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).
SS Manganese was sold to the Sinai Manganese Co, Egypt and was renamed "Manganese". The ship was deleted from Lloyd's Register in 1993. SS Manganese Manganese was a coaster that was built in 1925 by Norderwerft AG, Hamburg, Germany as Wiedau for German owners. She was seized by the Allies in May 1945, passed to the Ministry of War Transport (MoWT) and was renamed Empire Contract. Later that year, she was transferred to Greece and renamed "Herakleion". She was sold into merchant service in 1948 and renamed Laconia. In 1965, she was sold to Egypt and renamed "Manganese". The ship was deleted