Cyclohexane

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 [1963] that 12,600 ppm produced evidence of lethargy, narcosis, increased respiration rate, and convulsions in animals [Treon et al. 1943]. Also, AIHA [1963] 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:

Species	Reference	LC50 (ppm)	LCLo (ppm)	Time	Adjusted 0.5-hr LC (CF)	Derived value
Mouse Rabbit	Lazarew 1929 Treon et al. 1943	----- -----	17,142 26,600	2 hr 1 hr	27,429 ppm (1.6) 33,250 ppm (1.25)	2,743 ppm 3,325 ppm

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rat Mouse	Kimura et al. 1971 NPIRI 1974	oral oral	12,705 813	----- -----	25,410 ppm 1,626 ppm	2,541 ppm 163 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%).

REFERENCES:

1. AIHA [1963]. Cyclohexane. In: Hygienic guide series. Am Ind Hyg Assoc J 24:529-531.

2. Flury F, Zernik F [1931]. Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, p. 275 (in German).

3. Kimura ET, Ebert DM, Dodge PW [1971]. Acute toxicity and limits of solvent residue for sixteen organic solvents. Toxicol Appl Pharmacol 19:699-704.

4. Lazarew NW [1929]. On the toxicity of various hydrocarbon vapors. Arch Exp Pathol Pharmakol 143:223-233 (in German). [From Treon JF, Crutchfield WE Jr, Kitzmiller KV [1943]. 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 [1974]. 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. [1963]. 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 [1943]. The physiological response of animals to cyclohexane, methylcyclohexane, and certain derivatives of these compounds. II. Inhalation. J Ind Hyg Toxicol 25(8):323-347.