Bioaccumulation and risk of polycyclic aromatic hydrocarbons (PAHs) in Tiga dam fish

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants known for their persistence, toxicity, and potential health risks. Understanding their bioaccumulation in aquatic ecosystems is crucial for assessing environmental and human health hazards. This study examines the concentrations, toxic equivalency factors (TEFs), and human health risks associated with polycyclic aromatic hydrocarbons (PAHs) in fish samples collected from Tiga Dam, Kano State, Nigeria, during both rainy and dry seasons. Four fish species (Tilapia zilli, Oreochromis niloticus, Clarias anguillaris, and Heterotis niloticus) were analyzed for PAH contamination in their flesh, gills, liver, and intestines. PAH concentrations were determined using gas chromatography equipped with a flame ionization detector (GC-FID). The mean concentrations of total PAHs in Tilapia zilli ranged from 3.00E-03 to 7.39E-02 mg/kg in liver tissue, while concentrations in Oreochromis niloticus liver ranged from 2.66E-02 to 3.44E-01 mg/kg. The highest BaP equivalent concentration (BaPeq) was observed in the intestines of Tilapia zilli during the dry season, with a value of 1.64E-01 mg/kg. Hazard quotient (HQ) values for non-carcinogenic risk assessment exceeded the safety threshold (HQ > 1) in several fish tissues, particularly in the liver and intestines of Tilapia zilli and Oreochromis niloticus. Incremental lifetime cancer risk (ILCR) values also suggested significant carcinogenic risks, with ILCR values exceeding the acceptable risk level of 1.00E-05 in liver and intestinal tissues for Heterotis niloticus. This study highlights the seasonal and tissue-specific accumulation of PAHs in fish from Tiga Dam, with potential health implications for consumers. This study reveals significant seasonal bioaccumulation of PAHs in fish from Tiga Dam, with liver and intestines showing the highest contamination. The associated health risks highlight the need for continuous monitoring and regulatory action to protect consumers and the environment.