Contractor Safety and Health: Manganese in Welding


With the high number of incidents occurring on the job site, it’s easy to see that the Occupational Safety and Health Administration (OSHA) and other regulatory agencies set their priorities towards immediate reaction hazards and high-risk safety programs.  Prioritizing efforts based on leading factors is effective, yet, there is less of a spotlight that is strictly focused on the unseen hazards of contractor work through some of the most popular occupational safety outlets, meaning, the information is not as widespread as the OSHA Top Ten or other comparable safety initiatives.

Industrial hygiene hazards have the potential to cause acute, immediate health effects, or prolonged chronic effects later in life.  Much like certain general industry environments, contractors are subject to these hazards also and can be protected from them if the right knowledge is shared with employees on the job site.


Welding, cutting, and brazing are common practices in most industrial construction sites.  In 2018, the Bureau of Labor Statistics reported that there were 424,700 jobs in the United States as welders.  There is no definite environment for which a welder works.  They are subject to outdoor welding, rooftop work at heights, underwater welding operations, and confined spaces with poor ventilation.  Welding is the joining of two separate pieces of metal by using heat to create a chemical reaction infusing a bond.  Commonly associated hazards with welding include fire and burn hazards, electrical shock, metal splatter, radiant energy associated with optical hazards, and fumes.

One of the fume hazards associated with the welding trade is from a chemical element found in most metals called Manganese.  Manganese (Mn) is not found in nature as a natural element but is commonly found in minerals combined with iron.  Manganese Phosphate is used as a corrosion prevention technique on steel.

Due to the high volume of steel welding, Manganese is a prevalent element present during the process.  Manganese can be present in welding rods ranging from 1 to 20% of the metals present during welding.

In 1989, OSHA set the welding fume Threshold Limit Value, or TLV, at five mg/m3 for an eight-hour time-weighted average.  That value has since been rescinded with no replacement established.  The American Conference of Governmental Industrial Hygienists (ACGIH) adopted a TLV time-weighted average of 1 mg/m3 and a short-term exposure level of 3 mg/m3 for welding fumes from 1979 to 1994.  This TLV was dramatically decreased to 0.2 mg/m3 for Manganese in 1995.

Manganese health effects range and they are dependent on how they enter the respiratory system.  Through studies conducted on different particle sizes for different welding techniques, it was shown that the majority of inhaled welding particles would deposit in a particularly hazardous part of the respiratory system that lacks its own removal process of the Manganese particles. Through studies conducted on retired shipyard arc welders in 1983, it was determined that metals associated with the act of welding, can remain in the lungs of a person long after removal from the actual source.  Excess Manganese can lead to devastating adverse neurological effects.  In addition, liver dysfunction, carbon monoxide poisoning, organic solvent exposure, and brain accumulation of iron have all been linked to Manganese poisoning.

There have not been any large-scale, well-controlled studies on the effects of Manganese on welders.  Furthermore, long-term health effects are not well reported nor sufficiently linked to the occupational exposures that patients had in the past.  With this knowledge, Industrial Hygiene communities and employers should take steps to ensure that information is reported accurately, and that welding contractors are well aware of the possible chronic effects of their occupation.


Albini, E., Antonini, J., Jenkins, N., Lucchini, R., & Santamaria, A. (October 10, 2005). Fate of manganese associated with the inhalation of welding fumes: potential neurological effects. Retrieved from

Bureau of Labor. (September 4, 2019). Welders, cutters, solderers, and brazers.  Occupational Outlook Handbook. Retrieved from

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