Although there was no chemical payload aboard Iraqi missiles that exploded in and around Tel Aviv, Israel, yesterday, Iraq is known to possess such weapons.
A spokesman for the Israeli military said that early reports that the missiles carried chemical weapons were unfounded.
Iraq has the capability to use both nerve agent, which kills within minutes, and mustard agent, a lethal blistering substance best known from its use in World War I, U.S. Army and chemical weapons experts have said.
The type of nerve agent Iraq has stockpiled and reportedly loaded into some missiles is non-persistent nerve agent. It evaporates at about the same rate as water and poses its greatest threat through inhalation, although it can kill if a heavy dose comes in contact with the skin, U.S. Army officials say.
A non-persistent agent is designed to kill the enemy quickly and allow the user to move into an area sprayed with it within hours of an attack, U.S. Army officials have said.
But U.S. intelligence officials also say they believe that Iraq has developed persistent nerve agent, which poses its greatest threat through skin contact, though it, too, can kill through inhalation. The U.S. Army's version of that type of agent -- Agent VX -- takes about 1,000 times as long as non-persistent agent to evaporate and can contaminate an area for weeks.
Exposure to a very small amount of either type of nerve agent -- both of which are odorless and tasteless -- can kill within seconds or take up to 15 minutes, say officials at the U.S. Army's Chemical Research, Development and Engineering Center at Aberdeen Proving Ground.
Similar to the non-persistent nerve agents, mustard -- which derives its name from its mustard- or garlic-like smell -- is deadliest wheninhaled. It can kill its victims within hours after it burns and blisters the lungs and windpipe, Army studies have shown.
Mustard in small to moderate doses burns the eyes and can cause blindness. It also causes first- and second-degree burns on exposed skin, although the irritation does not show up for hours after contact. In severe cases, those burns can severely ulcerate days later, according to documents from both the Army and the Centers for Disease Control.
Nerve agents depress an enzyme in the body known as acetylcholinesterase, which is needed to control muscle movements in the body.
Symptoms of exposure to nerve agent -- which affects muscles, glands and the central nervous system -- are drooling, excessive sweating, vomiting, diarrhea, weakness, muscle twitching, convulsions and coma. Ultimately, victims suffocate after their respiratory muscles are paralyzed, Army officials say.
The use of the term "gas" is a misnomer in describing the agents, since both mustard and nerve agents are liquids that are dispersed in mist-like droplets.