Mustard: A liquid agent that gives off a hazardous vapor, causing burns and blisters to exposed skin. When inhaled, mustard damages the respiratory tract; when ingested, it causes vomiting and diarrhea. It attacks and damages the eyes, mucous membranes, lungs, skin, and blood-forming organs. Iraq used mustard gas numerous times between 1983 and 1988. The most serious of the long-term effects arise because mustard gas is carcinogenic and mutagenic; there is no antidote.

Tabun: A colorless to brownish liquid that is a non-persistent nerve agent similar to a pesticide. Depending on exposure, reactions include obstructed vision, difficulty in breathing, muscular twitching, sweating, vomiting, diarrhea, coma, convulsions, and absence of breathing, leading to death. It has been weaponized and used by the current Iraqi regime.

Cyanide: A highly poisonous chemical agent that, whether inhaled, ingested, or in contact with the skin, affects the body's use of oxygen. Reactions include difficulty in breathing, convulsions, coma, and possibly death.

Sarin: A colorless liquid or vapor that, depending on exposure, can cause obstructed vision, difficulty in breathing, muscular twitching, sweating, vomiting, diarrhea, coma, convulsions, and absence of breathing leading to death. High exposure may be lethal, as witnessed by the 1995 Aum Shinrikyo sarin gas attack in the Tokyo subway system. Iraq has admitted to producing 100 to 150 metric tons of sarin, weaponized in sarin-filled artillery shells, 122-millimeter rockets, and aerial bombs.

VX: An oily liquid that is persistent, clear, and odorless and is considered among the most toxic substances ever made. Airborne VX can kill in minutes, but the main uptake is through the skin. Reactions include obstructed vision, difficulty in breathing, muscular twitching, sweating, vomiting, diarrhea, coma, convulsions, and absence of breathing leading to death. The Iraq regime aggressively tried to hide the extent of its VX stockpile from U.N. inspectors. It produced about four tons of VX from 1988 to 1990. In 1998, U.N. weapons inspectors discovered evidence of VX on Iraqi missile warheads.

Source: U.S. Department of State, Bureau of Nonproliferation.