DESIGNATIONS
CAS No.: 127-18-4
Registry name: Tetrachloroethene
Chemical name: Tetrachloroethene
Synonyms, Trade names: Perchloroethene, PER, ethylene tetrachloride, 1,1,2,2-tetrachloroethene, Cecolin 2, Dekapir 2, Digrisol, Dow-Per, Drosol, Dynaper, Etilin, Peran, Perawin, Perclone, Sirius 2, Tetralex, Tetralina, Ankliostin, Didakene, Nema, Perc and many others
Chemical name (German): Tetrachlorethen, Perchlorethylen
Chemical name (French): Tetrachloroéthène, perchloréthène
Appearance: colourless liquid with chloroform-like odour, vapour is much denser than air
BASIC CHEMICAL AND PHYSICAL DATA
Empirical formula: | C2Cl4 |
Rel. molecular mass: | 165.83 g |
Density: | 1.624 g/cm3 at 20°C |
Relative gas density: | 5.73 |
Boiling point: | 121.1°C |
Melting point: | -23°C |
Vapour pressure: | 18.9 hPa at 20°C; 32 hPa at 30°C; 84 hPa at 50°C |
Flash point: | none |
Odour threshold: | 0.3-5 mg/l in water |
4.7-70 ppmv in air | |
Solvolysis/solubility: | in water: 129 mg/l |
readily soluble in organic solvents | |
Conversion factors: | 1 ppm = 6.89 mg/m3 |
1 mg/m3 = 0.145 ppm |
ORIGIN AND USE
Usage:
Tetrachloroethene is a useful solvent. According to BGA (1988),
35% of the amount produced is used to degrease metal surfaces and
50% in dry cleaning establishments. LAI (1988) estimates that
60-65% are used for the treatment of metal surfaces and 20% in
dry cleaning establishments. Stabilisers with widely differing
chemical compositions are added to reduce the vapour pressure.
Important products are e.g. contact adhesives, degreasing agents,
wax removers, shoe polishes, garden pesticides, upholstery
cleaners and carpet cleaners. In most products, tetrachloroethene
has been replaced by other less toxic solvents.
Origin/derivation:
Tetrachloroethene is produced by oxyhydrochlorination,
perchlorination and dehydrochlorination of hydrocarbons or
chlorinated hydrocarbons.
Production figures:
Worldwide | 1978-80 | 1,100,000 t | (RIPPEN, 1989) |
Worldwide | 1985 | 650,000 t | (ULLMANN, 1986) |
EC | 1980 | < 500,000 t | (BGA, 1988) |
USA | 1977 | 304,000 t | (BGA, 1988) |
USA | 1985 | 220,000 t | (ULLMANN, 1986) |
D | 1979 | 113,000 t | (BMI, 1985) |
D | 1985 | 110,000 t | (ULLMANN, 1986) |
D | 1986 | 75,000 t | (LAI, 1988) |
Japan | 1973 | 57,000 t | (RIPPEN, 1989) |
France | 1981 | 26,000 t | (RIPPEN, 1989) |
Mexico (Import) | 1984 | 15,000 t | (RIPPEN, 1989) |
Sweden | 1977 | 5,300 t | (RIPPEN, 1989) |
Toxicity
Humans: | LD0 140 mg/m3 (1.3 or 7.5 h/d for 5 d/w) | acc. WHO, 1984 |
Mammals: | ||
Mouse: | LD50 8,000-11,000 mg/m3, oral | acc. VERSCHUEREN, 1983 |
Mouse: | LC100 135,000 mg/m3 (2 h) | acc. MALTONI et al., 1986 |
Mouse: | LC50 332,200 mg/m3 (0,5 h) | acc. MALTONI et al., 1986 |
Rat: | NEL 475 mg/m3, inhalation (8 h/d for 5 d/w) | acc. VERSCHUEREN, 1983 |
Rat: | LD50 > 5,000 mg/kg, oral | acc. VERSCHUEREN, 1983 |
Rat: | LD50 13,000 mg/kg, oral (6 h) | acc. WHO, 1984 |
Rat: | LC100 20,000 ppm, inhalation (0,4 h) | acc. MALTONI et al., 1986 |
Rat: | LC100 2,500 ppm, inhalation (7 h) | acc. MALTONI et al., 1986 |
Rabbit: | LD 20,000 ppm, inhalation (2 h) | acc. MALTONI et al., 1986 |
Guinea pig: | LC100 37,000 ppm, inhalation (0,67 h) | acc. MALTONI et al., 1986 |
Cat: | LCL0 6,074 ppm, inhalation (2 h) | acc. MALTONI et al., 1986 |
Aquatic organisms: | ||
Water flea: | LC50 18 mg/l (48 h) | acc. WHO, 1984 |
Water flea: | NEL 10 mg/l (48 h) | acc. WHO, 1984 |
American minnow: | LC50 23.5 ng/l (24 h) | acc. VERSCHUEREN, 1983 |
Blue perch: | LC50 46 mg/l (24 h) | acc. WHO, 1984 |
Blue perch: | LC50 13 mg/l (96 h) | acc. WHO, 1984 |
Characteristic effects:
Humans/mammals: Tetrachloroethene is resorbed through the skin because of its fat-dissolving properties. Concentrations above 680 mg/m3 irritate the eyes and the respiratory tract, concentrations of 4,000-6,000 mg/m3 during 45 minutes cause numbness. The substance acts on the central nervous system and produces headaches, dizziness and nausea. Inhalation often results in delayed neurological damage.
Both, the WHO and the German Research Foundation (DFG) have classified tetrachloroethene as a substance suspected of carcinogenic potential. A few experiments with yeast cells have also revealed mutagenic effects. There is no proof of teratogenity or fetal toxicity yet.
ENVIRONMENTAL BEHAVIOUR
Water:
Tetrachloroethene sinks in water because of its poor water
solubility and its high density. Thus, it may accumulate in
groundwater and surface water. Tetrachloroethene is classed as
very hazardous to water (in Germany: water hazard class 3). It is
toxic to aquatic organisms and decomposes slowly to form
trichloroacetic acid and hydrochloric acid. Degradation by
microorganisms has been observed (from sequential
dehydrochlorination up to mineralisation). Tetrachloroethene
finds its way into the water cycle via industrial waste water.
Air:
Because of its high vapour pressure, about 80-90% of the
substance ingresses into the atmosphere where it is ubiquitously
distributed. Tetrachloroethene may be degraded by photolysis and
is probably involved in the depletion of the ozone layer.
Exchange takes place between air and water with the transition
into the atmosphere being the most common path.
Soil:
The accumulation of tetrachloroethene in soil is dependent on
the grain size and the water and humus content. Biological
degradation takes place in soil. High concentrations are to be
found in the immediate vicinity of emission sources.
Half-life:
The half-life for hydrolysis in aerated water is between 9 months
and 6 years (UBA, 1986). In the troposphere, half-life amounts to
approx. 12 weeks or, if photodegradation takes place, up to 8
weeks (UBA, 1986 and MALTONI et al., 1986). The persistence in
water-unsaturated soils is 2-18 months (DVGW, 1985).
Degradation, decomposition products:
Degradation in soil takes place via methanogenic, anaerobic
microorganisms (UBA, 1986). In the troposphere, the substance is
decomposed by photo-oxidation to form carbon dioxide and
hydrochloric acid. In water, trichloroacetic and hydrochloric
acid are formed (BGA, 1985). Other decomposition products are
phosgene (COCl2), di- and trichloroacetyl chloride.
The liver degrades tetrachloroethene in the human body.
Food chain:
There is a moderate accumulation of tetrachloroethene in fatty
tissues.
ENVIRONMENTAL STANDARDS
Medium/ acceptor |
Sector | Country/organ. | Status | Value |
Cat. | Remarks | Source |
Water: | Drinkw | D | L |
0.01 mg/l |
acc. TVO, 1990 | ||
Drinkw | EC | G |
0.001 g/m3 |
acc. LAU-BW, 1989 | |||
Drinkw | WHO | G |
10 µg/l |
acc. WHO, 1984 | |||
Surface | USA | 20 µg/l |
acc. WHO, 1987 | ||||
Waste water | CH | L |
0.05 g/m3 |
For drinking water | acc. LAU-BW, 1989 | ||
Waste water | D | L |
5 g/m3 |
At point of discharge | acc. ROTH, 1989 | ||
Air: | D | L |
35 mg/m3 |
MIK | Long-time value | acc. BAUM, 1988 | |
D | L |
110 mg/m3 |
MIK | Short-time value 2) | acc. BAUM, 1988 | ||
D | L |
100 mg/m3 |
1) | acc. KÜHN & BIRETT, 1988 | |||
D | G |
5 mg/m3 |
3) | acc. BGA, 1988 | |||
DDR | L |
0.5 mg/m3 |
Short-time value | acc. HORN, 1989 | |||
DDR | L |
0.06 mg/m3 |
Long-time value | acc. HORN, 1989 | |||
WHO | G |
5 mg/m3 |
24 h guide value | acc. LAU-BW, 1989 | |||
WHO | G |
8 mg/m3 |
30 min | acc. LAU-BW, 1989 | |||
Emiss. | D | L |
0.1 g/m3 |
mass flow > 2 kg/h | acc. TA Luft, 1986 | ||
Workp | A | (L) |
260 mg/m3 |
Long-time value | acc. MALTONI et al., 1986 | ||
Workp | AUS | (L) |
670 mg/m3 |
Long-time value | acc. WHO, 1987 | ||
Workp | B | (L) |
670 mg/m3 |
Long-time value | acc. WHO, 1987 | ||
Workp | BG | (L) |
10 mg/m3 |
acc. MALTONI et al., 1986 | |||
Workp | BR | (L) |
525 mg/m3 |
48 h/w | acc. WHO, 1987 | ||
Workp | CH | (L) |
345 mg/m3 |
Long-time value, skin | acc. WHO, 1987 | ||
Workp | CS | (L) |
250 mg/m3 |
4) | acc. WHO, 1984 | ||
Workp | CS | (L) |
1,250 mg/m3 |
Short-time value | acc. WHO, 1984 | ||
Workp | D | L |
345 mg/m3 |
TRK (IIIB) | DFG, 1989 | ||
Workp | DDR | (L) |
300 mg/m3 |
Long-time value | acc. HORN, 1989 | ||
Workp | DDR | (L) |
900 mg/m3 |
Short-time value | acc. HORN, 1989 | ||
Workp | E | (L) |
110 mg/m3 |
Long-time value | acc. MALTONI et al., 1986 | ||
Workp | ET | (L) |
267 mg/m3 |
Long-time value | acc. MALTONI et al., 1986 | ||
Workp | F | (L) |
405 mg/m3 |
Long-time value | acc. MALTONI et al., 1986 | ||
Workp | F | (L) |
1,080 mg/m3 |
4) | acc. MALTONI et al., 1986 | ||
Workp | GB | (L) |
678 mg/m3 |
Long-time value | acc. WHO, 1987 | ||
Workp | GB | (L) |
1,000 mg/m3 |
10 min | acc. WHO, 1987 | ||
Workp | H | (L) |
10 mg/m3 |
Long-time value | acc. WHO, 1987 | ||
Workp | H | (L) |
50 mg/m3 |
30 min | acc. WHO, 1987 | ||
Workp | I | (L) |
400 mg/m3 |
Long-time value | acc. MALTONI et al.,1986 | ||
Workp | I | (L) |
1,000 mg/m3 |
Skin | acc. MALTONI et al.,1986 | ||
Workp | J | (L) |
268 mg/m3 |
Long-time value | acc. MALTONI et al.,1986 | ||
Workp | J | (L) |
345 mg/m3 |
4) | acc. WHO, 1987 | ||
Workp | NL | (L) |
190 mg/m3 |
Long-time value | acc. MALTONI et al.,1986 | ||
Workp | NL | (L) |
240 mg/m3 |
Long-time value, skin | acc. WHO, 1987 | ||
Workp | PL | (L) |
60 mg/m3 |
4) | acc. WHO, 1987 | ||
Workp | RO | (L) |
400 mg/m3 |
Long-time value | acc. WHO, 1987 | ||
Workp | RO | (L) |
500 mg/m3 |
4) | acc. WHO, 1987 | ||
Workp | S | (L) |
140 mg/m3 |
1 day | acc. WHO, 1987 | ||
Workp | S | (L) |
350 mg/m3 |
15 min | acc. WHO, 1987 | ||
Workp | SF | (L) |
335 mg/m3 |
acc. WHO, 1987 | |||
Workp | SU | (L) |
10 mg/m3 |
4) | acc. MALTONI et al.,1986 | ||
Workp | USA | (L) |
335 mg/m3 |
TWA | ACGIH, 1986 | ||
Workp | USA | (L) |
1,340 mg/m3 |
STEL | 15 min | ACGIH, 1986 | |
Workp | YU | (L) |
10 mg/m3 |
Long-time value | acc. WHO, 1987 | ||
Workp | YU | (L) |
200 mg/m3 |
Long-time value | acc. MALTONI et al.,1986 | ||
Workp | D | L |
100 µg/dl |
BAT | Blood | DFG, 1989 | |
Workp | D | L |
9.5 ml/m3 |
BAT | Alveolar air | DFG, 1989 | |
Foodstuffs: | D | L |
1 mg/kg |
acc. BGA, 1988 | |||
D | L |
0.1 mg/kg |
acc. UMWELT, 1989 | ||||
D | L |
0.2 mg/kg |
5) | acc. UMWELT, 1989 | |||
Cosmetics: | D | L |
0 mg/kg |
Ban | acc. DVGW, 1985 | ||
EC | L |
0 mg/kg |
Ban | acc. WHO, 1984 |
Notes:
1) With mass flow of 2 kg/h and more
2) With in 4 hours with max. 30 min. overshoot
3) Indoor air
4) Maximum value
5) Cumulative value for several solvents in one foodstuff
Comparison/reference values
Medium/origin | Country | Value | Source |
Surface water | |||
Rhine (Basle, 1982): | D | 0.18-1.73 µg/l | acc. DVGW, 1985 |
Rhine (Karlsruhe, 1982): | D | 0.2-1.39 µg/l | acc. DVGW, 1985 |
Rhine (Wiesbaden, 1983): | D | 0.14-4.1 µg/l | acc. DVGW, 1985 |
Rhine (Cologne, 1983): | D | 0.16-0.63 µg/l | acc. DVGW, 1985 |
Main (Frankfurt, 1979): | D | 0.35-2.8 µg/l | acc. DVGW, 1985 |
Ruhr (Witten, 1983): | D | 0.1-0.6 µg/l | acc. DVGW, 1985 |
Elbe (1982/83): | D | 0.2-9.3 µg/l | acc. UBA, 1986 |
Weser (1982/83): | D | 0.5-1 µg/l | acc. UBA, 1986 |
Danube (1983-1985): | D | 0.1-2.8 µg/l | acc. UBA, 1986 |
Drinking water: | |||
Wiesbaden (1980) | D | < 1.8 µg/l | acc. DVGW, 1985 |
Taunus (1980) | D | < 10.5 µg/l | acc. DVGW, 1985 |
Medmenham (1981) | GB | < 0.01 µg/l | acc. DVGW, 1985 |
5 cities (1977) | J | 0.2-0.6 µg/l | acc. DVGW, 1985 |
22 cities (1977) | USA | < 2 µg/l | acc. DVGW, 1985 |
Gothenburg (1978) | S | < 0.008 µg/l | acc. DVGW, 1985 |
Sediment: | |||
Rhine: (Hitdorf, 1982) | D | 4 µg/kg | acc. DVGW, 1985 |
Ruhr: (1972-1981) | D | 4-36 µg/kg | acc. DGVW, 1985 |
Assessment/comments
According to the Chemicals Law, tetrachloroethene is classed as non-toxic in Germany, but the risk of cancer has not yet been ruled out. Due to the various sources of contamination, chronic exposure of employees to concentrations which may cause adverse effects is frequent.
Assessment is made more difficult because of the variety of stabilisers which are added to technical tetrachloroethene. Some of the reactive hydrocarbons contained in the stabiliser mixtures such as epichlorohydrin and 1,4-dioxane are suspected of being carcinogenic. The contamination of groundwater and drinking water is of major concern as tetrachloroethene is only slowly degraded in groundwater.
Therefore, the usage of tetrachloroethene should be considerably restricted, production plants should be converted into closed systems and provided with solvent-recovery systems. Whenever it is necessary to work on open systems (e.g. servicing, repairs), these have to be cooled down previously, and respiratory protection must be worn.