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DESCRIPTION
Manganese is an essential element used in a variety of occupational settings.
FORMS AND USES
- Manganese is used in foundry work and electroplating, as well as in the manufacture of batteries, permanganate, fertilizers, ceramics, and matches.
- Methylcyclopentadienyl manganese tricarbonyl (MMT) was used as a gasoline anti-knock agent, but this use has been curtailed because of MMT's interference with catalytic converters in exhaust.
- Potassium permanganate is a strongly corrosive oxidant.
TOXIC DOSE
- Acute ingestion of inorganic manganese salts does not produce toxicity.
- Chronic inhalation leads to toxic effects, but with variable individual susceptibility.
PATHOPHYSIOLOGY
Neurologic toxicity of manganese is related to CNS dopamine depletion and formation of toxic compounds (dopamine quinone, hydrogen peroxide).
EPIDEMIOLOGY
- Poisoning is rare.
- Toxic effects are mild after acute ingestion.
CAUSES
Toxicity most often results from chronic occupational exposure to dust.
WORKPLACE STANDARDS
- ACGIH. TLV TWA 0.2 mg/m3.
- OSHA. PEL TWA is 5 mg/m3; evidence suggests, however, that chronic exposure at this level may result in pulmonary and neurologic symptoms.
- NIOSH. REL TWA is 1 mg/m3 of manganese; STEL is 3 mg/m3; IDLH is 500 mg/m3.
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SIGNS AND SYMPTOMS
- Potassium permanganate ingestion often causes hemorrhagic gastritis, abdominal pain, and vomiting.
- Metal fume fever is a flulike syndrome that may occur 4 to 8 hours following inhalation of fumes from welding or melting manganese-containing compounds (see SECTION II, Metal Fume Fever).
Manganese Dioxide Dust
- Acute exposure may cause dermatitis, conjunctivitis, and sinusitis.
- Pneumonitis and bronchitis may occur after inhalation with dyspnea and cough.
- Abdominal pain, hepatic dysfunction, and pancreatitis also may occur with ingestion or dialysate contamination.
- Pulmonary symptoms resemble asthma or chronic obstructive pulmonary disease, and changes on lung ventilation tests may develop.
Manganese Madness
A syndrome that follows chronic high-level exposure to manganese dioxide. It includes
- emotional lability and psychosis with bizarre or compulsive behavior
- visual hallucinations and confusion
- lumbosacral pain
- urinary urgency and incontinence
- dysarthria, nystagmus
- increased sweating, salivation
- changes in gait
A Parkinson's-like Neurologic Disease
May occur following chronic exposure. It involves the insidious development of apathy, fatigue, changes in sleep, decreased libido, headache, paresthesia, muscle cramps, and leg weakness.
PROCEDURES AND LABORATORY TESTS
Essential Tests
No tests are usually needed after acute exposure.
Recommended Tests
- MRI sometimes reveals lesions in the globus pallidum and striatum following chronic exposure.
- Pulmonary function testing should be performed in patients with respiratory symptoms.
- Chest radiographs are used to assess other causes of pulmonary symptoms.
- For potassium permanganate ingestion, tests should be ordered as for caustic base ingestion.
- Following chronic, high-level exposure with personality changes, complete evaluation for altered mental status should be performed.
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- Treatment is largely supportive, with emphasis on removal of the patient from exposure.
- Further care depends on the severity of exposure and development of systemic effects.
DIRECTING PATIENT COURSE
The health-care professional should call the poison control center when:
- Severe or persistent effects develop.
- Underlying disease presents an unusual problem.
The patient should be referred to a health-care facility when:
- Toxic effects develop.
- Underlying disease presents an unusual problem.
Admission Considerations
- Inpatient therapy may be needed if patients cannot care for themselves.
- Following potassium permanganate ingestion, any symptomatic patient should be admitted.
DECONTAMINATION
- Immediate irrigation is recommended following ocular or dermal exposure.
- Following inhalation, the patient should be moved to fresh air, and oxygen should be administered.
- Ingestion may be diluted with a small amount (4 oz) of milk or water.
- Gastric lavage and activated charcoal are not recommended because of caustic properties.
ANTIDOTES
There is no antidote for manganese poisoning.
ADJUNCTIVE TREATMENT
- Therapy with chelating agents has been proposed, but there is little evidence to support their use.
- Amelioration of symptoms from chronic exposure has been reported with the use of intravenous p-aminosalicylic acid; spontaneous improvement without treatment, however, is typical.
- L-dopa and trihexyphenidyl may relieve symptoms such as tremor and bradykinesia.
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EXPECTED COURSE AND PROGNOSIS
- The symptoms of manganese dioxide dust exposure usually resolve, but severe exposures may be fatal.
- Psychosis associated with manganese madness typically resolves following removal from exposure.
- Symptoms of metal fume fever typically resolve spontaneously within 1 to 2 days.
DISCHARGE CRITERIA/INSTRUCTIONS
- Patients with acute exposures can usually be discharged after appropriate decontamination.
- Patients with chronic exposure can be discharged with appropriate follow-up arranged, providing they can care for themselves.
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TREATMENTPotassium permanganate is treated as a caustic ingestion rather than manganese ingestion.
ICD-9-CM 985.2Toxic effect of other metals: manganese and its compounds.
See Also: SECTION III, Metal Fume Fever chapter; and SECTION IV, Caustics-Basic.
RECOMMENDED READING
Brown DSO, Wills CE, Yousefi V, et al. Neurotoxic effects of chronic exposure to manganese dust. Neuropsychol Behav Neurol 1991;4:238-250.
Author: Lada Kokan
Reviewer: Richard C. Dart