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Monitoring manganese exposure
Manganese (Mn) is an essential trace element with many industrial uses. Manganese is the 12th most abundant element in the earth's crust and is used predominantly in the production of steel. These industrial processes cause elevated environmental exposures to airborne manganese dust and fumes, which in turn have lead to well-documented cases of neurotoxicity among exposed workers. Mining and iron and steel production have been implicated as sources of exposure.
Inhalation is the primary source of entry for manganese toxicity. Signs of toxicity may appear quickly or not at all; neurological symptoms are rarely reversible. Manganese toxicity is generally recognized to progress through 3 stages. Levy describes these stages. "The first stage is a prodrome of malaise, somnolence, apathy, emotional lability, sexual dysfunction, weakness, lethargy, anorexia, and headaches. If there is continued exposure, progression to a second stage may occur, with psychological disturbances, including impaired memory and judgment, anxiety, and sometimes psychotic manifestations such as hallucinations. The third stage consists of progressive bradykinesia, dysarthrian axial and extremity dystonia, paresis, gait disturbances, cogwheel rigidity, intention tremor, impaired coordination, and a mask-like face. Many of those affected may be permanently and completely disabled."(1)
Few cases of manganese deficiency or toxicity due to ingestion have been documented. Only 1% to 3% manganese is absorbed via ingestion, while most of the remaining manganese is excreted in the feces. As listed in the United States National Agriculture Library, manganese adequate intake is 1.6 mg/day to 2.3 mg/day for adults. This level of intake is easily achieved without supplementation by a diverse diet including fruits and vegetables, which have higher amounts of manganese than other food types. Patients on a long-term parenteral nutrition should receive manganese supplementation and should be monitored to ensure that circulatory levels of manganese are appropriate.
0-15 years: not established
> or =16 years: 0.1-0.9 mcg/L
Manganese in urine represents the excretion of excess manganese from the body, and may be used to monitor exposure or excessive nutritional intake.
Reference values have not been established for random urine specimens. Assessment of overexposure may require collection of a blood specimen or a 24-hour urine specimen.
Specimens collected from healthy, unexposed adults have extremely low levels of manganese. Because of the high environmental concentration of manganese, contamination is always a possibility when considering elevated results. Precautions must be taken to ensure the specimen is not contaminated. Metal-free urine collection procedures must be followed.
High concentrations of gadolinium and iodine are known to interfere with most metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen cannot be collected for 96 hours.
1. Levy BS, Nassetta WJ: Neurologic effects of Manganese in humans: A review. Int J Occup Environ Health Apr/Jun 2003;9(2):153-163
2. Paschal DC, Ting BG, Morrow JC, et. at. Trace metals in urine of United States residents: Reference range concentrations. Environmental Research 1998;7:53-59.