Benzene

Bensen, Bensen

 Benzene is the simplest aromatic hydrocarbon and belongs to the group volatile organic compounds (VOC). Benzene is a colourless liquid with a gasoline-like odour. It is highly flammable and has low water solubility.¹

Uses

Benzene is used for production of other chemicals during manufacture of plastics, nylon, synthetic fibres and resins. Benzene is also used in the production of rubber, lubricants, dyes, detergents, pharmaceuticals and pesticides.² It may be present in products such as base oils, binders for adhesives and paints, solvents, car care products and fuels.³ Benzene is present in complex hydrocarbons, which are blends of different organic substances produced during refining of crude oil and coal tar. Since the substance is classified as carcinogenic, the content of benzene in these products cannot succeed certain threshold values if they are to be available to consumers. Only professional use is allowed for products exceeding the thresholds.⁴

Sources and transportation pathways

VOCs are emitted to air during incomplete combustion and by evaporation. In the past, the transport sector has been an important contributor to national emissions of NMVOCs, but as a result of effective measures (e.g. the introduction of catalysts) emissions from this sector have decreased substantially. Today, the most important source is evaporation from solvents within the sector product use.⁵, ⁶

Road traffic is one of the most important sources of benzene. Other emission sources include small-scale wood burning and emissions from other combustion engines (snowmobiles, boats).⁷ In Sweden, the largest point sources of benzene emissions to air are, in descending order, facilities within the energy sector, chemical industry and production and processing of metals.⁸ In air, benzene is degraded within a few days. In soil and water, the degradation rate is slower, and benzene may therefore end up in the groundwater.⁹

Effects on environment and health

Benzene is toxic to aquatic organisms. It may cause hereditary genetic defects. Recurring or long-term exposure, even to very low levels, may cause temporary or permanent harm or even death. Benzene is carcinogenic and chronic exposure may cause leukaemia.¹⁰ As a VOC, benzene can be involved in the formation of ground-level ozone. Ground-level ozone may damage vegetation and during episodes of elevated VOC levels, it may cause irritation of the respiratory tract in humans.

International agreements and regulations

As a VOC, benzene is indirectly regulated by the UN Convention on Long-Range Transboundary Air Pollution (CLRTAP) and the UN Framework Convention on Climate Change (UNFCCC), as well as by the EU National Emissions Ceilings Directive (2001/81/EC) and the EU Industrial Emissions Directive (2010/75/EU).

Benzene is regulated by the EU Water Framework Directive (2000/60/EC) and the EU Drinking Water Directive (98/83/EC). The presence of benzene in products is for example regulated by the EU REACH regulation (EC 1907/2006) and the EU regulation on cosmetic products (EC 1223/2009). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on benzene emissions is made available.

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¹ https://rib.msb.se/
² https://toxnet.nlm.nih.gov/
³ https://www.kemi.se/prio-start
⁴ https://www.kemi.se/prio-start/kemikalier-i-praktiken/kemikaliegrupper/komplexa-kolvaten
⁵ http://envs.au.dk/en/knowledge/air/emissions/air-pollutants/nmvoc/
⁶ http://www.naturvardsverket.se/Sa-mar-miljon/Statistik-A-O/Flyktiga-organiska-amnen-utslapp-till-luft/
⁷ https://www.naturvardsverket.se/Sa-mar-miljon/Klimat-och-luft/Luftfororeningar/Kolvaten/
⁸ https://utslappisiffror.naturvardsverket.se/Sok/
⁹ https://toxnet.nlm.nih.gov/
¹⁰ https://www.kemi.se/prio-start/sok-i-prio