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May 1994

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


CAS number: 75-05-8

NIOSH REL: 20 ppm (34 mg/m3) TWA

Current OSHA PEL: 40 ppm (70 mg/m3) TWA

1989 OSHA PEL: 40 ppm (70 mg/m3 TWA), 60 ppm (105 mg/m3) STEL

1993-1994 ACGIH TLV: 40 ppm (67 mg/m3) TWA, 60 ppm (101 mg/m3) STEL

Description of substance: Colorless liquid with an aromatic odor.

LEL: 3.0% (10% LEL, 3,000 ppm)

Original (SCP) IDLH: 4,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the UCC [1965] report that a 4-hour exposure to 4,000 ppm killed 3 of 30 rats, 8,000 ppm killed 10 of 30 rats, and 16,000 ppm killed 17 of 30 rats. It is also based on the statement by AIHA [1960] that some deaths occurred in rats, dogs, and guinea pigs at 4,000 ppm, but no deaths occurred at 1,000 ppm. Pozzani et al. [1959] reported that a 53,000 ppm exposure was lethal to 3 of 6 rats in 30 minutes.

Short-term exposure guidelines: None developed


Lethal concentration data:

SpeciesReferenceLC50(ppm)LCLo(ppm)TimeAdjusted 0.5-hr LC (CF) Derived Value
G. pigPozzani et al. 19595,655-----4 hr11,310 ppm (2.0)1,131 ppm
DogPozzani et al. 1959-----16,0004 hr32,000 ppm (2.0)3,200 ppm
RabbitPozzani et al. 19592,828----- 4 hr5,656 ppm (2.0)566 ppm
RatPozzani et al. 195953,000-----30 min53,000 ppm (1.0)5,300 ppm
RatPozzani et al. 19597,500-----8 hr18,750 ppm (2.5)1,875 ppm
MouseWillhite 19812,693-----1 hr3,366 ppm (1.25)337 ppm

Human data: Exposures to 160 ppm for 4 hours has caused flushing of the face and a feeling of constriction in the chest; exposures to 500 ppm for brief (undefined) time periods has resulted in only irritation to the nose and throat [Deichmann and Gerarde 1969].

Revised IDLH: 500 ppm

Basis for revised IDLH: The revised IDLH for acetonitrile is 500 ppm based on acute inhalation toxicity data in humans [Deichmann and Gerarde 1969]. 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 [1960]. Acetonitrile. In: Hygienic guide series. Am Ind Hyg Assoc J 21:265-266.
  2. Deichmann WB, Gerarde HW [1969]. Acetonitrile (methyl cyanide; ethanenitrile). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., p. 65.
  3. Pozzani UC, Carpenter CP, Palm PE, Weil CS, Nair JH III [1959]. An investigation of the mammalian toxicity of acetonitrile. J Occup Med 1:634-642.
  4. UCC [1965]. Toxicology studies: acetonitrile. New York, NY: Union Carbide Corporation.
  5. Willhite CC [1981]. Inhalation toxicology of acute exposure to aliphatic nitriles. Clin Toxicol 18(8):991-1003.
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