Lipophilicity of mercury and genotoxicity of polycyclic aromatic hydrocarbon (PAHs) in selected fishes at Port Harcourt metropolis, Nigeria

Godson Ndubuisi Iwuoha and Temple Nwoburuigwe Chikwe

Abstract

This research evaluates the lipophilicity and toxicity of (methyl) mercury in two fishes namely; Catfish and Bonga fish samples from three different sampling locations in Port Harcourt metropolis. The genotoxicity of PAHs in the fresh and smoked/dried fish was also investigated. The mercury loadings were determined using the cold vapor Atomic Absorption spectrophotometer and PAHs analysis was carried out using a Gas Chromatography-Flame ionization Detector (GC-FID 6890 model). The three sampling market locations are at Alakahia, Rumuokoro and Borokiri (Greek road) all in PortHarcourt Metropolis Rivers state Nigeria. The results obtained for mercury loadings showed that the average mercury in the form of methyl mercury is slightly higher in the Bonga (0.0614mg/kg) fish (fresh and dried/smoked) than in Catfish samples (0.0474mg/kg). This could be attributed to the relatively higher fat content of Bonga fish than that of catfish. However, both are below the WHO/FAO maximum permissible limits of 0.5 to 1.0 mg/kg in seafood. Methyl mercury will bioconcentrate, bioaccumulate and biomagnify more in Bonga fish due to its lipophilicity in higher fat content making continuous consumption of Bonga fish and Catfish as well risky to children and fetuses. There seems to be no threat of genotoxicity of PAHs in all the fishes as their respective loadings in the fish samples are below the detection limits of the instrumentation used i.e. 0.01mg/kg.