Manganese compounds (as Mn)

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

ACUTE TOXICITY DATA:

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].

Revised IDLH: 500 mg Mn/m3 Basis for revised IDLH: The revised IDLH for manganese is 500 mg Mn/m3 based on acute inhalation toxicity data in animals [Gupta et al. 1981]. This may be a conservative value due to the lack of relevant acute toxicity data for workers.

REFERENCES:

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.