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CHEMINFO Record Number: 565
CCOHS Chemical Name: Phosgene

Carbonyl chloride
Carbon oxychloride
Chlorformyl chloride

Chemical Name French: Phosgène
Chemical Name Spanish: Fosgeno
CAS Registry Number: 75-44-5
UN/NA Number(s): 1076
RTECS Number(s): SY5600000
EU EINECS/ELINCS Number: 200-870-3
Chemical Family: Inorganic carbon compound / carbonic acid halide / carbonic acid dichloride / carbonyl chloride / oxychloride / carbon oxychloride
Molecular Formula: C Cl2 O
Structural Formula: Cl-C(=O)-Cl


Appearance and Odour:
Colourless gas which, at low concentrations, smells sweet, like freshly mown hay. At high concentrations the odour is pungent and objectionable. Pale yellow liquid below 8.2 deg C or under pressure; lachrymator (vapour irritates the eyes and causes tears).

Odour Threshold:
0.5 ppm (detection) (1); 1 ppm (9)

Warning Properties:
POOR - Odour threshold is above the TLV. Also, fatigue or adaptation can occur so that gradually increasing concentrations are not noticed. Irritant properties do not provide sufficient warning.

Commercial phosgene products may contain small amounts of free chlorine (0.1% maximum) and hydrogen chloride (0.2% maximum.(12)

Uses and Occurrences:
Primarily used as an intermediate for the chemical synthesis of many different chemicals, including isocyanates, carbamates and urethanes, and for the production of polycarbonates (thermoplastic resins), pesticides and dyes. Used in metallurgy to separate ores by chlorination of the oxides and volatilization. It was historically used as a war gas.
Phosgene is a combustion, thermal decomposition or photodecomposition product of certain volatile chlorinated hydrocarbons (for example, trichloroethylene or perchloroethylene). These chlorinated hydrocarbon compounds can evolve phosgene if they come into contact with very hot metal, flame, or ultraviolet light (e.g. during welding).(4)


Colourless gas, which has a sweet smell, like freshly mown hay, at low concentrations, and a pungent, objectionable odour at high concentrations. Pale yellow liquid below 8.2 deg C or under pressure. Will not burn. Can decompose at high temperatures forming toxic gases and vapours, such as chlorine, carbon monoxide and carbon tetrachloride. COMPRESSED GAS. Slowly reacts with water to form hydrochloric acid and carbon dioxide. VERY TOXIC. May be fatal if inhaled. CORROSIVE to the respiratory tract. Causes lung injury--effects may be delayed. Causes eye irritation.


Effects of Short-Term (Acute) Exposure

Phosgene is an extremely toxic gas with poor warning properties. Very brief exposures (30-60 minutes) to levels around 10 ppm can be life-threatening. Longer exposures to levels as low as 1.25-2.5 ppm may also produce a harmful response. All exposures should be considered serious.(3,4,7,8)
In cases of serious poisoning, there is typically a 3-phase response. Initially, the victim may experience throat irritation, coughing, chest pain, nausea and perhaps some difficulty breathing. This initial phase usually subsides once the exposure is stopped. However, it is important to realize that a serious exposure may occur without experiencing these irritation health effects.
During the second phase the victim feels fine and may even return to work. This latent period can last from 1-24 hours, depending on the extent of the exposure.
The third and final phase of response involves a rapidly worsening difficulty in breathing, accompanied by coughing. Victims may feel as if they cannot catch their breath. This third phase is due to the development of a life-threatening accumulation of fluid in the lungs (pulmonary edema). Pulmonary edema can lead to a lack of oxygen, which can cause death.
Severe acute exposures may result in long-lasting effects such as shortness of breath and pulmonary emphysema (larger than normal air spaces in the lungs which decrease lung efficiency). The lack of oxygen caused by pulmonary edema can also result in brain damage.

Skin Contact:
There are reports of accidental splashing with liquid phosgene which has resulted in serious inhalation health effects (pulmonary edema). The toxicity was due to inhalation of the gas formed by rapid evaporation rather than from absorption of the liquid through the skin.(3,4) It liquid phosgene contacts the skin or clothing, an inhalation exposure should be suspected. See inhalation above for more detail.
Hazards due to skin contact with the gas are unknown. Contact with liquid phosgene has occurred rarely, but skin effects have not been reported. Some references indicate that liquid phosgene may cause severe burns. This is unlikely since phosgene itself is probably not irritating. It does, however, react slowly with moisture to form hydrochloric acid which can be corrosive.

Eye Contact:
Phosgene reacts slowly with moisture in the eye to form hydrochloric acid.
Airborne levels of 1-2 ppm can cause eye irritation. Splashes of the liquid may cause severe irritation and burns.(4,6) Permanent eye damage could result.(6)

Not applicable to gases.

Effects of Long-Term (Chronic) Exposure

The limited human information available indicates that no effects have been seen following exposure to levels of 0.125-0.5 ppm for extended periods. Animal studies have found that repeated exposure to high concentrations, relative to the TLV (25-40 ppm), for extended periods (a life-threatening exposure for humans), may result in chronic, irreversible lung damage.(1,m3)
Chronic exposure toxicity in industry is not known, but it is generally accepted that loss of lung efficiency may result from repeated minor exposures.(1,8)


No human information available. No carcinogenicity was seen in either guinea pigs or rats exposed by inhalation.

The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.

The American Conference of Governmental Industrial Hygienists (ACGIH) has not assigned a carcinogenicity designation to this chemical.

The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.

Teratogenicity and Embryotoxicity:
There is one report which describes a woman in her seventh month of pregnancy who was exposed to phosgene for 3 hours. The woman became ill, developed pulmonary edema (a life-threatening accumulation of fluid in the lungs) and was hospitalized. After 2 months, she gave birth to a healthy child.(3) This is the only information available and it is insufficient for assessing the embryotoxicity and teratogenicity of phosgene.

Reproductive Toxicity:
No information available

No information available. Phosgene has been too difficult to test for mutagenicity because of its reactivity. However, it may be capable of reacting with DNA.(12)

Toxicologically Synergistic Materials:
No information available

Potential for Accumulation:
Phosgene is highly reactive - accumulation is not expected.


Take proper precautions to ensure your own safety before attempting rescue (e.g. wear appropriate protective equipment, use the buddy system). Remove source of contamination or move victim to fresh air. If breathing is difficult, oxygen may be beneficial if administered by trained personnel, preferably on a doctor's advice. DO NOT allow victim to move about unnecessarily. Symptoms of pulmonary edema can be delayed up to 48 hours after exposure. Immediately transport victim to an emergency care facility.

Skin Contact:
GAS: Not applicable to skin. See eye and inhalation above. LIQUID: Take proper precautions to ensure own safety before attempting rescue (e.g. wear appropriate protective equipment, use the buddy system). Avoid direct contact with this chemical. As quickly as possible, remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). Quickly and gently blot or brush away excess chemical. Wash gently and thoroughly with water and non-abrasive soap for 5 minutes or until the chemical is removed. Take first aid actions for inhalation exposures as well. Obtain medical attention immediately. Completely decontaminate clothing, shoes and leather goods and discard.

Eye Contact:
Take proper precautions to ensure own safety before attempting rescue (e.g. wear appropriate protective equipment, use the buddy system). GAS: Remove source of contamination or move victim to fresh air. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 5 minutes, or until the chemical is removed, while holding the eyelid(s) open. Obtain medical advice immediately. LIQUID: Quickly and gently blot or brush away excess chemical. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for at least 20 minutes, or until the chemical is removed, while holding the eyelid(s) open. Take care not to rinse contaminated water into the non-affected eye or onto the face. If irritation persists, repeat flushing. Obtain medical attention immediately.

Not applicable. Phosgene is a gas at room temperature.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
Consult a doctor and/or the nearest Poison Control Centre for all exposures.
Some recommendations in the above sections may be considered medical acts in some jurisdictions. These recommendations should be reviewed with a doctor and appropriate delegation of authority obtained, as required.
All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.


Flash Point:
Will not burn

Lower Flammable (Explosive) Limit (LFL/LEL):
Not applicable

Upper Flammable (Explosive) Limit (UFL/UEL):
Not applicable

Autoignition (Ignition) Temperature:
Not applicable

Sensitivity to Mechanical Impact:
Stable material. Probably not sensitive.

Sensitivity to Static Charge:
Stable material. Not sensitive. Phosgene does not burn.

Combustion and Thermal Decomposition Products:
Chlorine, carbon tetrachloride.

Fire Hazard Summary:
Very toxic gas. Can cause death if it penetrates the fire fighter's normal protective gear. Will not burn. However, during a fire, decomposition occurs at temperatures above 250 deg C (482 deg F), resulting in the formation of toxic gases such as chlorine, carbon monoxide and carbon tetrachloride. WATER REACTIVE. Will react slowly with water to produce corrosive hydrochloric acid. Gas is heavier than air and may accumulate in low areas. Can also accumulate in confined spaces, resulting in a toxicity hazard. Compressed gas. Heat from a fire can cause a rapid build-up of pressure inside cylinders, which may cause explosive rupture. Can produce corrosive hydrochloric acid. Phosgene is heavier than air and may accumulate in low areas. It can also accumulate in confined spaces.

Extinguishing Media:
Will not burn. Use extinguishing media suitable for surrounding materials.

Fire Fighting Instructions:
Phosgene does not burn. However, during a fire, toxic/irritating gases may be formed. Phosgene is an extremely toxic gas. Evacuate area. DO NOT enter the area without specialized protective equipment. Normal fire fighter's protective clothing and breathing apparatus will not provide adequate protection against inhalation or skin contact.
Fight fire from a safe distance or a protected location. Approach fire from upwind to avoid hazardous gas and toxic decomposition products. Use remote equipment wherever possible. Extinguish fire using extinguishing agents suitable for the surrounding fire.
Isolate materials not yet involved in fire and protect personnel. Heat from fire can cause a rapid build-up of pressure inside cylinders, which may cause explosive rupture. Move containers from fire area if this can be done without risk. Keep cooling streams of water on fire-exposed tanks or containers. Stay away from ends of tanks. Withdraw immediately in case of rising sound from venting safety device or any discolouration of tank due to fire.


NFPA - Health: 4 - Very short exposure could cause death or major residual injury.
NFPA - Flammability: 0 - Will not burn under typical fire conditions.
NFPA - Instability: 1 - Normally stable, but can become unstable at elevated temperatures and pressures, or may react vigorously, but non-violently with water.


Molecular Weight: 98.92

Conversion Factor:
1 ppm = 4.04 mg/m3; 1 mg/m3 = 0.25 ppm at 25 deg C (calculated)

Physical State: Gas
Melting Point: -128 deg C (-198 deg F)
Boiling Point: 7.48 deg C (45 deg F) (9,12); 8.2 deg C (47 deg F) (1,10)
Relative Density (Specific Gravity): Not applicable (gas)
Solubility in Water: Slightly soluble (slowly decomposes to hydrochloric acid and carbon dioxide).
Solubility in Other Liquids: Soluble in most hydrocarbons (aromatic, aliphatic and chlorinated) including benzene, toluene and xylene as well as organic acids and esters.
Coefficient of Oil/Water Distribution (Partition Coefficient): Not applicable
pH Value: Not applicable (decomposes in water to form hydrochloric acid which is strongly acidic).
Vapour Density: 3.5 (air = 1)
Vapour Pressure: 63 kPa (472 mm Hg) at 21.1 deg C; 359 pKa (2692 mm Hg) at 54.4 deg C (10)
Vapour Pressure at 50 deg C: 420 kPa (4.1 atm) (3200 mm Hg) (estimated from graph) (22)
Saturation Vapour Concentration: Not applicable. Gas.
Critical Temperature: 181.9 deg C (359.4 deg F) (10)
Critical Pressure: 5674 Kpa, abs. (823 PSIA) (10)


Normally stable. Slowly reacts with water to form hydrochloric acid and carbon dioxide.

Hazardous Polymerization:
Not expected

Incompatibility - Materials to Avoid:

NOTE: Chemical reactions that could result in a hazardous situation (e.g. generation of flammable or toxic chemicals, fire or detonation) are listed here. Many of these reactions can be done safely if specific control measures (e.g. cooling of the reaction) are in place. Although not intended to be complete, an overview of important reactions involving common chemicals is provided to assist in the development of safe work practices.

ALCOHOLS - Reacts with all alcohols (e.g. isopropyl alcohol reacts to form a compound that will decompose explosively in the presence of iron salts).(9)
ALUMINUM - Powdered aluminum burns in phosgene gas.(9)
BASES (e.g. ammonia, sodium hydroxide) - Heat releasing reaction (exothermic) which can increase the liberation of gaseous phosgene from liquid phosgene.(9)
t-BUTYL AZIDOFORMAT- Can react to form explosive carbazide.(9)
POTASSIUM - Mixture explodes when shocked.(9)
SODIUM - Vapours of sodium and phosgene react with luminescence at temperatures of about 260 deg C.(9)
SECONDARY AMINES - Can react to form hazardous products.(9)
WATER - Can react to produce hydrochloric acid and carbon dioxide, producing enough pressure in a closed container to lead to a rupture.(4)

Hazardous Decomposition Products:
Hydrochloric acid, carbon dioxide.

Conditions to Avoid:
Temperatures above 250 deg C. Moisture.

Corrosivity to Metals:
If no moisture is present, phosgene is not corrosive to metals. However, in the presence of moisture, phosgene is corrosive to copper, steel, stainless steel, cast iron and aluminum.(9,11) In the presence of moisture, materials such as ceramics, special glasses and porcelain are corrosion resistant. For more information on the corrosive resistance of materials to hydrochloric acid see reference 16 or CHEMINFO record 13E.


LC50 (mouse): 5.1 ppm (20 mg/m3) (30 minute exposure) (2)
LC50 (mouse): 33 ppm (132 mg/m3) (5 minute exposure) (2)
LC50 (dog): approximately 51-70 ppm (200-280 mg/m3) (30 minute exposure).(15)

EYE IRRITATION: High concentrations of the gas have caused eye damage in cats.(6)

SHORT-TERM INHALATION EXPOSURE: Phosgene is a very severe irritant of the respiratory tract. Pulmonary edema (a life- threatening accumulation of fluid in the lungs) has been observed in a number of animal species (rats, dogs, rabbits) following very brief exposures (less than 1 hour) to low concentrations (around 44-100 ppm). Death often occurred due to respiratory failure.(1,3)
Following brief exposures (less than 7 days) to very low concentrations (about 1 ppm) of phosgene, some animals developed a tolerance to higher levels of phosgene and other irritants. However, it is important to realize this "tolerance" may result in chronic irreversible lung changes such as emphysema (larger than normal air spaces in the lungs which decrease lung efficiency) of fibrosis (scar tissue in the lungs).(1,5)

REPEATED INHALATION EXPOSURES: Dogs repeatedly exposed (up to 40 times) to concentrations of 24-40 ppm for 30-minute periods every other day for 1 week developed chronic respiratory problems (bronchiolitis). Early signs of emphysema were also observed.(3,5) In these studies, normal lung function had not returned 13 weeks after exposure. Pulmonary edema was seen in cats and guinea pigs exposed daily for 10 minute periods to 5 to 6.25 ppm (20-25 mg/m3) for up to several weeks. Similar effects were seen in cats exposed to 2.5 to 3.75 ppm (10-15 mg/m3), but no such effect was seen in guinea pigs exposed to the lower concentration.(3)

CARCINOGENICITY: No tumors were reported in rats and guinea pigs exposed for 18 and 24 months, respectively, by inhalation. The exposure concentrations were not provided.(13) No further information is available.


Selected Bibliography:
(1) Documentation of the threshold limit values and biological exposure indices. 5th ed. ACGIH, 1991. p. 481-482
(2) Igaku, S. Inhalation toxicity of phosgene and trichloronitromethane (chloropicrin). Japanese Journal of Industrial Health. Vol. 15 (1973). p. 406
(3) Criteria for a recommended standard.....occupational exposure to phosgene. National Institute for Occupational Safety and Health, 1976
(4) Phosgene. Rev. 1990 (Hygienic guide series) American Industrial Hygiene Association
(5) Cucinell, S.A. Review of the toxicity of long-term phosgene exposure. Arch Environ Health. Vol. 28 (May 1974). p. 272-275
(6) Grant, W.M. Toxicology of the eye. 3rd ed. Charles C. Thomas, 1986. p. 733
(7) Patty's industrial hygiene and toxicology. 3rd rev. ed. Vol. 2C. John Wiley & Sons, 1982. p. 4126-4128, 4139
(8) Sheet number 91 : phosgene. (Hazard data bank) The Safety Practitioner (July 1987). p. 34-35
(9) Properties and essential information for handling and use of phosgene. (Chemical safety data sheet SD-95). Revised. Manufacturing Chemists Association, 1978
(10) Compressed Gas Association. Handbook of compressed gases. 2nd ed. Van Nostrand Reinhold Company, 1981. p. 430-435
(11) Corrosion data survey : metals section. 6th ed. NACE, 1985. p. 96-97
(12) Final report : Monograph on human exposure to chemicals in the workplace : Phosgene (SRC-TR-85-193). National Cancer Institute, July, 1985
(13) Schepers, G.W.H. Lung tumors of primates and rodents : Part II. Industrial Medicine and Survey. Vol. 40, no. 2 (May, 1971). p. 23-31
(14) Matheson : guide to safe handling of compressed gases. Matheson Gas Products, Inc, 1983. p. 17, 281-282
(15) Underhill, F.P. The lethal war gases. Yale University Press, 1920. p. 1-21
(16) Hamner, N.E. Nonmetals section : corrosion data survey. 5th ed. National Association of Corrosion Engineers, 1983. p. 183-184
(17) NIOSH pocket guide to chemical hazards. NIOSH, June 1994. p. 252-253
(18) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(19) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 49; NFPA 491
(20) Emergency response planning guidelines. AIHA Journal. Vol. 56, no. 2, 1995. p. 202
(21) European Economic Community. Commission Directive 96/54/EC. July 30, 1996
(22) Yaws, C.L. Matheson gas data book. 7th ed. McGraw-Hill, 2001. p. 758

Information on chemicals reviewed in the CHEMINFO database is drawn from a number of publicly available sources. A list of general references used to compile CHEMINFO records is available in the database Help.

Review/Preparation Date: 1993-06-30

Revision Indicators:
WHMIS (detailed class) 1994-03-01
TLV-TWA 1995-11-01
EU number 1996-05-01
Sampling 1996-05-01
Respiratory guidelines 1996-05-01
ERPG 1996-05-01
US transport 1998-03-01
EU Classification 1998-11-01
EU Risk 1998-11-01
EU Safety 1998-11-01
EU Comments 1998-11-01
TDG 2002-05-27
Carcinogenicity 2003-05-24
WHMIS classification comments 2003-05-24
PEL transitional comments 2003-10-30
PEL-TWA final 2003-10-30
Resistance of materials for PPE 2004-03-28
Bibliography 2006-01-18
Relative density 2006-09-28

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