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

CAS number: 126–99–8

NIOSH REL: 1 ppm (3.6 mg/m3) 15-minute CEILING; NIOSH considers ß-chloroprene to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 25 ppm (90 mg/m3) TWA [skin]

1989 OSHA PEL: 10 ppm (35 mg/m3) TWA [skin]

1993-1994 ACGIH TLV: 10 ppm (36 mg/m3) TWA [skin]

Description of Substance: Colorless liquid with a pungent, ether-like odor.

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

Original (SCP) IDLH: 400 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that no mice died from a 1-hour exposure to 277 ppm, but all mice died from a 1-hour exposure to 829.2 ppm [von Oettingen et al. 1936].

Short-term exposure guidelines: None developed


Lethal concentration data:






Adjusted 0.5-hr








Izmerov et al. 1982

von Oettingen et al. 1936

von Oettingen et al. 1936

von Oettingen et al. 1936


LC100: 829







4 hr

1 hr

8 hr

8 hr

6,414 ppm (2.0)

1,036 ppm (1.25)

2,629 ppm (2.5)

876 ppm (2.5)

641 ppm

104 ppm

263 ppm

88 ppm

Human data: Exposure to 973 ppm has resulted in nausea and giddiness in volunteers in 10 to 15 minutes [Nystrom 1948]. Extreme fatigue and unbearable chest pain has occurred following a month of exposure to concentrations ranging from 56 to 334 ppm [Nystrom 1948].

Revised IDLH: 300 ppm

Basis for revised IDLH: The revised IDLH for ß-chloroprene is 300 ppm based on acute inhalation toxicity data in humans [Nystrom 1948]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for ß-chloroprene at concentrations above 1 ppm.]


1. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 38.

2. Nystrom AE [1948]. Health hazards in the chloroprene rubber industry and their prevention. A clinical and experimental study, with special reference to chloroprene and its oxidation and polymerization products. Acta Med Scand 123 (Suppl 219):5-125.

3. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1320.

4. von Oettingen WF, Hueper WC, Deichmann-Grubler W, Wiley FH [1936]. 2-Chlorobutadiene (chloroprene): its toxicity and pathology and the mechanism of its action. J Ind Hyg Toxicol 18 (4):247-249.

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