Abstract

This study investigates the contamination of Polycyclic Aromatic Hydrocarbons (PAHs) in three commercially important fish species—Tilapia zilli, Clarias anguillaris, and Heterotis niloticus—collected from Alau Dam, Konduga, Borno State, Nigeria. The aim was to evaluate the seasonal variations in PAH concentrations and assess potential health risks. Fish samples were collected during both the dry and rainy seasons and analyzed for 16 priority PAHs using Gas Chromatography–Mass Spectrometry (GC–MS). The results revealed significantly higher PAH levels during the rainy season, which were attributed to agricultural runoff and surface water inflows from surrounding areas, including the Sambisa Forest. Health risk assessments, based on Incremental Lifetime Cancer Risk (ILCR), Hazard Quotient (HQ), and Hazard Index (HI), indicated ILCR values ranging from 1.61 × 10?¹² to 1.47 × 10?? mg/kg/day, all of which were below the World Health Organization (WHO) threshold of 1.00 × 10?? mg/kg/day, suggesting minimal cancer risk. Similarly, HQ and HI values for all species were below the international safety limits set by the WHO and the Agency for Toxic Substances and Disease Registry (ATSDR). Compared with the European Union’s permissible limit for benzo(a)pyrene in fish (0.002 mg/kg/day), the observed PAH levels were within acceptable ranges. Although higher concentrations were recorded during the rainy season, the PAH levels in fish from Alau Dam currently pose no significant health risk. Continued environmental monitoring and the implementation of watershed management strategies are recommended to reduce pollution influx and safeguard public health.

Key words: Polycyclic Aromatic Hydrocarbons (PAHs), fish, Alau Dam, benzo(a)pyrene, cancer risk.