Toxicologic Characteristics of Nanodisperse Manganese Oxide: Physical-Chemical Properties, Biological Accumulation, and Morphological-Functional Properties at Various Exposure Types

Abstract

Nanosized manganese oxide has excellent prospects. Some data imply that its particles can be toxic when introduced in various ways, and it requires further examination of this nanomaterial. The authors conducted research of nanodisperse MnO 2 water suspension at intragastric, inhalation, and skin-resorptive introduction into small rodents and obtained profound characteristics of its toxic effects, determined target organs and revealed dose-dependent effects. The substance was characterized with acute toxicity, and its bioaccumulation under long-term exposure caused morphofunctional disorders in brain, lipid peroxidation activation, and lower antioxidant system activity. The authors detected vessel hyperemia, subarachnoid hemorrhages, brain edema with perivascular and pericellular spaces dilatation, nerve fiber demyelinization, and focal dystrophic changes in vessels endothelium. After a long-term introduction in doses from 0.25 to 2.5 mg/kg, oxidizing-antioxidant imbalance occurred, neurotransmitters and electrolytes balance was violated, and there was also brush border epithelium insufficiency. Nanodisperse MnO 2 water suspension in doses equal to 2.5 and 0.25 mg/kg at intragastric introduction into Wistar rats did not have embryotoxic or teratogenic effects. It did not have any mutagenic effects in doses equal to 10.3 and 5.15 mg/kg or gonadotoxic effects either when introduced into Wistar male rats in doses equal to 10.3–5.15 mg/kg via gastric tube.