INTRODUCTION:

Manganese is a naturally occurring element in the environment. It is also an essential nutrient in the body. Manganese as a metal exist in the environment mainly as oxides, silicates and carbonates, in different valency states, with a majority occurring as Mn²⁺ or Mn³⁺.

Image of metal manganese from google

 

SOURCES:

Manganses is used in the following:

• Mostly in production of steel to improves the toughness and strength of steel
• production of dry-cell batteries
• chemical manufacturing
• fireworks
• glass in the textile industries
• fertilize

 

Manganese improves toughness and strength of steel

 

Manganese is an essential trace element required by the human body for its physiological function. Manganese is found in food that includes:

• nuts
• seeds
• legumes
• green leafy vegetables
• tea
• whole grains.

Food rich in manganse. Image from google

 

EXPOSURE ROUTE:

Exposure to manganese in the general population occur through

• Inhalation: primary source of overexposure to manganese in the general population
  
• Dermal contact
• Ingestion of food and water containing manganese.
• Intravenous injection: illegal narcotics that contain manganese is also a route of exposure.

 

MECHANISM OF ACTION:

The mechanisms of manganese toxicity in humans have not been agreed upon. It is thought to probably involve both endocrinological dysfunction and excessive oxidative damage in the tissues. Neural toxicity is a consistent finding reported in people exposed to chronic manganese toxicity.

 

SIGNS AND SYMPTOMS:

Signs and symptoms may appear in 1 to 2 months following high level exposure to manganese or as late as 20 years after manganese exposure. Exposure to high levels of manganese can result in a condition called manganism, which manifest as an extra-pyramidal neurological disease characterized by:

• mask-like expression
• rigidity
• bradykinesia
• action tremor
• gait disturbances
• cognitive dysfunction
• micrographia
• mood disorder

The above symptoms of manganism are similar to symptoms seen in Parkinson’s disease leading to association of manganese toxicity with parkinson’s disease.

Milder form of manganese toxicity manifest as

• hyperirritability
• hallucination
• violent acts
• disturbances of libido.
• Other subtle signs of chronic manganese toxicity including motor incoordination, delayed reaction time and impaired memory.

 

Video associating manganese toxicity with parkinson’s disease.Video from Google 

Biomarkers:

Manganese toxicity may be revealed through laboratory tests that detect high levels of manganese in the blood, urine as well as in hair samples. Plasma manganese represent a biomarker of current inhalation exposure to manganese. Excess manganese in the body accumulates in the basal ganglia of the brain. Magnetic resonance imaging can be used to reveal the accumulation of manganese in the brain.

 

CARCINOGENICITY:

Some evidence from animal studies exist that manganese may causes cancer in humans. A concrete conclusions cannot be drawn because of the mixed results received in animal studies. A few data suggest that inorganic manganese may be carcinogenic.

 

ESSENTIALITY AND DEFICIENCY:

Manganese is an essential nutrient because the body requires it to function properly. Manganese is a cofactor in many body enzymes.

Manganese is needed in the body for:

• normal development
• maintenance of nerve
• immune cell functions
• regulation of blood sugar
• regulation of vitamins

Deficiency of manganese in the body call result in:

• abnormal metabolism of carbohydrate
• Abnormal metabolism of fat
• poor bone growth
• impaired glucose tolerance
• slow or impaired growth
• low fertility.

 

References:

Agency for Toxic Substance. Toxicological profile for manganese. Accessed from:https://www.atsdr. cdc.gov./toxprofiles/tp151-c2.pdf

O’Neal, S. L. & Zheng, W. (2015). Manganese Toxicity Upon Overexposure: a decade in review. Current environmental health reports, 2(3), 315–328. doi:10.1007/s40572-015-0056-x

Neal, A. P. & Guilarte, T. R. (2013). Mechanisms of lead and manganese neurotoxicity. Toxicology research, 2(2), 99–114. doi:10.1039/C2TX20064C

Keen, C.L. & Zidenberg-Cherr, S. (2003). Manganese Toxicity. Encyclopedia of Food Services and Nutrition. Retrieved from: https://www.sciencedirect.com/topics/medicine-and-dentistry/toxicity-of-manganese

Cadet, J.L. & Bolla, K I. (2007). Environmental toxins and disorders of the nervous system.  Neurology and Clinical Neuroscience. Accessed from: https://www.sciencedirect.com/ topics/medicine-and-dentistry/toxicity-of-manganese