Tetrachloroethylene (CAS No. 127-18-4), also known as perchloroethylene, tetrachloroethene, or simply PERC, is a clear, colourless liquid with an ether-like odour. Its molecular formula is C₂Cl₄, and its molar mass is 165.8 g/mol. At room temperature, it is non-flammable and only sparingly soluble in water, but it evaporates easily into the air.
What is Tetrachloroethylene used for?
The primary use of tetrachloroethylene is in the dry cleaning industry, where it makes up the bulk of cleaning fluid formulations. Other uses include:
Textile mills and metal degreasing operations
Rubber coatings and adhesives
Added to printing inks, polishes, lubricants, sealants, and silicones
Because of its stability and effectiveness as a solvent, PERC remains one of the most common cleaning and degreasing chemicals.
In textile mills, tetrachloroethylene is widely used as a solvent in cleaning formulations during various stages of textile processing, including scouring and degreasing.
In the Environment
Much of the tetrachloroethylene released into soil or water quickly evaporates into the air.
In soil and groundwater, microorganisms can break it down into other compounds.
In the air, it is degraded by sunlight and returned to land and water by rainfall.
PERC does not accumulate in fish or aquatic animals, suggesting a low risk of bioaccumulation.
Sources of Emission & Routes of Exposure
Sources of Emission
Industrial: emissions from dry cleaners, chemical manufacturers, metal degreasing operations, electroplating, pulp and paper facilities, and ink production.
Diffuse: emissions from paint removers, varnishes, cleaning products, and consumer goods containing PERC.
Natural: does not occur naturally.
Transport: small emissions from recently dry-cleaned clothing.
Consumer products: present in aerosol paints, hard surface cleaners, rug and upholstery cleaners, lubricants, greases, correction fluids, waterproofing sprays, and textile finishes.
Routes of Exposure
Inhalation: the most common route, due to PERC’s volatility.
Skin or eye contact: possible when handling products or in workplaces.
Ingestion: through contaminated food or drinking water.
Occupational exposure: workers in dry cleaning, degreasing, or chemical production facilities are at highest risk.
Consumer exposure: can occur in homes from dry-cleaned clothes or through use of consumer products containing PERC.
Health Effects
Acute Effects
Humans: exposure to high vapour concentrations can cause eye, throat, and respiratory irritation, kidney dysfunction, dizziness, headaches, sleepiness, poor coordination, or unconsciousness.
Animals: acute inhalation exposure causes effects on the liver, kidney, and central nervous system.
Chronic Effects
Long-term inhalation is linked to neurological problems, including headaches, cognitive impairment, reduced coordination, and colour vision loss.
At higher exposures, liver and kidney damage may occur.
Animal studies confirm similar chronic effects on the liver, kidney, and CNS.
The EPA Reference Concentration (RfC) is 0.04 mg/m³ (based on neurotoxicity), and the Reference Dose (RfD) is 0.006 mg/kg/day.
Reproductive/Developmental Effects
Some studies of exposed workers show menstrual irregularities, altered sperm structure, and reduced fertility, but findings are inconclusive.
Studies on contaminated drinking water suggest possible associations with birth defects, though limitations prevent firm conclusions.
Animal studies report foetal loss and developmental effects at high inhalation exposures.
Cancer Risk
Human studies: associations with bladder cancer, non-Hodgkin lymphoma, and multiple myeloma, with suggestive evidence for kidney, breast, cervical, and oesophageal cancers.
Animal studies: increased liver tumours in mice and kidney tumours and leukaemias in rats.
EPA: classifies tetrachloroethylene as “likely to be carcinogenic to humans.”
IARC: classifies it as “probably carcinogenic to humans (Group 2A).”
Safety
First Aid Measures
Eye contact: Remove contact lenses if present and flush eyes with plenty of water for at least 15 minutes. Seek medical attention if irritation persists.
Skin contact: Rinse thoroughly with water, remove contaminated clothing and shoes, and wash before reuse. Apply an emollient or antibacterial cream if irritation develops. Seek medical attention if symptoms occur.
Inhalation: Move the person to fresh air. If breathing is difficult, provide oxygen; if not breathing, administer artificial respiration. Seek medical assistance immediately.
Ingestion: Do not induce vomiting unless directed by medical staff. Never give anything by mouth to an unconscious person. Loosen tight clothing and get medical attention if symptoms appear.
Exposure Controls and Personal Protection
Engineering Controls
Provide adequate ventilation or local exhaust systems to keep airborne vapour concentrations below recommended exposure limits.
Personal Protective Equipment
For routine handling: safety glasses, gloves, lab coat, and an approved vapour respirator.
For large spills or high-risk exposure: splash goggles, a full protective suit, gloves, boots, a vapour respirator, and a self-contained breathing apparatus (SCBA).
Always consult a safety specialist before handling large quantities to ensure protective equipment is adequate.
Regulation
United States
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
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)
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