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Manganese compounds (as Mn)

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 7439–96–5 (Metal)

NIOSH REL: 1 mg/m3 TWA, 3 mg/m3 STEL

Current OSHA PEL: 5 mg/m3 CEILING

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 5 mg/m3 TWA

Description of substance: Varies

Original (SCP) IDLH*: No Evidence [*Note: “Effective” IDLH = 10,000 mg Mn/m3 — see discussion below.]

Basis for original (SCP) IDLH: The available toxicological data do not indicate that exposure to a high concentration of manganese could impede escape within 30 minutes. For this draft technical standard, therefore, respirators have been assigned on the basis of the assigned protection factor afforded by each device up to 2,000 ´ the OSHA PEL (2,000 ´ 5 mg Mn/m3 is 10,000 mg Mn/m3; only the “most protective” respirators are permitted for use in concentrations exceeding 10,000 mg Mn/m3).

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
Mn Rat Marhold 1972 oral 9,000 —– 63,000 mg Mn/m3 6,300 mg Mn/m3
MnC4H6O4 Rat Marhold 1977 oral 2,940 —– 6,586 mg Mn/m3 659 mg Mn/m3
MnCl2 Mouse Gupta et al. 1981 oral 1,715 —– 5,282 mg Mn/m3 528 mg Mn/m3

Human data: Chronic exposures to workers averaging 47 mg/m3 caused manganese poisoning, while no cases occurred at exposures less than 30 mg/m3 [Flinn et al. 1940]. Chronic exposure to concentrations averaging 210 mg/m3 have been associated with pneumonia [Lloyd-Davies 1946]. Workers chronically exposed to concentrations of manganese dust averaging 20 mg/m3 showed signs of manganism [Smyth et al. 1973].


1. Flinn RH, Neal PA, Reinhart WH, Dallavalle JM, Fulton WB, Dooley AE [1940]. Chronic manganese poisoning in an ore-crushing mill. Public Health Bulletin 247:1-77.

2. Gupta PK, Murthy RC, Chandra SV [1981]. Toxicity of endosulfan and manganese chloride: cumulative toxicity rating. Toxicol Lett 7:221-227.

3. Lloyd-Davies TA [1946]. Manganese pneumonitis. Br J Ind Med 3:111-135.

4. Marhold JV [1972]. Sbornik vysledku toxixologickeho vysetreni latek a pripravku. Czechoslovakia: Institut Pro Vychovu Vedoucicn Pracovniku Chemickeho Prumyclu Praha, p. 21 (in Czechoslovakian).

5. Marhold JV [1977]. Personal communication. Pardubice, Czechoslovakia: VUOS, 539-18, 3/29/77.

6. Smyth LT, Ruhf RC, Whitman NE, Dugan T [1973]. Clinical manganism and exposure to manganese in the production and processing of ferromanganese alloy. J Occup Med 15:101-109.