Air toxics and indoor air quality in Australia
State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4
Part C: Factsheets (continued)
Toluene (methylbenzene)
| Substance name: | Toluene (methylbenzene) |
| CASR number: | 108-88-3 |
| Molecular formula: | C7H8 |
| Synonyms: | Toluol; phenyl methane; methylbenzol; methyl-benzene; monomethylbenzene |
Physical and chemical properties
Toluene is a clear, colourless liquid with a sweet smell.
Melting point: -95°C
Boiling point: 110.6°C
Specific gravity: 0.867 at 20°C
Vapour pressure: 3.13
Flashpoint: 4°C
Toluene is noncorrosive, flammable and insoluble in water, but soluble in most organic solvents.
Common uses
Most toluene is used as a component of petrol. It is also used in paints, lacquers, inks, adhesives, rubber, and cleaning agents. It is used to manufacture benzene, urethane raw materials, and other organic chemicals, and in the production of pharmaceuticals, dyes, and cosmetic nail products. In Australia, it is used against roundworms and hookworms, in metal and timber coatings, in the dewaxing of lubricating oils and as a solvent in epoxy resins.
Sources of emissions
Point sources
The primary sources of toluene are the industries that manufacture it or use it in production. These include oil refineries, the chemical industry, rubber manufacturers, the pharmaceutical industry and manufacturers of paints, varnishes and lacquers. It is also emitted in metal degreasing and printing These emissions are mainly to the air, but also to the soil and water. Residues may be present in empty drums.
Diffuse sources, and point sources included in aggregated emissions data
Other possible emitters of toluene are vapours and spilling of petrol, commercial and household painting and paint, varnish and lacquer removal, tobacco smoke, and consumer products containing toluene. These emissions are to the air unless there is a spill.
Natural sources
Natural sources of toluene include volcanoes, forest and bush fires and crude oil.
Mobile sources
Some toluene is found in vehicle exhaust.
Consumer products that may contain toluene
Products include adhesives, auto polish and cleaners, floor polish, hard surface cleaners, paints, inks, paint cleaners, paint and varnish removers and thinners, coatings, particleboard, leather dressings, lubricating oils, fingernail enamels and removers, shoe polish and cleaners, solvent-thinned products (exterior stains, primers, interior stains, clear finish), colouring pens and markers, wood office furniture and vinyl flooring.
Health effects
How might I be exposed to toluene?
Consumers are most likely to be exposed to toluene by smoking or by using consumer products containing toluene (paints, varnish, nail polish, paint cleaners, stain removers, etc.), especially if there is not good ventilation. Because toluene is used in many consumer products and is found in tobacco smoke, short-term indoor concentrations may be elevated above the levels considered safe for workers. Workers in the industries that use or produce toluene are at risk of exposure. Consumers can also be exposed to toluene by exposure to air from production and processing facilities that use toluene, and from automotive exhaust. Sniffing glue or paint can also lead to high exposures.
By what pathways might toluene enter my body?
Toluene will enter the body if we breathe in contaminated air, breathe in tobacco smoke, or consume contaminated food or water. It can be absorbed through the skin if liquid toluene is in contact with the skin. Human exposure occurs mainly by breathing air containing toluene. Toluene usually leaves the body within 12 hours.
Health guidelines
National Occupational Health and Safety Commission (NOHSC):
- TWA (eight-hour time weighted average) exposure limit in the workplace: 100 ppm (377 mg/m³)
- STEL (short-term exposure limit) (15 minutes): 150 ppm (565 mg/m³).
Toluene is listed by the NOHSC as a substance under review regarding skin absorption.
Australian Drinking Water Guidelines (NHMRC and ARMCANZ 1996):
- for health: maximum of 0.8 mg/L (0.0008 g/L)
- for aesthetic reasons: maximum of 0.025 mg/L (0.000025 g/L).
What effect might toluene have on my health?
Short-term exposure to high levels of toluene results first in light-headedness and euphoria, followed by dizziness, sleepiness, unconsciousness, and in some cases death. When exposure is stopped prior to death the symptoms disappear. Long-term exposures at low levels can affect the kidneys. Long-term exposures to high levels by intentional abuse have been linked to permanent brain damage. Also reported are problems with speech, vision, and hearing, loss of muscle control, loss of memory and balance and reduced scores on psychological tests.
Environmental effects
Environmental fate
Toluene quickly evaporates to a gas if released as a liquid. It evaporates from both water and soil when exposed to air. It breaks down in the air in a few days into other chemicals (benzaldehyde and cresol, which are harmful to humans). In soil and water, bacteria break it down.
Environmental transport
Industrial emissions of toluene can produce elevated concentrations in the atmosphere around the source. Because of its short life-expectancy in the atmosphere, toluene is expected to be confined to the local area within which it is emitted. Toluene that makes its way into the ground, and does not evaporate, may move through the ground and enter groundwater (bore water); it is degraded in the water within days.
Environmental guidelines
Australian Water Quality Guidelines for Fresh and Marine Waters (ANZECC 1992):
- Maximum of 300 µg/L (0.0003 g/L)
What effect might toluene have on the environment?
Toluene evaporates when exposed to air. It also evaporates from water. In air, it quickly reacts to form other chemicals; in water and soil, bacteria break it down. Toluene has caused membrane damage to the leaves in plants. It has moderate toxicity to aquatic life in the short and long terms. Chronic and acute effects on birds or land animals have not been determined. Toluene is expected to bioaccumulate minimally.
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