Methylcyclohexane

IDLH Documentation
CAS number: 108­87­2

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

1993­1994 ACGIH TLV: 400 ppm (1,610 mg/m3) TWA

Description of substance: Colorless liquid with a faint, benzene­like 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 [1965] that Treon et al. [1943] were able to produce light narcosis in mice at 10,054 ppm. Browning [1965] also reported that Lazarew [1929] found the narcotic dose for mice to be 7,500 to 10,000 ppm. ACGIH [1971] noted that this narcotic dose (7,500 to 10,000 ppm) was for a 2­hour exposure [Lazarew 1929; Treon et al. 1943].

Short­term 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
MouseIzmerov et al. 1982 10,172
-----
2 hr
16,275 ppm (1.6)
1,268 ppm
MouseLazarew 192910,000-12,500
-----
2 hr
16,000-20,000 ppm (1.6)
1,600-2,000 ppm
RabbitTreon 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
MouseIzmerov 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%).

REFERENCES:

1. ACGIH [1971]. Methylcyclohexane. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 162­163.

2. Browning E [1965]. Toxicity and metabolism of industrial solvents. New York, NY: Elsevier Publishing Company, pp. 136­137.

3. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 82.

4. Lazarew NW [1929]. Uber die giftigkeit verschiedener kohlenwasserstoffdampfe. Arch Exp Pathol Pharmakol 143:223­233 (in German).

5. Lazarew NW [1929]. Zur toxikologie des benzins (The toxicology of gasoline). Arch Hyg, pp. 228­239 (translated).

6. Treon JF, Crutchfield WE, Kitzmiller KV [1943]. The physiological response of animals to cyclohexane, methyl cyclohexane, and certain derivatives of these compounds. II. Inhalation. J Ind Hyg Toxicol 25(8):323­347.
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