Petroleum hydrocarbon pollution in the Niger Delta: human health risk assessment of BTEX in biota

Abstract

Based on the context of extensive petroleum hydrocarbon pollution in southern Nigeria, the concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) in seafood were determined, and the health risks of these compounds were evaluated. Biota samples (Crayfish, Goby fish, Moonfish, Mudskipper, Mullet, Sardine and Tilapia) were collected from the Bonny Estuary from 2016 to 2018 and analyzed according to US EPA method 5030/8260C to determine the concentrations of BTEX. Risk assessment of BTEX to humans through the dietary route was conducted based on the lifetime cancer risk (LTCR) for benzene and the hazard quotient (HQ) for BTEX. The following BTEX concentration ranges were observed: benzene: < 0.01–0.36 mg/kg; toluene: 0.22–19.85 mg/kg; ethylbenzene: < 0.00–1.54 mg/kg; xylene: < 0.00–7.28 mg/kg. The median LTCR for benzene in children and adults was 0.65 and 0.30, respectively, which are higher than the limit recommended by the World Health Organization. The model showed that the LTCR is reducible by 99.9% and 66.6% if the concentration of benzene is 0.00001 mg/kg, and fresh seafood consumption is reduced to 10.4 g/day. The HQ for all BTEX compounds was greater than 1 (benzene: 1.0 × 104 (child), 4.9 × 103 (adult); toluene: 1.9 × 105 (child), 9.0 × 104 (adult); ethylbenzene: 9.4 × 103 (child), 4.4 × 103 (adult); xylene: 2.5 × 104 (child), 1.2 × 104 (adult)), which signifies a high non-cancer health risk to humans. These results are a reflection of the high level of petroleum hydrocarbon pollution in southern Nigeria and the debilitating human health consequences that could accompany it.