Abstract
Increasing rate of consumption of the common African catfish, Clarias gariepinus, a popular delicacy in Delta State, Nigeria has raised worries about the safety of health of consumers in the face of perceived rising input of recalcitrant pollutants such as the heavy metals in aquatic habitats. This research investigated the presence and levels of Zn in muscle and brain tissues of C. gariepinus sourced from selected markets in Delta State. Replicate adult fish samples were obtained from seven market locations in Oleh, Asaba, Ekpan, Ogwashi-Ukwu, Okere, Abraka and Ughelli towns, labeled and taken to the laboratory in iced coolers. The presence and levels of the heavy metal were determined spectrophotometrically. Concentrations ranged from 0.015 - 0.19 (0.09 ± 0.02) mg/kg d.w. in muscle and 0.035 - 0.36 (0.16 ± 0.03) mg/kg d.w. in brain tissues, even as accumulation levels differed significantly (t = 0.005) between the tissues at p (100.97) > Fcrit(4.02)] at the 95% confidence limit; with least accumulation of 0.03 (±0.01) mg/kg d.w. recorded in fish samples obtained from Ughelli and maximum accumulation of 0.28 (±0.07) mg/kg d.w. recorded in those obtained from Oleh locations. However, levels were below the Food and Agricultural Organization and World Health Organization acceptable limits for Zn in edible fish. Results revealed that lipophilic brain tissues accumulated more heavy metal than muscle tissues. Since accumulation levels were low, they do not currently constitute public health risks to consumers in Delta State.
Highlights
In inland aquatic ecosystems, fish species have severally been utilized as biomonitors of heavy metals accumulation [1]-[3]
Harmful substances like heavy metals, released by anthropogenic activities could be accumulated in aquatic organisms through the food chain and as a result, human health can be at risk when fish contaminated with these toxic chemicals are consumed
Delta State is located in the Niger Delta region of Nigeria, within the geographical coordinates 5 ̊30'N and 6 ̊00'E
Summary
Fish species have severally been utilized as biomonitors of heavy metals accumulation [1]-[3]. Fish are widely consumed mainly because they are part of the local delicacy, and because of their high protein, low saturated fat and omega fatty acids contents that are known to contribute to good health [5]. In this State, the main pollution sources are industrial production lines, which effluents and wastewaters are channel into nearby rivers, streams and ponds. Some of the discharged effluents could contain toxic chemicals such as the heavy metals from improperly treated wastewaters
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