Risk assessment of heavy metals and polycyclic aromatic hydrocarbons in surface water and white croaker fish from bonny river, Southern Nigeria

This study evaluated the proximate profile of fish and levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in selected seafood and surface water from Bonny River in Rivers State, Nigeria. The laboratory analyses were done using standard methods. Proximate analysis of sampled fish parts showed fish skin to be richer in moisture and crude protein content. The physicochemical parameters of surface water obtained from Bonny River showed values within USEPA recommended standards. The mean concentration of heavy metals varied across the analyzed samples, although Hg was below detectable limits in all the samples.  PAH in surface water samples and fish muscle recorded mean values of 107.82mg/kg and 29.93mg/kg respectively. Surface water sample recorded total carcinogenic PAHs of 12.75mg/kg which constituted 11.83% of the total PAHs in the surface water sample. Comparatively, fish skin showed lower level of total PAHs, recording 2.50mg/kg (8.31% carcinogenic) as compared with fish muscle which had 6.31mg/kg (21.07% carcinogenic). All samples analyzed showed B[a]P levels below detectable limits. Calculated Chronic Daily Intake Dose (CDI ingest) and Hazard Quotient (HQ) in the sampled fish revealed Hazard Index of 1.35 in fish muscle in exposed adult population, with minimum Total Life Cancer Risk (TLCR) of 2.54E-05 recorded for fish skin. Values obtained were above standards stipulated by USEPA. The study revealed significant presence of heavy metals and PAHs in white croaker fish and surface water samples. This could pose serious public health concern as results indicated probabilistic risk for both carcinogenic and non-carcinogenic adverse health effects.