Human health risk assessment of metals and metalloid in food crops harvested from crude oil impacted community in Niger Delta, Nigeria

Abstract

This study evaluated the human health risks associated with consuming food crops contaminated with metals and metalloids in a crude oil–impacted area of the Niger Delta, Nigeria. A total of 48 composite samples (12 each of yam, cassava, cocoyam, and waterleaf) were collected from the Ibaa community and its Right-of-Way (ROW) zone. Edible portions were acid-digested (HNO₃/HClO₄, 3:1) and analyzed for As, Pb, Cd, Cu, and Zn using Graphite Furnace Atomic Absorption Spectrophotometry (GF-AAS; Hitachi Z-2000, Tokyo, Japan). Quality assurance included reagent blanks, certified reference materials, and spike recoveries, with recoveries of 92–107%, RSD < 5%, and detection limits of 1.73 µg/L (Pb), 0.02 µg/L (Cd, Cu, Zn), and 2.0 µg/L (As). Mean concentrations (mg/kg) in crops from the ROW were Pb: 0.0028–0.0118, As: 0.0002–0.0030, Cd: 0.0008–0.0027, Cu: 7.99–9.37, and Zn: 16.17–77.51, while control samples showed significantly lower levels. Principal Component Analysis (PCA) indicated two dominant contamination sources: anthropogenic Pb–Cd inputs from petroleum activities and Cu from agrochemical use. Estimated Daily Intake (EDI) revealed higher exposure in children, with maximum values for Zn (7.9 × 10-1 mg/kg/day), Cu (1.0 × 10-1), and As (9.5 × 10-5) in cocoyam. Target Hazard Quotients (THQ) for Zn and Cu in children exceeded unity, and the Hazard Index (HI) peaked at 5.5 for cocoyam, surpassing the USEPA safety threshold (HI > 1). Total Lifetime Cancer Risk (TLCR) for As reached 1.5 × 10-4, exceeding the acceptable limit (1 × 10-4). These findings demonstrate significant non-carcinogenic and carcinogenic health risks, particularly for children consuming food crops from petroleum-exposed soils. Enhanced regulatory oversight, phytoremediation, and continuous biomonitoring are strongly recommended to mitigate dietary exposure in oil-impacted communities.