• What is the American Conference of Governmental Industrial Hygienists (ACGIH) recommended exposure limit for Trichloroethylene?
• What are the fire and explosion dangers associated with Trichloroethylene?
• Is Trichloroethylene stable when exposed to air, moisture, or heat?
• Are there any conditions to avoid when using Trichloroethylene?
• Does Trichloroethylene have an odour threshold (at what level can I smell it)?
• Is the odour of Trichloroethylene reliable as a warning property?
• How can I work with Trichloroethylene safely?
• What can be done to control hazardous conditions?

What is the American Conference of Governmental Industrial Hygienists (ACGIH) recommended exposure limit for Trichloroethylene?

TIME-WEIGHTED AVERAGE (TLV-TWA): 50 ppm - Carcinogenicity Designation A5

STEL: 100 ppm - Carcinogenicity Designation A5

TLV BASIS - CRITICAL EFFECT(S): CNS (Central Nervous System); Headache; Liver

CARCINOGENICITY DESIGNATION A5 - Not suspected as a Human Carcinogen: Substance is not suspected to be a human carcinogen on the basis of properly conducted human studies. Negative evidence of carcinogenicity in laboratory animals will be considered if it is supported by other relevant data.

BIOLOGICAL EXPOSURE INDICES (BEIs): The ACGIH has adopted a BEI for this chemical. BEIs provide an indication of worker exposure by measuring the chemical or its breakdown products in the body or by measuring biochemical changes resulting from exposure to the chemical. Consult the BEI documentation for further information.

NOTE: In many jurisdictions, exposure limits are similar to the ACGIH TLVs. Since the manner in which exposure limits are established, interpreted, and implemented can vary, obtain detailed information from the appropriate government agency in each jurisdiction.

What are the fire and explosion dangers associated with Trichloroethylene?

Trichloroethylene is not flammable under most conditions of use. However, it can probably burn if strongly heated (high temperatures and a strong flame). No flash point has been measured by standard tests. However, under certain circumstances (e.g. ignition by a high-energy source such as a welding arc or hot wire ignition), trichloroethylene can form combustible vapour-air mixtures. Therefore, in hot work situations trichloroethylene should be regarded as flammable. Addition of small quantities of combustible substances or increasing oxygen content significantly increases flammability.

The liquid can accumulate static charge by flow or agitation. During a fire, irritating and toxic hydrogen chloride gas, chlorine and phosgene may be generated. Trichloroethylene can accumulate in low lying areas. Closed containers can explode if exposed to the heat of a fire or excess heat for a sufficient period of time.

Is Trichloroethylene stable when exposed to air, moisture, or heat?

Trichloroethylene is moderately stable. Trichloroethylene is decomposed slowly by air forming phosgene, hydrogen chloride and dichloroacetyl chloride. Sunlight (especially ultraviolet light), heat and moisture accelerate this reaction. In the presence of water, corrosive dichloroacetic acid and hydrochloric acid are formed.

Are there any conditions to avoid when using Trichloroethylene?

Excessive heat, open flames, sparks, electrical arcs, welding arcs, hot surfaces or other high temperature sources, sunlight, moisture, depletion of stabilizers.

Does Trichloroethylene have an odour threshold (at what level can I smell it)?

A wide range of values have been reported; 0.5 to 167 ppm. Reliable values are 82 ppm (detection) and 110 ppm (recognition). Some people may not smell trichloroethylene at higher concentrations because they become accustomed to the odour.

Is the odour of Trichloroethylene reliable as a warning property?

POOR - odour threshold is above the TLV. Irritation occurs above the TLV.

How can I work with Trichloroethylene safely?

This material is a VERY TOXIC liquid (MUTAGEN, SKIN/EYE IRRITANT, SUSPECT CANCER HAZARD and POSSIBLE REPRODUCTIVE HAZARD). Before handling, it is extremely important that engineering controls are operating and that protective equipment requirements and personal hygiene measures are being followed. People working with this chemical should be properly trained regarding its hazards and its safe use. Maintenance and emergency personnel should be advised of potential hazards.

If trichloroethylene is released, immediately put on a suitable respirator and leave the area until the severity of the release is determined. In case of leaks or spills, escape-type respiratory protective equipment should be available in the work area.

Immediately report leaks, spills or ventilation failures.

Unprotected persons should avoid all contact with this chemical including contaminated equipment.

Closed handling systems for processes involving this material should be used. If a closed handling system is not possible, use in smallest possible amounts in well-ventilated area, separate from the storage area. Avoid generating vapours or mists. Prevent the release of vapours/mist into the workplace air. Do not use near welding operations, flames or hot surfaces because of the risk of formation of toxic hydrogen chloride or phosgene. Do not perform any welding, cutting, soldering, drilling or other hot work on an empty vessel, container or piping until all liquid and vapours have been cleared.

Follow the chemical supplier/manufacturer's advice regarding checking and maintaining appropriate levels of stabilizers.

Do not use with incompatible materials such as strong bases (e.g. sodium hydroxide) and alkali metals (e.g. sodium and its alloys). Never return contaminated material to its original container.

Inspect containers for leaks before handling. Stand upwind of all opening, pouring and mixing operations. Prevent damage to containers. Label containers. Open containers on a stable surface. Keep containers tightly closed when not in use. Assume that empty containers contain residues which are hazardous. Never return contaminated material to its original container. Keeping work areas clean is essential. Use work surfaces that can be easily decontaminated. Follow handling precautions on Material Safety Data Sheet. Have suitable emergency equipment for fires, spills and leaks readily available. Practice good housekeeping. Maintain handling equipment. Comply with applicable regulations.

What can be done to control hazardous conditions?

Engineering control methods to reduce hazardous exposures are preferred. Methods include mechanical ventilation (dilution and local exhaust), process or personnel enclosure, control of process conditions and process modification (e.g. substitution of a less hazardous material). Administrative controls and personal protective equipment may also be required.

Because of the high potential hazard associated with this substance, stringent control measures such as enclosure or isolation may be necessary. A closed system should be considered for handling this material. A totally enclosed, intrinsically safe system with an associated purging system should be considered for unloading bulk material and sampling process liquids. To prevent the release of this material due to equipment failure, backup controls (e.g. double mechanical seals for process pumps) should be considered.

Use a non-sparking, grounded ventilation system separate from other exhaust ventilation systems. Exhaust directly to the outside, taking necessary precautions for environmental protection.

Supply sufficient replacement air to make up for air removed by exhaust systems.

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Document last updated on December 21, 1998

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