n-Hexane: Sources of emissions
Description
n-Hexane is a chemical extracted, and further quantities synthesised, from crude oil. It is used in laboratories, primarily when it is mixed with similar chemicals to produce solvents. Common names for these solvents are commercial hexane, mixed hexanes, petroleum ether, and petroleum naphtha. The major use for solvents containing n-hexane is to extract vegetable oils from crops such as soybeans, flax, peanuts, and safflower seed. They are also used as cleaning agents in the textile, furniture, shoemaking, and printing industries, particularly rotogravure printing. N-hexane is also an ingredient of special glues that are used in the roofing, shoe, and leather industries. n-Hexane is used in binding books, working leather, shaping pills and tablets, canning, manufacturing tires, and making baseballs.
Substance details
Substance name: n-Hexane
CASR number: 110-54-3
Molecular formula: C6H14
Synonyms: n-hexane; normal hexane; hexyl hydride; skellysolve B; dipropyl; gettysolve-b; hex
Physical properties
Colourless liquid with a mild petrol-like odour detectable at 65 to 248 ppm. It evaporates very easily into the air. It is miscible with alcohol, chloroform, and ether.
Melting Point: -95°C
Boiling Point: 68.7°C
Specific Gravity: 0.659
Vapour Density: 2.97
1 ppm = 3.52 mg/m3
Slightly soluble 0.000947 g/100 mL
Chemical properties
Hexane is highly flammable, and its vapours can be explosive. Heat, sparks, and flames may ignite it. Flammable vapour may spread away from a spill. n-Hexane can react vigorously with oxidising materials such as liquid chlorine, concentrated oxygen, and sodium and calcium hypochlorite. It will attack some forms of plastics, rubber, and coatings. It is incompatible with strong oxidisers.
Further information
The National Pollutant Inventory (NPI) holds data for all sources of n-hexane emissions in Australia.
Description
The only people known to have suffered ill-health effects from n-hexane were exposed to it at work. Exposure to n-hexane can cause toxicity in peripheral nerves, muscle wasting, and atrophy. It can cause numbness to the feet and hands and muscle weakness in the feet and lower legs, which can lead to paralysis of the arms and legs. It can also cause dermatitis, nausea, confusion, jaundice, and coma.
Entering the body
Hexane evaporates very quickly and so the most common exposure is from breathing air containing hexane. It can also enter via the skin.
Exposure
The most probable route of human exposure to hexane is by inhalation. Individuals are most likely to be exposed to hexane in the workplace. Monitoring data indicate that hexane is a widely occurring atmospheric pollutant.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standard for n-hexane through the workplace exposure standards for airborne contaminants:
- Maximum eight hour time weighted average (TWA): 20 parts per million (72 mg/m3)
These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
Drinking water guidelines
There is no guideline for n-hexane in the Australian Drinking Water Guidelines.
Description
Because of its very low solubility in water and high volatility, it will usually be rapidly transported to the atmosphere without major damage to the biota. In the atmosphere it is one of the volatile organic substances that contribute to the formation of photochemical smog, through interaction with nitrogen dioxide and ozone.
Entering the environment
Hexane is carried in the air. If released to soil, hexane will usually quickly evaporate to the atmosphere. Hexane is only slightly soluble in water, but is readily absorbed by the lipid phase (fatty parts) of aquatic organisms, which can result in transport in the environment.
Where it ends up
Due to its high volatility and low solubility in water, hexane in the environment will be mainly in the atmosphere. In the atmosphere, hexane is expected to exist almost entirely in the vapour phase due to its relatively high vapour pressure. The dominant tropospheric loss process for hexane is by reaction with the hydroxyl (OH) radical. The calculated half-life and lifetime of hexane due to reaction with the OH radical are 1.8 days and 2.6 days, respectively. The products of the OH radical-initiated reaction include 2-hexanone, 2- and 3-hexyl nitrate and 5-hydroxy-2-pentanone.
Environmental guidelines
No national guidelines.
Industry sources
Releases from industries producing, using or handling hexane. For example, rubber and plastics products industries, oil refineries, chemical plants, footwear manufacturing, petrol, and paints and adhesives.
Diffuse sources, and industry sources included in diffuse emissions data
Releases from service stations; evaporation of fuels during petrol refilling; underground storage tanks that leak. Releases during use of adhesives, paints, and paint thinners.
Natural sources
Hexane is a natural constituent of crude petroleum. It also occurs naturally as a plant volatile and can be released from volcanoes. Also occurs naturally in, forest fires, and some plants.
Transport sources
Vehicle exhaust. Evaporation of vehicle fuels from motors and vehicle fuel tanks.
Consumer products
Consumer products that contain small amounts of n-hexane include petrol, rubber cement, type-over correction fluids, non-mercury (low temperature) thermometers, alcohol preparations, and aerosols in perfumes. n-Hexane is also a component of preparations such as paint thinners, general-purpose solvents, degreasing agents, and cleaners.
Sources used in preparing this information
- Australian and New Zealand Environment and Conservation Council (ANZECC) (1992), Australian Water Quality Guidelines for Fresh and Marine Waters.
- CalEPA Air Resources Board Toxic Air Contaminant Summary (accessed, May, 1999)
- ChemFinder WebServer Project (1995) (accessed, May, 1999)
- Chemical Backgrounder (accessed, May, 1999)
- Environmental Defense Fund - Summary, Uses, Consumer Products, Rank (industrial, by quantity) (accessed, May, 1999)
- EPA Health Effects Notebook for Hazardous Air Pollutants (accessed, May, 1999)
- EPA Integrated Risk Information System Report (accessed, May, 1999)
- IPCS International Chemical Safety Card (accessed, May, 1999)
- Meagher, D (1991), The Macmillan Dictionary of The Australian Environment, Macmillan Education Australia Pty Ltd.
- National Toxicology Program Health and Safety Information Sheet (accessed, May, 1999)
- New Jersey Health and Safety (accessed, May, 1999)
- Richardson, M (1992), Dictionary of Substances and their Effects, Royal Society of Chemistry, Clays Ltd, England.
- Sittig, M (1991), Handbook of Toxic and Hazardous Chemicals and Carcinogens, 3rd edition, Noyes Publications, USA.
- Technical Advisory Panel (1999), Final Report to the National Environment Protection Council.
- US Department of Health and Human Services (1990), NIOSH Pocket Guide to Chemical Hazards, Publication No. 90-117.
- Safe Work Australia, Workplace exposure standards for airborne contaminants, accessed January 2019.
- National Health and Medical Research Council (NHMRC), Australian Drinking Water Guidelines (2011) - Updated October 2017, accessed May 2018.