Atmosphere

Air toxics and indoor air quality in Australia

State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4

Part C: Factsheets (continued)

Xylenes (individual or mixed isomers)

Substance name: Xylenes (individual or mixed isomers)
CASR number: 1330-20-7
Molecular formula: C8H10
Synonyms: Dimethylbenzene, xylol, dimethylbenzene (mixed isomers), xylenes (o-, m-, p-isomers) m-xylene (CAS 108-38-3), o-xylene (CAS 95-47-6), p-xylene (CAS 106-42-3)

Physical and chemical properties

Xylene is a colourless liquid, with a strong, sweet odour.

m-Xylene

Melting point: -47.4°C
Boiling Point: 139.3°C
Specific gravity: 0.87

o-Xylene

Melting point: -25.2°C
Boiling Point: 144.4°C
Specific gravity: 0.88

p-Xylene

Melting point: 13–14°C
Boiling Point: 137°C
Specific gravity: 0.86

Mixed

Melting point: -48°C
Boiling Point: 137°C
Specific gravity: 0.87

There are three xylenes: m-xylene (CAS 108-38-3), o-xylene (CAS 95-47-6), p-xylene (CASR 106-42-3); since their molecular formula is the same, they are called isomers. Their chemical structures are slightly different. They are often sold and used as 'mixed isomers', so, unless a particular isomer is specifically mentioned, the following information will be discussing a mixture of the three isomers. Xylenes are flammable liquids and fire hazards. Xylenes are moderately soluble in water.

Common uses

Xylene is used as a solvent, to manufacture petrol, as a raw material to manufacture chemicals used to make polyester fibre, and to make dyes, paints, lacquers, and insecticides. It is used to sterilise some materials.

Sources of emissions

Point sources

Sources include chemical and petrol manufacture, polyester manufacture, and the manufacture of paints, dyes, and lacquers. Most xylene emissions will be to the air, unless there is a spill. Much of any spilt xylene will end up as an airborne pollutant due to evaporation.

Diffuse sources, and point sources included in aggregated emissions data

Commercial and household painting, woodburning stoves, and fireplaces. These emissions are to the air.

Natural sources

m-Xylene and p-xylene occur naturally in petroleum. o-Xylene is found in coal tar, petroleum, forest and bush fires, and plant emissions.

Mobile sources

Motor vehicles give off emissions to the air.

Consumer products that may contain xylenes (individual or mixed isomers)

Xylenes are common in domestic products such as aerosol paints, architectural coatings, automobile and machinery paints and primers, caulks, insecticides and fungicides for yards and gardens, hard surface cleaners, lubricating oils, markers, automotive chemicals, paints and varnish, paint and varnish removers and thinners, pet flea and tick products, pesticides, shoe polish, interior clear finishes, undercoats, and primers, sealants, resin and rubber adhesives, waterproofing compounds, and wood office furniture.

Health effects

How might I be exposed to xylenes (individual or mixed isomers)?

Consumers are most likely to be exposed to xylene from petrol, automotive exhaust or when using consumer products containing xylene, especially if there is not good ventilation. Since xylene is used in many consumer products, short-term indoor concentrations may be elevated above the levels considered safe for workers. Workers in the industries that use or produce xylene are at risk of exposure. Consumers can also be exposed to xylene by exposure to air from production and processing facilities that use xylene. When xylene is released to the water or soil, it will evaporate rapidly; exposure from contaminated water is therefore unlikely.

By what pathways might xylenes (individual or mixed isomers) enter my body?

Xylene will enter the body if we breathe in contaminated air or breathe tobacco smoke. It can also be absorbed through the skin if liquid xylene is in contact with the skin.

Health guidelines

National Occupational Health and Safety Commission (NOHSC):

Xylene is listed by the NOHSC as a substance under review regarding skin absorption.

Australian Drinking Water Guidelines (NHMRC and ARMCANZ 1996):

What effect might xylenes (individual or mixed isomers) have on my health?

Xylene may irritate the skin, eyes, nose and throat. It is classified by the NOHSC as harmful by inhalation and in contact with skin. Xylenes may cause stomach problems, drowsiness, loss of memory, poor concentration, nausea, vomiting, abdominal pain and incoordination. High levels may cause dizziness, passing out, and death. Repeated exposures may damage bone marrow, which causes a low blood cell count. Xylenes may damage a developing foetus.

Environmental effects

Environmental fate

Most xylenes are released into the atmosphere, where they are quickly degraded by sunlight. When released to soil or water, they quickly evaporate. They may leach into the groundwater (bore water).

Environmental transport

Industrial emissions of xylene can produce elevated, but still low-level, concentrations in the atmosphere around the source. Because of its short life expectancy in the atmosphere, xylene is expected to be confined to the local area within which it is emitted. Since it does not bind to soil well, xylene that makes its way into the ground may move through the ground and enter groundwater (bore water).

Environmental guidelines

There are no national guidelines.

What effect might xylenes (individual or mixed isomers) have on the environment?

Xylene has high acute (short-term) toxicity to aquatic life. It causes injury to various agricultural and ornamental crops. It also has high chronic (long-term) toxicity to aquatic life. There are not sufficient data to predict the acute or chronic toxicity of xylene to birds or land animals. Xylene is expected to moderately bioaccumulate, in fish.

Key

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