Manganese is also used in portland cement mixtures. Manganese is an important element for human health, essential for development, metabolism, and the antioxidant system. Nevertheless, excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and symptoms similar to Parkinson's disease. The classes of enzymes that have manganese cofactors is large and includes oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins. The reverse transcriptases of many retroviruses (though not lentiviruses such as HIV) contain manganese. The best-known manganese-containing polypeptides may be arginase, the diphtheria toxin, and Mn-containing superoxide dismutase (Mn-SOD).
Manganese of manganese in air have dropped. Many racing competitions specifically ban manganese compounds in racing fuel for carts and minibikes. MMT contains 24.4–25.2% manganese. Elevated atmospheric manganese concentrations are strongly correlated with automobile traffic density. The Level of manganese emitted by MMT fuels has been found to be safe for the general population and vulnerable groups such as infants and the elderly by the EPA and European and Canadian environmental agencies. The tobacco plant readily absorbs and accumulates heavy metals such as manganese from the surrounding soil into its leaves. These are subsequently inhaled during tobacco smoking. While manganese is