Uranium (soluble compounds, as U)

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

CAS number: Varies

NIOSH REL: 0.05 mg/m3 TWA; NIOSH considers soluble uranium compounds to be potential occupational carcinogens as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 0.05 mg/m3 TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.2 mg/m3 TWA, 0.6 mg/m3 STEL

Description of substance: Varies

Original (SCP) IDLH: 20 mg U/m3

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that UO2(NO3)2×6H20 of respirable particle size and dusts and mists of UF6, UO2F2, and UCl4 were generally fatal to most laboratory species when exposed daily for 1 month at 20 mg/m3 [Wilson et al. 1953]. No useful data on acute inhalation toxicity are available on which to base the IDLH.

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50




Adjusted LD Derived value


Spector 1956 oral ----- 12 84 mg/m3 8.4 mg/m3


Spector 1956 oral ----- 238 1,666 mg/m3 167 mg/m3

Other animal data: No grossly observable signs or symptoms were induced in mice, rats, guinea pigs, rabbits, or dogs following the first day of exposure to 20 mg/m3 of UF6 (13.5 mg U/m3), UO2F2 (15.5 mg U/m3), Ucl4 (12.5 mg U/m3), or UO2(NO3)2×H2O (9.5 mg U/m3) [Wilson et al. 1953].

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

Revised IDLH: 10 mg U/m3

Basis for revised IDLH: The revised IDLH for soluble uranium compounds is 10 mg U/m3 based on chronic toxicity data in animals [Wilson et al. 1953]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for soluble uranium compounds at concentrations above 0.05 mg U/m3.]


1. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1167.

2. Spector WS, ed. [1956]. Handbook of toxicology. Vol. I. Acute toxicities. Philadelphia, PA: W.B. Saunders Company, p. 310.

3. Wilson HB, Stokinger HE, Sylvester GE [1953]. Acute toxicity of carnotite ore dust. AMA Arch Ind Hyg Occup Med 7:301-309.

Page last reviewed: December 4, 2014