Novel analytical data on cadmium, mercury, lead, arsenic and selenium content in fish from Tanzania and Mozambique: Implications for food safety

Fish are important for food security and nutrition in many coastal communities; however, fish consumption is also a major source of metal and metalloid exposure to humans. Data on metal/metalloid content in fish from Tanzania and Mozambique marine waters are limited. This study analysed the content and assessed the risk of exposure from 17 fish species sampled off the coast of Tanzania and Mozambique by research vessel Dr. Fridtjof Nansen during an ecosystem survey in 2018. The samples were prepared according to local consumption habits (fillet, whole and dressed) and were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Three metals, cadmium (Cd), mercury (Hg) and lead (Pb), and two metalloids, arsenic (As) and selenium (Se), were measured. The content varied among the species and tissue analysed. Hg content was higher in fillets from large predatory fish, while As, Se, Cd and Pb were higher in small fish that traditionally are consumed whole. The mean Se-Hg molar ratio was higher in whole and dressed small fish compared to fillets from large fish. In all analysed samples, HQ Cd and HQ Hg values were <1 except for O. bartramii , where HQ Cd was marginally above 1. Thus, the consumption of the fish species, prepared to resemble the eating habits collected in this study, has no adverse health effects on humans, and the consumption of whole fish is highly recommended from a nutritional point of view. However, species diversification and the use of safe consumption limits may also be important in reducing multiple contaminant exposure. • Heavy metal and metalloid content was analysed in 17 marine fish species. • The contents of Cd, Hg, Pb, As and Se varied by species and tissues analysed. • Se and Hg correlated positively in fillet, but negative in whole and dressed fish. • Fish from Tanzania and Mozambique marine waters is safe for human consumption. • Species diversification and consumption of whole fish is highly recommended.