Substance fact sheet
The National Pollutant Inventory (NPI) provides information on the types and amounts of pollutants being emitted in the Australian community.
This page provides facts about benzene. It describes how you might be exposed to this substance, how exposure might effect you and the environment, common uses, comparative data about benzene and its physical and chemical properties.
For more information about some of the terms used in this page, see the NPI glossary.
The National Pollutant Inventory (NPI) holds data for all sources of benzene emissions in Australia.
This depends on how much benzene you have been exposed to, for how long, and your current state of health. In certain circumstances, even a brief exposure to very high levels of benzene can result in death. Worksafe Australia classifies benzene as a toxic health hazard, listing its concentration cut off level at 0.10% weight/weight. Exposure can result in symptoms such as skin and eye irritations, drowsiness, dizziness, headaches, and vomiting. Benzene is carcinogenic and long-term exposure at various levels can affect normal blood production and can be harmful to the immune system. It can cause Leukaemia (cancer of the tissues that form white blood cells) and has also been linked with birth defects in animals and humans.
Benzene evaporates very quickly and so the most common exposure is from breathing air containing benzene. Very small amounts are found in some foods such as canned beef and if drinking water has been contaminated. While benzene is poorly absorbed by the skin, it can enter the skin in this way, with potentially dangerous contact being with products such as petrol.
Most people are exposed outdoors to low levels of benzene from tobacco smoke and car exhaust. Smoking cigarettes and passive smoking, especially indoors, increases the intake of benzene to higher levels. People living near industries that produce or use benzene, or near freeways may also be exposed to higher levels in the surrounding air.
See Sources for more information.
Australian Drinking Water Guidelines (NHMRC and ARMCANZ , 1996):
Maximum of 0.001 mg/L (i.e. 0.000001 g/L)
Benzene has a high acute toxic effect on aquatic life. Long- term effects on marine life can mean shortened lifespan, reproductive problems, lower fertility and changes in appearance or behaviour. It can cause death in plants and roots and damage to the leaves of many agricultural crops.
Benzene is carried in the air. If released to soil, benzene will usually breakdown quickly. It can be mobile in soil, however, and may contaminate groundwater. Benzene 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.
In the atmosphere, benzene can react with other chemicals to produce phenol, nitrophenol, nitrobenzene, formic acid and peroxyacetyl nitrate. It is a "precursor" hydrocarbon leading to the formation of photochemical smog. It will usually breakdown (decompose) over a few days, with the products eventually ending up in the air. It can be washed out of the air by rain, but will evaporate and continue to contaminate the air. It can attach to rain or snow and be carried back down to the ground. Benzene in soil or water will decompose with the presence of oxygen. It does not build up concentration levels in plant or animal tissues.
Australian Water Quality Guidelines for Fresh and Marine Waters: (ANZECC, 1992):
Maximum of 0.3 mg/L (i.e. 0.0003 g/L)
Benzene is used in the manufacture of a large number of chemicals that contribute to the production of plastics (such as polystyrene) synthetic fibres, detergents, pharmaceuticals, and pesticides. It is used as a solvent for fats, oils, inks, paints, plastics, and rubbers, and as a degreasing agent. Benzene is also used to make some types of rubbers as well as being a constituent in motor fuels.
Releases to air from industries producing, using or handling benzene eg. rubber industry, oil refineries, chemical plants, footwear manufacturing, petrol.
Present in crude oil; cigarette smoke (will affect both active and passive smokers). Releases to air from service stations; evaporation of fuels during petrol refilling; releases to groundwater from underground storage tanks that leak.
Occurs naturally in volcanoes, forest fires, some plants and animals. Is present in crude oil.
Vehicle exhaust, Evaporation of vehicle fuels from motors and vehicle fuel tanks.
Glues, adhesives, household cleaning products, paint strippers, some art supplies and petrol. These products may contain benzene as a contaminant rather than a deliberately added component (e.g. Shellite may contain 0.1% benzene by volume).
Approximately 400 substances were considered for inclusion on the NPI reporting list. A ranking and total hazard score was given based on health and environmental hazards and human and environmental exposure to the substance.
Benzene was ranked as 14 out of 400. The total hazard score taking into account both human health and environmental criteria is 3.3.
On a health hazard rating of 0 - 3 benzene registers 2.3. A score of 3 represents a very high hazard to health, 2 represents a medium hazard and 1 is harmful to health.
On an environmental rating of 0 - 3 benzene registers 1.0. A score of 3 represents a very high hazard to the environment and 0 a negligible hazard.
Factors taken into account to obtain this ranking and these scores include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the measure of its ability to remain active in the environment and whether it accumulates in living organisms. It does not take into account exposure to the substance. Environmental exposure is reflected in the NPI rank for this substance (see comparative data below). A substance that scores highly as an environmental hazard is oxides of nitrogen at 3.0 and one of the lower scores is benzene at 0.8. A substance that scores highly as a health hazard is arsenic at 2.3 and one of the lowest scores is ammonia at 1.0.
| Substance name | Benzene |
| CASR number | 71-43-2 |
| Molecular formula | C6H6 |
| Synonyms | Benzol, Benzoline, Coal naphtha, Cyclohexatriene, Phene, Phenyl hydride, Pyrobenzol |
| Physical properties: Clear colourless to light-yellow liquid, Aromatic odour, Evaporates into the air very quickly Melting Point (°C): 5.5 Boiling Point (°C): 80.1 Specific Gravity: 0.879 Vapour Density: 2.77 |
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| Chemical properties: Highly flammable Dissolves slightly in water |
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There is more information that may be useful in understanding some of the issues surrounding the NPI.