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General Description

Synonyms: Benzene hexahydride; Hexahydrobenzene; Hexamethylene; Hexanaphthene

OSHA IMIS code: 0810

CAS number: 110-82-7

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method:
  • charcoal tube (100/50 mg sections, 20/40 mesh)
  • maximum volume: 5 L
  • maximum flow rate: 0.2 L/min
  • current analytical method: gas chromatography; GC/FID
  • analytical solvent: carbon disulfide
  • alternate analytical solvent: (99:1) carbon disulfide:dimethylformamide
  • method reference: NIOSH 1500 (partially validated)

Exposure Limits and Health Effects (Updated September 6, 2012)

Standard Set By Exposure Limit Health Effect Codes -- Health Effects and Target Organs

OSHA PEL - General Industry
See 29 CFR 1910.1000 Table Z-1

300 ppm (1,050 mg/m3) TWA HE8 -- narcosis
HE16 -- mild throat and eye irritation
OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A
300 ppm (1,050 mg/m3) TWA HE8 -- narcosis
HE16 -- mild throat and eye irritation
OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z-Shipyards
300 ppm (1,050 mg/m3) TWA HE8 -- narcosis
HE16 -- mild throat and eye irritation
NIOSH 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
ACGIH TLV® (1964) 100 ppm (350 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
CAL/OSHA PELs 300 ppm (1,050 mg/m3) TWA  

Carcinogenic classification:

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

ATSDR Inhalation Minimal Risk Levels (MRLs): Not established

NIOSH 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).

Partial reference list:

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Cyclohexane. 2016.
  • EPA: Integrated Risk Information System - Cyclohexane (CASRN 110-82-7). 2003.
  • EPA: Toxicological Review of Cyclohexane. 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. Health71(8): 560-565, 1998.
  • NIOSH: Occupational Health Guideline - Cyclohexane. 1978.
  • NIOSH/CEC/IPCS: International Chemical Safety CardsCyclohexane. 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.

Chemical Sampling Information

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