Human Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Water Samples around Eket Metropolis, Akwa Ibom State, Nigeria

Aims: Polycyclic aromatic hydrocarbons (PAHs) are very toxic and persistent environmental contaminants. The paper is aimed at investigating the cancer risk exposure of PAHs in borehole water collected around five automobile repair workshops within Eket metropolis.

Place and Duration of Study: Samples were collected between June - August (2018) in wet season and November (2018) – January (2019) in dry season from boreholes around the vicinity of five automobile repair workshops within Eket metropolis.

Methodology: The water samples were prepared in the laboratory following standard procedures and analysed for 16 United States Environmental Protection Agency (US EPA) priority PAHs using Gas Chromatography–Mass Spectrometer (GC–MS). A total of fifteen PAH congeners were detected in the samples.

Results: Total PAHs concentrations in borehole water from all sampling sites were in the range of 1.71–16.07 mg/L and 1.07–12.97 mg/L for both dry and wet seasons respectively. The low PAHs levels recorded in water for the wet season was linked to dilution effect. Low molecular weight PAHs were more dominant in all samples. The estimated cancer risks of exposure to PAHs by ingestion in the water samples ranged from 7.10 × 10-7 to 1.12 × 10-4 and 6.76 × 10-6 to 3.69 × 10-1 for adults and children respectively in both seasons. The estimated cancer risks due to dermal exposure to PAHs in the water samples ranged from to 7.18 × 10-3 to 1.07 × 10-1 and 5.67 × 10-3 to 1.08 × 10-1 for adults and children respectively in both seasons.

Conclusion: Carcinogenic risks due to dermal exposure calculated for both adults and children were higher than the US EPA acceptable cancer risk and much higher for children, which suggest that children could be prone to cancer and need to be monitored.