According to their internal documents, from 1932 to 1980, the manufacturers of welding rods systematically concealed evidence that linked their welding rods to serious adverse health effects on welders. Welding rod manufacturers discovered that welding fumes posed serious health risks to welders, but because of economic concerns, the industry covered up the problems associated with their product for almost 50 years.

Welding is the process by which two metal parts are jointed. This is accomplished by melting the parts at the points of contact and simultaneously forming a connection with molten metal from the parts themselves, called the parent metal, or form filler material.

The filler material used to join the metal parts is called the consumable, and is usually a coated electrode or wire that contributes metal to the joint. Welding rods, welding electrodes, and welding wire are commonly used consumables. There are many types of welding consumables. Typically, welding electrodes (or rods) will contain the most manganese. There are, however, types of welding wire that contain as much as 25% manganese.

The welding consumables (rods, electrodes, and/or wire) contain the element manganese. When manganese is contained in the welding consumable, it is also contained in the fumes produced during welding. Typically, the rods or electrodes used in Shielded Metal Arc, or stick welding, will contain the most manganese. Some types of welding wire, used in Metal Inert Gas (MIG) welding are quite high in manganese as well.

Manganese is toxic. The element passes into the blood stream and then rapidly to the tissues. Manganese toxicity is usually reported due to industrial and agricultural exposures. Industrial exposure to manganese is mostly seen among welders. Manganese toxicity typically results from pulmonary absorption. Manganese dust and fumes are responsible for most of industrially-associated manganese toxicity. The neurotoxicity of manganese was established as early as the 19th century.

Exposure to high levels of manganese by inhalation in humans results primarily in central nervous system effects. Inhalation of fumes or dusts of manganese cause neurological symptoms. Exposure to heavy concentrations of dusts or fumes for as little as three months may produce the condition.

• Shielded Metal Arc Welding (SMAW, stick)
• Gas Metal Arc Welding (GMAW, MIG)
• Gas Tungsten Arc Welding (GTAW, TIG)
• Flux Colored Arc Welding (FCAW)
• Plasma Arc Welding (PAC, PAW)
• Submerged Arc Welding (SAW)
• Carbon Arc Welding (CAW)
• Electro Gas Welding (EGW)
• Stand Welding
• Oxyacetylene Welding
• Beddon Plate Welding
• Torch Brazing
• Oxygen Cutting
• Air Carbon Arc Cutting

• Metal fume fever (flu-like symptoms)
• Respiratory problems
• Gastrointestinal effects including chronic gastritis, gastroduodentitis, ulcers etc
• Reproductive risks
• Cancers
• Kidney and heart damage
• Central nervous system effects including tremors, manganism, etc