Manganese to life and health. Generally, exposure to ambient Mn air concentrations in excess of 5 μg Mn/m3 can lead to Mn-induced symptoms. Increased ferroportin protein expression in human embryonic kidney (HEK293) cells is associated with decreased intracellular Mn concentration and attenuated cytotoxicity, characterized by the reversal of Mn-reduced glutamate uptake and diminished lactate dehydrogenase leakage. Waterborne manganese has a greater bioavailability than dietary manganese. According to results from a 2010 study, higher levels of exposure to manganese in drinking water are associated with increased intellectual impairment and reduced intelligence quotients in school-age children. It is hypothesized that long-term exposure due
Manganese white magnesia alba (magnesium oxide), which provided the name magnesium for the free element when it was isolated much later. Several colorful oxides of manganese, for example manganese dioxide, are abundant in nature and have been used as pigments since the Stone Age. The cave paintings in Gargas that are 30,000 to 24,000 years old contain manganese pigments. Manganese compounds were used by Egyptian and Roman glassmakers, either to add to, or remove color from glass. Use as "glassmakers soap" continued through the Middle Ages until modern times and is evident in 14th-century glass from Venice. Because it was used