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Chemical Sampling Information (CSI)
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General Description

Synonyms: Isoacetophorone; 3,5,5-Trimethyl-2-cyclohexene-1-one; 3,5,5-Trimethyl-2-cyclohexenone; 3,5,5-Trimethyl-2-cyclo-hexen-1-one

OSHA IMIS Code Number: 1538

Chemical Abstracts Service (CAS) Registry Number: 78-59-1

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: GW7700000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 1993 128 (combustible liquid, n.o.s.)

NIOSH Pocket Guide to Chemical Hazards, Isophorone: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

OSHA Permissible Exposure Limit (PEL):

General Industry: 29 CFR 1910.1000 Table Z-1 - 25 ppm, 140 mg/m3 TWA

Construction Industry: 29 CFR 1926.55 Appendix A - 25 ppm, 140 mg/m3 TWA

Maritime: 29 CFR 1915.1000 Table Z-Shipyards - 25 ppm, 140 mg/m3 TWA

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 5 ppm, 28 mg/m3 Ceiling; Appendix A3 - Confirmed Animal Carcinogen with Unknown Relevance to Humans

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 4 ppm, 23 mg/m3 TWA

Health Factors

Carcinogenic Classification:

Environmental Protection Agency (EPA): Group C, possible human carcinogen

NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 200 ppm

Potential Symptoms: Irritation of eyes, nose, throat; cough, sore throat; shortness of breath; headache, nausea, dizziness, lassitude (weakness, exhaustion); malaise (vague feeling of discomfort), narcosis; blurred vision; dry, cracking skin, dermatitis; in animals: kidney, liver damage

Health Effects: Irritation-Eye, Nose, Throat, Skin---Marked (HE14); Acute CNS effects (HE4)

Affected Organs: Eyes, skin, respiratory system, CNS, liver, kidneys


  1. Above 84ºC, explosive vapor/air mixtures may be formed.
  2. EPA's oral reference dose (daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) for isophorone is 0.2 mg/kg/day, and EPA's provisional reference concentration is 12 µg/m3.
  3. The concentration of isophorone causing a 50% decrease in the respiratory rate of mice (a measure of sensory irritation) was reported to be 27.8 ppm.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Isophorone.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Isophorone.
  • EPA Air Toxics Website: Isophorone. U.S. Environmental Protection Agency Technology Transfer Network.
  • De Ceaurriz, J., Micillino, J.C., Bonnet, P. and Guenier, J.P.: Sensory irritation caused by various industrial airborne chemicals. Toxicol Lett. 9(2): 137-143, 1981.
  • Pohanish, R.P. (editor): Isophorone. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1342-1344.

Date Last Revised: 06/29/2006

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Petroleum Base Charcoal Tube (100/50 mg sections, 20/40 mesh)
    analytical solvent: Carbon Disulfide
    alternate analytical solvent: (99:1) Carbon Disulfide:Dimethylformamide
    maximum volume: 12 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: NIOSH Analytical Method (NIOSH 2508 [20 KB PDF, 3 pages])
    method classification: Fully Validated
    note: The flowrate was dropped to 0.2 L/min on May 11, 1995 since in the 4th edition of NIOSH methods it states that the breakthrough was performed at 0.19 L/min but no data is given for 1 L/min.

  • sampling media: XAD-4 (80/40 mg sections, 20/40 mesh)
    analytical solvent: diethyl ether
    maximum volume: 25 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: NIOSH Analytical Method (NIOSH 2556 [80 KB PDF, 4 pages])
    method classification: Partially Validated
    note: Samples should be refrigerated as soon as possible after sampling and sent cold to the laboratory.

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