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  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-hrLC (CF)||Derived value|
|Carpenter et al. 1949Izmerov et al. 1982
Izmerov et al. 1982
Specht et al. 1940
|1,000 mg/m39,000 mg/m3
|4 hr4 hr
|2,000 ppm (2.0)18,000 ppm (2.0)
16,000 ppm (1.6)
4,800 ppm (2.4)
|200 ppm1,800 ppm
Lethal dose data:
|Species||Reference||Route||LD50(mg/kg)||LDLo(mg/kg)||Adjusted LD||Derived value|
|Hann &Jansen 1974Hann & Jansen 1974
Izmerov et al. 1982
|1,922 ppm1,716 ppm
|192 ppm172 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%).|
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2. Hann W, Jansen PA . 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 . Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 80.
4. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1758.
5. Shell . 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 . 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 . Acute response of guinea pigs to the inhalation of ketone vapors. NIH Bulletin 176:1-66.