Heavy Metals Bioaccumulation and Health Risks with Associated Histopathological Changes in Clarias gariepinus from the Kado Fish Market, Abuja, Nigeria

Abstract

Background. Aquatic pollution by heavy metals has become a global problem and is of great concern due to the detrimental effects on aquatic ecosystems and possible human uptake. Objectives. The present study aimed to evaluate tissue bioaccumulations of heavy metals and possible human health risks in addition to associated cellular damages in fish for sale in a fish market in Abuja, Nigeria. Methods. Clarias gariepinus sold at the Kado Fish Market in Abuja, Nigeria, in March–April 2017 and March–April 2018 were randomly purchased and sampled. The heavy metal contents of the sampled fish were assayed and used to assess the extent of potential health risks to human consumers. The extent of histopathological changes associated with the bioaccumulations in the sampled fish were also evaluated according to standard procedures. Results. Levels of most heavy metals were above permissible limits, except for lower levels of zinc (Zn) in liver and muscle and higher levels of lead (Pb) in muscle in the sampled fish. Similarly, significant (p<0.05) liver bioaccumulation occurred for Zinc (Zn), chromium (Cr), iron (Fe), and copper (Cu) compared to their levels in muscle. The total hazard index (non-cancer risk across all metals) was 0.0415, which is very low and acceptable. The cancer risks ranged between the acceptable values of 1.98 × 10−5 – 3.71 × 10−6. Associated histopathological changes, which occurred in the sampled fish, differed between the various assayed tissues. Conclusions. Most of the heavy metals were significantly bioaccumulated (p<0.05) and were above the permissible levels, particularly in liver samples. The levels of muscle heavy metal bioaccumulation in the sampled fish posed no apparent cancer or non-cancer health risks to human consumers. However, further efforts are needed to minimize heavy metal aquatic environmental pollution to safeguard the health of aquatic flora and fauna and human consumers because of the tendency of these pollutants to persist and bioaccumulate to toxic levels over time. Competing Interests. The authors declare no competing financial interests.

Keywords

• clarias gariepinus
• aquatic pollution
• heavy metals bioaccumulation
• health risk assessment
• histopathological changes