Cadmium and arsenic levels in edible fishes, Oreochromis niloticus (Nile tilapia) and Ompok bimaculatus (butter catfish) from Padaviya Reservoir, Sri Lanka and human health risk assessment associated with their dietary exposure

Consumption of fish contaminated with toxic heavy metals is a threat to human health. Cadmium and arsenic are suspected as potential risk factors for chronic kidney disease of unknown aetiology (CKDu), which is highly prevalent in agricultural settlements in dry zone districts of Sri Lanka causing a severe public health crisis. Objectives of this study were (i) to determine cadmium and arsenic levels in muscle, liver and kidney of two edible fishes (Nile tilapia and butter catfish) from the Padaviya reservoir located in the North Central Province, Sri Lanka where CKDu is highly prevalent and (ii) to assess the potential human health risks associated with the dietary exposure through edible muscle of these fishes. Cadmium and arsenic levels of the tissues in the two fish species were determined using inductively coupled plasma mass spectrometry. In both fish species, highest cadmium levels were found in kidney (p < 0.05) whereas no significant tissue specific differences (p > 0.05) were evident for arsenic. In the edible muscle, the maximum detected cadmium level in Nile tilapia was 0.1 mg/kg in wet weight. However, cadmium levels in the muscle of all Butter catfish were < 0.05 mg/kg. Arsenic levels in the muscle of all Nile tilapia and Butter catfish were < 0.05 mg/kg. Cadmium contents in muscle of most fishes and arsenic contents in all fishes (n = 60) were within the maximum permissible limits set by the international food standards regulatory authorities. Based on the estimated daily intake and target hazard quotients (< 1) for lifetime exposure, it is highly unlikely that cadmium and arsenic contents of the muscle meat of these fishes would pose human health risks to moderate level consumers.