Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 110–82–7
NIOSH REL: 300 ppm (1,050 mg/m3) TWA
Current OSHA PEL: 300 ppm (1,050 mg/m3) TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 300 ppm (1,030 mg/m3) TWA
Description of Substance: Colorless liquid with a sweet, chloroform-like odor.
LEL: . . 1.3% (10% LEL, 1,300 ppm)
Original (SCP) IDLH: 10,000 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on a statement by Patty  that 12,600 ppm produced evidence of lethargy, narcosis, increased respiration rate, and convulsions in animals [Treon et al. 1943]. Also, AIHA  reported that 9,300 ppm for 30 minutes resulted in restlessness, impaired coordination, and exhaustion, but no narcosis or deaths in cats, rabbits, and pigs [Flury and Zernik 1931].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA
Lethal concentration data:
|Adjusted 0.5-hr |
|Lazarew 1929 |
Treon et al. 1943
|2 hr |
|27,429 ppm (1.6) |
33,250 ppm (1.25)
|2,743 ppm |
Lethal dose data:
|Kimura et al. 1971 |
|25,410 ppm |
|2,541 ppm |
Human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 1,300 ppm [LEL] |
Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in animals [Lazarew 1929; Treon et al. 1943], a value of about 3,000 ppm would have been appropriate. However, the revised IDLH for cyclohexane is 1,300 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 1.3%).
1. AIHA . Cyclohexane. In: Hygienic guide series. Am Ind Hyg Assoc J 24:529-531.
2. Flury F, Zernik F . Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, p. 275 (in German).
3. Kimura ET, Ebert DM, Dodge PW . Acute toxicity and limits of solvent residue for sixteen organic solvents. Toxicol Appl Pharmacol 19:699-704.
4. Lazarew NW . On the toxicity of various hydrocarbon vapors. Arch Exp Pathol Pharmakol 143:223-233 (in German). [From Treon JF, Crutchfield WE Jr, Kitzmiller KV . The physiological response of animals to cyclohexane, methylcyclohexane, and certain derivatives of these compounds. II. Inhalation. J Ind Hyg Toxicol 25(8):323-347.]
5. NPIRI . Raw materials data handbook, physical and chemical properties, fire hazard and health hazard data. Vol. 1. Organic solvents. Bethlehem, PA: National Printing Ink Research Institute, p. 17.
6. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1210.
7. Treon JF, Crutchfield WE Jr, Kitzmiller KV . The physiological response of animals to cyclohexane, methylcyclohexane, and certain derivatives of these compounds. II. Inhalation. J Ind Hyg Toxicol 25(8):323-347.
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