Benzene, toluene, ethylbenzene, xylenes (as BTEX)
BTEX is a group of chemicals, which is quantified by one analytical method. For details concerning benzene see the substance description for benzene.
Toluene, ethylbenzene and xylene, which includes three structurally related isomers are colourless liquids, immiscible with water but miscible with organic solvents. They have a characteristic strong odour and are highly flammable.
Toluene is primarily used as a solvent and in blending petrol. It is a constituent of crude oil and is also produced during the process of making gasoline and other fuels from crude oil, in making coke from coal, and as a by-product in the manufacture of styrene. It is used in paints, paint thinners, fingernail polish, lacquers, adhesives, and rubber and in some printing and leather tanning processes. It is also used in the production of other chemicals.
Ethylbenzene is predominantly used as a chemical intermediate in the manufacture of styrene monomer. It is used as a component of solvents, as a diluent in paints and lacquers and as a solvent in the rubber and chemical industries.
Currently, mixed xylenes are primarily used for blending into petrol. The remainder is used in a variety of solvent applications, as well as to produce the individual isomers of xylene. Xylene based solvents are widely used in the paint and printing ink industries, for polyester fibre, film and fabricated items and perfumes, pesticide formulations, pharmaceuticals and adhesives. It is also used for household products such as aerosol paints and lacquers. Xylene is also used as a cleaning agent, and as a thinner for paint and varnishes. Individual isomers of xylene are used in the manufacture of certain plastics.
Toluene, ethylbenzene and xylenes can enter the environment during manufacture or use of these substances or products containing them. Due to the high volatility of BTEX compounds, emissions are expected to occur principally to air.
Impacts on human health and environment
Excessive exposure to toluene may impair hearing and cause health effects on the brain (neurological), and the unborn child; while for ethylbenzene the brain, eye, lung and skin are of principal concern. Excessive exposure to xylene isomers may cause health effects on the brain, digestive system, ear, eye, heart, kidney, liver, lung, skin, nose, reproductive system, throat and the unborn child.
The BTEX compounds are categorised as Volatile Organic Compounds (VOCs) that may contribute to the formation of ground-level ozone and photochemical smog, which can cause damage to plants and materials as well as pose human health concerns. BTEX compounds are considered harmful to aquatic organisms.
Benzene, toluene and ethylbenzene are all priority substances under the Existing Substances Regulation 793/93. Risk Assessment Reports have been completed on toluene and benzene and can be downloaded from http://ecb.jrc.it/existing-chemicals/.
Emission to water reporting threshold: 200 kg/year
Data source: European Pollutant Emission Register