Carcinogenic and non-carcinogenic health risk assessment of heavy metals in water from selected oil pollution-prone communities in the Niger delta region

Abstract

Water is vital to human health, yet its quality is threatened by industrial activity and crude oil pollution. This study evaluated water quality and associated carcinogenic and non-carcinogenic health risks from ten heavy metals for infants, children, teenagers, and adults through oral and dermal exposure routes in selected communities of Edo and Cross River States. A total of 113 samples from boreholes, wells, and a surface water source were analysed for As, Pb, Cd, Cr, Ni, Zn, Fe, Cu, Mn, and Ag using ICP-MS. Health risks were quantified following USEPA protocols. Findings revealed elevated concentrations of Pb (0.03±0.000–0.066±0.001 mg/L), Cd (0.001±0.001–0.011±0.002 mg/L) and Fe (0.301±0.078–0.950±0.000 mg/L) exceeding regulatory thresholds (WHO, SON, and NESREA). Water Quality Index (WQI) classed 13 water sources as “good”, 55 “poor,” 31 “very poor,” and 14 unsuitable for use. Degree of Contamination (C deg ) values (4.23–16.27) and Contamination Factor (CF) values confirmed widespread contamination, particularly from Pb (1.60–9.10), Cd (0.67–4.33), Ni (0.10–2.80), and Fe (0.13–4.01). Pollution Load Index (PLI) values (0.10–0.46) and Nemerow Pollution Index (P n ) values (1.24–2.28) on the other hand suggested no acute pollution. Non-carcinogenic health risks were primarily linked to cadmium (HQ>1), especially for infants, with all 113 samples posing potential risks (HI>1). Total mean cancer risk exceeded the USEPA threshold (1 × 10⁻⁴) in all samples, with infants (1.80 × 10⁻²) being most vulnerable. The contribution of metals to the cancer risk was in the order, Ni>Fe>As>Cr>Cd>Pb. These findings underscore the urgent need for continuous monitoring, effective water treatment, and stricter environmental regulation.