Mesityl oxide

CAS number: 141–79–7

NIOSH REL: 10 ppm (40 mg/m³) TWA

Current OSHA PEL: 25 ppm (100 mg/m³) TWA

1989 OSHA PEL: 15 ppm (60 mg/m³) TWA, 25 ppm (100 mg/m³) STEL

1993-1994 ACGIH TLV: 15 ppm (60 mg/m³) TWA, 25 ppm (100 mg/m³) STEL

Description of substance: Oily, colorless to light-yellow liquid with a peppermint- or honey-like odor.

LEL: . 1.4% (10% LEL, 1,400 ppm)

Original (SCP) IDLH: 5,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that 5,000 ppm might be dangerous to life in 30 to 60 minutes [Smyth et al. 1942].

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA:

Lethal concentration data:

Species	Reference	LC50	LCLo	Time	Adjusted 0.5-hr LC (CF)	Derived value
Rat Rat Mouse G. pig	Carpenter et al. 1949 Izmerov et al. 1982 Izmerov et al. 1982 Specht et al. 1940	1,000 mg/m3 9,000 mg/m3 10,000 mg/m3 2,000 mg/m3	----- ----- ----- -----	4 hr 4 hr 2 hr 7 hr	2,000 ppm (2.0) 18,000 ppm (2.0) 16,000 ppm (1.6) 4,800 ppm (2.4)	200 ppm 1,800 ppm 1,600 ppm 480 ppm

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rat Rabbit Mouse	Hann &Jansen 1974 Hann & Jansen 1974 Izmerov et al. 1982	oral oral oral	1,120 1,000 710	----- ----- -----	1,922 ppm 1,716 ppm 1,218 ppm	192 ppm 172 ppm 122 ppm

Human data: The probable response to 100 ppm was predicted to be eye and mucous membrane irritation, difficulty breathing, headache, and vertigo [Shell 1957]. It has been stated that 5,000 ppm might be dangerous to life in 30 to 60 minutes [Smyth et al. 1942].

Revised IDLH: 1,400 ppm [LEL] Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in humans [Smyth et al. 1942], a value of about 4,000 ppm would have been appropriate for mesityl oxide. However, the revised IDLH for mesityl oxide is 1,400 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 1.4%).

REFERENCES:

1. Carpenter CP, Smyth HF Jr, Pozzani UC [1949]. The assay of acute vapor toxicity, and the grading and interpretation of results on 96 chemical compounds. J Ind Hyg Toxicol 31(6):343-346.

2. Hann W, Jansen PA [1974]. Water quality characteristics of hazardous materials. Vols. 1-4. College Station, TX: Texas A & M University, Civil Engineering Department, Environmental Engineering Division.

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. 80.

4. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1758.

5. Shell [1957]. Mesityl oxide: safety data sheet SC:57-105. New York, NY: Shell Chemical Corporation, pp. 1-3.

6. Smyth HF Jr, Seaton J, Fischer L [1942]. Response of guinea pigs and rats to repeated inhalation of vapors of mesityl oxide and isophorone. J Ind Hyg Toxicol 24(3):46-50.

7. Specht H, Miller JW, Valaer PJ, Sayers RR [1940]. Acute response of guinea pigs to the inhalation of ketone vapors. NIH Bulletin 176:1-66.