Manganese is a chemical element with the symbol Mn and atomic number 25. 

Manganese is a hard, brittle, silvery metal, often found in minerals in combination with iron. 

It is an essential human dietary element, important in macronutrient metabolism, bone formation, and free radical defense systems. 

It is a critical component in dozens of proteins and enzymes.

Manganese is an essential mineral that plays a critical role in many functions in the body, including the metabolism of amino acids, energy production, and bone development. 

It also acts as an antioxidant and supports the immune system.

Too much manganese exposure can lead to negative health effects. 

Prolonged exposure to high levels of manganese through inhalation can cause neurological symptoms, including tremors, difficulty with speech and balance, and cognitive decline. 

The recommended daily intake for adults is 1.8 to 2.3 milligrams. 

Manganese is in many fruits and vegetables, such as spinach, kale, pineapple, and raspberries. 

It’s also present in nuts, whole grains, and legumes.

It is found mostly in the bones, but also the liver, kidneys, and brain.

In the human brain, manganese is bound to manganese metalloproteins, most notably glutamine synthetase in astrocytes.

Manganese is a mineral that is essential for human health. 

It is involved in many physiological processes in the body, including metabolism, bone development, and antioxidant activity.

Manganese deficiency is rare, as the mineral is found in many different foods such as nuts, whole grains, leafy green vegetables, and tea. 

Excessive exposure to manganese can be toxic and lead to a condition called manganism, which has symptoms similar to Parkinson’s disease such as tremors, rigidity, and difficulty with movement.

Ingesting high levels of manganese through food sources is generally considered safe. 

Inhaling high levels of manganese for extended periods, such as in certain occupational settings, can result in manganese toxicity. 

Adequate intake of manganese for adults is around 2.3-2.6 mg/day, while pregnant and lactating women may require slightly higher amounts. 

Individuals with with liver disease, iron deficiency anemia, or other underlying health conditions may require additional manganese intake.

Manganese supplements are not typically necessary for most people who consume a balanced diet, and excessive intake of supplements can be harmful. 

Manganese is used in production of alloys with aluminium. 

Aluminium with roughly 1.5% manganese has increased resistance to corrosion through grains that absorb impurities which would lead to galvanic corrosion.

The corrosion-resistant aluminium alloys are used for most beverage cans.

Manganese oxide was used in the original type of dry cell battery as an electron acceptor from zinc, and is the blackish material in carbon–zinc type flashlight cells, and in alkaline batteries.

Copper alloys of manganese, are commonly found in metal element shunt resistors used for measuring relatively large amounts of current. 

Its alloys have very low temperature coefficient of resistance and are resistant to sulfur,  making them useful in harsh automotive and industrial environments.

Methylcyclopentadienyl manganese tricarbonyl is an additive in some unleaded gasoline to boost octane rating and reduce engine knocking.

Manganese(IV) oxide (manganese dioxide, MnO2) is used as a reagent in organic chemistry for the oxidation of benzylic alcohols, used to oxidize and neutralize the greenish tinge in glass from trace amounts of iron contamination, used in the manufacture of oxygen and chlorine and in drying black paints.

The metal is occasionally used in coins.

Manganese compounds have been used as pigments and for the coloring of ceramics and glass. 

The classes of enzymes that have manganese cofactors include oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. 

Other enzymes containing manganese are arginase and Mn-containing superoxide dismutase (Mn-SOD). 

The enzyme class of reverse transcriptases of many retroviruses contains manganese. 

Manganese-containing polypeptides are the diphtheria toxin, lectins and integrins.

Manganese is an essential human dietary element. 

It is present as a coenzyme in several biological processes, which include macronutrient metabolism, bone formation, and free radical defense systems. 

Mn is a critical component in dozens of proteins and enzymes.

The human body contains about 12 mg of manganese, mostly in the bones. 

The soft tissue remainder is concentrated in the liver and kidneys.

In the human brain, the manganese is bound to manganese metalloproteins, most notably glutamine synthetase in astrocytes.

Nutrition: The adequate intake (AI) for manganese: 2.3 mg/day for adult men and 1.8 mg/day for adult women, appears sufficient to prevent deficiency in most individuals.

Current AIs of Mn by age group and sex:

Males Females

Age AI (mg/day) Age AI (mg/day)

1–3 1.2 1–3 1.2

4–8 1.5 4–8 1.5

9–13 1.9 9–13 1.6

14–18 2.2 14–18 1.6

19+ 2.3 19+ 1.8

pregnant: 2

lactating: 2.6

Tolerable upper intake levels (ULs) In the case of manganese the adult UL is set at 11 mg/day. 

For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV), and is to 2.3 mg .

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.

Manganese deficiency in humans is rare.

Manganese compounds are less toxic than those of other metals, such as nickel and copper.

However, exposure to manganese dusts and fumes should not exceed the ceiling value of 5 mg/m3  because of its toxicities.

Manganese poisoning has been linked to impaired motor skills and cognitive disorders.

Permanganate exhibits a higher toxicity than manganese compounds. 

The fatal dose of permanganate is about 10 g.

The strong oxidative effect leads to necrosis of the mucous membranes, and the esophagus is affected if the permanganate is swallowed. 

Only a limited amount is absorbed by the intestines, but has severe effects on the kidneys and on the liver.

People can be exposed to manganese in the workplace by breathing it in or swallowing it: the permissible exposure for manganese exposure in the workplace as 5 mg/m3 over an 8-hour workday, and 

has set a recommended exposure limit of 1 mg/m3 over an 8-hour workday and a short term limit of 3 mg/m3. 

At levels of 500 mg/m3, manganese is immediately dangerous to life and health.

Exposure to ambient Mn air concentrations in excess of 5 μg Mn/m3 can lead to Mn-induced symptoms. 

Waterborne manganese has a greater bioavailability than dietary manganese, and 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 possible that  long-term exposure due to inhaling the naturally occurring manganese in shower water puts up to 8.7 million Americans at risk.

However,  human body can recover from certain adverse effects of overexposure to manganese if the exposure is stopped- body can clear the excess.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is a gasoline additive used to replace lead compounds for unleaded gasolines to improve the octane rating of low octane petroleum distillates, and reduces engine knock.

Manganese is a constituent of tobacco smoke, but concentrations are not hazardous for human health.

Manganese overexposure is most frequently associated with manganism, a rare neurological disorder associated with excessive manganese ingestion or inhalation. 

Manganism is a biphasic disorder. 

In its early stages, an intoxicated person may experience depression, mood swings, compulsive behaviors, and psychosis. 

Late-stage manganism, which resembles Parkinson’s disease, wit hweakness, monotone and slowed speech, an expressionless face, tremor, forward-leaning gait, inability to walk backwards without falling, rigidity, and general problems with dexterity, gait and balance.

Unlike Parkinson’s disease, manganism is not associated with loss of the sense of smell and patients are typically unresponsive to treatment with L-DOPA.

Symptoms of late-stage manganism become more severe over time.

Chronic manganese exposure has been shown to produce a parkinsonism-like illness characterized by movement abnormalities,which is not responsive to typical therapies used in the treatment of PD, suggesting an alternative pathway than the typical dopaminergic loss within the substantia nigra.

Manganese may accumulate in the basal ganglia, leading to the abnormal movements.

A mutation of 

The SLC30A10 gene is a manganese efflux transporter necessary for decreasing intracellular Mn.

A SLC30A10 gene mutation has been linked with the development of this Parkinsonism-like disease.

Several studies found the effects of chronic low-dose manganese overexposure on child development displayed lower performance on tests of manual dexterity and rapidity, short-term memory, and visual identification, compared to children from an uncontaminated area.  

The current maximum safe concentration under EPA rules is 50 μg Mn/L.

DMT1 protein is the major transporter in manganese absorption from the intestine, and may be the major transporter of manganese across the blood–brain barrier, and nasal epithelium. 

The proposed mechanism for manganese toxicity is that dysregulation leads to oxidative stress, mitochondrial dysfunction, glutamate-mediated excitotoxicity, and aggregation of proteins.

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