o-Methylcyclohexanone

CAS number: 583–60–8

NIOSH REL: 50 ppm (230 mg/m³) TWA, 75 ppm 345 mg/m³) STEL [skin]

Current OSHA PEL: 100 ppm (460 mg/m³) TWA [skin]

1989 OSHA PEL: 50 ppm (230 mg/m³) TWA, 75 ppm (345 mg/m³) STEL [skin]

1993-1994 ACGIH TLV: 50 ppm (229 mg/m³) TWA, 75 ppm (344 mg/m³) STEL [skin]

Description of substance: Colorless liquid with a weak, peppermint-like odor.

LEL:. . . Unknown

Original (SCP) IDLH: 2,500 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that rabbits and cats exhibited sleepiness, respiratory irregularities, and poor coordination after a 1-hour exposure to 2,500 ppm; a 30-minute exposure to 3,500 ppm caused prostration in mice, guinea pigs, and rats [Gross as cited by Lehmann and Flury 1943].

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
Rat	Smyth et al. 1969	2,800	-----	4 hr	5,600 ppm (2.0)	560 ppm

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rat	Smyth et al. 1969	oral	2,140	-----	3,215 ppm	322 ppm
Rabbit	Treon et al. 1943	oral	-----	1,000-1,250	1,502-1,878 ppm	150-188 ppm

Other animal data: Mice, guinea pigs, and rats exposed at 3,500 ppm for 30 minutes suffered irritation of the mucous membranes and exhibited signs of central nervous system depression [Clayton and Clayton 1981]. Rabbits and cats exhibited sleepiness, respiratory irregularities, and poor coordination after a 1-hour exposure to 2,500 ppm [Clayton and Clayton 1981].

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 600 ppm Basis for revised IDLH: The revised IDLH for o-methylcyclohexanone is 600 ppm based on acute inhalation toxicity data in animals [Smyth et al. 1969]. This may be a conservative value due to the lack of relevant acute inhalation toxicity data for workers.

REFERENCES:

1. Clayton GD, Clayton FE, eds. [1981]. Patty's industrial hygiene and toxicology. 3rd rev. ed. Vol. 2C. Toxicology. New York, NY: John Wiley & Sons, Inc., pp. 4722-4723, 4782-4784.

2. Gross E [?]. Unpublished. [From Lehmann KB, Flury F, eds. [1943]. Toxicology and hygiene of industrial solvents. Translated by E. King and H.F. Smyth, Jr. Baltimore, MD: Williams & Wilkins Company, p. 247.]

3. Lehmann KB, Flury F, eds. [1943]. Toxicology and hygiene of industrial solvents. Translated by E. King and H.F. Smyth, Jr. Baltimore, MD: Williams & Wilkins Company, p. 247.

4. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1770.

5. Smyth HF Jr, Carpenter CP, Weil CS, Pozzani UC, Striegel JA, Nycum JS [1969]. Range-finding toxicity data: list VII. Am Ind Hyg Assoc J 30(5):470-476.

6. Treon JF, Crutchfield WE Jr, Kitzmiller KV [1943]. The physiological response of rabbits to cyclohexane, methylcyclohexane, and certain derivatives of these compounds. I. Oral administration and cutaneous application. J Ind Hyg Toxicol 25(6):199-214.