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Mesityl oxide

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

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


Lethal concentration data:

Species Reference LC50 LCLo Time Adjusted 0.5-hr


Derived value



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




Adjusted LD Derived value



Hann &Jansen 1974

Hann & Jansen 1974

Izmerov et al. 1982










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%).


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.