Trichloroethylene

2022-04-22

The chemical compound trichloroethylene is a chlorinated hydrocarbon commonly used as an industrial solvent. It is a clear non-flammable liquid with a sweet smell. The IUPAC name is trichloroethene. [1]

Uses[2]

Trichloroethylene was once used as an extractant in food processing and has been used as an anaesthetic and analgesic for medical purposes. Currently, it is widely used as a solvent in the industrial degreasing of metals, with secondary solvent uses in adhesive paint and polyvinyl chloride production. Trichloroethylene is used as a solvent in the textile industry, as a solvent for adhesives and lubricants, and as a low-temperature heat transfer fluid. In addition, it is implemented in the manufacturing of pesticides and other chemicals.

Trichloroethylene in the environment and potential exposure

Trichloroethylene dissolves a little in water, but it can remain in ground water for a long time. Upon contact with surface water it quickly evaporates, so it is commonly found as a vapour in the air. Trichloroethylene evaporates less easily from the soil than from surface water. It may stick to particles and remain for a long time. Furthermore, it may stick to particles in water, which will cause it to eventually settle to the bottom sediment. It does not build up significantly in plants and animals. [3] Trichloroethylene has been detected in ambient air at levels less than 1 part per billion (ppb). Because of its moderate water solubility, trichloroethylene in soil has the potential to migrate into groundwater. The relatively frequent detection of trichloroethylene in groundwater confirms its mobility in soils. Drinking water supplies relying on contaminated groundwater sources may contain trichloroethylene. Workers may be exposed to trichloroethylene in the factories where it is manufactured or used. In addition, persons breathing air around these factories may be exposed to trichloroethylene. Persons may be exposed to trichloroethylene through the use of products containing the chemical and from evaporation and leaching from waste disposal sites. [4]

Health Hazard Information [4]

Acute Effects

Central nervous system effects are the primary effects noted from acute inhalation exposure to trichloroethylene in humans, with symptoms including sleepiness, fatigue, headache, confusion, and feelings of euphoria.

Effects on the liver, kidneys, gastrointestinal system, and skin have also been noted. Neurological, lung, kidney, and heart effects have been reported in animals acutely exposed to trichloroethylene.

Tests involving acute exposure of rats and mice have shown trichloroethylene to have low toxicity from inhalation exposure and moderate toxicity from oral exposure.

Chronic Effects

As with acute exposure, chronic exposure to trichloroethylene by inhalation also affects the human central nervous system. Case reports of intermediate and chronic occupational exposures included effects such as dizziness, headache, sleepiness, nausea, confusion, blurred vision, facial numbness, and weakness. Effects to the liver, kidneys, and immune and endocrine systems have also been seen in humans exposed to trichloroethylene occupationally or from contaminated drinking water. Research has demonstrated that simultaneous alcohol consumption and trichloroethylene inhalation increases the toxicity of trichloroethylene in humans. Neurological, liver, and kidney effects were reported in chronically-exposed animals.

Reproductive/Developmental Effects

A study of nurses occupationally exposed by inhalation to trichloroethylene along with other chemicals in operating rooms, and another epidemiological study of women exposed occupationally or non-occupationally to trichloroethylene and other solvents, have reported increases in the incidence of miscarriages. The presence of other chemicals, however, limits the ability to draw conclusions specific to trichloroethylene. An epidemiological study of 2,000 male and female workers exposed to trichloroethylene via inhalation found no increase in malformations in babies born following exposure. Several studies have evaluated and not found an association between adverse reproductive effects in humans and exposure to trichloroethylene in contaminated drinking water. An association was found between the occurrence of congenital heart disease in children and a drinking water supply contaminated with trichloroethylene and other similar chemicals; however, no causal relationship with trichloroethylene could be concluded. Animal studies have reported developmental effects from exposure to trichloroethylene and its metabolites (trichloroacetic acid [TCA] and dichloroacetic acid [DCA]).

Cancer Risk

The cancer epidemiology for trichloroethylene has grown in recent years with several large, well-designed studies being published. A recent analysis of available epidemiological studies reports trichloroethylene exposure to be associated with several types of cancers in humans, especially kidney, liver, cervix, and lymphatic system. Consistency across epidemiological studies is strongest for an association between trichloroethylene exposure and kidney cancer. These results are supported by recent molecular epidemiology studies showing specific renal cell mutations found primarily in renal cell carcinoma patients exposed to trichloroethylene. Animal studies have reported increases in lung, liver, kidney, and testicular tumours and lymphoma from inhalation and oral exposures in rats and mice.

Safety

First Aid Measures [8]

  • Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Cold water may be used. Do not use an eye ointment. Seek medical attention.
  • Skin Contact: After contact with skin, wash immediately with plenty of water. Gently and thoroughly wash the contaminated skin with running water and non-abrasive soap. Be particularly careful to clean folds, crevices, creases and groin. Cover the irritated skin with an emollient. If irritation persists, seek medical attention. Wash contaminated clothing before reusing.
  • Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek medical attention.
  • Inhalation: Allow the victim to rest in a well ventilated area. Seek immediate medical attention.
  • Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. Seek medical attention.
  • Ingestion: Do not induce vomiting. Loosen tight clothing such as a collar, tie, belt or waistband. If the victim is not breathing, perform mouth-to-mouth resuscitation. Seek immediate medical attention.

Exposure Controls and Personal Protection [7]

  • Exposure Controls

  • Trichloroethylene should only be used in areas from which all naked lights and other sources of ignition have been excluded.

  • Ventilation hoods and fans required when working with organic solvents or in hot melt applications.
  • Trichloroethylene should be kept away from food, drink and animal feeding stuffs. Wash hands and face before breaks and immediately after handling the products.

Personal Protective Equipment

The following personal protective equipment is recommended when handling trichloroethylene:

  • Respiratory protection: In the case of insufficient ventilation, wear suitable respiratory equipment.
  • Hand protection: Solvent-resistant gloves (butyl rubber).
  • Eye protection: Goggles giving complete protection to eyes.
  • Skin and body protection: Chemical resistant apron/flame retardant antistatic protecting clothing, heavy duty work shoes.

Regulation

United States [9]

OSHA: The Occupational Safety & Health Administration has set the following Permissible Exposure Limit (PEL) for trichloroethylene:

  • General Industry: 29 CFR 1910.1000 Z-2 Table — 100 ppm TWA; Also, exposures shall not exceed 200 ppm (ceiling) with the following exception: exposures may exceed 200 ppm, but not more than 300 ppm (peak), for a single time period up to 5 minutes in any 2 hours.
  • Construction Industry: 29 CFR 1926.55 Appendix A — 100 ppm (535 mg/m3) TWA
  • Maritime: 29 CFR 1915.1000 Table Z-Shipyards — 100 ppm (535 mg/m3) TWA

ACGIH: American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) (2006) for trichloroethylene of 10 ppm (54 mg/m3) TWA; 25 ppm (135 mg/m3) STEL; A2; BEI.

NIOSH: National Institute for Occupational Safety and Health has set a Recommended Exposure Limit (REL):Appendix A – NIOSH Potential Occupational Carcinogens; Appendix C – supplementary Exposure Limits – 2 ppm 1-hour Ceiling as an anaesthetic agent and 25 ppm 10-hour TWA all other exposures.

Australia [6]

In Australia, any product containing more than 0.1% trichloroethylene is classed as a Hazardous Substance. Trichloroethylene is Class 6.1. under the Australian Dangerous Goods Code. Where trichloroethylene is used for vapour degreasing, the degreasers should be made to Australian Standard AS 2661. In addition, the Australian Standard 2865: Safe working in a confined space should be strictly followed for trichloroethylene. The current national exposure standards are an average exposure limit of 50 ppm TWA and a short-term exposure limit of 200 ppm STEL.

European Union [5]

EU legislation includes: Directive 76/464 Pollution of the aquatic environment by dangerous substances (plus daughter directives). It is also regulated under the EC Solvents Directive (VOC emissions). [5]

International [5]

As a VOC it is regulated internationally by the UNECE Convention on Long-Range Transboundary Air Pollution and by the Basel Convention on the Transboundary Movements of Hazardous Wastes and their Disposal. It is also listed as a candidate substance for selection, assessment and prioritisation under the OSPAR and Helsinki Conventions. [5]

Reference

http://en.wikipedia.org/wiki/Trichloroethylene

http://oehha.ca.gov/air/chronic_rels/pdf/79016.pdf

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=172&tid=30

http://www.epa.gov/ttn/atw/hlthef/tri-ethy.html

http://www.environment-agency.gov.uk/business/topics/pollution/246.aspx

http://www.nicnas.gov.au/Publications/Information_Sheets/Safety_Information_Sheets/SIS_10_Trichloroethylene_PDF.pdf

http://www.lomb.com.au/Trichloroethylene.pdf

https://www.sciencelab.com/msds.php?msdsId=9927416

https://www.osha.gov/dts/chemicalsampling/data/CH_273000.html