Inorganic contaminants in fish of the Mediterranean Sea: biomonitoring and toxicologic analysis

Aquatic systems throughout the world are increasingly under a wide array of anthropogenic stressors, including the release of a myriad of toxic substances into the environment. The presence of twenty-seven heavy metals, vitamins, and minerals was investigated in muscle tissues collected from 46 wild fishes distributed among Thunnus thynnus (TT), Pagellus bogaraveo, and Dentex dentex (DD) from the Mediterranean Sea. The mean concentration of each element was calculated and compared to the provisional tolerable daily or weekly intake (PTWI) or to the established tolerable upper intake when possible. Specie-specific distribution was documented for the following chemical elements: aluminum (Al), potassium (K), cobalt (Co), molybdenum (Mo), silver (Ag), cadmium (Cd), tin (Sn), and thorium (Th). For the elements without regulated maximum dietary limits, iron (Fe) was highest in TT, while Th was significantly predominant in DD. Several metals were found, often simultaneously, in quantities above the acceptable levels. Specifically, the median concentrations of mercury (Hg) and Cd in the pooled species were significantly higher than their relative PTWI. Significant differences among species were reported for selenium (Se), inorganic arsenic (As), nickel (Ni), and zinc (Zn). Other elements [Al, chromium (Cr), copper (Cu), Sn, lead (Pb), and manganese (Mn)] were found to be at or below the corresponding acceptable levels. The maximum safe consumption calculated for Hg leads to advising a limited recommended weekly intake for all the tested Mediterranean Sea fish species.