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May 1994

Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)


CAS number: 111–65–9

NIOSH REL: 75 ppm (350 mg/m3) TWA,

385 ppm (1,800 mg/m3) 15-minute CEILING

Current OSHA PEL: 500 ppm (2,350 mg/m3) TWA

1989 OSHA PEL: 300 ppm (1,450 mg/m3) TWA, 375 ppm (1,800 mg/m3) STEL

1993-1994 ACGIH TLV: 300 ppm (1,400 mg/m3) TWA, 375 ppm (1,750 mg/m3) STEL

Description of substance: Colorless liquid with a gasoline-like odor.

LEL: . . 1.0% (10% LEL, 1,000 ppm)

Original (SCP) IDLH: 5,000 ppm

Basis for original (SCP) IDLH: Because no human exposure data are available for octane, the chosen IDLH is based on an analogy with heptane which has an IDLH of 5,000 ppm.

Short-term exposure guidelines: None developed


Lethal dose data:


SpeciesReferenceRouteLD50 (mg/kg)LDLo (mg/kg)Adjusted LDDerived value
MouseJeppsson 1975i.v. -----428631 ppm 63 ppm

Other animal data: Narcosis resulted in mice exposed for 0.5 to 1.5 hours to 6,600 to 13,700 ppm [Fuhner 1921]. Respiratory arrest occurred in 1 of 4 mice within 5 minutes at 16,000 ppm and in 4 of 4 mice within 3 minutes at 32,000 ppm [Swann et al. 1974].

Human data: The narcotic concentration has been estimated to be either 8,000 ppm [Flury and Zernik 1931] or 10,000 ppm [Patty and Yant 1929]. The fatal concentration has been estimated to be 13,500 ppm [Flury and Zernik 1931].


Revised IDLH: 1,000 ppm [LEL]

Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in humans [Flury and Zernik 1931; Patty and Yant 1929], a value of about 3,000 ppm would have been appropriate for octane. However, the revised IDLH for octane is 1,000 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 1%).


1. Flury F, Zernik F [1931]. Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, pp. 257-264 (in German).

2. Fuhner H [1921]. The narcotic effect of gasoline and its components (pentane, hexane, heptane, octane). Biochemische Zeitschrift 115:235-261 (in German).

3. Jeppsson R [1975]. Parabolic relationship between lipophilicity and biological activity of aliphatic hydrocarbons, ethers and ketones after intravenous injections of emulsion formulations into mice. Acta Pharmacol Toxicol 37:56-64.

4. Patty FA, Yant WP [1929]. Odor intensity and symptoms produced by commercial propane, butane, pentane, hexane, and heptane vapor. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, Bureau of Mines Report, Investigation No. 2979.

5. Swann HE, Kwon BK, Hogan GK, Snellings WM [1974]. Acute inhalation toxicology of volatile hydrocarbons. Am Ind Hyg Assoc J 35:511-518.

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