Aromatics Online: Frequently asked Questions Xylenes

Frequently asked Questions
Xylenes

18. What are xylenes?

Xylenes are liquids composed of 8 carbon atoms and 10 hydrogen atoms, configured in a 6 atoms ring shape with a two single atom appendixes. Because there are three possible positions in which the two single atoms can be linked, there are three different xylenes which are often mixed when produced (“Mixed xylenes”). All substances with a basic ring structure are called aromatic hydrocarbons, as they often have a characteristic, “aromatic” smell.

Xylenes are present in products such as gasoline (petrol), other fuels and coal tar. xylenes constitute a range of important raw material for the manufacture of a large number of intermediates, used to produce many items essential to everyday life. For more on the uses of xylenes, see: What are xylenes used for?

19. What are xylenes used for?
Xylenes are an important raw material for the manufacture of a large number of intermediates, used to produce many items indispensable to our health, safety and comfort. These include common consumer goods such as pharmaceuticals, detergents, solvents, paints, etc. Mixed-xylenes are also the basic raw material to isolate paraxylene (used in PET for bottles and in the production of polyester fibres), metaxylene (used in PET for bottles and in plastics), and orthoxylene (also used in plastics). Some amount of xylenes can be found in gasoline .

Of course, that is putting it in a nutshell ; for more, see the section Aromatics in everyday life.

20. Are consumers exposed to xylenes?
Xylenes are not sold as such as a consumer product, but we can find them in articles such as paints, varnishes, thinners and some adhesives used in the home. They are used as a solvent in printing (e.g. in rotogravure, for the production of illustrated brochures), rubber and leather industries. Along with other solvents xylenes are also used as a cleaning agent. Small amount of xylenes (between 5 and 10%) can be found in airplane fuel and gasoline .

The overall exposure of an individual to xylenes is unique to that individual, since it is dependent on his/her life-style and daily activities, as well as the levels of xylenes exposure associated with each of these. In rural areas, exposure due to gasoline are far lower than those found in the cities, and when a room is freshly painted with paint containing solvents, the exposure in the room is greater than in pristine air, which is why freshly painted rooms should always be carefully aired.

However, it should be remembered that all products in which xylenes are present are regulated by authorities in collaboration with the industry with the aim of applying stringent standards and protecting consumers from any risk.

21. Do workers run risks when handling xylenes?
According to our current state of knowledge, today’s very stringent "occupational exposure" limits, controls and working practices provide excellent protection against any risks associated to potential exposure to xylenes.

Besides painters and paint industry workers, others who may be exposed to xylenes include biomedical laboratory workers, distillers of xylenes, wood processing plant workers, automobile garage workers, metal workers and furniture refinishers. In these cases, xylenes are present in the air of workplace as vapour and respiration is the major route of absorption. Less frequently xylenes enter the body through the skin following direct contact.

European regulations recommend an exposure limit in the air of 100 ppm.

22. Are there risks for the health?
The main effects of xylenes on human health are respiratory irritation, gastrointestinal disturbances and narcosis. High level exposure for short period can cause central nervous system depressant reversible effects – similar to the effects of alcohol. The regulation limit is recommended to minimise the potential for eye and upper respiratory tract irritation and should also provide substantial protection from narcosis, gastrointestinal disturbances and chronic effects believed to result from exposure to higher concentrations. According to our current state of knowledge, today’s controls and working practices provide very good protection against the development of these symptoms.

It should be remembered that zero-risk products, whether natural or man-made, do not exist. Even common, over-the-counter pain-killers, for example, have to be taken following strict precautions, such as not exceeding a certain dose, or not ingesting them on an empty stomach. This is what "managing the risks" means.

23. Why are there xylenes in gasoline ? What about “clean fuels”?
Xylenes are a natural component of crude oil, from which gasoline is produced after refining. Industry is taking significant steps to reduce the level of aromatic compounds by adapting its formulation of gasoline .

Automotive fuel quality plays an important role in determining the nature and quantity of pollutants emitted by motor vehicles. Cleaner fuels can significantly reduce this source of air pollution.

The European Commission has already fixed stringent standards like the total aromatics content, to be reduced in the gasoline from 42% to 35% by January 1st 2005 at latest, with a possibility of a further reduction to 30% by 2008.

24. Is xylenes transportation safe?
Xylenes transport is mainly carried out by sea or inland waterways, but also by truck and rail tanks and is subject to a number of international guidelines for safe handling of cargoes. In Europe and the USA, xylenes transport meets rigorous standards that exceed those prescribed by the European or American authorities. This forms part of our voluntary commitment to the responsible handling and transport of aromatics.

For more details on the regulations governing chemicals transport, and indeed on the industry initiatives to minimise all risks related to it, click here.

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