Heavy metals concentration profile of an aquatic environment and health implications of human exposure to fish and prawn species from an urban river (Densu)

Fish is a good source of protein; however, certain anthropogenic activities can contaminate their habitat with elevated heavy metals levels. In this study, copper, lead, mercury, cadmium, and arsenic in fish tissue, water and sediment were determined using PerkinElmer PINAAcle 900T Graphite AAS. Standard indices in human health risk assessment were used to estimate non-carcinogenic implications associated with consuming Clarias batrachus, Clarias gariepinus, Hemichromis fasciatus, Chrysichthys nigrodigitatus, and Macrobrachium rosenbergii from Densu River. Heavy metal concentration levels recorded in November 2017 were in the order of surface water < pelagic fish < benthic fishes < sediments. Cadmium and Lead levels in all investigated fish tissues exceeded FAO/WHO recommended standard. Pb, Cd, and Hg mean concentration levels in the water exceeded the WHO threshold level of 0.01, 0.003, and 0.001mg/kg, respectively. Concentration level of all sediment samples was below the USEPA set limit for analyzed heavy metals. From the correlation analysis, Hemichromis fasciatus was identified as an applicable bioindicator for assessing heavy metal pollution because it correlated with water and sediment significantly. Principal component analysis ascribed heavy metal pollution in Densu River to anthropogenic activities along the river. The interpretation of estimated daily intake computation showed that the content of individual heavy metals in the fishes is not likely to endanger the health of the consumers. However, the recorded hazard index for Clarias gariepinus, Clarias batracus, and Macrobrachium rosenbergii exceeded one (HI>1), an indication of a non-cancer risk to consumers.