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According to Dinh Thuc Nga from the Department of occupational diseases of the National Institue of Occupational and Enviromental Health, Manganese (Mn) compounds that are used in industry are mainly oxides and salts of Mn (MnO2, Mn3O4, MnCO3 ...). Mn penetrates the body mainly through the respiratory tract in the form of dust or aerosol, sometimes through the digestive tract due to insufficient hygiene regulations.

Occupational manganese poisoning is a toxic disease caused by exposure to manganese and manganese compounds during working.

Here is the list of occupational spheres where the workers are exposed to  Mn : Mn ore exploitation, iron ore; iron, steel (iron alloy workshop), production of electric cables, welding rods, dry batteries, colored products, glassware, pottery ...


Mn is a typical neurotoxin that causes central nervous system disorders and mental traumas. Mn also causes liver toxicity (glucose metabolism disorder), lung disease, endocrine disorders, thyroid gland, etc. Occupational exposure to Mn can be acute or chronic.

Acute poisoning symptoms: Employees of some plants and factories often work in environments where manganese concentrations exceed the allowable short-term exposure limits specified in the hygiene standard. The disease can develop very quickly after the exposure within 2 minutes and still develop after discontinuing of the Mn exposure about for 48 hours with such clinical manifestations:

- Irritation of mucous membranes, eyes, skin if exposed to high concentrations;

- Irritations, inflammation of the respiratory tract: cough, bronchitis, pneumonia and decreased respiratory function.

Chronic poisoning symptoms: Workers whose occupational environment is connected with regular contact with Mn in the concentrations exceeding hygiene standards. The disease may appear after 2 months of exposure or even after discontinuation of exposure during 20 years. The disease may have such clinical manifestations:

- Central nervous system: Neural disease such as Parkinson syndrome due to manganese poisoning with neurological manifestations. Early and secretive symptom is primarily motility or sometimes cognitive decline;

Manganese poisoning develops through the following stages:

Stage I: discomfort, weakness, anorexia, headache, easily change emotion, insensitivity, decreased sexual desire, muscle weakness, sleepy;

Stage II: memory loss, decreased ability to analyze, anxiety, sometimes manifesting psychosis as hallucinations;

Stage III: Progressive lowering of consciousness, paraplegia, quadriplegia, awkward posture, unstable posture, paralysis, stiffness of facial appearance, shivering when focused,  non-coordinated movements.

- Respiratory system: Similar to acute poisoning.

- Blood manganese> 36μg / L;

- Short-term memory test: decrease;

- Hand tremor test: increase;

- Simultaneous testing of motion time: stretching.

Preventive measures:

Manganese occupational poisoning as well as other occupational diseases is very difficult to treat and often results are disappointing. Therefore, prevention must be at the first.

* Technical measures:

- Carry out industrial hygiene measures to prevent dust and Mn gases from polluting the working environment.

- Replace dry drilling with wet drilling when mining Mn.

            - Installation of ventilation, dust extraction of toxic gas at basic level.

* Medical measures:

- Organize examination to sort out individuals who have physical damage of the nervous system, lungs, etc.

- Regular physical examinations and medical check-ups for workers to detect manganese poisoning symptoms early.

- Periodic monitoring of the concentration of Mn in the working environment.

- Rotation of  the positions of workers with Mn exposure to non- exposure positions so that the body has time to eliminate the overdose.

*  Personal remedies

- Compliance with the use of labor protection equipment in accordance with regulations, especially respiratory protection equipment.

- Bathing, conducting careful personal hygiene at the end if the working day.

- Do not eat at workplace, take preventive medicine to increase Mn elimination and supply nutrition to the body (vitamins, calcium,  etc.)



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