Overview

Hexane, whose chemical structure is CH ₃ (CH ₂ )CH ₃ , is an organic solvent made of crude oil that has numerous industrial uses (ATSDR - ToxFAQs and National Center for Environmental Research). Hexane is a neurotoxicant and exposure can cause numbness in the feet and hands and later weakness or numbness throughout the arms and legs (ATSDR - ToxFAQs and OSHA). These anesthetic qualities have led some to abuse products that contain hexane, including smelling gasoline and rubber cement.

Chemical Description

Hexane (also known as n-Hexane) is a highly volatile aliphatac hydrocarbon. It is a commercial and industrial product that contains a mixture of hydrocarbons with six carbon atoms (hence the prefix "hex") (ATSDR - Toxicological Profile.

It is a colorless liquid at room temperature with a slight gasoline smell (OSHA). It is flammable and may be an explosion hazard. It also is highly reactive with certain materials, including liquid chlorine, concentrated oxygen, and sodium hypochlorite (ATSDR - Toxicological Profile).

Production

Hexane is made from crude oil (ATSDR - Toxicological Profile).

Isomers

Hexane, CH3CH2CH2CH2CH2CH3, a straight chain of six carbon atoms. 2-Methylpentane (Isohexane), CH3CH(CH3)CH2CH2CH3, a five-carbon chain with one methyl branch on the second. 3-Methylpentane, CH3CH2CH(CH3)CH2CH3, a five-carbon chain with one methyl branch on the third. 2,3-Dimethylbutane, CH3CH(CH3)CH(CH3)CH3, a four-carbon chain with one methyl branch on the second and third. 2,2-Dimethylbutane, CH3C(CH3)2CH2CH3, a four-carbon chain with two methyl branches on the second.

Uses

Pure hexane is used mainly in laboratories while hexane mixed with other similar Solvents - Chemical Profiles and External Links is used extensively. These solvents are used to extract vegetable oils from crops such as soybeans and is also used as a cleaning agent in the printing, textile, furniture, and shoemaking industries. It is also in the roofing and shoe industries in glues and can be found in numerous consumer products including gasoline, quick-drying glues, and rubber cement (ATSDR ToxFAQs).

Health Effects

Hexane is a neurotoxicant and is often used as a narcotic as well. Nearly all those affected by hexane are workers (ATSDR ToxFAQs).

Acute Exposure
Acute exposure to hexane leads to numbness in the extremities, dizziness, confusion, nausea, headache, and irritation of the eyes, nose, throat, and skin (OSHA and ATSDR ToxFAQs).

Chronic Exposure
Repeated exposure to hexane may have adverse health effects over the long term including decreased motor nerve conduction, changes in vision, and muscle weakness. Chronic exposure is only a worry if you constantly handle hexane or hexane containing solvents.

Environmental Effects

Hexane enters the environment in both its production and its use and a lot of it is released. In 1996, a total of 70,685,942 lbs of hexane entered the environment in 1996 and this substance has been found in at least 60 of the 1,467 [National Priorities List] sites identified by the Environmental Protection Agency (EPA) (OSHA, ATSDR - ToxFAQs, and ATSDR - Toxicological Profile).

Hexane evaporates easily on land and does not adhere well to soil (ATSDR ToxFAQs and {INCHEM]). Information about hexane's affect on aquatic ecosystems are not well known (INCHEM).

Precautions

Workers handling hexane should do so with protective clothing and in ventilated areas. Parents need to keep products containing hexane, especially quick drying glues, away from children.

Regulation and Exposure Limits

EPA Regulations:
The EPA does not classify hexane as a possible carcinogen and neither has the World Health Organization (WHO) or the International Agency for Research on Cancer (IARC) (ATSDR - Toxicological Profile). It also requires that only hexane spills of greater than 5,000 lbs need by reported to the EPA.

Hexane is designated as a "haxardous air pollutant" by the EPA under the Clean Air Act (ATSDR - Toxicological Profile).

OSHA Limit:
[OSHA] has set the permissible exposure limit (PEL) for n-hexane is 500 ppm (1800 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration (OSHA).

NIOSH Limit:
The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for n-hexane of 50 ppm (180 mg/m(3)) as a TWA for up to a 10-hour workday and a 40-hour workweek (OSHA).

External Links

• MSDS on Hexane
  

References

ATSDR. "TOX-Faqs for _n -Hexane". Last Updated 02/07/2007. Accessed 9-4-07.

ATSDR. "Toxicological Profile for _n -Hexane". June 1999. Accessed 9-4-07.

Anuradee Witthayapanyanon and Linh Do. Environmental Protection Agency's National Center for Environmental Research. "Presentation Abstract: Nanostructured Microemulsions as Alternative Solvents to VOCs in Cleaning Technologies and Vegetable Oil Extraction". Accessed 9-4-07.

International Programme on Chemical Safety (INCHEM). "ENVIRONMENTAL HEALTH CRITERIA 122 - _n Hexane". 1991. Accessed 9-4-07.

Occupational Safety and Health Administration. "Occupational Safety and Health Guideline for n-Hexane". Accessed 9-4-07.