Trichlorobenzenes (TCB)

TCB, Triklorbensener, summa isomerer

 Trichlorobenzenes belong to the group volatile organic compounds (VOC). Trichlorobenzenes exist as several different isomers, that is chemical compounds with the same molecular weight and chemical formula but that differ from each other by the location of the chlorine atoms’ placement on the benzene ring. 1,2,3-trichlorobenzene and 1,3,5-trichlorobenzene occur as colourless solids whereas 1,2,4-trichlorobenzene is a colourless liquid.¹

Uses

Trichlorobenzenes are primarily used as solvents and intermediates for production of other compounds. As solvents they are used to dissolve specific materials, such as oils, waxes, resins and rubber. It is also used in the production of dyes and textiles and have in the past been used as a pesticide to combat termites.^{2 3}

Sources and transportation pathways

Trichlorobenzenes do not occur naturally in the environment but are emitted during their production and use.⁴ Chemical industry, waste management and wastewater treatment are the largest emission sources of the large point sources in Europe.⁵ The most important transportation pathways are by air and water.⁶

Effects on environment and health

As a VOC, trichlorobenzenes 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.

Trichlorobenzenes are very toxic to aquatic organisms and exposure results in long-term effects. Digestion is harmful to humans, and exposure may cause severe eye and skin irritation.⁷

International agreements and regulations

Trichlorobenzenes are regulated by the EU Water Framework Directive (2000/60/EC). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on trichlorobenzene emissions is made available.

As a VOC, trichlorobenzenes are 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).

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¹ https://pubchem.ncbi.nlm.nih.gov/compound
² https://pubchem.ncbi.nlm.nih.gov/compound
³ https://www.atsdr.cdc.gov/toxprofiles/tp199-c1.pdf
⁴ https://www.atsdr.cdc.gov/toxprofiles/tp199-c1.pdf
⁵ http://prtr.ec.europa.eu
⁶ http://www.eurochlor.org/media/49375/8-11-4-19_marine_ra_124_trichlorobenzene.pdf
⁷ https://rib.msb.se/Portal/Template/Pages/Kemi/Substance.aspx?id=2506&q=12002-48-1&p=1