DESIGNATIONS
CAS No.: 79-01-6
Registry name: Trichloroethene
Chemical name: Ethene, trichloro
Synonyms, Trade names: Tri, ethene trichloride, trichloroethene, Chlorylen, Algylen, Benzinol, Circosolv, Lanadin, Perm-a-chlor, Triasol, Trichloran, Triclene, Trimar, Vitran and many others
Chemical name (German): Trichlorethen
Chemical name (French): Trichloroéthène, éthène trichloré
Appearance: colourless, volatile liquid with sweet odour reminiscent of chloroform, the gas is much denser than air.
BASIC CHEMICAL AND PHYSICAL DATA
Empirical formula: | C2HCl3 |
Rel. molecular mass: | 131.4 g |
Density: | 1.46 g/cm3 at 20°C |
Relative gas density: | 4.54 |
Boiling point: | 86.7°C |
Melting point: | -73 to -87°C |
Vapour pressure: | 77 hPa at 20°C |
Ignition temperature: | 410°C |
Explosion limits: | 7.9 - 41 Vol% |
Odour threshold: | 50 ppm in air |
Solvolysis/solubility: | in water: 1.1 g/l at 20°C; readily soluble in organic solvents |
Conversion factors: | 1 ppm = 5.46 mg/m3 |
1 mg/m3 = 0.18 ppm |
ORIGIN AND USE
Usage:
Trichloroethene is used for a wide range of applications. 75-80%
of the worldwide trichloroethene production is used for
degreasing in the metal and glass industry (DVGW, 1985). Because
of its good solvent properties, it was formerly used in
dry-cleaning facilities and for the extraction of natural
substances (e.g. for decaffeinated coffee and for fruit juice
extracts). It is also used as an intermediate product in the
manufacture of chloroacetic acid and as a solvent for greases,
oils, waxes, resins, rubber, paints, lacquers, cellulose ester
and cellulose ether.
Origin/derivation:
Trichloroethene is an artificial compound; it is produced
synthetically from 1,2-dichloroethane. Stabilisers are added to
the marketed product.
Production figures:
Worldwide | 1978-80 | 600,000 t | (RIPPEN, 1989) |
EC | 1984 | 200,000 t | (ULLMANN, 1986) |
USA | 1984 | 110,000 t | (ULLMANN, 1986) |
Federal Republic of Germany | 1984 | 30,400 t | (RIPPEN, 1989) |
Japan | 1984 | 80,000 t | (ULLMANN, 1986) |
with a common annual decline of 5 - 7 % worldwide
Toxicity
Humans: | LD100 150 g, dermal | acc. RIPPEN, 1989 |
TCL0 44 mg/l, inhalation (83 min) | acc. RIPPEN, 1989 | |
Mammals: | ||
Rat: | LC50 7,200 mg/kg, oral (14 d) | acc. RIPPEN, 1989 |
LC50 28-29 mg/kg, dermal | acc. RIPPEN, 1989 | |
NEL 400 mg/kg, oral (28 d) | acc. RIPPEN, 1989 | |
Mouse: | LD50 2,400 mg/kg, oral | acc. RIPPEN, 1989 |
LC50 45 mg/l, inhalation (4 h) | acc. RIPPEN, 1989 | |
Rabbit: | LD 7,330 mg/kg | acc. DVGW, 1985 |
Cat: | LD 5,860 mg/kg | acc. DVGW, 1985 |
Dog: | LD50 5,900 mg/kg | acc. DVGW, 1985 |
Aquatic organisms: | ||
LC50 120-150 mg/l (48 h) | acc. RIPPEN, 1989 | |
American minnow: | LC50 41-67 mg/l (96 h) | acc. RIPPEN, 1989 |
EC50 22 mg/l (96 h) | acc. RIPPEN, 1989 | |
Blue perch: | LC50 41-45 mg/l (96 h) | acc. RIPPEN, 1989 |
Water flea: | EC50 21 mg/l (48 h) | acc. RIPPEN, 1989 |
Plants: | ||
Green algae: | EC50 530 mg/l (24 h) | acc. RIPPEN, 1989 |
Characteristic effects:
Humans/mammals: Trichlorethene irritates the eyes and skin as well as having a narcotic effect; loss of consciousness occurs on inhaling an amount of more than 3 mg/kg weight. Loss of weight and nervous phenomena such as headaches, disturbance of consciousness, agitation and frenzy are the consequences of chronic absorption which damages the central nervous system (with female employees from more than 200 vppm; RIPPEN, 1989).
Trichloroethene likewise affects the heart, liver and kidneys. For a long time the substance was considered carcinogenic, but the current opinion is that the pure substance is not. The enhanced tumour rates in animal experiments were the result of stabilisers added to trichloroethene such as epichlorohydrin or epoxybutane. Experiments performed in the USA with pure trichloroethene have, however, revealed an increase in the number of tumours in two types of animal (UBA, 1986).
A direct degradation product has likewise proven to be injurious to humans: trichloroacetyldehydride forms in the body and has a mutagenic effect.
Plants: Trichloroethene inhibits cell reproduction and stunts growth. Slight yellowing of leaves is sometimes encountered.
ENVIRONMENTAL BEHAVIOUR
Water:
Trichloroethene is denser than water and sinks gradually to the
bottom even in groundwater. Groundwater contamination may last
for many decades. It is listed in water hazard class 3 (extremely
hazardous) in Germany.
Air:
Because of its volatility, large quantities of the substance
produced (an estimated 50,000 t in 1979; DVGW, 1985) evaporate
and are uniformly distributed in the atmosphere (ubiquitous).
Exchange takes place between air and water. According to RIPPEN
(1989), the substance makes a minor contribution to the formation
of smog. It is washed out by precipitation and thus ingresses
into surface water or groundwater.
Soil:
The substance accumulates in sediment; in sewage sludge,
sometimes even to an extent which damages anaerobes.
Half-life:
The estimated dwell time in the atmosphere is roughly 1 week. If
not evaporated, trichloroethene is persistent for 2-18 months in
water-unsaturated soils. The half-life in seawater (pH 8 / 10°C)
is 39 weeks and 2.5 - 6 years in freshwater (RIPPEN, 1989). The
half-life in darkness is 11 months. Trichloroethene is stable
under normal conditions (pH 7 / 25°C) (RIPPEN, 1989).
Degradation, decomposition products:
Trichloroethene is converted when exposed to light and heat
in the atmosphere to phosgene, formyl chloride, acetyl chloride
and finally to CO2 and HCl. In water, it forms CHCl2COCl.
Hexachlorobenzene is formed at high temperatures; reaction with
alkaline materials (e.g. mortar) to form dichloroacetylene.
Anaerobic transformation to dichloroethene isomers and vinyl
chloride takes place in contaminated groundwater, in anaerobic
soil and on dumps. There is no transformation in sandy soils.
There is degradation by adapted microorganisms.
Food chain:
Approx. 2-4% of the human intake of trichloroethene results from
drinking water, 3-26% from foodstuffs and 70-95% from the air
(UBA, 1986). Metabolism and accumulation take place in the bodily
tissue.
ENVIRONMENTAL STANDARDS
Medium/ acceptor |
Sector | Country/organ. | Status | Value | Cat. | Remarks | Source |
Water: | CH | G |
25 µg/l |
1) | acc. RIPPEN, 1989 | ||
Drinkw | A | L |
30 µg/l |
2) | acc. RIPPEN, 1989 | ||
Drinkw | A | 100 µg/l |
3) | acc. RIPPEN, 1989 | |||
Drinkw | D | G |
10 µg/l |
TVO | 4) | acc. DVGW, 1985 | |
Drinkw | DDR | G |
1 µg/l |
acc. RIPPEN, 1989 | |||
Drinkw | EC | G |
1 µg/l |
5) | acc. DVGW, 1985 | ||
Drinkw | USA | G |
75 µg/l |
6) | acc. RIPPEN, 1989 | ||
Drinkw | WHO | G |
30 µg/l |
acc. DVGW, 1985 | |||
Surface | USA | G |
27 µg/l |
acc. UBA, 1986 | |||
Waste water | D | R |
5 g/m3 |
At point of discharge | acc. ROTH, 1989 | ||
Air: | Emiss. | D | L |
0.1 g/m3 |
mass flow > 2 kg/h | acc. TA Luft, 1986 | |
Workp | D | L |
270 mg/m3 |
TRK | Kat. 3 | DFG, 1994 | |
Workp | DDR | L |
750 mg/m3 |
MAKK | acc. HORN, 1989 | ||
Workp | DDR | L |
250 mg/m3 |
MAKD | acc. HORN, 1989 | ||
Workp | SU | (L) |
10 mg/m3 |
PDK | acc. RIPPEN, 1989 | ||
Workp | USA | (L) |
270 mg/m3 |
TWA | acc. RIPPEN, 1989 | ||
Workp | USA | (L) |
1,080 mg/m3 |
STEL | ACGIH, 1986 | ||
D | L |
30 mg/m3 |
MIKK | acc. BAUM, 1988 | |||
D | L |
90 mg/m3 |
MIKD | acc. BAUM, 1988 | |||
D | G |
5 mg/m3 |
1/2 h, VDI Guideline 2310 | acc. LAU-BW, 1989 | |||
DDR | L |
4 mg/m3 |
MIKK | acc. HORN, 1989 | |||
DDR | L |
1 mg/m3 |
MIKD | acc. HORN, 1989 | |||
WHO | G |
1 mg/m3 |
24 h | acc. LAU-BW, 1989 | |||
D | L |
500 µg/dl |
BAT | 8) | DGE, 1989 | ||
D | L |
100 mg/l |
BAT | 9) | DFG, 1989 | ||
Foodstuffs: | D | L |
0 mg/kg |
LHmV | acc. UMWELT, 1989 | ||
D | L |
0.2 mg/kg |
LHmV | 10) | acc. UMWELT, 1989 |
Notes:
1) Provisional tolerance value (sum total of all chlorinated solvents)
2) Sum total of 14 halogenated hydrocarbons
3) Sum total of 14 halogenated hydrocarbons in less than 6 months
4) Sum total of trichloroethane, trichloroethene, tetrachloroethene and dichloromethane
5) Sum total of organic chlorine compounds except pesticides
6) With chronic exposure
7) Criterion for water quality
8) Parameter, trichloroethanol in whole blood
9) Parameter, trichloroacetic acid in urine
10) Cumulative value for several solvents in one item of food
COMPARISON/REFERENCE VALUES
Medium/origin | Country | Value | Source |
Drinking water: | |||
Bremen (1980) | D | 0.1 µg/l | acc. DVGW, 1985 |
Mannheim (1980) | D | 0.3 - 7.1 µg/l | acc. DVGW, 1985 |
Taunus (1980) | D | <9.5 µg/l | acc. DVGW, 1985 |
Great Britain (1981) | GB | 0.24 µg/l | acc. DVGW, 1985 |
Japan (1977) | J | 0.2-0.9 µg/l (5 cities) | acc. DVGW, 1985 |
USA (1977) | USA | 0.1-0.5 µg/l (5 cities) | acc. DVGW, 1985 |
Vienna 1984) | A | <3.5 µg/l | acc. RIPPEN, 1989 |
Zurich (1977) | CH | 0.005-0.105 µg/l | acc. DVGW, 1985 |
Gothenburg | S | 0.015 µg/l | acc. DVGW, 1985 |
Surface water | |||
Rhine (Basle, 1982) | D | 0.2-2.44 µg/l | acc. DVGW, 1985 |
Rhine (Cologne, 1983) | D | 0.06-0.81 µg/l | acc. DVGW, 1985 |
Main (1980) | D | 0.4-13 µg/l | acc. DVGW, 1985 |
Lake Constance (1982) | D | 0.01- 0.08 µg/l | acc. DVGW, 1985 |
Liverpool Bay | GB | 0.3 µg/l | acc. RIPPEN, 1989 |
Niagara (1981) | USA | 8 µg/l (mean value) | acc. RIPPEN, 1989 |
Lake Ontario (1981) | CDN | 13 µg/l (mean value) | acc. RIPPEN, 1989 |
Gulf of Kavala | GR | 0.26-2.80 ng/l | acc. RIPPEN, 1989 |
Switzerland (1981-83) | CH | <1.3 µg/l (mean value) | acc. RIPPEN, 1989 |
Japan (1974) | J | 5 µg/l (mean value) | acc. RIPPEN, 1989 |
Gulf of Mexico, coast | MEX | 10-50 ng/l | acc. RIPPEN, 1989 |
South Pacific (1981) | 0.1-0.7 ng/l | acc. RIPPEN, 1989 | |
Groundwater | |||
North Bremen (1985) | D | <100 µg/l | acc. DVGW, 1985 |
Holland | NL | <1,000 µg/l (mean value) | acc. RIPPEN, 1989 |
Holland, contaminated | NL | 3,000 µg/l | acc. RIPPEN, 1989 |
Great Britain | GB | <0.01 - 60 µg/l | acc. RIPPEN, 1989 |
Minnesota | USA | 0.2 - 6.8 µg/l | acc. RIPPEN, 1989 |
Ohio, contaminated | USA | <6,000 µg/l | acc. RIPPEN, 1989 |
Switzerland (1981-83) | CH | <15 µg/l | acc. RIPPEN, 1989 |
Sediment/soil: | |||
Rhine (1978) | D | <300 µg/kg | acc. DVGW, 1985 |
Rhine (Hitdorf) (1982) | D | <10 µg/kg | acc. DVGW, 1985 |
Black Forest, west facing | D | 8 - 30 µg/m3 | acc. RIPPEN, 1989 |
Close to dry cleaning establishments | D | 30 - 200 µg/m3 | acc. RIPPEN, 1989 |
Sewage sludge (dry subst.) | USA | 0.048 - 44 mg/kg | acc. RIPPEN, 1989 |
Air | |||
Northern hemisphere | 87 ng/m3 | acc. RIPPEN, 1989 | |
Southern hemisphere | 8.2 ng/m3 | acc. RIPPEN, 1989 | |
Arctic (1980-82) | 22 - 220 ng/m3 | acc. RIPPEN, 1989 | |
Frankfurt, city centre | D | 2-46 µg/m3 (max.: 1,100) | acc. RIPPEN, 1989 |
Berlin (1977) | D | 1-61 µg/m3 | acc. RIPPEN, 1989 |
Japan (1979) | J | 0.08-32 µg/m3 | acc. RIPPEN, 1989 |
Sweden (city) | S | 10 µg/m3 | acc. RIPPEN, 1989 |
Mammals: | |||
Invertebrates | 1-10 µg/kg | acc. RIPPEN, 1989 | |
Fish | 0.5-100 µg/kg | acc. RIPPEN, 1989 | |
Waterfowl | 1-100 µg/kg | acc. RIPPEN, 1989 | |
Mammals | 1-10 µg/kg | acc. RIPPEN, 1989 | |
Humans (fat) | < 32 µg/kg | acc. RIPPEN, 1989 | |
Humans (total) | 1 µg/kg | acc. RIPPEN, 1989 | |
Foodstuffs: | |||
Beverages | D | <0.1-8 µg/kg | acc. RIPPEN, 1989 |
Solid food | D | 0.1-64 µg/kg | acc. RIPPEN, 1989 |
Assessment/comments
Because of the high toxicity in aquatic organisms, the US EPA recommends a general surface-water concentration of zero. As the risk of cancer due to the consumption of contaminated drinking water cannot be precluded, a quality value has been established for the sum of four similar chlorinated hydrocarbons. Despite an extremely broad span in various countries, this figure should not exceed 10 m g/l for drinking water.
As trichloroethene is a typical contaminant for sewage water from cities and communities, it must be handled carefully to minimise emissions.
In the Nineties, several countries restricted the use of trichloroethene by law, so that gradually a replacement is taking place.