NIOSH logo and tagline

Isobutyl alcohol

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

CAS number: 78–83–1

NIOSH REL: 50 ppm (150 mg/m3) TWA

Current OSHA PEL: 100 ppm (300 mg/m3) TWA

1989 OSHA PEL: 50 ppm (150 mg/m3) TWA

1993-1994 ACGIH TLV: 50 ppm (152 mg/m3) TWA

Description of substance: Colorless, oily liquid with a sweet, musty odor.

LEL(@123°F): 1.7% (10% LEL(@123°F), 1,700 ppm)

Original (SCP) IDLH: 8,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that 2 of 6 rats died when exposed for 4 hours to 8,000 ppm [Smyth et al. 1954].

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50(ppm) LCLo(ppm) Time Adjusted 0.5-hrLC (CF) Derived value
Rat Smyth et al. 1954 LC33: 8,000 —– 4 hr 16,000 ppm (2.0) 1,600 ppm

Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
RabbitRat Munch and Schwartze 1925Smyth et al. 1954 oraloral ———- 3,7502,460 8,522 ppm5,591 ppm 852 ppm559 ppm

Other animal data: RD50 (mouse), 1,818 ppm [DeCeaurriz et al. 1981].

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


1. DeCeaurriz JC, Micillino JC, Bonnet P, Guenier JP [1981]. Sensory irritation caused by various industrial airborne chemicals. Toxicol Lett 9(2):137-143.

2. Munch JC, Schwartze EW [1925]. Narcotic and toxic potency of aliphatic alcohols upon rabbits. J Lab Clin Med 10:985-995.

3. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1448.

4. Smyth HF Jr, Carpenter CP, Weil CS, Pozzani UC [1954]. Range-finding toxicity data: list V. AMA Arch Ind Hyg Occup Med 10:61-68.