Risk Assessment of Heavy Metals in Imported Frozen Fish Scomber scombrus Species Sold in Nigeria: A Case Study in Zaria Metropolis

Abstract

This study assesses the likely health risks to human contamination of heavy metals from fish consumption. The analysis of the idea of fish destination and status (fishing area) for heavy metals was determined by the assessment of its risk limits (daily intake of metal and health risk index). Variations in the accumulation of heavy metals concentrations were between various tissues/organs (skin, muscle, gills, liver, intestine, kidneys, brain, and bones) across the batches of two fishing origins. Post hoc (Duncan) multicomparison shows that there are significant differences ( < 0.05) across batches. The concentrations of heavy metals analyzed, in the investigated tissues of Scomber scombrus, showed higher levels of heavy metals accumulations in the order: Fe > Hg > Pb > Cd > Ni and were above the recommended safety limits outlined by FAO/WHO. However, the consumer's health risk with the consumption of fish muscles tissues shows that there are greater tendencies for cadmium, lead, and mercury exposure. Also consumption of Scomber scombrus species above the recommended daily intake (stated in this study) might lead to ingestion of heavy metals at unacceptable concentrations.

Risk Assessment of Heavy Metals in Wild and Farmed Clarias gariepinus (Burchell, 1822) in Zaria, Kaduna State, Nigeria

“…Statistical analysis showed that there's no significant difference (P < 0.05) between both groups, thus the path of contamination is homogenous. The liver and kidney in wild C. gariepinus accounted for Fe concentrations (0.98mg.kg -1 and 0.85mg.kg -1 , respectively) which were above the FAO/WHO standard safety limits (0.8 mg.kg -1 ) but were remarkably lower when compared to results obtained by Abubakar et al (2015) where they showed Fe concentrations as high as 375.93mg.kg -1 in the liver, 225.25mg.kg -1 in the gills, 15.89mg.kg -1 in the skin, 11.44mg.kg -1 in the muscles, all in Scomber scombrus imported into Nigeria from Russian and European shipping origins. Their report was synonymous with those of Erhan et al (2004) who recorded Fe concentrations of 200.86mg.kg -1 in liver tissues of Liza abu and Bashir et al (2013) showed Fe concentrations of 1007.1mg.kg -1 and 1975mg.kg -1 in A. thalassinus and P. Anea, respectively.…”

“…In Table 2 Ni concentrations in wild C. gariepinus ranged between 0.00157mg.kg -1 in the brain and 0.142mg.kg ) and 0.00167mg.kg -1 in the bone was the lowest. A wide disparity when compared to reports of Abubakar et al (2015), Israa et al (2009), andErhan et al (2004) who all reported over 8mg.kg , it is still very significant if the consequence generated by the addition of other chemical is put in perspective.…”

“…Method validation, was modified from Abubakar et al (2015) by conducting limit of detection (LOD), limit of quantification (LOQ), and precision relative standard deviation (RSD r ) for repeatability within the laboratory was also assessed with consideration to six levels of standard solutions (n = 6) with concentration values ranging between 0.1 and 2.5 mg.kg -1 which were prepared. Evaluation of metal concentrations was carried out in triplicates per sample of fish tissues.…”

“…In this study, risk assessment was determined by using only the muscle tissues (edible part) to evaluate the Daily Intake of Metal (DIM) and Health Risk Index (HRI) as espoused by Khan et al (2009), Okunola et al (2011 and Abubakar et al (2015).…”

“…However, there wasn't any significant difference (P < 0.05) between the two groups. Liver and brain tissues have been reported to have as much as 70.9mg.kg -1 and 76mg.kg -1 respectively (Abubakar et al, 2015) Hg concentrations, but Hg in the brain of C. gariepinus in this study showed very low concentrations in wild (0.0098mg.kg -1 ) and farmed groups (0.0065mg.kg -1 ), which differed markedly with Abubakar et al (2015) and Mieiro et al (2011), who all advanced that the brain is one of the vital organs in fish that stores very high levels of mercury. However, Hg gets into fish tissues mainly through absorption and ingestion by the skin and gills (Mieiro, 2011), which gives reason for the high Hg concentrations in the skin (0.325mg.kg ) of wild C. gariepinus.…”