Polycyclic aromatic hydrocarbons in three commercially available fish species from the Bonny and Cross River estuaries in the Niger Delta, Nigeria.

The concentrations and compositional patterns of the USEPA 16 polycyclic aromatic hydrocarbons were investigated in three commercially available fish species, Chrysichthys nigrodigitatus, Cynoglossus senegalensis and Polydactylus quadratifilis, from the Bonny and Cross River systems in the eastern Niger Delta of Nigeria. The objective of the study was to provide useful information on the levels and sources of polycyclic aromatic hydrocarbons (PAHs) and the associated risks with their consumption. The 16 PAHs in the fish samples were extracted by ultrasonication with hexane/dichloromethane, and the concentrations of PAHs in the extracts were quantified by gas chromatography-mass spectrometry. The measured concentrations of the Ʃ16 PAHs in Chrysichthys nigrodigitatus, Polydactylus quadratifilis and Cynoglossus senegalensis ranged from 106 to 491, from 43.1 to 1734 and from 96.4 to 937 μg kg(-1) in the Bonny River system and from 20.0 to 975, from 24.7 to 506 and from 24.9 to 387 μg kg(-1) in the Cross River system, respectively. The compositional patterns of the PAHs showed that the three- and four-ringed PAHs were the major contributors to the PAH burden in these fish species. The diagnostic ratios indicate that the PAHs in these fish samples originated mainly from combustion processes. The health risk assessment, as determined from the benzo[a]pyrene potency equivalent factor, margin of exposure and incremental lifetime cancer risk, indicates that PAHs in the majority of these fish species can induce potential carcinogenic effects.