Safety Tidbit 3.16 - Welding Fumes - Manganese

Safety Tidbit 3.16 – Welding Fumes - Manganese

Reference: NIOSH – Welding and Manganese

This week, I reviewed three reports with elevated levels of manganese. Additionally, the site I was at this week, conducting air sampling on welders, I spent a bit of time explaining the effects of manganese to the welders. They seemed unfamiliar with the hazard.  Therefore, I figured the cosmos was telling me this should be my topic this week. Also, I discussed manganese last year in Safety Tidbit 2.21 in more general terms.

Personal exposures can vary considerably depending on the amount of manganese in the welding wire, rods, flux and base metal. Numerous studies indicate that welders may be at increased risk of neurological and neurobehavioral health effects when exposed to metals such as lead, iron and manganese. Carbon monoxide, heat and stress can also contribute to neurological impairments in welders. Some studies indicate that welders exposed to low levels of manganese (<0.2 mg/m³ ) perform more poorly on tests of brain function and motor skills. These effects include changes in mood and short-term memory, altered reaction time, and reduced hand-eye coordination. It is not known if these findings have clinical significance. Affected workers frequently show abnormal accumulations of manganese in a region of the brain known as the globus pallidus. The globus pallidus plays an important role in movement regulation. NIOSH is currently reviewing its Recommended Exposure Limit (REL) for manganese as a result of these studies. Although the research is complicated and its validity is challenged more studies are currently underway.

Ultimately, when you observe welding operations good industrial hygiene practices are in order. Namely, ensure the fumes are being vented away from the worker. The old-fashioned canopy hood for welding operations is not a good design as the welding fumes pass through the welder’s breath zone on its way to the canopy. Ensure the welders pull or push the fumes away from their breathing zone or capture them as close to the source as possible. Welding fume extraction units are nice portable alternatives but I usually see the hoods more than twelve inches away from the point of generation. At twelve inches the hood capture is negligible at the point of generation so there really isn’t anything to force the fumes into the duct. Always follow the manufacturer’s recommendations but a good rule of  thumb is to have the capture hood approximately six inches from the generation point.

Hope this was helpful and thanks for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have an interesting safety or health question please let me know.