (25.25–50 mg/L), and TH (6–230 mg/L) were generally within World Health Organization (WHO) permissible limits, except for TDS in Utunwali and Omambala Ifite-Ogwari, TA in Omambala Aguleri, and TH in Omambala Umueze Anam, which were below recommended thresholds. pH values (2.5–10) were mostly below the WHO range of 6.5–8.5, except in Ulasi and Aniasa (within limits) and Utunwali (above limit). DO (27.4–41.6 mg/L) and BOD (72–141 mg/L) exceeded WHO guidelines, indicating organic pollution. Heavy metal concentrations followed the trend: Fe > Cu > Zn > Cr > Pb > Co > Mn > Ni > Cd, with notable exceedances in Cr(VI), Cd, and Pb. Cancer risk for adults ranged from 8.48E−07–5.31E−05 and from 1.32E−06–8.26E−05 for children, while non-cancer risk ranged from 0.12 to 0.68 for adults and 0.17–0.99 for children, indicating higher vulnerability in children. The findings reveal pollution hotspots and significant ecological risks, offering a framework for environmental monitoring and policy development aligned with SDGs 3, 6, and 14.