VX is an amber-colored viscous liquid similar in appearance to motor oil. It is an organophosphate nerve agent with an extended persistence (evaporation rate about 1/1500th that of water). It has been reported that it has an odor of "rotten fish," but most sources indicate no detectable odor for the purified agent.

CHEMICAL AND PHYSICAL PROPERTIES

DETECTION

nerve agent sensitive chemical agent detectors (e.g., CAM, M18A2, M256, etc.) and papers (e.g., M8, M9) may be used for detection.

SYMPTOMS AND EFFECTS

Lowered acetylcholinesterase levels are indicators of nerve agent intoxication in victims.

Depending on the degree of intoxication, symptoms may include:

Onset is usually rapid, occurring within minutes of exposure.

MEDICAL COUNTERMEASURES

Useful Drugs	Atropine sulfate	Pralidoxime salts	Diazepam

The immediate treatment for nerve agent intoxication is intravenous injection of 2 mg atropine sulfate (intramuscular injection should be considered if the patient is hypoxic and ventilation can not be initiated, as there is a risk of ventricular fibrillation). This should be followed by additional injections of atropine at 10-15 minute intervals, continuing until bradycardia has been reversed (e.g., until the heart rate is at 90 beats/minute). If breathing has stopped, a mechanical respirator should be used to ventilate the patient. While exhaled air is not ordinarily a hazard, DO NOT ATTEMPT MOUTH-TO-MOUTH RESUCITATION without proper shields owing to the possible presence of residual agent on the face. If possible, oxygen or oxygen-enriched air should be used for ventilation. If possible, monitor cardiac activity.

Pralidoxime salts are effective in restoring acetylcholinesterase activity after exposure to VX. Thus, as a supplement to treatment with atropine, treatment with pralidoxime salts should be initiated as soon as possible after exposure, with a slow intravenous infusion of 500 mg to 1 g being given initially.

Diazepam should be administered to control convulsions. It also has value in controlling fear on the part of the patient. An initial dose of 5 mg may be followed by additional doses at 15 minute intervals up to a total of 15 mg.

PHYSICAL COUNTERMEASURES

Protective equipment (self-contained breathing equipment or gas mask, barrier suit) must be used. Medical personnel treating casualties should avoid direct (skin-to skin) contact; protective gear including breathing protection should be worn when treating casualties prior to decontamination. Latex gloves are not adequate protection. Casualties should be decontaminated as rapidly as possible (see the section on decontamination). Remove casualties from exposure as rapidly as possible. Casualties must not be moved into clean treatment areas where unmasked/ungloved personnel are working until decontamination is complete.

Also refer to 2004 Emergency Response Guidebook (ERG2004) Guide 153.

DECONTAMINATION

Victims

Decontamination of victims is accomplished by removing the victim from the contaminated area, removal of clothing, and removal or neutralization of agent present on the skin. Skin should be washed using large amounts of soap and water immediately; household bleach or a 10% sodium carbonate solution may also be used, followed by a rinse using large amounts of water. Any visible droplets should be blotted (not wiped) away using an absorbant material (e.g., paper towels, facial tissues, etc.); if available, towelettes moistened with a neutralizing solution should be used. Adsorbent powders may also be used for removal of droplets (in the absence of standard adsorbents, field expedients such as flour may be useful). Hair should be thoroughly cleaned using soap and water, with care being taken to prevent wash water from contacting skin.

Property

Surface decontamination may be accomplished using hypochlorite bleach slurries, dilute alkalis, or DS2 decontaminating solution. Steam and ammonia may be used for the decontamination of confined spaces. Hot, soapy water can also be effective.

Large amounts of decontaminants (especially bleach) should be used, since some of the products initially formed during decontamination are also toxic and so require further reaction.

VX has low solubility in water (3% at 20°). It hydrolyzes with a half-life of 350 days at pH 7 and 25° and 100 days at pH 2-3; basic condition accelerate hydrolysis (half-life 16 minutes at pH13 and 1.3 minutes at pH 14). A number of toxic hydrolysis products form at pH 7-10, notably EA 2192 (CAS Registry Number 73207-98-4).

SELECTED PRECURSORS

• Diethyl methylphosphonite
• Diisopropylamine
• Diisopropylaminoethyl chloride
• O-Ethyl O-2-diisopropylaminoethyl methylphosphonite (code designation QL)
• O-Ethyl methylphosphonothioic acid (also known as EMPTA)
• Ethyl hydrogen methylphosphonite
• Methylphosphonous dichloride (also known as SW)
• Methylphosphonous difluoride
• Methylphosphonothioic dichloride (also known as SWS)
• Phosphorus pentasulfide
• Phosphorus trichloride
• Sulfur

COMMENTS

Binary weapons in which VX is formed at the time of use have been developed. One component in the binary is O-ethyl O-2-diisopropylaminoethyl methylphosphonite (Code QL; CAS Registry Number 57856-11-8) and the other is a source of sulfur. Sulfur sources used include materials identified by the codes NE, which is sulfur (CAS Registry Number 10544-50-0) to which an anticaking material (a silica aerogel) has been added, and NM, a mixture of dimethylpolysulfides and sulfur.

Historical Notes

VX is one of a family of organophosphates, known as phosphonothiolates, that were investigated as possible pesticides, as well as for possible military uses, beginning in the late 1940's.

Details regarding the sequence of investigations that led specifically to VX remain shrouded in secrecy. It has been suggested that the development parallels that of the G agents, beginning with the investigations into pesticides of Dr. Ranjit Ghosh's team for Imperial Chemical Industries which led to the discovery of materials of great toxicity to both insects and humans. ICI brought one of these, Amiton (also known as VG) to market, but problems with its toxic effects in people caused it to be withdrawn. It has been suggested that the toxic effects attracted the attention of the British chemical warfare establishment, which initiated more systematic studies of the class at the facility at Porton Down. It should be said that there were several other studies of this class happening at about the same time, with those of Tammelin at the Swedish government's chemical warfare defense laboratory and of Schrader (of sarin fame) being frequently noted (and those carried out at the I. M. Sechenov Institute in Leningrad being less frequently noted) and that these also possibly contributed to the interest.

At some point, the British researchers at Porton Down began to share information with the American chemical warfare establishment at Edgewood, where additional studies were conducted which eventually led to VX being selected by the United States for mass production as its second generation nerve agent in 1958.

Outside awareness that a new agent was entering the U.S. Army's arsenal began in 1959, when the FMC Corporation of New York City was awarded a contract to construct a VX production plant in Newport, Indiana. The construction included conversion of a plant used in the nuclear program, the Dana heavy Water Production Plant. The plant began operation in 1961, and produced its last batch in 1968, over which time about 4,400 tons of VX-filled munitions were produced.

Exactly what was being produced, however, was intended to be a closely held secret. The structural formula for VX was not declassified until the mid-1970's (although it had been correctly speculated on by many researchers). The secrecy may have backfired, however, as it simply seems to have encouraged attempts to figure out just what it was.

When the decision to declassify was finally reached, it may have gone too far - several patents dealing with methods for producing the agents were declassified at the same time by the British and American governments, and these are said to have been used for guidance by Aum Shinrikyo and Iraq in their programs for producing VX. Interestingly, the patents demonstrate a continuing link between insecticides and nerve agents - quoting from the preamble to the claims of one of the British patents:

Basic esters of the type hereinbefore described are usually highly toxic compounds, as is now known. When mixed with suitable inert carrier material, they may be used as insecticidal compounds.

Project 112 Testing

Beginning in 1962, a variety of tests of chemical and biological agents were carried out as a result of the Project 112 review of U.S. chemical and biological warfare capabilities. These tests were supervised by the Deseret Test Center, which had been established to conduct them. Some of these tests involved VX. The table below provides a brief synopsis of the tests which included VX and their objectives.

Iraq and VX

Iraq investigated VX beginning in the mid-1980s, in part apparently because of its lower volatility and greater persistence. As with all things about the Iraqi chemical program, there is much confusion about details. UNSCOM inspectors were presented with a claim that less than 260 kg of VX had been produced in an exploratory program begun in September of 1987 that was subsequently abandoned in September 1988. As the UN inspectors uncovered more evidence of Iraq's VX program, the Iraqi government raised the amount of the agent they admitted producing, claiming in 1996 to have produced only 3.9 tons of the agent. UNSCOM found this total incompatible with the large quantities of precursor produced, estimating that at least 50 tons of VX had been produced, with several hundred tons of precursors being unaccounted for. The period over which the program ran also expanded, with a start date in 1985 and a final production run in 1990 becoming the new accepted period. Similarly, Iraq claimed to have never weaponized the agent; a claim that was considered suspect after UNSCOM found VX contamination on fragments from missile warheads.

Iraq appears to have settled on a production method which involved preparing EMPTA as a precursor. This process is not considered the optimal route for VX manufacture, but it is thought that the Iraqis settled on it because the EMPTA route allows for production and isolation of VX in a simple final stage, which could be carried out in the field if necessary.

Iraq may have used VX in the battle of Fao on April 17 and 18, 1988.

Iraq may also have used VX in its chemical cocktail attacks on Iraqi Kurds.

Significant Accidental Releases

On March 13, 1968, at the Dugway Proving Grounds in Utah, a malfunction in a spray tank used in a test of aerial spraying with VX coupled with unfortunate winds resulted in the contamination of a significant amount of grazing land in the vicinity of Skull Valley outside the boundaries of the test site. Over the course of the following week more than 6000 sheep grazing in the area died.

After initially denying any connection to the deaths of the sheep, the army paid damages - without, however, accepting blame.

The official estimate of the amount of VX that was disseminated outside the test site was 9 kg; unofficial estimates have suggested that this is low. However, many of the larger unofficial estimates fail to take into account the fact that a primary route of exposure for the sheep seems to have been ingestion of grass contaminated with VX. This route of exposure makes the official estimate more credible.

In July of 1969, a VX leak from weapons at a storage facility on Okinawa led to the hospitalization of 24 people (23 U.S. military and 1 civilian), and caused considerable consternation to the Japanese government, which had apparently been unaware that chemical weapons were present. The Japanese government, and the government of the Ryuku island chain, asked the United States to remove all chemical weapons from Okinawa.

In 1971, in Operation Red Hat, the weapons were moved to storage on Johnston Island. (They couldn't be taken back to the United States, since Public Law 91-672, passed in 1971, known as the Foreign Military Sales Act Amendment, specifically prohibited the transport of chemical weapons from the island of Okinawa to the United States. This was in part a response to the tremendous public opposition to the Army's initial plan to mave the weapons to the Umatilla Army Depot in Oregon, USA.) The weapons were eventually destroyed on the island (the final M23 VX-containing land mine in the Johnston Island stocks was destroyed on November 29, 2000).

It must be noted that the program of destroying VX at mainland US sites, required under the Chemical Weapons Convention, has not gone as well as that at Johnston Island. There have been frequent delays to respond to safety and environmental concerns, and the project is currently behind schedule.

Terrorist Use

Aum Shinrikyo

VX was synthesized and used to commit murder and assault by the Aum Shinrikyo organization.

According to testimony at the trials of the Aum leadership, VX was used within Aum Shinrikyo facilities to kill at least 10 members of the cult who were seen as dissidents, in at least some cases reportedly by direct injection of the agent. The bodies of the murdered individuals were disposed of, and the incidents did not come to the attention of any outside agency.

VX was also used in attacks on individuals outside the cult.

• On December 12, 1994, in Osaka, Japan, Tadahiro Hamaguchi was sprayed with VX from a syringe while walking to work. He died in the hospital ten days later. It would subsequently emerge that he was thought to be spying on the cult, and "interfering" with the cult's "practice of the truth."
• In Tokyo, in the fall of 1994, cult members made several attempts to kill the attorney Taro Takamoto, who had been assisting former Aum members. A number of these involved the use of VX, including one in which the agent was painted on the door of his car and another in which a VX-containing mixture was squirted into a keyhole. All failed.
• On November 28 and again on December 2, 1994, Noboru Mizuno, who had helped former cult members find shelter, had VX sprayed at him. The second attempt resulted in his hospitalization for 45 days.
• Hiroyuki Nagaoka, who had been helping members of the cult to leave, was sprayed with VX in front of his home in Tokyo on January 4, 1995. He was unconscious for an extended period, but survived.
• Cult members injected VX into the air conditioning system of a car belonging to Ryuho Okawa in February of 1995. Mr. Okawa was the head of the Institute for Research into Human Happiness, viewed as a rival group by Aum's leadership.

al Qaeda

On August 20, 1998, the al-Shifa Pharmaceutical factory in Khartoum, Sudan was destroyed by U.S. cruise missiles. The reason cited for the destruction was the belief that the factory was producing VX precursors for the al Qaeda terrorist organization. Cited reasons for this belief included the presence of a VX precursor (EMPTA) in a soil sample taken from the vicinity of the factory and evidence that Osama bin Laden, the leader of al Qaeda, had financial interests in the plant. However, questions were raised regarding the reliability of the information and it must currently be considered that the allegations that the plant was involved in precursor production are unproven.

Asbat al-Ansar/Ansar al-Islam

Published reports claim that U.S. intelligence agencies have evidence that a quantity of VX gas had been smuggled to either the Asbat al-Ansar or Ansar al-Islam terrorist groups in October or November of 2002. However, there has been no use of these agents.

Related International Classification of Diseases Codes

Heading	ICD-9-CM
Toxic effect of organophosphate & carbamate	989.3
Toxic effect of unspecified gases, fumes, or vapors	987.9
Accidental poisoning by other specified solid and liquid substances	E866.8
Accidental poisoning by unspecified solid and liquid substances	E866.9
Accidental poisoning by other specified gases and vapors	E869.8
Accidental poisoning by unspecified gases and vapors	E869.9
Suicide and self-inflicted poisoning using other and unspecified solid and liquid substances	E950.9
Suicide and self-inflicted poisoning using other specified gases and vapors	E952.8
Suicide and self-inflicted poisoning using unspecified gases and vapors	E952.8
Assault by poisoning using other solid and liquid substances	E962.1
Assault by poisoning using other gases and vapors	E962.2
Injury due to terrorism involving chemical weapons	E979.7
Injury due to war operations by gases, fumes, and chemicals	E997.2
Death due to terrorism involving chemical weapons	U01.7
Heading	ICD-10
Accidental poisoning by and exposure to other and unspecified chemicals and noxious substances	X49
Intentional self-poisoning (suicide) by and exposure to other gases and vapors	X67
Assault (homicide) by gases and vapors	X88
Assault (homicide) by other specified chemicals and noxious substances	X89
Assault (homicide) by unspecified chemical or noxious substance	X90
War operations involving chemical weapons and other forms of unconventional warfare	Y36.7

Selected References and Resources

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