Metal pollution in freshwater fish: A key indicator of contamination and carcinogenic risk to public health

Abstract

Metals are micropollutants that cannot be degraded by microorganisms and are infiltrated into various environmental media, including both freshwater and marine water. Metals from polluted water are absorbed by many aquatic species, especially fish. Fish is a staple food in the diets of many regions in the world; hence, both the type and concentration of metals accumulated and transferred from contaminated water sources to fish must be determined and assessed. In this study, the heavy metal concentration was determined and assessed in fish collected from freshwater sources via published literature and Estimated Daily Intake (EDI), Target hazard quotient (THQ), and Carcinogenic Risk (CR) analyses, aiming to examine the metal pollution in freshwater fish. The fish was used as a bioindicator, and Geographic information system (GIS) was sued to map the polluted regions. The results confirmed that Pb was detected in fish sampled at 28 locations, Cr at 24 locations, Cu and Zn at 30 locations, with values Pb detected ranging from 0.0016 mg kg−1 to 44.3 mg kg−1, Cr detected ranging from 0.07 mg kg−1 to 27 mg kg−1, Cu detected ranging from 0.031 mg kg−1 to 35.54 mg kg-1, and Zn detected ranging from 0.242 mg kg−1 to 103.2 mg kg−1. The strongest positive associations were discovered between Cu–Zn (r = 0.74, p < 0.05) and Cr–Zn (r = 0.57, p < 0.05). Spatial distribution maps depicting the consumption of fish as food and its corresponding Pb and Cr intake revealed a higher incidence of both carcinogenic and non-carcinogenic health concerns attributed to Pb and Cr in the region with populations consuming the fish.