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Hexone

General Description

  • Synonyms: 4-Methyl-2-pentanone; Methyl isobutyl ketone; Isobutyl methyl ketone; MIBK
  • OSHA IMIS Code Number: 1385
  • Chemical Abstracts Service (CAS) Registry Number: 108-10-1
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: SA9275000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 1245 127
  • NIOSH Pocket Guide to Chemical Hazards - Hexone: physical description, chemical properties, potentially hazardous incompatibilities, and more
  • U.S. Environmental Protection Agency (EPA) Hazard Summary - Hexone: Uses, sources and potential exposure, acute and chronic health hazard information, and more

Exposure Limits and Health Effects

Exposure Limit Limit Values HE Codes Health Factors and Target Organs

OSHA Permissible Exposure Limit (PEL) - General Industry
See 29 CFR 1910.1000 Table Z-1

100 ppm
(410 mg/m3) TWA

HE7

Dizziness, headache, weakness
Target organs: Brain, central nervous system

HE8

Narcosis, coma

HE16

Eyes, nose, throat, and respiratory irritation; burning eyes

OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A

100 ppm
(410 mg/m3) TWA

HE7

Dizziness, headache, weakness
Target organs: Brain, central nervous system

HE8

Narcosis, coma

HE16

Eyes, nose, throat, and respiratory irritation; burning eyes

OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z-Shipyards

100 ppm
(410 mg/m3) TWA

HE7

Dizziness, headache, weakness
Target organs: Brain, central nervous system

HE8

Narcosis, coma

HE16

Eyes, nose, throat, and respiratory irritation; burning eyes

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

50 ppm
(205 mg/m3) TWA

HE7

Dizziness, headache, weakness
Target organs: Brain, central nervous system

HE8

Narcosis, coma

HE16

Eyes, nose, throat, and respiratory irritation; cough; burning eyes

75 ppm
(300 mg/m3) STEL

HE16

Skin irritation, dermatitis

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2009)

20 ppm
(82 mg/m3) TWA

75 ppm
(307 mg/m3) STEL

A3, BEI

HE7

Dizziness, headache, weakness
Target organs: Brain, central nervous system

HE8

Narcosis, coma

HE16

Eyes, nose, throat, and respiratory irritation; burning eyes

CAL/OSHA PELs

50 ppm
(205 mg/m3) TWA

75 ppm
(300 mg/m3) STEL

 

 

Notes on Other Potential Health Effects and Hazards

  1. Because hexone's odor is detectable at levels below the REL, hexone is treated as a chemical with adequate warning properties (NIOSH 1988).
  2. Hexone is highly flammable, and vapor/air mixtures can be explosive (NIOSH/IPCS 1997).
  3. The EPA RfC is based on a study showing reduced fetal body weight, skeletal variations, and increased fetal death in mice, and skeletal variations in rats (EPA 2003; Tyl et al. 1987).
  4. Although only a small fraction of the hexone absorbed by the lungs is excreted into urine (~0.12%), the measurement of hexone in urine has been recommended as a biological marker for occupational exposure (Kawai et al. 2003).
  5. One case study with six follow-up exams over a period of 10 years reported a lasting impairment of working memory in a 44-year-old worker with a history of hexone exposure to 100 ppm, with daily excursions to higher (unknown) levels for six years. A co-worker also showed memory deficits (Grober and Schaumburg 2000).
  6. Two-year studies conducted by the National Toxicology Program indicated some evidence of carcinogenic activity of MIBK in male F344/N rats, equivocal evidence of carcinogenic activity  of MIBK in female F344/N rats, and some evidence of carcinogenic activity of MIBK in male and female B6C3F1 mice (NTP 2007).

Date Last Revised: 9/6/2012

Literature Basis

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Methyl Isobutyl Ketone. 2010.
  • EPA: Toxicological review of methyl isobutyl ketone (CAS No. 108-10-1). March 2003.
  • Grober, E. and Schaumburg, H.H.: Occupational exposure to methyl isobutyl ketone causes lasting impairment in working memory. Neurology 54(9): 1853-1855, 2000.
  • Kawai, T. et al.: Methyl isobutyl ketone and methyl ethyl ketone in urine as biological markers of occupational exposure to these solvents at low levels. Int. Arch. Occup. Environ. Health 76(1): 17-23, 2003.
  • NIOSH: Occupational Safety and Health Guideline - Hexone. 1988.
  • NIOSH/IPCS: International Chemical Safety Cards - Methyl isobutyl ketone. July 10, 1997.
  • NTP: NTP Technical Report on the Toxicology and Carcinogenesis Studies of Methyl Isobutyl Ketone (CAS NO. 108-10-1) in F344/N Rats and B6C3F1 mice (Inhalation Studies), February 2007.
  • Tyl, R.W., K.A. France, L.C. Fisher, I.M. Pritts, T.R. Tyler, R.D. Phillips, and E.J. Moran: Developmental toxicity evaluation of inhaled methyl isobutyl ketone in Fischer 344 rats and CD-1 mice. Fundam Appl Toxicol. 8:310-327, 1987.

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • Anasorb CMS
  • analytical solvent: (99:1) Carbon Disulfide:N,N-Dimethylformamide
  • maximum volume: 12 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • method reference: OSHA Analytical Method (OSHA 1004)
  • method classification: Fully Validated
On-Site Sampling Techniques/Methods:
  • Diffusive Sampler:
    • SKC 575-002 Passive Sampler; or
    • 3M 3520 Organic Vapor Monitor
  • analytical solvent: (99:1) Carbon Disulfide:N,N-Dimethylformamide
  • sampling time: 5 to 240 Minutes
  • current analytical method: Gas Chromatography; GC/FID
  • method reference: OSHA Analytical Method (OSHA 1004)
  • method classification: Fully Validated
  • note: Persons using diffusive samplers to monitor workplace air must ensure that the sampling devices are properly closed before transporting such devices to the laboratory for analysis. The device will continue to sample until properly closed. Diffusive sampler accessories used for analysis of samplers must be included with transported samples. Persons using such devices must provide sampling-site station barometric pressure and temperature to the analytical laboratory to improve accuracy of sampling results.
  • Charcoal Tube (100/50 mg sections, 20/40 mesh)
  • analytical solvent: Carbon Disulfide
  • alternate analytical solvent: (99:1) Carbon Disulfide:Dimethylformamide
  • alternate analytical solvent: (95:5) Methylene Chloride:Methanol
  • maximum volume: 10 Liters
  • maximum flow rate: 0.2 L/min (TWA)
  • maximum volume: 3 Liters
  • maximum flow rate: 0.2 L/min (STEL)
  • current analytical method: Gas Chromatography; GC/FID
  • method reference: NIOSH Analytical Method (NIOSH 1300)
  • method classification: Fully Validated
  • note: Ship cold.

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