NIOSH logo and tagline

Cobalt metal dust and fume (as Co)

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

CAS number: 7440–48–4 (Metal)

NIOSH REL: 0.05 mg/m3 TWA

Current OSHA PEL: 0.1 mg/m3 TWA

1989 OSHA PEL: 0.05 mg/m3 TWA

1993-1994 ACGIH TLV: 0.05 mg/m3 TWA

Description of Substance: Varies

Original (SCP) IDLH: 20 mg Co/m3

Basis for original (SCP) IDLH: Browning [1969] made the statement that “metallic cobalt by inhalation and soluble salts by intratracheal injection act as acute lung irritants, producing oedema, and hemorrhage with a considerable outpouring of fluid from the capillaries in the peritoneal cavity. Many of the animals subjected to intratracheal injection of a suspension of cobalt metal dust developed acute pneumonia, often rapidly fatal as an initial reaction.” Because no data on acute inhalation toxicity are available on which to base an IDLH for cobalt metal fume and dust, the chosen IDLH is based on the statement by Patty [1963] that animals chronically exposed to a cobalt-metal blend at a concentration of 20 mg Co/m3 developed lesions in the lungs.

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
RatRabbit FDRL 1984Simesen 1939 oraloral 6,170—– —–750 43,190 mg Co/m35,250 mg Co/m3 4,319 mg Co/m3525 mg Co/m3


Other animal data: It has been reported that animals chronically exposed for 3 years to a cobalt-metal blend at a concentration of 20 mg Co/m3 developed fibrotic lesions in the lungs [Patty 1963].

Human data: None relevant for use in determining the revised IDLH.



1. Browning E [1969]. Toxicity of industrial metals. 2nd ed. New York, NY: Appleton-Century-Crofts, p. 136.

2. FDRL [1984]. Acute oral LD50 study of cobalt powder-325 mesh t3N in Sprague Dawley rats. Waverly, NY: Food & Drugs Research Laboratories, Inc., FDRL Study No. 8005B.

3. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1032.

4. Simesen M [1939]. The fate of cobalt after oral administration of metallic cobalt and subcutaneous injection of carbonatotetraminecobalt chloride, with remarks on the quantitative estimation of cobalt in organic materials. Arch Int Pharmaco Ther 62(3):347-356.