Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)
Chromium metal (as Cr)
CAS number: 7440–47–3
NIOSH REL: 0.5 mg/m3 TWA
Current OSHA PEL: 1 mg/m3 TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 0.5 mg/m3 TWA
Description of Substance: Blue-white to steel-gray, lustrous, brittle, hard, odorless solid.
LEL: . . Noncombustible Solid
Original (SCP) IDLH*: No Evidence [*Note: "Effective" IDLH = 500 mg Cr/m3 -- see discussion below.]
Basis for original (SCP) IDLH: The available toxicological data show no evidence that an acute exposure to a high concentration of chromium metal would impede escape or cause any irreversible health effects within 30 minutes. For this draft technical standard, therefore, respirators have been selected on the basis of the assigned protection factor afforded by each device. However, for some particulate substances for which no evidence of an IDLH exists, the determination of allowable respiratory protection based on protection factors may result in the assignment of respirators for concentrations that are not likely to be encountered in the occupational environment. Therefore, for all such particulate substances it has been arbitrarily determined that only the "most protective" respirators are permitted for use in concentrations exceeding 500 × the OSHA PEL of 1 mg Cr/m3, or 500 mg Cr/m3.
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA
Animal or human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 250 mg Cr/m3
Basis for revised IDLH: The available toxicological data contain no evidence that an acute exposure to a high concentration of chromium metal would impede escape or cause any irreversible health effects within 30 minutes. However, the revised IDLH for chromium metal is 250 mg Cr/m3 based on being 500 times the NIOSH REL of 0.5 mg Cr/m3 (500 is an assigned protection factor for respirators and was used arbitrarily during the Standards Completion Program for deciding when the "most protective" respirators should be used for particulates).
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