Manganese

Despite its essentiality, manganese (Mn) is a common environmental contaminant, which can cause toxic effects in humans. Mn exposure may start before birth from maternal exposure through inhalation and ingestion of food items from the environmental pollution. Postnatal exposure can also be relevant due to a relative high concentration of Mn in formulas and continued exposure during childhood and adulthood from both environmental and occupational exposures. Although its accumulation is also associated with reproductive effects, Mn is generally described as a neurotoxicant selectively affecting the basal ganglia. Mn-induced neurotoxicity leads to a degenerative brain disorder, referred to as manganism. It is characterized by clinical signs and morphological lesions similar to those seen in Parkinson disease. Cumulative mechanisms of Mn action are not sufficiently known and may vary with environmental factors and individual susceptibilities, including single nucleotide polymorphisms that may alter Mn homeostasis, transport, and metabolism.