Welding, Manganese Exposure and Parkinson’s: The Next Asbestos?
In late 2003, a jury awarded $1 million to an Illinois man who said he developed Parkinson’s disease from years of breathing fumes from welding rods. Parkinson’s Disease is caused by the progressive destruction of nerve cells that control muscle movement. It was the first time a plaintiff prevailed in such a case. Since this award, numerous similar suits are being filed. This could result in increased insurance costs for welders.
Manganese is a highly reactive gray-white metal resembling iron, and adding manganese to steel increases its hardness, stiffness and strength. Manganese is a major component of welding fumes, particularly those from mild steel welds using shielded metal arc welding (SMAW). Mild steel is the most common steel used in industry, and SMAW is the most common type of commercial welding, but manganese exposures can result from other types of welding.
In shielded metal arc welding, a metallic electrode is connected to an electric current and the workpiece, forming an electric arc with intense heat that melts both the electrode, which acts as filler, and the workpiece. The electrode is coated with a flux that vaporizes, providing arc shielding and removing the oxide film or tarnish from the base metal. The electrode is sometimes referred to as the “stick,” so SMAW is also commonly referred to as stick or electrode welding. Manganese is a common component of the stick and flux.
The Cal/OSHA Permissible Exposure Limit for manganese is 0.2 mg/m 3, the same as the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value. Recent studies have measured welders' exposures to manganese that exceed these limits.
Chronic overexposure to manganese can lead to a disease known as manganism with symptoms similar to Parkinson's disease. At lower exposures, the most commonly observed symptoms involve injury to the central nervous system, such as longer reaction times, decreased short-term memory, and impaired hand-eye coordination. Other reported symptoms include respiratory difficulties and increased cough, colds and pneumonia, mood swings, abnormal facial expressions, tremors and a spastic gait with a tendency to fall. Decreased fertility in males has also been reported. Once someone suffers from neurological symptoms, those symptoms tend to continue and worsen, even after exposure to manganese ends.
Welders can protect themselves from manganese and other welding fume and gas exposures with good local or general ventilation. The most effective control is local exhaust ventilation in which an exhaust hood is placed near the welding arc or flame, and the contaminants are drawn away from the welder's breathing zone. Exhausted air should be discharged to the outdoors, if possible. If these controls are not feasible or do not adequately reduce exposures, proper respiratory protection should be used.
Welding in confined spaces such as tanks and pipelines is especially hazardous and requires additional ventilation or the use of an air-supplied respirator.
More information
The California Office of Health Hazard Assessment has a fact sheet on manganese exposure at www.oehha.ca.gov/air/chronic_rels/pdf/mangnREL.pdf.
The Agency for Toxic Substances and Disease Registry (ATSDR) has a fact sheet on manganese at www.atsdr.cdc.gov/tfacts151.html.
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