Certain elements in low concentrations are vital for the normal functioning of the human body, but in high concentrations, they can constitute a threat to its development and normal functioning, this is the case of manganese. Say no to plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”?Get the original essayManganese is found in low amounts in virtually all diets and plays an essential role as a cofactor in many enzymatic reactions in humans and other organisms. This element exists in several forms, both physical and chemical, in the earth's crust, in water and in particles in the atmosphere. Due to the configuration of its outer electron shell, it can donate up to 7 electrons (USEPA, 1984[1]) and adopt different oxidation states, but in living organisms Mn is mainly found in the form of Mn2+ , Mn3+ and possibly Mn4+ (Archibald and Tyree, 1987[2]). Although essential biological functions related to Mn depend on its oxidation state, little is known about how the oxidation state of high Mn exposures affects cellular uptake and function/toxicity (Reaney , 2002). Manganese ingestion represents the primary route of human exposure, although inhalation also occurs, primarily in occupationally exposed groups. Regardless of intake, Mn levels in biological tissues remain stable thanks to homeostatic mechanisms that effectively regulate the absorption and excretion of this metal. However, it is also well known that chronic exposure to high levels of manganese (Mn) in the air results in adverse neurological, reproductive and respiratory effects (Mergier et al., 1994, Bader et al., 1999, Aschner and Dorman, 2006). , ). This was discovered as early as 1837 when Couper observed neurological problems in workers employed in grinding manganese oxide used in the manufacture of bleaching powder (Guilarte 2010). Industrial emissions are the main source of anthropogenic release of manganese into the air, particularly dust and fumes containing manganese dioxide and manganese tetroxide—present primarily during mining, crushing, and smelting of ore as well. than during steel production (Schiele, 1991). Alternative sources of manganese incorporation into air are the combustion of fossil fuels and the resuspension of manganese-containing soils (ATSDR, 2000[3]). Several studies on exposure cases linked to mining and manufacturing activities have found a relationship between Mn inhalation and increased risk. of a broad spectrum of clinical symptoms. Among others, some nonspecific neurological symptoms have been reported such as postural instability, mood and psychiatric changes (i.e., depression, agitation, hallucinations) (Mena et al., 1967), and triggering or acceleration of symptoms similar to those of Parkinson's disease (PD) (Rodier, 1955; Tanaka & Lieben, 1969; Huang et al., 1989, 1998; Roels et al., 1987a, 1992; Wang et al., 1989; Mergler et al., 1994; Hochberg et al., 1996; Bader et al., 1999), such as bradykinesia, rigidity, tremor, gait disturbances, postural instability and/or dystonia. ataxia (Josephs et al., 2005). However, for some researchers this relationship remains questionable, given current clinical, toxicological and epidemiological evidence, which is inconclusive as to the existence of such a relationship, based on the argument that in 1 million welders worldwide and until 2007, only about 15 case reports were published in the.