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VX

INTRODUCTION

VX: CH₃-P (=O)(-SCH₂CH₂N[CH(CH₃)₂]₂)(-OC₂H₅)

VX remains on material, equipment and terrain for very long periods. Absorption is essentially through skin but also through inhalation of the substance as a gas or aerosol.

The "V" of VX signifies its long persistence. So it is more dangerous and toxic than "G" variety such as GA (Tabun) and GB (Sarin), that dissipate rapidly and have short-term effects only. In liquid form of VX, it is absorbed through the eyes or the skin of the victim. It requires an hour to take effect and its effects result in death. The gaseous form is more potent than liquid form and acts almost instantaneously on the victim. The effects are worst when it is inhaled and death is an end to the suffering.

The LD₅₀ can be as little as 10mg for humans. It operates by cutting off the nervous system. It binds to enzyme that sends out signals to nerves and inhibits them. Hence, nerves become isolated and unstable. The antidote, atropine, is a toxin itself but it counteracts the effect of the VX by removing it from the enzyme. It is an anti-nerve agent so does the reverse of the VX, a nerve agent. It is generally injected into the arm or thigh but for gaseous attacks the atropine must go immediately into the heart. So full body protection and gas masks are essential to avoid exposure in a VX missile attack.

VX has not been used to its maximum potential yet as it is too dangerous to use for local attacks with wind that could carry VX back onto base. This factor has helped to keep VX from being used to cripple local nations. If such weapons were launched against a country then there would be a possibility of a nuclear counterattack because VX is a weapon of mass destruction that spreads from impact point killing all in its path. This would be countered by another, which in a lot of cases, would be a nuclear bomb. The only known countries to possess VX are U.S. France and Russia. England after inventing it abandoned the thought for thermonuclear warfare.

CHARACTERISTICS

· boiling point: 300C
· volatility at 20C: 10 mg/m3
· odor: like rotten fish
· solubility in water is between 1% and 5% at room temperature
· more resistant than Sarin due to hydrolysis, especially in alkaline solution
· inhibits acetylcholinesterase, thus disrupting nerve impulse transmission
· persistent; will remain on ground for several weeks

TOXICOLOGY

· casualty dosage (unmasked): 5 mg-min/m3 (milligrams per minute per cubic meter)
· lethal dosage: 10 mg-min/m3
· slightly slower onset of symptoms than Sarin
· primarily toxic by the dermal route

SYMPTOMS

· at low concentration
· miosis
· headache
· increased salivation
· increased nasal secretion
· bronchoconstriction
· at high concentration
· cough
· increased perspiration
· gastro-intestinal effects (nausea, vomiting, colic, diarrhea)
· effects on skeletal musculature
· death by suffocation due to effects on respiratory musculature and respiratory centre in central nervous system

It takes at least 2 weeks to recover from a sublethal dose.

CAUTIONS

· prolonged exposure, hazard by contamination of ground, vegetation and equipment is possible
· its hydrolysis products are nearly as toxic as VX at ph 7
· protection required: gas mask and protective clothing
· clothing should be decontaminated and skin washed thoroughly if VX exposure is suspected

FIRST-AID AND THERAPY

· Artificial Respiration And Oxygen
· atropine-oxime therapy (especially 2 mg atropine + 150 mg obidoxime chloride in an autoinjector)
· Supplemental administration of muscular relaxants may be helpful
· Prophylactic treatment with pralidoxime (2-PAM) is recommended if exposure is anticipated (e.g. In decontamination procedures)

NEUTRALIZATION AND DECONTAMINATION

Clothing, boots, gloves, etc., In the field can be decontaminated with aqueous hypochlorite solution (household bleach). For bulk decontamination a solution of 10% sodium hydroxide in methanol can be used, but be careful as sodium hydroxide is corrosive.

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