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

CAS number: 109–66–0

NIOSH REL: 120 ppm (350 mg/m3) TWA,

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

Current OSHA PEL: 1,000 ppm (2,950 mg/m3) TWA

1989 OSHA PEL: 600 ppm (1,800 mg/m3) TWA, 750 ppm (2,250 mg/m3) STEL

1993-1994 ACGIH TLV: 600 ppm (1,770 mg/m3) TWA, 750 ppm (2,210 mg/m3) STEL

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

LEL :. . 1.5% (10% LEL, 1,500 ppm)

Original (SCP) IDLH: 15,000 ppm [LEL]

Basis for original (SCP) IDLH: Patty [1963] reported the following: “n-pentane causes narcosis in 5 to 60 minutes at 90,000 to 120,000 ppm. Only a narrow margin exists between the concentrations that cause narcosis and death in mice. In human studies, a 10-minute exposure to 5,000 ppm did not cause mucous membrane irritation or other symptoms. The odor of n-pentane at this concentration is readily detectable” [Fuhner 1921]. AIHA [1966] reported that the atmospheric concentration immediately hazardous to life is unknown for man, but that the lethal concentration for mice has been reported as 128,200 ppm for a 37-minute exposure [Spector 1956]. Because the data indicate that acute toxic effects occur above the lower explosive limit (LEL) of 15,000 ppm, the LEL has been chosen as the IDLH (i.e., the concentration above which only the “most protective” respirators are permitted).

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50 LCLo Time Adjusted 0.5-hrLC (CF) Derived value
Mouse Flury & Zernik 1931 —– 130,000 mg/m3 30 min 130,000 ppm (1.0) 13,000 ppm
Mouse Spector 1956 —– 128,200 ppm 37 min 137,175 ppm (1.07) 13,718 ppm
Mouse Stoughton & Lamson 1936 —– 325,000 mg/m3 2 hr 173,333 ppm (1.6) 17,333 ppm

Other animal data: It has been reported that narcosis occurs after 5 to 60 minutes of exposure to 90,000 to 120,000 ppm [Patty 1963].

Human data: Mucous membrane irritation or other symptoms were not noted after a 10-minute exposure of 5,000 ppm [Patty and Yant 1929].


1. AIHA [1966]. Pentane (n-pentane). In: Hygienic guide series. Am Ind Hyg Assoc J 27:207-209.

2. Flury F, Zernik F [1931]. Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, pp. 257-284 (in German).

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

4. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1198.

5. Patty FA, Yant WP [1929]. Odor intensity and symptoms produced by commercial propane, butane, pentane, hexane, and heptane vapor. Pittsburgh, PA: Department of Commerce, U.S. Bureau of Mines, Report of Investigations, No. 2979, pp. 1-10.

6. Spector WS, ed. [1956]. Handbook of toxicology. Vol. I. Acute toxicities. Philadelphia, PA: W.B. Saunders Company, pp. 346-347.

7. Stoughton RW, Lamson PD [1936]. The relative anaesthetic activity of the butanes and pentanes. J Pharmacol Exp Ther 58:74-77.