Nonessential pollutant metals in the food chain: state of art and particular focus on thallium and platinum group metals (PGMs)

Unfortunately, the legislation currently in force imposes maximum concentration limits for these metals only for very few elements and only for very few types of food matrices. This chapter therefore wants to bring attention to the great problem of toxic metals, which are little taken into consideration by the regulations of International Organizations for the protection of human health. The same regulations, and rightly so, consider in an extremely detailed manner the numerous organic compounds that can be present as truly dangerous pollutants in food matrices placed on the market for sale and human consumption. It should therefore be underlined that greater attention by International Organizations to the inorganic part, specifically toxic metals, especially nonessential ones, would be not only very important, but also decidedly desirable. Therefore, the relevant International Organizations should have among their main objectives precisely that of filling this gap, i.e., the lack of clear and, above all, exhaustive laws regarding the maximum allowable concentrations in matrices involved in the food chain, expanding to the maximum both the number of metals taken into consideration and the types of metrics considered. This work aims to highlight the state of the art regarding the presence of nonessential, and therefore toxic and potentially very dangerous, metals in the food chain. The metals taken into consideration in this discussion are only marginally the nonessential and toxic metals par excellence—Pb, Cd and Hg—of which there is a vast literature, but some future food metal contaminants, absolutely nonessential and which have appeared in the environment only recently, starting from the end of the past century, i.e., thallium and platinum group metals (PGMs): Pt, Pd, Rh, Os, Ru, and Ir. The types of matrices considered are: sea food (mussels, clams, oysters, fishes and algae), wine, vegetables, meals, meat, milk and milk derivatives, tea, and herbal medicines.