Carbon black

CAS number: 1333–86–4

NIOSH REL: 3.5 mg/m³ TWA; 0.1 mg PAHs/m³ TWA

Note: NIOSH considers carbon black in the presence of polycyclic aromatic hydrocarbons (PAHs) to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 3.5 mg/m³ TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 3.5 mg/m³ TWA

Description of Substance: Black, odorless solid.

LEL: . . Solid

Original (SCP) IDLH*: No Evidence [*Note: "Effective" IDLH = 1,750 mg/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 carbon black 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; in the case of carbon black, 500 × the OSHA PEL of 3.5 mg/m³ is 1,750 mg/m³.

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA

Animal or human data: None indicating that high concentrations of carbon black would have significant health effects to workers within 30 minutes.

Revised IDLH: 1,750 mg/m3 Basis for revised IDLH: The available toxicological data contain no evidence that an acute exposure to a high concentration of carbon black would impede escape or cause any irreversible health effects within 30 minutes. However, the revised IDLH for carbon black is 1,750 mg/m3 based on being 500 times the NIOSH REL and OSHA PEL of 3.5 mg/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).