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Benzene

SPRI Emission Reporting Threshold
1,000 Kg/yr Pollutant Emissions to Air
10.0 Kg/yr Pollutant Emissions to Water
10.0 Kg/yr Pollutant Emissions to Waste Water
200 Kg/yr Pollutant Emissions to Land
Disclaimer
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Benzene is a colourless liquid with a distinctive smell. It evaporates easily and is highly flammable when heated or exposed to flame. It is only slightly soluble in water, but mixes well with most organic (carbon-containing) solvents. Benzene is part of the group of compounds known as the volatile organic compounds (VOCs).
What is it used for?
The main uses of benzene are for the production of chemical substances such as dyes, detergents, coatings, plastics, fibres, pesticides, adhesives, lubricants, dry cleaning agents and in some types of rubber. It is also a constituent of petrol.
Where does it come from?
The main sources of benzene are from vehicle exhaust and other combustion processes and from industry producing or using it. Benzene is also released naturally from volcanoes and forest fires, but the amounts released are insignificant in comparison to those emitted by man's activities.
How might it affect the environment?
Normal environmental concentrations of benzene are unlikely to damage animals or plants. It does have a low to moderate toxicity for aquatic organisms, but this is only likely to be apparent when high concentrations arise from significant spills. Benzene quickly reacts with other chemicals in the air and is thus removed within a few days of release. In soils and water bodies it breaks down more slowly and can pass into groundwater where it can persist for weeks. Benzene does not accumulate in animals or plants. As a VOC, air-borne benzene can react with other air pollution to form ground levels ozone which can damage crops and materials. It is however unlikely that benzene has any environmental effects at a global level.
How might exposure to it affect human health?
Benzene is a proven carcinogen. However, exposure to normal environmental concentrations in air (from the vapourisation of petrol during re-fuelling of vehicles, from tobacco smoke, glues, paint, furniture wax and detergents) is thought unlikely to be dangerous in this respect. Inhalation of extremely high levels of benzene (following an accidental releae) could be fatal and longer term exposure to lower concentrations (in occupational settings for example) may damage blood-forming organs. When ingested or applied directly to the skin (only likely in occupational settings), benzene is very toxic. Inhalation of ground level ozone (in the formation of which benzene can be involved) can exacerbate respiratory conditions such as asthma.
What steps are being taken to limit the potential impacts?
In the UK (including Scotland) the main legislation controlling releases of benzene is the National Air Quality Strategy; regulations on pollution of surface waters (SI 1997/2560); and Pollution, Prevention and Control (PPC) regulations. European Directives controlling emissions of benzene include those concerned with the pollution of aquatic environments (76/464); assessment and management of ambient air quality (96/62/EC); control of solvents (99/12/EC); and the Hazardous Wastes Directive; and it is listed as a "priority substance" for the proposed water framework directive. Internationally, releases of benzene are controlled through the OSPAR convention which protects the marine environment of the north-east Atlantic sea; the UNECE convention on long-range transboundary air pollution and the Basel convention on transboundary movements and disposal of hazardous wastes.