97: Manganese

HISTORY AND EPIDEMIOLOGY

Manganese is the 12th most abundant element in the Earth’s crust (0.106%). The name manganese derives from Magnesia, a prefecture of Thessaly in ancient Greece. Ores from this region are particularly abundant in manganese oxides and carbonates. Manganese salts are brightly pigmented and the earliest known uses were artisanal. Manganese dioxide was found in prehistoric paints and was used as a decolorant in glassmaking during the Roman Empire.

Adding manganese to iron produces a stronger metal alloy, and manganese-iron alloys are found in weapons from ancient Sparta. By the early 19th century, manganese became an important component in the manufacture of steel, which remains the largest industrial use of manganese today. Currently, more than 85% of manganese is used in the production of ferromanganese alloys. Manganese chloride is used in dry-cell battery manufacture and the metal is a catalyst for chlorination of organic compounds, manganese dioxide is used in batteries and glass production, and manganese sulfate is used to make ceramics, fungicides, and pesticides.

Most reported cases of manganese toxicity, or manganism, are associated with occupational exposure. Manganism was first described in 1837, when the development of a characteristic neuropsychiatric syndrome in French pyrolusite mill workers was linked with exposure to high concentrations of manganese oxide dusts.²⁰ Manganese, primarily in the form of oxides, is released during mining, and inhalation exposure to dusts from grinding manganese ore has historically been the most important source of manganese toxicity. Inhalation of inorganic manganese compounds may also occur during smelting, welding, or burning of coal, oil, or fuel containing manganese compounds. A neuropsychiatric syndrome in welders has been attributed to the inhalation of manganese oxide fumes.^{12,14,37,46,68}

Manganism has also been described in several nonoccupational settings. Manganese chloride and manganese sulfate are employed as nutritional supplements,⁹ and manganese toxicity is well documented in patients receiving excessive doses in total parenteral nutrition.^24,52,58 Infants, young children, and patients with impaired clearance from chronic liver disease are particularly at risk. More recently, epidemic manganese toxicity has been reported from the use of intravenous psychostimulant drugs such as methcathinone and a “Russian cocktail” prepared using potassium permanganate as an oxidizing agent.^41,79

Environmental exposure to excessive manganese in drinking water has been linked to neurodevelopmental deficiencies in children, including effects on cognition, behavior, memory, and motor function.^11,18,39 Concerns have also been raised about the potential environmental health risks of methylcyclopentadienyl manganese tricarbonyl (MMT), an antiknock agent added to gasoline as an alternative to lead.^22,31 MMT has been allowed in Canada since 1976 and in the United States since 1995; however, more research is needed to understand its contribution to the environmental burden of manganese and to human health.⁷⁶ Permanganates were first discovered to be strong ...