Levels of polycyclic aromatic hydrocarbons in borehole waters around automobile workshops in Southeastern Nigeria and their health risk assessment
Polycyclic Aromatic Hydrocarbons (PAHs) are hazardous pollutants in water and have been reported to cause severe health effects in humans due to 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 a period of 4 months (September – December, 2016). Liquid-liquid extraction (LEE) method was utilized for total extraction of PAHs from water samples and analyzed using gas chromatography – flame ionization detection (GC-FID). 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 World Health Organization (WHO) limits. Individual PAH levels ranged from below 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 European Union (EU). Although non-carcinogenic risk of PAHs estimated through dermal absorption was very low compared with the target value while carcinogenic risk determined was high for both adults and children. Diagnostic ratios suggest that target hydrocarbons (HCs) are predominantly from pyrolytic sources. It therefore could be inferred that the borehole water is conspicuously polluted; hence, efforts should be made to control all activities contributing to such magnitude of pollution at the sites.