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

CAS number: 75-07-0

NIOSH REL: None established; NIOSH considers acetaldehyde to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 200 ppm (360 mg/m3) TWA

1989 OSHA PEL: 100 ppm (180 mg/m3) TWA, 150 ppm (270 mg/m3) STEL

1993-1994 ACGIH TLV: 25 ppm (45 mg/m3) CEILING, A3

Description of substance: Colorless liquid or gas (above 69øF) with a pungent, fruity odor.

LEL: 4.0% (10% LEL, 4,000 ppm)

Original (SCP) IDLH: 10,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statements by Patty [1963] and ACGIH [1971] that all rats survived a 4-hour exposure to 8,000 ppm, but all rats died from a 16,000 ppm exposure [Smyth 1956].

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50(ppm) LCLo(ppm) Time Adjusted 0.5-hr LC (CF) Derived Value
Rat Appelman et al. 1982 13,000 ----- 4 hr 26,000 ppm (2.0) 2,600 ppm
Hamster Feron 1979 17,000 ----- 4 hr 34,000 ppm (2.0) 3,400 ppm
Rat Skog 1950 20,000 ----- 30 min 20,000 ppm (1.0) 2,000 ppm
Rat Skog 1950 20,536 ----- 30 min 26,536 ppm (1.0) 2,054 ppm

Other animal data: RD50 (mouse), 4,946 ppm [Alarie 1981].

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

Revised IDLH: 2,000 ppm
Basis for revised IDLH: The revised IDLH for acetaldehyde is 2,000 ppm based on acute inhalation toxicity data in animals [Alarie 1981; Skog 1950]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for acetaldehyde at any detectable concentration.]


  1. ACGIH [1971]. Acetaldehyde. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 1-2.
  2. Alarie Y [1981]. Dose-response analysis in animal studies: prediction of human responses. Environ Health Perspect 42:9-13.
  3. Appelman LM, Woutersen RA, Feron VJ [1982]. Inhalation toxicity of acetaldehyde in rats. I. Acute and subchronic studies. Toxicology 23(4):293-307.
  4. Feron VS [1979]. Effects of exposure to acetaldehyde in Syrian hamsters simultaneously treated with benzo(a)pyrene or diethylnitrosamine. Prog Exp Tumor Res 24:162-176.
  5. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1967.
  6. Skog E [1950]. A toxicological investigation of lower aliphatic aldehydes. I. Toxicity of formaldehyde, acetaldehyde, and butryaldehyde; as well as acrolein and crotonaldehyde. Acta Pharmacol Toxicol 6(4):299-318.
  7. Smyth HF Jr [1956]. Improved communication: hygienic standards for daily inhalation. Am Ind Hyg Assoc Q 17(2):129-185.
Page last reviewed: December 4, 2014