THEORY OF OBJECTS. ARTICLE 23. EXTERNAL CONTAMINANTS: PESTICIDES, HEAVY METALS, MICROPLASTICS, PFAS AND RADIOISOTOPES. SOURCES, MECHANISMS, THRESHOLDS AND REDUCTION STRATEGIES

This article is the third and final in the block of toxicological works of the cycle (Articles 21–23) and is devoted to external contaminants: chemical, biological and physical agents that are neither native components of raw materials nor products of their processing, but get into food from the outside - from the environment, packaging, soil, water, air or as a result of anthropogenic activities. The article systematizes the main classes of external contaminants: pesticides and their metabolites, heavy metals (lead, cadmium, mercury, arsenic), microplastics and nanoplastics, per- and polyfluoroalkyl substances (PFAS), radioactive isotopes, mycotoxins as a result of mold contamination during storage, migrants from packaging, veterinary drugs and hormones, dioxins and polychlorinated biphenyls. For each class, sources, routes of entry into food, toxicity mechanisms, thresholds, regulatory limits, and reduction strategies are described. Particular attention is paid to the cumulative effect and the cocktail effect, when several contaminants act simultaneously, reinforcing each other. It is shown that external contaminants form the third of the three groups of food toxicants taken into account in the toxicity index (IT). Together with Articles 21 and 22, this paper completes the scientific basis for the IT methodology described in Article 25.