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IAQ UK is an independent organisation with the aim of 'raising the agenda of indoor air quality within the home and workplace'

IAQUK Resources - Trichlorethylene

Sources of Pollution


Trichloroethylene was first synthesized by Berlin chemist Hermann Emil Fischer in 1864 whilst working on tetrachlorethan but wasn’t commercially produced inGermany until the 1900s as a degreaser. Fischer is noted for for the Nobel Prize in Chemistry 1902, for the 'complete synthesis' of caffeine and his work on sugar and purine syntheses. 

 

Most Trichloroethylene is produced from ethylene. First, ethylene is chlorinated to produce 1,2-dichloroethane and then heated to around 400 °C with additional chlorine, 1,2-dichloroethane is converted to Trichloroethylene.  When it was first widely produced in the 1920s, Trichloroethylene's major use was to extract vegetable oils from plant materials such as soy, coconut, and palm. Other uses in the food industry included coffee decaffeination and the preparation of flavoring extracts from hops and spices. It has also been used fordrying out the last bit of water for production of 100% ethanol. From the 1930s through the 1970s it was used as an anesthetic and thought to possess less hepatotoxicity (toxic to the liver) than chloroform, and without the unpleasant pungency and flammability of ether.  However, Trichloroethylene was found to cause cardiac arrhythmias (irregular heartbeat or abnormal heart rhythm) and was replaced in the 1950s by a faster induction and recovery time of halothane. Trichloroethylene was also used as an inhalation analgesic in childbirth, concerns about fetal toxicity and carcinogenic potential led to a replacement anesthetic.

 

Trichloroethylene has primarily been as a degreaser for metal parts. The demand for Trichloroethylene as a degreaser began to decline in the 1950s in favour of the less toxic 1,1,1-trichloroethane. However, 1,1,1-trichloroethane production has been phased out in most of the world under the terms of the Montreal Protocol, and as a result Trichloroethylene has experienced some resurgence in use as a degreaser.

 

Legislation has forced the substitution of Trichloroethylene in many processes inEurope as the chemical was classified as a carcinogen carrying an R45 risk phrase. Many degreasing chemical alternatives are being promoted such as Ensolv and Leksol, however, each of these is based on n-propyl bromide, which carries an R60 risk phrase and they would not be a legally acceptable substitute.

 

As a solvent or as a component of solvent blends, Trichloroethylene is used in adhesives, lubricants, paints, varnishes, paint strippers, carpet shampoos and waterproofing agents. The textile industry uses it to scour cotton, wool and other fabrics (remove oils or lubricants), and in waterless dyeing and finishing.

 

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Health effects


When inhaled, Trichloroethylene produces central nervous system depression resulting in general anesthesia. The symptoms of acute non-medical exposure are similar to those of alcohol intoxication, beginning with headache, dizziness, and confusion and progressing with increasing exposure to unconsciousness.  Respiratory and circulatory depression can result in death.

 

At low concentrations it is relatively non-irritating to the respiratory tract.

Higher concentrations result in tachypnea (rapid breathing). Many types of cardiac arrhythmias can occur and are exacerbated by epinephrine (adrenaline). 

Very large exposures may cause irreversible cardiac problems, nerve and liver damage, and death.

 

Chronic (long-term) exposures to Trichloroethylene have been shown to cause nausea, intolerance to fatty foods, respiratory irritation, renal (kidney) toxicity, and immune system depression. Alcohol consumption increases the toxicity of Trichloroethylene and may cause 'degreaser's flush', which appears as red blotches on the skin.

 

Much of what is known about the human health effects of Trichloroethylene is based on occupational exposures. Beyond the effects to the central nervous system, workplace exposure to Trichloroethylene has been associated with toxic effects in the liver and kidney.

 

Trichloroethylene is a cleaning solvent that was used to clean military weapons during the Gulf War. There are reports associating exposure to this solvent with amyotrophic lateral sclerosis (a form of motor neuron disease), and also with a neurologic syndrome resembling Parkinson's disease.

 

The International Agency for Research on Cancer has classified Trichloroethylene as a 'probable human carcinogen'.

Technical - Trichlorethylene - C
2
HCl
3


  • Colourless, voltaile liquid
  • Sweet odour
  • CAS Number: 70-07-6
  • LTEL - 100ppm (550 mg/m³)
  • STEL - 150ppm (820 mg/m³)
  • Risk Phrases: R20, 21, 22, 40, 52, 53
  • Safety Phrases: S23, 36, 37, 61
  • Carcinogen

The Trichloroethylene is a chlorinated hydrocarbon commonly used as an industrial solvent. It is a clear non-flammable liquid with a sweet smell.

 

It is also used for processing and finishing in the textile industry, as an extraction solvent, veterinary anthelmintic (drugs that are used to treat infections with parasitic worms), heat-exchange fluid, grain fumigant, and in the manufacture of fluorocarbons (compounds that contain only carbon and fluorine bonded together). It was also used in the dry cleaning industry until the mid-1950s, when it was replaced by tetrachloroethylene.

 

It is one of the 50 most significant VOCs (in terms of mass emission) released into the UK environment.

 

Other names for Trichloroethylene include Trichloroethene and Ethylene Trichloride.

 


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