Manganese in Welding Fumes: The Adverse Health Effects & How to Reduce Them
April 25th, 2022 | Posted in General
Welding is both a labor-intensive and dangerous profession, and the health and safety of welders is a top priority. Although exposure to extreme heat is a major concern, so is the manganese in welding fumes, which can cause serious health effects if proper control measures aren’t taken.
Read more about manganese exposure in welding and how you can reduce the risks and help improve workplace safety.
What Is Manganese, and How Does It Get in Welding Fumes?
Manganese is a mineral element and essential nutrient that’s found in whole grains, nuts, seeds, and other kinds of food, and according to the Centers for Disease Control and Prevention (CDC), “A healthy person with normal liver and kidney function can excrete excess dietary manganese.” However, when this mineral is inhaled, it bypasses the body’s normal defense functions and can cause adverse health effects to the central nervous system.
In the welding industry, manganese is incorporated in consumables, such as rods and wires, for three types of welding processes:
- Shielded Metal Arc Welding or “Stick” Welding
- Gas Metal Arc Welding or “MIG”
- Flux Core Arc Welding
When these processes are used for carbon steel welding projects, some of the manganese and steel are vaporized by the heat of the electric arc. As a result, they rapidly condense into the nano-scale particles called welding fumes.
Why Is Manganese Added to Welding Consumables?
There are several reasons why manganese is added to commonly used welding consumables, including:
- Low amounts of manganese increase the hot ductility of the weld. This is important for reducing the tendency of welds to crack as they cool and contract. As the weld metal is heated to the liquid state during the welding process, it expands to its fullest extent. When the metal solidifies and cools, it contracts, which places tensile stress on the weld. If the metal cannot yield a little as it cools and contracts, the weld will crack rather than “give a little.” Low amounts of manganese facilitate the ductility necessary to avoid weld cracking.
- The cloud of fumes produced by the vaporization of Shielded Metal Arc Welding, Gas Metal Arc Welding, and Flux Core Arc Welding displaces the oxygen and nitrogen that comprise the atmosphere. Some of the oxygen and nitrogen may not be completely displaced and will compromise the weld quality and cause embrittlement if it combines with the liquid weld metal. Manganese in the fumes combines with this oxygen and incorporates the oxygen in the slag that forms during the welding process, prohibiting the oxygen from affecting the weld metal.
Be Aware of the Health Hazards of Manganese Overexposure
Welders who use consumables with manganese, and also work in a confined space, face overexposure through inhalation. This can cause a variety of negative health effects, such as damage to the lungs, liver, kidney, and central nervous system.
The U.S. Environmental Protection Agency notes that “Mn workers [workers exposed to manganese] performed worse than controls on several measures of neurobehavioral function…Five measures of eye-hand coordination (precision, percent precision, imprecision, percent imprecision, and uncertainty) reflected more erratic control of fine hand-forearm movement in the Mn-exposed group than in the controls, with mean scores on all five measures being highly significantly different for the two groups.”
Additionally, in Annals of Occupational Hygiene, Fabian Taube explained, “In the case of welders, neurological and neurobehavioral deficits, such as changes in mood and short-term memory, altered reaction time, and reduced hand–eye coordination, may occur when workers are exposed to levels of manganese less than 0.2 mg/m3 in welding fumes.”
Research has shown that it is likely welders are overexposed to manganese, and its effect on hand-eye coordination diminishes a critical skill. Not only that, but prolonged exposure to manganese can lead to Parkinson-like symptoms.
Here’s How You Can the Reduce the Risk of Exposure and Keep Workers Safe
A safe workplace is of utmost importance for welders, and to prevent overexposure to welding fumes, keep these control measures in mind:
- Inform welders of the health hazards associated with overexposure to manganese in welding fumes per the OSHA Hazard Communication Standard (29 CFR 1910.1200).
- Perform personal breathing zone monitoring on welders and analyze for respirable manganese.
- Compare the monitoring results with the American Conference of Governmental Industrial Hygienists Threshold Limit Value exposure limit of 0.02R mg/m3 for manganese.
- If the monitoring results exceed 0.02R mg/m3, consider implementing exposure controls in the form of Local Exhaust Ventilation, or “Source Capture” ventilation. Source capture air cleaners are a viable option too.
- If ventilation is not feasible, consider implementing a Respiratory Protection Program in accordance with the OSHA Respiratory Protection Standard at 29.
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Sources:
- https://iris.epa.gov/static/pdfs/0373_summary.pdf
- https://www.cdc.gov/niosh/welding/about/
- “Manganese in Occupational Arc Welding Fumes—Aspects on Physiochemical Properties, with Focus on Solubility,” Fabian Taube, Ann. Occup. Hyg., Vol. 57, No. 1, pp. 6–25, 2013