Assessment of Polycyclic Aromatic Hydrocarbon Concentrations and Heavy Metal Profile of Traditional Drum-Smoked and Convective Kiln-Smoked Bonga Shad and Nigerian Tongue Sole

Abstract

This study assessed the polycyclic aromatic hydrocarbon (PAH) concentrations and heavy metal profile of traditional drum-smoked and convective kiln-smoked Bonga shad and Nigerian tongue sole. Forty samples of fresh Bonga shad and Nigerian tongue sole were purposively collected from twenty processing centers in Lagos State. The samples were divided into two batches with each batch smoked using traditional drum and kiln methods. Chemical PAHs and heavy metals (lead, mercury, cadmium, and chromium) were analyzed. Results showed that the concentrations of major PAHs fluorene, anthracene, benzo(b)fluoranthene, benzo(a)anthracene, benzo(a)pyrene, and benzo(ghi)perylene were as follows: for Bonga shad, 0.54 ± 0.03, 0.56 ± 0.07, 0.59 ± 0.07, 0.54 ± 0.04, 0.53 ± 0.04, and 0.57 ± 0.01, respectively and for Nigerian tongue sole, 0.48 ± 0.06, 0.62 ± 0.03, 0.57 ± 0.03, 0.56 ± 0.06, 0.62 ± 0.08, and 0.61 ± 0.08 mg kg−1, respectively for drum-smoked samples while for kiln-smoked samples, the values were: for Bonga shad, 0.43 ± 0.13, 0.52 ± 0.08, 0.37 ± 0.11, 0.36 ± 0.13, 0.34 ± 0.20, and 0.38 ± 0.23 and for Nigerian tongue sole, 0.41 ± 0.18, 0.49 ± 0.06, 0.37 ± 0.11, 0.37 ± 0.10, 0.28 ± 0.07, and 0.34 ± 0.13 mg kg−1, respectively. The values for drum-smoked fish samples exceeded the maximum permissible level of 0.5 mg kg−1 (Regulation EU 1272/2013). Lead, mercury, cadmium, and chromium contents of drum-smoked Bonga shad and Nigerian tongue sole were 0.12 ± 0.03, 0.20 ± 0.04, 0.22 ± 0.05, and 0.10 ± 0.03, respectively and 0.15 ± 0.04, 0.13 ± 0.04, 0.19 ± 0.05, and 0.12 ± 0.04 mg kg−1, respectively while the values for kiln-smoked Bonga shad and Nigerian tongue sole were 0.16 ± 0.05, 0.19 ± 0.05, 0.24 ± 0.05, and 0.12 ± 0.03, respectively and 0.18 ± 0.04, 0.15 ± 0.04, 0.19 ± 0.05, and 0.16 ± 0.04 mg kg−1, respectively which were within safety limits of World Health Organization. The smoking methods and fish types had significant difference on PAHs (t = 8.326, df = 5.0, p = 0.0002). In conclusion, the study showed that drum-smoked fish had higher chemical contaminants when compared with kiln-smoked fish and could pose health risks to consumers if not appropriately monitored.