Cyclohexane is a cycloalkane with the molecular formula C6H12.  It is a colourless flammable liquid with a mild, sweet odour resembling that of chloroform or benzene that occurs naturally in crude oil, volcanic gases, and cigarette smoke but is also produced synthetically to be used as a solvent in numerous industries. [2,3]
This compound is used as a solvent to dissolve cellulose ethers, lacquers, resins, fats, waxes, oils, bitumen and crude rubber. It is also used in perfume manufacturing, during surface coating operations (lacquers), in synthesis of adipic acid for production of nylon 66 and engineering plastics, during synthesis of caprolactam in nylon 6, paint and varnish remover, in the extraction of essential oils, in analytical chemistry for molecular weight determinations, in the manufacturing of adipic acid, benzene, cyclohexyl chloride, nitrocyclohexane, cyclohexanol and cyclohexanone, in the manufacturing of solid fuel for camp stoves, in fungicidal formulations (possesses slight fungicidal action) in the industrial recrystallising of steroids, organic synthesis, recrystallising medium glass substitutes, solid fuels, in analytical chemistry and in manufacturing of adhesives.
Sources of Emission & Routes of Exposure
Sources of Emission 
- Industry sources: The primary point sources are petroleum refining, automotive repair shops, and commercial printing and publishing.
- Diffuse sources: Sub-threshold facilities.
- Natural sources: Cyclohexane is a natural constituent of crude petroleum. It also occurs naturally as a plant volatile and can be released from volcanoes.
- Transport sources: Cyclohexane has been detected in motor vehicle exhaust.
- Consumer products: Cyclohexane is used as a solvent, oil extractant, paint and varnish remover, and in solid fuels.
Routes of Exposure [2,5]
Exposure to cyclohexane can occur through inhalation, ingestion, and eye or skin contact. Cyclohexane enters the body when breathed in with contaminated air or when consumed with contaminated food or water. It can also be absorbed through skin contact. Cyclohexane is not likely to remain in the body due to its breakdown and removal in exhaled air and in urine.
Health Effects 
The effects of cyclohexane on human health depend on how much of the chemical is present and the length and frequency of exposure. Effects also depend on the health of a person when exposure occurs. Breathing large amounts of cyclohexane for short periods of time adversely affects the human nervous system. Effects range from headaches to anaesthesia, tremors, and convulsions. Contact with cyclohexane liquid or vapour can damage the eyes. These effects are not likely to occur at levels of cyclohexane that are normally found in the environment. Human health effects associated with breathing or otherwise consuming smaller amounts of cyclohexane over long periods of time are not known. Information about cyclohexane’s potential to cause cancer, developmental effects, or reproductive effects either does not exist or is not adequate. Studies show that repeat exposure to large amounts of cyclohexane in air causes nervous system effects, eye damage, and respiratory effects in animals. The cyclohexane industry is now studying how its chemical affects the reproductive system and the development of the foetus of animals.
First Aid Measure
- Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Get medical attention.
- Skin Contact: In case of contact, immediately flush skin with plenty of water. Cover the irritated skin with an emollient. Remove contaminated clothing and shoes. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention.
- Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek medical attention.
- Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention.
- Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. Seek medical attention.
- Ingestion: If swallowed, do NOT induce vomiting. Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. Aspiration hazard if swallowed- can enter lungs and cause damage. Loosen tight clothing such as a collar, tie, belt or waistband. Get medical attention. Get medical attention if symptoms appear.
Fire & Explosion Information
- Cyclohexane is highly flammable in presence of open flames and sparks, of heat. It is also slightly explosive in presence of open flames and sparks.
- Cyclohexane is insoluble in water. Dry chemical powder should be used to extinguish small fires. For large fires, use water spray or fog.
- Vapour may travel considerable distance to source of ignition and flash back.
- When mixed hot with liquid dinitrogen tetraoxide an explosion can result.
Exposure Controls & Personal Protection
When handling cyclohexane, exhaust ventilation or other engineering controls should be used to keep the airborne concentrations of vapours below their respective threshold limit value. Ensure that eyewash stations and safety showers are proximal to the work-station location.
Personal Protective Equipment
The following personal protective equipment should be used when handling cyclohexane:
- Splash goggles
- Lab coat
- Vapour respirator (be sure to use an approved/certified respirator or equivalent)
Personal Protection in Case of a Large Spill:
- Splash goggles
- Full suit
- Vapour respirator
- A self-contained breathing apparatus should be used to avoid inhalation of the product.
- Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.
Occupational Exposure Limits
- OSHA: The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for cyclohexane is 300 ppm (1050 milligrams per cubic metre (mg/m3) as an 8-hour time-weighted average (TWA) concentration [29 CFR 1910.1000, Table Z-1].
- NIOSH: The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for cyclohexane of 300 ppm (1050 mg/m3) as a TWA for up to a 10-hour workday and a 40-hour workweek [NIOSH 1992].
- ACGIH: The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned cyclohexane a threshold limit value (TLV) of 300 ppm (1030 mg/m3) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 17].
- Safe Work Australia: Safe Work Australia has established an 8 hour time weighted average (TWA) for cyclohexane of 350 mg/m3 and a short term exposure limit (STEL) of 1050 mg/m3.