Evaluation of physicochemical characteristics and health risk of polycyclic aromatic hydrocarbons in borehole waters around automobile workshops in Southeastern Nigeria

Abstract

Polycyclic Aromatic Hydrocarbons (PAHs) are environmentally hazardous pollutants that have been linked to severe global health effects in humans as a result of ecosystem pollution. This work investigated the physicochemical parameters, the distribution, and contents of sixteen priority PAHs, the incremental lifetime cancer risk through ingestion, and dermal absorption in bore-hole waters close to automobile workshop in Southeastern Nigeria. A total of 70 bore-hole waters was collected from 6 senatorial zones over 4 months (September–December 2019). Electrical conductivity (EC) ranged from 42 ± 8–83 ± 12 μS/cm. Total hardness (TH) ranged from 4 ± 3–6 ± 2 mg/L. Turbidity ranged from 1.0 ± 0.02–4.3 ± 1.32 NTU and redox potential ranged from 37 ± 3–74 ± 10 mV. The values obtained for pH, salinity, temperature, alkalinity, ammonia, nitrate, sulfate, and phosphate for the water samples were within the World Health Organization (WHO) limits. Liquid-liquid extraction and solid-phase extraction (LLE-SPE) method was utilized for total extraction of PAHs from water samples and analyzed using gas chromatography – flame ionization detection (GC-FID). Individual PAH levels ranged from below the detection limit (BDL) to 33.21 μg/L. Total concentrations of the PAHs varied as BDL–55.11 μg/L have exceeded the maximum admissible concentrations (MAC) of PAHs (0.20 μg/L) for the water standard of the European Union (EU). Diagnostic ratios suggest that target hydrocarbons (HCs) are predominantly from pyrogenic sources. Carcinogenic risks calculated for both adults and children were higher than the United States Environmental Protection Agency (USEPA) acceptable cancer risk, and much higher for children, which suggests that children could be liable to cancer through ingestion.