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Chemical Sampling Information (CSI)
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General Description

Synonyms: Methyl butyl ketone; Butyl methyl ketone; Methyl n-butyl ketone; MBK

OSHA IMIS Code Number: 1690

Chemical Abstracts Service (CAS) Registry Number: 591-78-6

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: MP1400000

NIOSH Pocket Guide to Chemical Hazards, 2-Hexanone: 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 - 100 ppm, 410 mg/m3 TWA

Construction Industry: 29 CFR 1926.55 Appendix A - 100 ppm, 410 mg/m3 TWA

Maritime: 29 CFR 1915.1000 Table Z-Shipyards - 100 ppm, 410 mg/m3 TWA

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 5 ppm, 20 mg/m3 TWA; 10 ppm STEL; Skin; BEI (TLV listed under Methyl n-butyl ketone)

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 1 ppm, 4 mg/m3 TWA

Health Factors

NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 1,600 ppm

Potential Symptoms: Irritation of eyes, nose, throat; peripheral neuropathy; lassitude (weakness, exhaustion), paresthesia; dermatitis; headache; nausea; drowsiness; blurred vision; unconsciousness; INGES. ACUTE: sore throat, abdominal pain, diarrhea

Health Effects: Nervous system disturbances---Polyneuropathy (HE7) Narcosis (HE8); Irritation-Eye, Nose, Throat, Skin---Moderate (HE15); Explosive, flammable (HE18)

Affected Organs: Eyes, skin, respiratory system, CNS, peripheral nervous system


  1. Vapor/air mixtures can be explosive.
  2. 2-Hexanone is metabolized by CYP2E1 and alcohol dehydrogenase to 2,5-hexanedione, which can be measured in urine as a marker of exposure. Several other metabolites, including carbon dioxide, are also produced.
  3. Occupational exposure may be greater through the skin than by inhalation. It is estimated that immersion of both hands in 2-hexanone results in absorption of 6.4 mg/minute, whereas inhalation of 5 ppm in air leads to an estimated absorption 0.4 mg/minute.
  4. The metabolite 2,5-hexanedione causes peripheral neuropathy in animals and humans. It reacts with lysine residues in proteins, and may cause neuropathy by disturbing the transport and/or functions of proteins within nerve axons.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: 2-Hexanone: chemical description, physical properties, potentially hazardous incompatibilities, and more.
  • International Chemical Safety Cards (WHO/IPCS/ILO): 2-Hexanone.
  • Bolt, H.M., Roos, P.H. and Thier, R.: The cytochrome P-450 isoenzyme CYP2E1 in the biological processing of industrial chemicals: consequences for occupational and environmental medicine. Int. Arch. Occup. Environ. Health 76(3): 174-185, 2003.
  • Bos, P.M.J., de Mik, G. and Bragt, P.C.: Critical review of the toxicity of methyl n-butyl ketone: risk from occupational exposure. Am. J. Ind. Med. 20(2): 175-194, 1991.
  • Pohanish, R.P. (editor): Methyl n-Butyl Ketone. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1535-1538.
  • Zhu, M., Spink, D.C., Yan, B., Bank, S. and DeCaprio A.P.: Inhibition of 2,5-hexanedione-induced protein cross-linking by biological thiols: chemical mechanisms and toxicological implications. Chem. Res. Toxicol. 8(5): 764-771, 1995.

Date Last Revised: 08/19/2005

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Charcoal Tube (100/50 mg sections, 20/40 mesh)
    analytical solvent: Carbon Disulfide
    alternate solvent: (99:1) Carbon Disulfide:Dimethylformamide
    maximum volume: 10 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: NIOSH Analytical Method (NIOSH 1300 [26 KB PDF, 5 pages])
    method classification: Fully Validated

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