A high-aromatic oil (HA oil) is an oil extract obtained when crude oil is purified for the manufacturing e.g. of lubricant oils. In this process, aromatic hydrocarbons are washed out using solvents. The solvent is then driven off and there remains a high-aromatic residue, known as the HA oil extract. High-aromatic oil goes under the name of Distillate Aromatic Extract (DAE).
The HA oil contains large quantities of aromatic and polyaromatic hydrocarbons (PAHs), up to 10-30 per cent. PAHs are generally counted as comprising substances that have two or more condensed aromatic rings, i.e. the aromatic rings have one side in common. Several of the PAHs contained in HA oils are classified as carcinogenic. Check in the Classification List for individual PAHs. PAHs are included in PRIO as a separate substance group, and further information can be found there on the properties and risks of these substances.
HA oils are mostly used in rubber manufacturing and occur for instance in automotive tyres and in rubber sheets used for noise reduction alongside roads. The manufacturer of rubber polymer adds the HA oil to reduce viscosity and improve the "stickiness" of the unhardened rubber blend, but also to make the rubber polymer go further. The oil is dissolved in the rubber blend but does not react with it. Further HA oils are added in the manufacturing of automotive tyres to make the tyres soft.
Use in automotive tyres is a major source of the dispersal of HA oils in the environment. The annual requirement for the European tyre market of HA oil is 250,000 tonnes, which is used for the manufacturing of 2.1 million tonnes of automotive tyres, of which 60,000 tonnes of tyres are consumed in Sweden. A very large proportion of tyre treads, approximately 10,000 tonnes, is dispersed annually by tyre wear along Swedish roads in the form of rubber particles. Another route of exposure of HA-oils to the environment is rubber granulate made from recycled tyres used in synthetic turf.
The European Parliament and the Council decided in June 2005 to limit the concentration of PAHs in extender oils (e.g. HA oils) used in the manufacturing of new automotive tyres and treads for retreaded tyres. The legislation entered into force 1 January 2010. Read the directive 2005/69/EC here.
See also the section on complex hydrocarbons.
HA oils in automotive tyres – prospects of a national ban. Report on a government commission. KemI report 5/03, Swedish Chemicals Inspectorate, 2003.
Synthetic turf from a chemical perspective - a status report. KemI PM 3/06, Swedish Chemicals Agency, 2006.