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

CAS number: 108–10–1

NIOSH REL: 50 ppm (205 mg/m3) TWA, 75 ppm (300 mg/m3) STEL

Current OSHA PEL: 100 ppm (410 mg/m3) TWA

1989 OSHA PEL: 50 ppm (205 mg/m3) TWA, 75 ppm (300 mg/m3) STEL

1993-1994 ACGIH TLV: 50 ppm (205 mg/m3) TWA, 75 ppm (307 mg/m3) STEL

Description of Substance: Colorless liquid with a pleasant odor.

LEL(@200 F): 1.2% (10% LEL(@200 F), 1,200 ppm)

Original (SCP) IDLH: 3,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] from Smyth [1956] that rats survived a 4-hour exposure to 2,000 ppm; death occurred as a result of a 4-hour exposure to 4,000 ppm. Also, AIHA [1966] reported that exposure of rats to 4,000 ppm for 4 hours killed 6 of 6 and exposure at 2,000 ppm for 4 hours killed 0 of 6 [Smyth et al. 1951].

Short-term exposure guidelines: None developed


Lethal concentration data:






Adjusted 0.5-hr




Rat Smyth et al. 1951 LC100: 4,000 ----- 4 hr 8,000 ppm (2.0) 800 ppm

Other animal data: It has been reported that rats survived exposures to 2,000 ppm for 4 hours [Smyth et al. 1951].

Human data: It has been reported that 200 ppm has an objectionable odor and is irritating to the eyes [Silverman et al. 1946]. Among a group of workers exposed to concentrations of 500 ppm for 20 to 30 minutes and about 80 ppm for the rest of the shift, most experienced irritation of the eyes, nose, and throat, weakness, loss of appetite, headache, nausea, vomiting, and a sore throat [Linari et al. 1964].

Revised IDLH: 500 ppm

Basis for revised IDLH: The revised IDLH for hexone is 500 ppm based on acute inhalation toxicity data in humans [Linari et al. 1964; Silverman et al. 1946]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 500 ppm.


1. AIHA [1966]. Methyl isobutyl ketone. In: Hygienic guide series. Am Ind Hyg Assoc J 27:209-211.

2. Linari F, Pernell G, Varese D [1964]. Clinical observations and blood chemistry tests among workers exposed to the effect of a complex ketone methyl-isobutyl-ketone. Arch Sci Med, pp. 226-237 (in Italian). [From ACGIH [1991]. Methyl isobutyl ketone. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 1019-1021.]

3. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1738.

4. Silverman L, Schulte HF, First MW [1946]. Further studies on sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 28:262-266.

5. Smyth HF Jr [1956]. Improved communication: hygienic standards for daily inhalation. Am Ind Hyg Assoc Q 17(2):129-185.

6. Smyth HF Jr, Carpenter CP, Weil CS [1951]. Range-finding toxicity data: list IV. AMA Arch Ind Hyg Occup Med 4:119-122.