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DESIGNATIONS
CAS No.: 108-88-3
Registry name: Toluene
Chemical name: Toluene
Synonyms, Trade names: Toluene, methylbenzene, phenylmethane, methacide
Chemical name (German): Toluol, Methylbenzol, Toluen
Chemical name (French): Toluène, methylbenzène
Appearance: colourless liquid with benzene-like odour
BASIC CHEMICAL AND PHYSICAL DATA
| Empirical formula: | C7H8 |
| Rel. molecular mass: | 92.15 g |
| Density: | 0.867 g/cm3 at 20°C |
| Relative gas density: | 3.18 |
| Boiling point: | 110.6°C |
| Melting point: | -95°C |
| Vapour pressure: | 28 hPa at 20°C, 45 hPa at 30°C, 109 hPa at 50°C |
| Flash point: | 6°C |
| Ignition temperature: | 535°C |
| Explosion limits: | 1.2-7 vol% |
| Odour threshold: | 0.2 ppm |
| Solvolysis/solubility: | in water: 0.53 g/l at 20-25°C |
| in seawater: 0.38 g/l | |
| unlimited in chloroform, acetone, ether | |
| Conversion factors: | 1 ppm = 3.83 mg/m3 |
| 1 mg/m3 = 0.261 ppm |
ORIGIN AND USE
Usage:
Toluene is a parent substance in the manufacture of benzene
derivatives, caprolactam, saccharine, pharmaceuticals, dyes,
perfumes, TNT and detergents. It is used in fuels (anti-knock
additive) and as a solvent for paints and coatings, rubber,
resins, thinners in nitrocellulose lacquers and adhesives. It
serves as a raw material in the manufacture of phenol
(predominantly in Western Europe), benzene, cresol (chiefly
Japan) and a wide range of other substances.
Origin/derivation:
Natural sources: in coal tar and mineral oils; produced in the
combustion of natural resins (e.g. forest fires).
Production figures:
Estimates of worldwide production vary between 6.5 and more
than 10 million t/a.
| Federal Republic of Germany (1984) | 358,000 t |
| Canada (1984) | 430,000 t |
| France (1984) | 39,000 t |
| Italy (1984) | 312,000 t |
| Japan (1984) | 784,000 t |
| Mexico (1984) | 216,000 t |
| Taiwan (1984) | 169,000 t |
| USA (1984) | 2,390,000 t |
Emission figures (estimated):
Various estimates vary between 6 and 8 million t/a. The
proportional emissions were calculated as follows for a total of
6.2 million t:
| Losses into sea | 500,000 t/a |
| Losses into air from refineries | 2,500,000 t/a |
| Evaporation of fuels | 50,000 t/a |
| Exhaust fumes from motor vehicles | 2,000,000 t/a |
| Solvent losses | 1,000,000 t/a |
| Chemical industry losses | 100,000 t/a |
Toxicity
| Humans: | LD 50-500 mg/kg | |
| TCLo 0.77 mg/l, inhalation | ||
| >2.9 mg/l, inhalation | damage to central nervous system | |
| 50-100 ppm | fatigue, headaches | |
| 200 ppm | slight irritation of throat and eyes | |
| 100-300 ppm (8 h) | slight signs of lack of coordination | |
| 300-800 ppm (8 h) | distinct signs of lack of coordination | |
| >4,000 ppm (1 h) | loss of consciousness, fatal over a lengthy period | |
| 10,000-30,000 ppm | loss of consciousness after several minutes, | |
| fatal over lengthy period | ||
| Mammals: | ||
| Rat | LD50 5,000-7,000 mg/kg, oral | |
| Rat (new born) | LD50 870 mg/kg, oral | |
| Rat | NOEL >590 mg/kg and d, oral (193 d) | |
| Mouse | LC50 20 mg/l (8 h) | |
| Aquatic organisms: | ||
| Freshwater fish | LC50 13-240 mg/l (96 h) | |
| Golden orfe | LC50 70 mg/l | |
| Salmon | LC50 6.4-8.1 mg/l (96 h) | |
| Molluscs | LC50 24-74 mg/l (24 h) | |
| Water flea (Daphnia magna) | EC50 11.5-310 mg/l (48 h) | |
| Green algae | EC50 134-210 mg/l (reduction of photosynthesis) | |
| Blue algae | 10 mg/l (96 h, 75% reduction of photosynthesis) | |
| Plants: | ||
| Corn, soja | 200-20,000 ppm in soil toxic | |
| Carrots, tomatoes, barley | 3 ppm (0.5 h) in air toxic | |
Note:
The data cited from various sources; all quoted in RIPPEN,
1989.
Characteristic effects:
Humans/mammals: Inhalation (100 ppm) causes headaches, dizziness, irritation of eyes and nose. Long-term exposure impairs the central nervous system, alters the blood count and causes other chronic effects. Chromosome damage was established in rats. The investigation of employees exposed to toluene revealed controversial results. Toluene itself is not known to be carcinogenic, but other components in a solvent mixture may be carcinogenic. Rats and mice revealed abnormal skeletons and reduced fetal weight with mice likewise being subject to increased embryonic mortality.
Synerg./antagon.:
- reduction of metabolism in rats with benzene, trichloroethylene or styrene;
- enhancement of toxic effect of acetylsalicylic acid (in particular deformities and anomalies in embryo);
- likelihood of increased chromosome damage in smokers exposed to toluene;
- attenuation of various toxic effects of benzene in mice;
- increase in skin cancer induced by 7,12-dimethyl-benz[b]anthracene.
ENVIRONMENTAL BEHAVIOUR
Water:
Toluene is hazardous to water. Because of its volatility, it is
partly released into the atmosphere, but its solubility in water
is sufficient to cause surface water and groundwater pollution
problems.
Air:
The majority of the toluene which impacts the environment enters
the atmosphere because of its high vapour pressure. Degradation
is rather effective with the result that neither wet nor dry
deposition causes large quantities to return to the Earth's
surface.
Soil:
Adsorption takes place primarily on organic matter and clay
particles. The adsorption capacity increases with decreasing pH
value. If not spilled in large quantities, toluene which enters
the soil passes into the atmosphere or is subject to chemical
transformation and biodegradation.
Degradation, decomposition products, half-life:
The estimated mean half-life in air is about 60 h (reaction
with .OH). The dwell time in summer in northern
climates is approx. 4 days in contrast to several months in
winter. In the tropics, the figure is between several days and
several weeks irrespective of the time of year.
Laboratory experiments have shown that toluene escapes into the atmosphere with a half-life of 5 h from a uniformly mixed body of water with a depth of 1 m.
Some 20% of the dose absorbed by rats, rabbits and humans is exhaled. Approx. 80% is metabolised mainly into benzoic acid (via benzyl alcohol / benzaldehyde) with small quantities being converted into cresols.
Food chain:
Accumulation by way of the food chain is highly improbable since
toluene is only slightly persistent and highly volatile.
ENVIRONMENTAL STANDARDS
| Medium/ acceptor |
Sector | Country/organ. | Status | Value | Cat. | Remarks | Source |
| Water: | Drinkw | A | (L) |
20 µg/l |
acc. RIPPEN, 1989 | ||
| Drinkw | SU | (L) |
500 µg/l |
acc. RIPPEN, 1989 | |||
| Drinkw | USA | G |
14.3 µg/l |
acc. RIPPEN, 1989 | |||
| Surface | USA | G |
12.4 mg/l |
acc. RIPPEN, 1989 | |||
| Surface | USA | G |
2.3 mg/l |
24 h average1) | acc. RIPPEN, 1989 | ||
| Surface | USA | G |
5.2 mg/l |
Peak value1) | acc. RIPPEN, 1989 | ||
| Seawater | USA | G |
0.1 mg/l |
24 h average2) | acc. RIPPEN, 1989 | ||
| Seawater | USA | G |
0.23 mg/l |
Peak value2) | acc. RIPPEN, 1989 | ||
| Groundw | D(HH) | G |
15 µg/l |
Closer investigation | acc. DVGW, 1988 | ||
| Groundw | D(HH) | G |
30 µg/l |
Rehabilitation investigation | acc. DVGW, 1988 | ||
| Groundw | NL | G |
15 mg/l |
Reference | acc. RIPPEN, 1989 | ||
| Groundw | NL | L |
50 mg/l |
Intervention | acc. RIPPEN, 1989 | ||
| Soil: | NL | G |
0.05 mg/kg |
Reference | acc. TERRA TECH, 6/94 | ||
| NL | L |
130 mg/kg |
Intervention | acc. TERRA TECH, 6/94 | |||
| Air: | BG | (L) |
0.6 mg/m3 |
20 min/24 h | acc. EPA, 1983 | ||
| DDR | (L) |
2 mg/m3 |
30 min | acc. EPA, 1983 | |||
| DDR | (L) |
0.6 mg/m3 |
24 h | acc. EPA, 1983 | |||
| Europe | G |
8 mg/m3 |
30 min | WHO, 1987 | |||
| Europe | G |
1 mg/m3 |
24 h | WHO, 1987 | |||
| SU | (L) |
0.6 mg/m3 |
20 min/24 h | acc. WHO, 1985 | |||
| YU | (L) |
0.6 mg/m3 3) |
20 min/24 h | acc. EPA, 1983 | |||
| WHO | G |
1 mg/m3 3) |
30 min | acc. SLOOFF, 1988 | |||
| WHO | G |
8 mg/m3 |
24 h | acc. SLOOFF, 1988 | |||
| Emiss. | D | L |
0.1 g/m3 |
mass flow > 2 kg/h | acc. TA Luft, 1986 | ||
| Workp | AUS | (L) |
375 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | B | (L) |
375 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | BG | (L) |
50 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | CH | (L) |
380 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | CS | (L) |
800 mg/m3 |
Short term | acc. RIPPEN, 1989 | ||
| Workp | D | L |
190 mg/m3 |
MAK | DFG, 1994 | ||
| Workp | DDR | (L) |
200 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | H | (L) |
50 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | I | (L) |
300 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | IRL | (L) |
375 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | J | (L) |
375 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | NL | (L) |
375 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | PL | (L) |
100 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | RO | (L) |
300 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | S | (L) |
375 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | SF | (L) |
750 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | USA | (L) |
375 mg/m3 |
TWA | acc. RIPPEN, 1989 | ||
| Workp | USA | (L) |
560 mg/m3 |
STEL | acc. RIPPEN, 1989 | ||
| Workp | YU | (L) |
200 mg/m3 |
acc. RIPPEN, 1989 | |||
| Workp | D | L |
170 µg/dl |
BAT | In blood | acc. DVGW, 1988 | |
| Foodstuffs: | USA | G |
30 mg/d |
ADI | acc. RIPPEN, 1989 |
Notes:
1) Protection of freshwater organisms
2) Protection of saltwater organisms
3) Protected areas
Comparison/reference values
| Medium/origin | Country | Value | Source1) |
| Water: | |||
| Surface water | GB | 1.8-3.8 µg/l | |
| Rhine (Basle-Duisburg, 1976) | D | 0.7-1.9 µg/l | |
| Gulf of Mexico2) | 3-10 ng/l | ||
| Gulf of Mexico3) | 4-60 ng/l | ||
| Groundwater (contaminated) | USA | 0.01-0.1 µg/l (n=8) | |
| Drinking water (5 cities) | USA | 1.5-8,300 µg/l (n=6 of 13) | |
| 0.1-19 µg/l | |||
| Sediment/soil: | |||
| River Tees estuary | GB | ||
| Sewage sludge | USA | 1.2-6.4 µg/kg NG (n=4) | |
| 1.4-705 mg/kg TG (n=12 of 13) | |||
| Air: | |||
| Northern hemisphere4) (1980-83) | |||
| Southern hemisphere4) (1980-83) | 10-210 pptv (mean values) | ||
| Desert | Egypt | <5-90 pptv (mean values) | |
| Background impact | Brazil | 0.22 ppbv (mean value) | |
| Background impact | Kenya | 0.04-0.19 ppbv (n=6) | |
| Urban air | D | 0.05-1.08 ppbv (n=13) | |
| Low pollution areas | D | 0.52-27 ppbv | |
| Dump gas | D | 1.3 ppbv | |
| Rainwater | GB | 0.2-620 mg/m3 | |
| Rainwater | USA | 43 µg/l | |
| 0.9-220 ng/l | |||
Notes:
1) All data quoted as per RIPPEN, 1989
2) Background value
3) Under anthropogenic influence
4) Clean air
Assessment/comments
Toluene vapours are dangerous especially in confined areas such as cellars or sewage systems when they reach the explosion limit. Accumulation in the food chain is unlikely. The toxicity in aquatic organisms is moderate. Symptoms of poisoning are inhibited growth and reduced reproduction rates. Spilled toluene may cause groundwater pollution.