Tetrachloroethylene

2021-08-20

Tetrachloroethylene (CAS No. 127-18-4) is also known as perchloroethylene, tetrachloroethene, and 1,1,2,2-tetrachloroethene and is often abbreviated to PER or PERC. Its molecular formula is C2Cl4, and its relative molar mass is 165.8. At room temperature, tetrachloroethene is a clear, colourless liquid with an etheric odour. [1] It is nonflammable and mostly insoluble in water. [2]

Uses [2]

The largest user of tetrachloroethylene is the dry cleaning industry. It is a large percentage of all dry cleaning fluid used. Textile mills, vapour degreasers and metal cleaning operations, and rubber coatings also use tetrachloroethylene. It can be added to solvent soaps, printing inks, adhesives, sealants, polishes, lubricants and silicones.

In the Environment [3]

Much of the tetrachloroethylene that gets into water or soil evaporates into the air. Microorganisms can break down some of the tetrachloroethylene in soil or underground water. In the air, it is broken down by sunlight into other chemicals or brought back to the soil and water by rain. It does not appear to collect in fish or other animals that live in water.

Sources of Emission & Routes of Exposure

Sources of Emission [2]

  • Industry sources: The primary sources of tetrachloroethylene emissions are the industries that manufacture it or use it in production. Some of the industries that use it in production are dry cleaners, the chemical industry, rubber manufacturers, heavy equipment manufacturing (degreasing), electroplating facilities (degreasing), pulp and paper manufacture (for de-inking paper), the manufacturers of inks. These are emissions to the air unless there is a spill.
  • Diffuse sources: Other possible emitters of Tetrachloroethylene are degreasing operations, paint, varnish and lacquer removal, and consumer products containing Tetrachloroethylene. These are emissions to the air unless there is a spill.
  • Natural sources: Tetrachloroethylene does not occur naturally in the environment.
  • Transport sources: No major mobile sources, although it is possible to have emissions from clothes being transported from the dry cleaners.
  • Consumer products: Aerosol paints, agricultural chemicals, automotive chemicals, furniture polish and cleaners, hard surface cleaners, rug carpet and upholstery cleaners, lubricating greases and oils, paint and varnish removers and thinners, textile finishes, typewriter correction fluids and waterproofing compounds.

Routes of Exposure [2,4]

The major exposure routes to tetrachloroethylene are :inhalation, skin absorption, ingestion, skin and/or eye contact. Tetrachloroethylene evaporates quickly and so the most common exposure is from breathing air containing it. It may also enter the body if we eat or drink food or water that has been contaminated. It does not pass through the skin. Workers in the industries that use or produce tetrachloroethylene are at risk of exposure. Consumers can be exposed to tetrachloroethylene by exposure to air from production and processing facilities using tetrachloroethylene, or drinking water from contaminated water. Consumers may also be exposed to tetrachloroethylene when using consumer products containing tetrachloroethylene, or by spending time in dry cleaning facilities using tetrachloroethylene or by bringing dry cleaned clothes into their homes.

Health Effects [5]

Acute Effects

Effects resulting from acute, inhalation exposure of humans to tetrachloroethylene vapours include irritation of the upper respiratory tract and eyes, kidney dysfunction, and at lower concentrations, neurological effects, such as reversible mood and behavioural changes, impairment of coordination, dizziness, headache, sleepiness, and unconciousness. Animal studies have reported effects on the liver, kidney, and central nervous system (CNS) from acute inhalation exposure to high levels of tetrachloroethylene. Acute animal tests in mice have shown tetrachloroethylene to have low toxicity from inhalation and oral exposure.

Chronic Effects

The major effects from chronic inhalation exposure to tetrachloroethylene in humans are neurological effects, including sensory symptoms such as headaches, impairments in cognitive and motor neurobehavioral functioning and colour vision decrements. Other effects noted in humans, generally at higher exposures, include liver damage, kidney effects, immune and hematologic effects, and on development and reproduction. Animal studies have reported effects on the liver, kidney, and CNS from chronic inhalation exposure to tetrachloroethylene. EPA has calculated a Reference Concentration (RfC) of 0.04 milligrams per cubic metre (0.04 mg/m3) based on neurotoxicity in occupationally exposed adults. The Reference Dose (RfD) for tetrachloroethylene is 0.006 milligrams per kilogram body weight per day (mg/kg/d) based on neurotoxicity in occupationally exposed adults.

Reproductive/Developmental Effects

Some adverse reproductive effects, such as menstrual disorders, altered sperm structure, and reduced fertility, have been reported in studies of workers occupationally exposed to tetrachloroethylene. However, the evidence is inconclusive. Some studies of residents exposed to drinking water contaminated with tetrachloroethylene and other solvents during pregnancy suggest an association of tetrachloroethylene exposure with birth defects, however firm conclusions cannot be drawn due to several limitations of these studies. Increased foetal resorptions and effects to the foetus have been reported in animals exposed to high levels of tetrachloroethylene by inhalation.

Cancer Risk

Studies of dry cleaning workers exposed to tetrachloroethylene have shown associations between exposure to tetrachloroethylene and several types of cancer, specifically bladder cancer, non-Hodgkin lymphoma and multiple myeloma. There is also limited evidence suggestive of associations with oesophageal, kidney, cervical and breast cancer. Animal studies have reported an increased incidence of liver tumours in mice, from inhalation and gavage (experimentally placing the chemical in the stomach) exposure, and kidney and mononuclear cell leukaemias in rats, via inhalation exposure. EPA has classified tetrachloroethylene as likely to be carcinogenic to humans by all routes of exposure based on suggestive evidence in epidemiological studies and conclusive evidence in rats (mononuclear cell leukaemia) and mice (increased incidence of liver tumours). The International Agency for Research on Cancer (IARC) has classified tetrachloroethylene as probably carcinogenic to humans (Group 2A).

Safety [6]

First Aid Measures

  • Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Get medical attention if irritation occurs.
  • Skin Contact: In case of contact, immediately flush skin with plenty of water. Cover the irritated skin with an emollient. Remove contaminated clothing and shoes. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention.
  • Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek medical attention.
  • Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention if symptoms appear.
  • 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 unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. Loosen tight clothing such as a collar, tie, belt or waistband. Get medical attention if symptoms appear.

Exposure Controls & Personal Protection

Engineering Controls

Provide exhaust ventilation or other engineering controls to keep the airborne concentrations of vapours below their respective threshold limit value.

Personal Protective Equipment

The following personal protective equipment is recommended when handling tetrachloroethylene:

  • Safety glasses
  • Lab coat
  • Vapour respirator (be sure to use an approved/certified respirator or equivalent)
  • Gloves.

Personal Protection in Case of a Large Spill:

  • Splash goggles
  • Full suit
  • Vapour respirator
  • Boots
  • Gloves
  • A self-contained breathing apparatus should be used to avoid inhalation of the product.
  • Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulation

United States [3]

EPA: The U.S EPA has set a maximum contaminant level for the amount of tetrachloroethylene that can be in drinking water at 0.005 milligrams tetrachloroethylene per litre of water (0.005 mg/L).

OSHA: The U.S Occupational Safety and Health Administration has set a limit of 100 ppm for an 8-hour workday over a 40-hour workweek.

NIOSH: The National Institute for Occupational Safety and Health recommends that tetrachloroethylene be handled as a potential carcinogen and recommends that levels in workplace air should be as low as possible.

Australia [2]

Safe Work Australia: Safe Work Australia has established a time weighted average (TWA) concentration for tetrachloroethylene of 50 parts per million over an eight hour workshift, with concentrations not greater than 150 parts per million.

Australian Drinking Water Guidelines (NHMRC and ARMCANZ, 1996): Maximum of 0.05 mg/L (i.e. 0.00005 g/L)

References

http://www.who.int/ipcs/publications/cicad/cicad68.pdf

http://www.npi.gov.au/resource/tetrachloroethylene

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=264&tid=48

http://www.cdc.gov/niosh/npg/npgd0599.html

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

http://www.sciencelab.com/msds.php?msdsId=9927293