Chemical and Biological Warfare

I

Introduction

Chemical and Biological Warfare, use of harmful or deadly chemical or biological agents as weapons of war (see Warfare). These agents can kill many people and are considered weapons of mass destruction. Chemical weapons are made up of poisonous chemical compounds, whereas biological weapons use living microorganisms. Weapons that contain the poisonous chemical products of living organisms are known as toxin weapons and are sometimes classified separately. Chemical and biological weapons can cause injury in several ways. Most cause injury or death when inhaled, and some cause injury through contact with skin or through ingestion of contaminated food.

A chemical or biological attack usually involves dispersing agents into the air. This can be done in various ways, such as firing artillery shells that burst in midair, or using airplanes to spray the agents over an area. If released outdoors, these types of weapons can be affected by weather conditions. Rain would reduce the effectiveness of the agents, and wind might spread them in unexpected directions. In the 20th century, chemicals were used extensively as battlefield weapons only in World War I (1914-1918) and the Iran-Iraq War (1980-1988). The release of the nerve agent sarin in a Tokyo subway in 1995 was a rare terrorist chemical attack. The mailing of anthrax bacteria to government and news media offices in the United States in 2001 was a rare terrorist biological attack.

The 1972 Biological Weapons Convention and the 1993 Chemical Weapons Convention are the most recent international agreements prohibiting these types of weapons. Both have been signed by many countries. Nevertheless, analysts contend that following the Iran-Iraq War, more countries began to secretly develop chemical and biological weapons, and the threat of their use has become greater. Iraq in particular was accused of stockpiling such weapons. Iraqi resistance to United Nations (UN) weapons inspections in the late 1990s led to a new round of inspections in late 2002 and early 2003. The administration of United States president George W. Bush, however, decided that the Iraqi regime of President Saddam Hussein had failed to cooperate with weapons inspectors and was attempting to conceal its chemical and biological weapons. In March 2003 the United States and Britain invaded Iraq and overthrew the Hussein government (see U.S.-Iraq War). U.S. inspectors found no chemical and biological weapons after thorough searches of the country.

II

Chemical Warfare

Chemical warfare involves the use of chemical compounds to kill or seriously injure an enemy. Several countries began eliminating their chemical weapons stockpiles in the 1990s, but the threat of their use still exists.

---

---

A

Chemical Agents

Chemical warfare agents can be grouped into two general types: those that affect the body surfaces they contact, and those that damage the general nervous system. Surface agents include phosgene gas, chlorine gas, hydrogen cyanide, and mustard gas. The principal action of phosgene, chlorine, and hydrogen cyanide occurs through inhalation. Phosgene is a choking agent that causes the lungs to fill with water, while chlorine destroys the cells that line the respiratory tract. Hydrogen cyanide blocks oxygen from reaching the blood. Mustard gas is actually composed of tiny droplets of liquid that are dispersed in the air, where they are inhaled like a gas. Mustard is a blistering agent that damages any surface it contacts, including the skin, eyes, and lungs. It may cause death by respiratory failure. See also Tear Gas.

Nerve agents act by blocking the transmission of nerve messages throughout the body. These agents include sarin, soman, tabun, and VX. All act by disrupting the normal action of a neurotransmitter called acetylcholine. Whether inhaled or absorbed through the skin, a single drop of nerve agent can shut down the body’s nervous system. The most powerful of this group is VX, but all can cause death within minutes after exposure. See also Nerve Gas.

Herbicides, such as Agent Orange, are chemicals that kill vegetation. Agent Orange was used during the Vietnam War (1959-1975) as a defoliant, destroying jungle leaves to expose enemy troops. Some people regard herbicides as chemical weapons if used for hostile purposes, but there is no universal agreement about this, since herbicides are not directly intended to harm humans or animals. However, veterans of the Vietnam War suffered several health problems blamed on exposure to Agent Orange and other toxins, and the Vietnamese government charged that civilians were harmed by exposure to Agent Orange.

B

Early Development

Large-scale use of chemical weapons first occurred in 1915 during World War I (1914-1918), when German troops released chlorine gas from cylinders as the wind blew toward French lines a few hundred yards away. The yellow-green cloud enveloped the French soldiers, who choked and panicked. As the war continued, phosgene and other chemical weapons were used, culminating with Germany’s introduction of mustard gas in 1917. By the end of the war in 1918, all the major powers had used chemical weapons.

The suffering caused by the gas attacks led to the 1925 Geneva Protocol, which banned the use of chemical or bacteriological agents in war. Although most major countries became parties to the agreement, the United States declined to until 1975. Nevertheless, the Protocol encouraged an international norm that helped deter the use of these weapons.

	More from Encarta
	•  Important Notice: MSN Encarta to be discontinued. Learn more. •  Presidential Myths Quiz •  Coffee break: Recharge your brain