Manganese is a naturally element often found in groundwater. When consumed in trace amounts, manganese facilitates crucial biological functions including bone formation, cartilege formation, growth, and brain function. However, prolonged inhalation of manganese fumes or dust will injure the central nervous system.
Manganese is also often added to steel to help prevent corrosion.
Manganese poisoning results from prolonged exposure to manganese dust or fumes. Such poisoning often occurs in industrial or workplace settings, where welding activities cause small amounts of manganese to be released into the air where they can be inhaled. Welding wire and welding rods, which are used in welding to fuse pieces of metal together, may contain very high levels of manganese. This can place welders at a high risk of exposure, particularly if they are working in enclosed spaces or without adequate ventilation.
Prolonged exposure to manganese fumes or dust can result in manganism, a condition of the central nervous system similar in its symptoms to Parkinson's disease. Manganism may result from as little as six months to two years of workplace exposure.
The progression of manganism includes:
Behavioral Changes - Symptoms include muscle cramps, loss of appetite, fatigue, headache, apathy, dimished libido, and insomnia. The patient may also display psychotic reactions known as "locura manganica" ("manganese madness"), involving aggressive conduct and difficulty controlling emotions.
Parkinsonian Features - Symptoms include muscle stiffness, tremors, difficulty with movement and balance, impaired writing, postural instability, and an expressionless face.
Gait Disturbances and Dystonia - As manganism progresses, the patient displays a "cock-walk" gait, which involves walking with an extended trunk and flexed arms, while strutting on one's toes. The patient also displays dystonia - abnormal muscle tone. Patients often display a low amplitude postural tremor of the upper extremities - the arms, forearms and hands.
Once established in the most severe stage, manganism is a progressive illness even after the patient is removed from exposure. Although treatment with L-Dopa has been demonstrated to provide short-term improvement, this is believed to result from a placebo effect.
Lawyers representing workers with manganism allege that the manufacturers of welding products which contain manganese, such as welding wire, welding rods and electrodes, have been aware since the 1930's that use of their products can result in exposure to dangerous levels of manganese. Pursuant to this theory, the manufacturers' liability arises from their failure to disclose these known dangers, and their failure to make their products safer in light of these dangers. The workers' lawyers assert that manganism was first recognized in 1837, and documents known to the manufacturers since the mid-1930's acknowledge a connection between welders' exposure to manganese and the onset of manganism.
The manufacturers deny these allegations.