Polycyclic aromatic hydrocarbon in community drinking water, Nsisioken, Nigeria: Source and health risk assessment

In 2011, the United Nations Environment Programme discovered high levels of hydrocarbon pollution in drinking water wells in Nsisioken Agbi Ogale Rivers State, Nigeria. However, the level of polycyclic aromatic hydrocarbons (PAHs) in the same community's water supply was unknown. A comprehensive study of PAHs in three household dug wells and three boreholes was conducted using Agilent 7890B gas chromatography and 5975A mass spectrometry. The detected PAHs were mainly 4 - 5 ringed PAHs, such as Chrysene, Fluoranthene, Pyrene, Benzo[a]anthracene, and Benzo[b]fluoranthene. The total mean concentration was 5.8 ± 2.3 μg/L, with values ranging from not detected in borehole 3 to 8.0 μg/L at well 2. Source identification analysis suggested that the PAHs originated from fuel and biomass combustion. The incremental lifetime cancer risk for children and adults due to groundwater ingestion and skin contact ranged from ND to 7.448 × 10-3 and ND to 1.83 × 10-3 respectively. The Risk index (RI) values from ingestion and dermal routes were 1.5 ×10-2 and 2.4 × 10-2, indicating high risk of cancer. The hazard quotient for the two non-carcinogenic PAHs was greater than 1, indicating high toxicity. The PAH concentrations exceeded the maximum contamination limits set by the World Health Organization and the U.S. environmental Protection Agency, highlighting potential health risks associated with water use in the community. Authorities should provide a safe alternative water source for the community.