Toxic and essential elements in freshwater and marine fish species from a central Italian market: assessment of consumers’ health risks and benefits

The concentrations of selected toxic elements [mercury (Hg), lead (Pb), cadmium (Cd), and arsenic (As), inorganic As (iAs)] and essential elements [selenium (Se), zinc (Zn), manganese (Mn) and iron (Fe)] were determined in the muscles of freshwater (FF) and marine fish (MF) species collected from the market in Umbria and Marche regions (Italy). The consumers' exposure to all elements was determined, and a comprehensive benefit-risk assessment was conducted to assess the health impacts associated with fish consumption. The elements' concentration ranged as follows: Cd 0.01-0.01, Pb 0.01-0.02, Hg 0.04-0.12, As 0.07-11.42, Mn 0.21-0.56, Fe 2.35-6.79, Se 0.12-0.34, and Zn 5.76-4.77 mg/kg w/w. In all samples, Cd, Pb, and Hg were under the maximum allowed concentrations for safe human consumption in Europe. The Metal Pollution Index was estimated to be 0.014 for FF and 0.094 for MF, and the EDI for toxic elements ranged between 2.13E-05 and 2.64E-03 and for essential elements between 1.48E-03 and 1.75E-03 mg/kg bw/day for FF and MF, respectively. The contribution of fish to the daily reference intakes of essential elements set in the EC Reg. 1169/2011 was significant only for Se, which reached 15% of the threshold in both FF and MF; the Hg-Se balance was defined, revealing values >1 for the Se:Hg molar ratio and a positive Health Benefit Value for Se index. Risk was defined by the target hazard quotients that ranged from 0.0002 to 0.2471 and the hazard index with values of 0.0140 for FF and 0.3280 for MF, indicating the absence of non-carcinogenic risks. The carcinogenic risk and the margin of exposure both revealed no risk for carcinogenic effects for FF and low for MF. The results suggested that the consumption of MF species can pose a low, but still acceptable, carcinogenic risk due to iAs exposure and that both fish groups represent a significant source of Se, able to mitigate the toxic effect of Hg.