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General Description

  • Synonyms: Benzene hexahydride; Hexahydrobenzene; Hexamethylene; Hexanaphthene
  • OSHA IMIS Code Number: 0810
  • Chemical Abstracts Service (CAS) Registry Number: 110-82-7
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: GU6300000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 1145 128
  • NIOSH Pocket Guide to Chemical Hazards - Cyclohexane: Physical description, chemical properties, potentially hazardous incompatibilities, and more

Exposure Limits and Health Effects

Exposure Limit Limit Values HE Codes Health Factors and Target Organs
  • 300 ppm
  • (1,050 mg/m3) TWA
HE8 Narcosis
HE16 Mild throat and eye irritation
  • 300 ppm
  • (1,050 mg/m3) TWA
HE8 Narcosis
HE16 Mild throat and eye irritation
  • 300 ppm
  • (1,050 mg/m3) TWA
HE8 Narcosis
HE16 Mild throat and eye irritation
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)
  • 300 ppm
  • (1,050 mg/m3) TWA
HE7 Dizziness and nausea
Target organs: Central nervous system
HE8 Narcosis
HE16 Mild throat and eye irritation
  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2002)
  • 100 ppm
  • (334 mg/m3) TWA
HE3 Mild liver and kidney toxicity
HE7 Sedation, neurobehavioral effects
Target organs: Central nervous system
HE8 Narcosis
HE16 Mild throat and eye irritation
  • 300 ppm
  • (1,050 mg/m3) TWA

National Toxicology Program (NTP) carcinogenic classification: Not listed

International Agency for Research on Cancer (IARC) carcinogenic classification: Not listed

U.S. Environmental Protection Agency (EPA) carcinogenic classification: Data is inadequate for an assessment of human carcinogenic potential

EPA Inhalation Reference Concentration (RfC): 6 mg/m3

Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): Not established

NIOSH Immediately Dangerous to Life or Health (IDLH) concentration: 1,300 ppm (10% LEL)

Notes on Other Potential Health Effects and Hazards

  1. Vapor/air mixtures are explosive. Heating will cause a rise in pressure and a risk of bursting (NIOSH/IPCS 2008).
  2. Highly flammable (NIOSH/IPCS 2008).
  3. In human volunteers exposed to ~300 ppm of cyclohexane for 8 hours, the major urinary metabolites were 1,2- and 1,4-cyclohexanediol and their glucuronide conjugates. The mean elimination half-lives of these metabolites ranged from 16 to 17 hours (Mráz et al. 1998).  
  4. In contrast, workers exposed to lower airborne levels of cyclohexane from glues (geometric mean: 27 ppm) showed a 16-hour between-shift decrease in urinary cyclohexanol, from 876 to 96 µg/liter, yielding an estimated biological half-life of approximately 5 hours (Yasugi et al. 1994).
  5. EPA reference concentration established based on a two generation laboratory reproductive and developmental toxicity study resulting in reduced body weight in offspring and effects on hearing. (EPA 2003)

Date Last Revised: 11/16/2012

Literature Basis:

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Cyclohexane. 2002.
  • EPA Cyclohexane (CASRN 110-82-7), 2003
  • EPA Toxicological Review of Cyclohexane in Support of IRIS listing, 2003*
  • Kreckmann, KH; Baldwin, JK; Roberts, LG; et al. (2000) Inhalation developmental toxicity and reproduction studies with cyclohexane. Drug Chem Toxicol 23(4):555-73.
  • Mráz, J. Gálová, E., Nohová, H. and Vítková, D.: 1,2- and 1,4-Cyclohexanediol - major urinary metabolites and biomarkers of exposure to cyclohexane, cyclohexanone, and cyclohexanol in humans. Int. Arch. Occup. Environ. Health 71(8): 560-565, 1998.
  • NIOSH: Occupational Health Guideline - Cyclohexane. 1978.
  • NIOSH/IPCS: International Chemical Safety Cards - Cyclohexane. April 10, 2008.
  • Yasugi, T. et al.: Exposure monitoring and health effect studies of workers occupationally exposed to cyclohexane vapor. Int. Arch. Occup. Environ. Health 65(5): 343-350, 1994.

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • Charcoal Tube (100/50 mg sections, 20/40 mesh)
  • analytical solvent: Carbon disulfide
  • alternate analytical solvent: (99:1) Carbon Disulfide:Dimethylformamide
  • maximum volume: 5 Liters
  • maximum flow rate: 0.2 L/min
  • current analytical method: Gas chromatography; GC/FID
  • method reference: NIOSH Analytical Method (NIOSH 1500*)
  • method classification: Partially Validated

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