Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 67–66–3
NIOSH REL: 2 ppm (9.78 mg/m3) 60-minute STEL; NIOSH considers chloroform to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].
Current OSHA PEL: 50 ppm (240 mg/m3) CEILING
1989 OSHA PEL: 2 ppm (9.78 mg/m3) TWA
1993-1994 ACGIH TLV: 10 ppm (49 mg/m3) TWA, A2
Description of Substance: Colorless liquid with a pleasant odor.
LEL: . . Noncombustible Liquid
Original (SCP) IDLH: 1,000 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty  that 1,024 ppm produced dizziness, intracranial pressure, and nausea after 7 minutes with definite after-effects [Lehmann and Flury 1943]. Also, Lehmann et al.  reported that a 2-minute exposure to 1,107 ppm caused dizziness and vertigo. Because a person may become disoriented at concentrations greater than 1,000 ppm and be unable to escape, 1,000 ppm is chosen as the IDLH.
Existing short-term exposure guidelines: National Research Council [NRC 1984] Emergency Exposure Guidance Levels (EEGLs):
1-hour EEGL: 100 ppm
24-hour EEGL: 30 ppm
ACUTE TOXICITY DATA
Lethal concentration data:
Lehmann and Flury 1943
Lehmann et al. 1936
Tab Biol Per 1933
|32,000 ppm (1.6)
19,235 ppm (2.0)
14,113 ppm (2.0)
13,750 ppm (0.55)
Other animal data: It has been reported that inhalation of 10,000 ppm has produced clinical anesthesia [NIOSH 1974] and that exposure for 2 minutes to 1,107 ppm has caused dizziness and vertigo [Lehmann et al. 1936]. Workers exposed 4 hours/day to concentrations of 57 to 71 ppm complained of lassitude, loss of appetite, and nausea [Challen et al. 1958]. Exposures to 390 ppm were tolerated for 30 minutes without complaint, whereas 1,030 ppm resulted in dizziness, intracranial pressure, and nausea in 7 minutes, with headache for several hours [Lehmann and Flury 1943].
|Revised IDLH: 500 ppm
Basis for revised IDLH: The revised IDLH for chloroform is 500 ppm based on acute inhalation toxicity data in humans [Lehmann and Flury 1943]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for chloroform at concentrations above 2 ppm.]
1. Challen PJR, Hickish DE, Bedford J . Chronic chloroform intoxication. Br J Ind Med 15:243-249.
2. Clayton JW Jr . Fluorocarbon toxicity and biological action. Fluor Chem Rev 1(2):197-252.
3. Lehmann KB, Flury F, eds. . Toxicology and hygiene of industrial solvents. Translated by E. King and H.F. Smyth, Jr. Baltimore, MD: Williams & Wilkins Company, p. 141.
4. Lehmann KB, Schmidt-Kehl L, Ruf H, Crescitelli, Dahl, Eppinghausen, Eshe, Falker, Grotefendt, Junkenita, Maier, Mergner, Pantehtsch, Schlitzer, Shoenes, Spettmann, Wirges, Bamsreiter, Benninger, Lazarus, Manasse, Kummeth, Reuss, Schwarzweller . The 13 most important chlorinated hydrocarbons of the aliphatic series from the standpoint of occupational hygiene. Arch Hyg Bakteriol 116:132-200 (translated).
5. Lundberg I, Ekdahl M, Kronevi T, Lidums V, Lundberg S . Relative hepatotoxicity of some industrial solvents after intraperitoneal injection or inhalation exposure in rats. Environ Res 40:411-420.
6. NIOSH . Criteria for a recommended standard: occupational exposure to chloroform. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 75-114.
7. NRC . Emergency and continuous exposure limits for selected airborne contaminants. Vol. 1. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 57-76.
8. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1261.
9. Tab Biol Per ; 3:231 (in German).