Chloroforming is a toxic, irritating, corrosive, nonflammable, colorless to yellowish-green, slightly oily liquid with extremely irritating vapors. It is used as a tear gas and has been used as a poison gas in warfare. It also is used in the manufacture of dyes, fumigants, fungicides, insecticides, and pestcides. It may be shipped as the pure material, as “absorbed,” as a mixture with methyl chloride or methyl bromide, and as mixtures with other substances. The absorbed version is chloropicrin absorbed onto a dry, noncombustible, solid material.


Although nonflammable, if heated, chloropicrin in volumes greater than 30 gallons has been reported to be capable of being detonated by shock. Another source says chloropicrin can detonate if heated under confinement or if it is affected by “a strong initiating force.” It has a specific gravity of 1.65, a molecular weight of 164.4, and a vapor density of 5.67. It boils at 233.6° (at which temperature it is reported to explode or decompose violently), freezes at — 83.2°F, and is only slightly soluble in water. Its chemical formula is CCI3NO2, sometimes written CI3CNO2.


Chloropicrin is very toxic, as evidenced by the “4” in the health quadrant of the NFPA 704 designation. Its TLV-TWA (threshold limit value-time weighted average) developed by the ACGIH (American Conference of Governmental Industrial Hygienists) is 0.1 ppm (parts per million of air), the same value as for OSHA’s (Occupational Safety and Health Administration) PEL (permissible exposure limit). The STEL (short-term exposure limit) for chloropicrin is 0.3 ppm. The STEL usually is defined for a 15minute exposure, but a person may not be able to stand exposure to this level for more than a few seconds because of severe eye irritation. Its odor threshold has been reported at 1.1 ppm, which is 11 times the TLVTWA. The implication is that if you can smell chloropicrin, you are being exposed to damaging amounts. inhaling chloropicrin will producemany symptoms, among which are bronchitis, dizziness, faintness, increased sensitization, irregular heartbeat, lachrymation, nausea, sore throat, vomiting, unconsciousness, and death. Death can occur within 10 minutes at concentrations as low as 300 ppm. It has been reported that chloropicrin, when inhaled, will react with certain compounds in hemoglobin, thus interfering with oxygen transport.

Contact of the liquid w ith the eyes can cause blindness. Severe eye irritation can occur from contact with concentrations as lowas 0.3 ppm for as few as 10 seconds.

Contact of the liquid with the skin will cause burns by corrosive action. Severe irritation will occur even if only small amounts of chloropicrin contact the skin for short periods of time.

Ingesting chloropicrin w ill severely burn the mouth, throat, esophagus, and digestive system and will cause other symptoms similar to those caused by inhalation, including death.

Chloropicrin is corrosive to aluminum, magnesium, and alloys containing these metals. It also will attack some coatings, some rubber compounds, and some types of plastics, particularly polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC), also known as Saran.

Chloropicrin is considered a stable chemical (below 234°F) but will react violently with such classes of chemicals as organic amines, strong oxidizers, strong reducing agents, and such individual chemicals as 3-bromopropyne, propargyl bromide, sodium hydroxide, sodium methoxide, and sulfuric acid.

A strange property of chloropicrin allows it to detonate when shocked, particularly at temperatures of 234°F and higher. Some sources say this property is related to the volume of the material in a container. The critical volume is said to be 30 gallons, but all containers of chloropicrin should be considered extremely dangerous if the material is heated.

Although chloropicrin is considered nonflammable, some flammable mixtures of the material are prepared and shipped. Whenever chloropicrin decomposes, a wide array of very toxic gases, including carbon monoxide, chlorine, the nitrogen oxides, nitrosyl chloride, and phosgene, may be liberated.


Chloropicrin is so toxic that a release of any significant amount should activate the community’s emergency response plan. It is absolutely necessary that the incident commander have the expert advice of environmental authorities to minimize the environmental damage that may result from the release. All contaminated earth and other materials must be removed from the incident scene and disposed of in accordance with local, state, and federal regulations. Environmental experts will be able to guide the removal and recommend disposal methods.

Approach any release of chloropicrin from upwind and uphill, and always be ready to move emergency personnel if the wind shifts. The toxicity, corrosiveness, and irritant qualities of chloropicrin mean that all emergency responders must wear the proper protective equipment and that evacuation must be one of the first actions considered. Evacuation distances range from a radius of 1,500 feet around a large spill to three miles downwind.

A container leaking liquid may be patched (or have its valves turned) only if all emergency responders are properly protected and trained for this procedure. Use only compatible materials wTien attempting to stop the leak. Try to capture the leaking liquid in a compatible container to prevent spread of the contamination. Dry mild steel and Teflon™ coatings are recommended compatible materials.

If the leaking liquid cannot be captured and transferred to a secure container, try to contain the product to prevent spreading the contamination. Construct containment ponds by pushing dry soil, dry sand, or other dry inert materials into dikes. Containment pits might spread the contamination deep into the ground and complicate the removal of contaminated soil.

If the material is successfullv contained, it may be salvaged by suctioning or pumping the material into secure containers. Only properly trained and protected professional salvage workers using the proper compatible tools and equipment should perform such work.

If the material is successfully contained but cannot be removed immediately, cover the surface of the chloropicrin with firefighting foam in an attempt to reduce the evolution of vapors. Note that often there is some objection to using foam on materials such as chloropicrin because it may break down too rapidly to be effective and it may cause a reaction that actually will increase the evolution of vapors. Consult your suppliers of firefighting foams to determine if they recommend using their foams on releases of chloropicrin and other hazardous materials.

Covering the surface of the chloropicrin with a sheet of compatible material is another method of reducing vapor production. This method can be used only if the containment pond is small enough to be covered easily. If vapors are being generated, they are so “heavy” (the high vapor density) that they will move slowly downhill, following low spots in the terrain. Any concentration of chloropicrin vapors accumulating in low spots or confined areas will produce a deadly atmosphere for anyone entering without proper respiratory and eye protection. The concentration could be so high that it could damage the skin if proper protective clothing is not worn.



(Chemical Abstract Services)



(Standard Transportation Commodity Code)

4921414, liquid; 4921415, “absorbed” product; 4921416, 4921015, 4920505, and 4920105, various other mixtures


(Registry of Toxic Effects of Chemical Substances)

PB6300000, pure material; PB6310000, flammable mixture; PB320000, mixtures with no compressed gas or poison; PB6330000, chloropicrin/ methyl chloride mixture


(United Nations/North America)

1580, liquid; 1581 chloropicrin/methyl bromide mixture; 1582, chloropicrin/methyl chloride mixture; 1583, “absorbed” version and also mixture containing no poison A or compressed gas; 1955 chloropicrin and nonflammable, nonliquefied, compressed gas mixture; 2929, flammable mixture containing chloropicrin


(Chemical Hazard Response information System)



(U.S. Department of Transportation)

6.1, poisonous material

NFPA 704 Rating



(International Maritime Organization)

6.1 poison, UN 1580 and UN 1583; 2.1 poison gas, all other chloropicrin mixtures

Vapors being generated at the site of the release can be dispersed with high-pressure water spray or fog. However, if this dispersal technique is used, contain all runoff water.

Attempt to prevent chloropicrin liquid from entering sewers and waterways or other bodies of water. Block sewer and catch basin openings. Any product that enters a sewer will volatilize, producing very’ irritating and toxic vapors. According to one reference, phosgene gas w ill form when chloropicrin comes in contact with water. These vapors will drive any inhabitants of a storm sewer out onto the streets. The heavy chloropicrin vapors will flow downhill, following the slope of the sewer system. Warn sewage treatment facilities serving the district immediately if the material is present.

Any chloropicrin that enters a lake or pond will sink to the bottom and slowly dissolve, producing great danger to waterfowl and aquatic life exposed to the contaminated water. Chloropicrin settling in a low spot beneath the water may be suctioned from the water by professional salvaging crews. If the chloropicrin enters a moving stream or river, the product, propelled by the current, will sink to the bottom and move along the waterway bed. If the current is not too swift, the material can gather in low spots and can be suctioned into secure containers. Temporary spillway dams can be built to catch the chloropicrin while allowing clean water to flow’ over the top. The entire stream may be diverted into low-lying areas where the product may be removed from the water by aeration or other methods.

As soon as it has been confirmed that chloropicrin has entered the waterway, alert all downstream users of the water immediately. Be specific as to the identity of the chemical, especially to users of the water for drinking and other household purposes. In all cases, the environmental authorities must be involved from the beginning of the incident; they will determine when the water is no longer contaminated.


Chloropicrin is nonflammable, but it poses severe consequences if it is heated by radiated energy from any source, including a fire or the heat of impinging flames. All liquids, when heated, produce increased vapor pressures—that is, as the liquid absorbs more energy, the molecules of the material move faster and faster until they have enough energy to leave the liquid and enter the atmosphere above the liquid. This process, of course, is evaporation, which occurs in all liquids at faster and faster rates at higher and higher temperatures.

As the vapor pressure inside a closed container increases, the integrity of the container is threatened unless excess pressure can be relieved before the design strength of the container is reached. If there is no pressure-relief device to allow excess pressure to “bleed off’ into the atmosphere, the container will fail, often in the manner of a BLEVE (boiling-liquid, expanding-vapor explosion). This will spew hot toxic liquid and vapor, accompanied by the flying shrapnel of the failed tank, over a great distance. If a pressure-relief device is present, hot toxic vapor will be released. Chloropicrin vapor is so heavy it probably will sink to the ground as soon as it is released from the container.

The other threat posed by chloropicrin is that it has the potential to detonate if heated to 234°F or if shocked while heated. This detonation can be more devastating than the possible BLEVE. The vapors produced during the detonation probably will not be those of chloropicrin but of the other toxic gases, carbon monoxide, chlorine, nitrogen oxides, nitrosyl chloride, and phosgene, mentioned above. Hie danger of detonation may exist among heated containers of chloropicrin even after the fire has been extinguished. For this reason and many others, professional salvage firms—not firefighters—should perform overhaul and salvage operations around containers of chloropicrin after a fire.

Because of these dangers, all exposed containers of chloropicrin should be cooled by water delivered by unmanned appliances from as far away as possible. There may be no warning before the containers fail and, as mentioned, such failure can occur after the fire has been extinguished.

Any pools of exposed liquid probably would be decomposing into the series of toxic gases mentioned above. It is not known whether unconfined chloropicrin will detonate when heated and, consequently, shocked.


Choose protective clothing and equipment to prevent chloropicrin from contacting the eyes or skin. Rubber gloves, aprons, and boots may offer some skin protection, while splashproof chemical goggles should be worn to protect the eyes. Positivepressure, self-contained breathing apparatus must be used for respiratory protection. One manufacturer of total encapsulating suits claims that suits made of neoprene and polyethylene are suitable for protection. One reference suggests that Teflon™ is the only material that should be used in total encapsulating suits worn when trying to mitigate an incident involving chloropicrin. In any case, every hazardous materials response team should consult with the manufacturers of their suits with regard to their recommendations.


Inhalation. Move the victim to fresh air and keep him/her calm and warm. If the victim’s breathing has stopped or becomes labored, administer artificial respiration, being aware that such action might expose the first-aid giver to the material in the victim’s lungs and/or vomit. Seek immediate medical attention.

Eye contact. Flush the eyes immediately for at least 15 minutes, lifting the eyelids occasionally. Immediate medical attention is required.

Skin contact. Wash affected body areas with large amounts of soap and water. If irritation continues after washing, seek medical attention.

Ingestion. If the victim is conscious, make him/her drink large quantities of water immediately, and induce vomiting. Never try to make an unconscious person drink anything or vomit. Seek immediate medical attention.


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