Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 108–87–2
NIOSH REL: 400 ppm (1,600 mg/m3) TWA
Current OSHA PEL: 500 ppm (2,000 mg/m3) TWA
1989 OSHA PEL: 400 ppm (1,600 mg/m3) TWA
1993-1994 ACGIH TLV: 400 ppm (1,610 mg/m3) TWA
Description of substance: Colorless liquid with a faint, benzene-like odor.
LEL:. . 1.2% (10% LEL, 1,200 ppm)
Original (SCP) IDLH: 10,000 ppm
Basis for original (SCP) IDLH: With no reported human toxicological data, the chosen IDLH is based on the statement by Browning  that Treon et al.  were able to produce light narcosis in mice at 10,054 ppm. Browning  also reported that Lazarew  found the narcotic dose for mice to be 7,500 to 10,000 ppm. ACGIH  noted that this narcotic dose (7,500 to 10,000 ppm) was for a 2-hour exposure [Lazarew 1929; Treon et al. 1943].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
|Species||Reference||LC50 (ppm)||LCLo (ppm)||Time||Adjusted 0.5-hr
|Mouse||Izmerov et al. 1982||10,172||-----||2 hr||16,275 ppm (1.6)||1,268 ppm|
|Mouse||Lazarew 1929||10,000-12,500||-----||2 hr||16,000-20,000 ppm (1.6)||1,600-2,000 ppm|
|Rabbit||Treon et al. 1943||15,227||-----||1 hr||19,034 ppm (1.25)||1,903 ppm|
Lethal dose data:
|Species||Reference||Route||LD50 (mg/kg)||LDLo (mg/kg)||Adjusted LD||Derived value|
|Mouse||Izmerov et al. 1982||oral||2,250||-----||3,860 ppm||386 ppm|
Human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 1,200 ppm [LEL]
Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in animals [Izmerov et al. 1982; Lazarew 1929; Treon et al. 1943], a value of about 1,600 ppm would have been appropriate for methylcyclohexane. However, the revised IDLH for methylcyclohexane is 1,200 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 1.2%).
1. ACGIH . Methylcyclohexane. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 162-163.
2. Browning E . Toxicity and metabolism of industrial solvents. New York, NY: Elsevier Publishing Company, pp. 136-137.
3. Izmerov NF, Sanotsky IV, Sidorov KK . Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 82.
4. Lazarew NW . Uber die giftigkeit verschiedener kohlenwasserstoffdampfe. Arch Exp Pathol Pharmakol 143:223-233 (in German).
5. Lazarew NW . Zur toxikologie des benzins (The toxicology of gasoline). Arch Hyg, pp. 228-239 (translated).
6. Treon JF, Crutchfield WE, Kitzmiller KV . The physiological response of animals to cyclohexane, methyl cyclohexane, and certain derivatives of these compounds. II. Inhalation. J Ind Hyg Toxicol 25(8):323-347.