Manganese Fume (as Mn) - OSHA Exposure Limits and Health Effects

1910.1000 Air Contaminants
1910.1026 Chromium (VI)
1926.353 Ventilation and Protection in Welding, Cutting, and Heating

Standard Set By Exposure Limit Health Effect Codes -- Health Effects and Target Organs
OSHA PEL - General Industry
See 29 CFR 1910.1000 Table Z-1
5 mg/m3 Ceiling
HE7 -- manganism
target organs: brain, central nervous system
OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A
5 mg/m3 Ceiling
HE7 -- manganism
target organs: brain, central nervous system
OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z - Shipyards
5 mg/m3 Ceiling
HE7 -- manganism
target organs: brain, central nervous system
3 mg/m3 STEL
HE4 -- metal fume fever
HE7 -- poor coordination, memory/judgment trouble, emotional instability, shaking/tremor in hands and/or legs, difficulty speaking properly, hallucinations
HE11 -- manganese pneumonia
ACGIH TLV® (2012) 0.02 mg/m3 (respirable particulate matter) TWA
0.1 mg/m3 TWA
HE7 -- neurophysiological and neuropsychological effects, including impaired visual time, eye-hand coordination, and hand steadiness, decreased motor function, decreased behavioral tests, tremor
CAL/OSHA PELs 0.2 mg/m3 (respirable particulate matter) TWA
3 mg/m3 STEL
HE7 -- neurobehavioral dysfunction, decreased eye-hand coordination

Manganism (also known as Mn, Manganese metal, Colloidal manganese, and Manganese-55), is a condition that occurs when someone has been exposed to toxic levels of manganese. Symptoms tend to mimic Parkinson's Disease and include gait disturbances, clumsiness, tremors, speech disturbances, and psychological disturbances.
Metal fume fever is a temporary condition caused by inhaling manganese fumes. Symptoms typically include chills, fever, upset stomach, vomiting, dryness of the throat, cough, weakness, and achiness.

Carcinogenic Classification:

  • NTP: Not listed
  • IARC: Not listed
  • EPA: Not classifiable as to human carcinogenicity
  • EPA Inhalation Reference Concentration (RfC): 5x10-5 mg/m3
    ATSDR Inhalation Minimal Risk Levels (MRLs): 0.04 μg/m3 (chronic)
    NIOSH IDLH concentration: 500 mg/m3 (as Mn)

    Notes on other potential health effects and hazards:

      1. Manganese is combustible, and finely dispersed particles can form explosive mixtures in air (NIOSH/IPCS 2003).
      2. Data indicate that manganese exposure is associated with a range of neurobehavioral and neuropsychiatric changes, some of which may persist for long periods after occupational exposure ceases (ACGIH 2013).
      3. Even at lower levels of manganese exposure (about 0.0129 mg/m3), investigators found neuropsychological changes with respect to attention, mood, and fine motor control (Laohaudomchok et al. 2011).
      4. One study found that six deaths from pneumonia in a Norwegian ferroalloy plant could be attributed to occupational exposures to manganese (Hobbesland et al. 1997). Another study looking at welders found three fatalities due to pneumonia that could be traced back to manganese exposure (Wergeland and Iversen 2001).
      5. A study examining welders found that the only difference between welding-related Parkinsonism and idiopathic Parkinsonism is the age of onset. As a result, the authors concluded that welding could be a risk factor for developing Parkinson's Disease (Racette et al. 2001).
      6. Based on the findings of neurobehavioral impairment by Roels et al. (1987, 1992), the LOAEL for derivation of the EPA RfC is 0.15 mg/m3, and the LOAEL(HEC) is 0.05 mg/m3.

    Welding safety is necessary in establishing clean air and safe working conditions. Employers and welders are required to understand and abide by federal, state, and local standards to prevent accident and injuries from occuring in the workplace.

    OSHA Exposure Limits and Health Effects - Manganese Fume (as Mn)