Chemical Warfare

Chemical warfare involves the aggressive use of bulk chemicals that cause death or grave injury. These chemicals are different from the lethal chemical compounds that are part of infectious bacteria or viruses. The latter constitute biological warfare.

Forensic examinations are a part of chemical warfare, especially when the nature of the attack is unclear. Examination of the scene of the incident and of the victims provide clues that are used to determine the nature of the attack.

A number of compounds cause choking or irritation of lung tissue. Examples include chlorine, phosgene (carbonyl chloride), diphosgene, chloropicrin, ethyldichloroarsine, and perflurorisobutylene.

Chlorine gas is suffocating and quickly burns tissues in the nose, mouth, and lungs. The burned tissue can die and slough off, causing lasting damage. Chlorine gas dissipates in the air very quickly. If exposure is not too long, than damage can be minor. In contrast, the compound called disphosgene is a liquid at room temperature, and so persists much longer.

Blister agents cause the formation of large and painful blisters on the skin. Eye and lung tissue can also be damaged. A well-known example of a blistering agent dating from World War I is mustard gas. The damage to cells of the skin cause blistering up to 24 hours after exposure to mustard gas. These blisters take a long time to heal and can send the body into a lethal shock reaction.

Other examples of blistering agents include nitrogen mustard, lewisite, and phenyldichloroarsine. The latter compound is a liquid, which can be sprayed onto an enemy or released from a balloon, helicopter, or airplane.

Blood agents interfere with the body's ability to transport oxygen in the bloodstream. This is done by either blocking the use of oxygen by cells in the body or by blocking the ability of the blood to take up the oxygen. Examples include hydrogen cyanide (also called prussic acid), cyanogen chloride, arsine, carbon monoxide, and hydrogen sulfide.

Hydrogen cyanide is initially a liquid at room temperature, but it quickly evaporates. This compound is noteworthy in recent world history, as it was used by Iraq in 1988 on an attack on the Kurdish town of Halabja during the Iran-Iraq war. Because of its past use by Iraq, hydrogen cyanide was one of the major concerns of United Nations inspectors who inspected various facilities in Iraq during the winter of 2003.

Compounds such as arsine and carbon monoxide destroy the ability of the hemoglobin component of the blood to bind oxygen. Arsine does this by destroying the red blood cells. Carbon monoxide binds to hemoglobin, blocking the binding of oxygen.

Nerve agents interfere with the body's transmission of nerve impulses. This is done by disrupting the activity of a chemical called acetyl cholinesterase, which functions to bridge the gap between adjacent nerve cells, permitting an electrical nerve signal to pass from one nerve cell to the next.

Nerve agents were first developed in 1936, following the development of organophosphate types of pesticides. The first nerve agent that was made is called tabun. It is a member of what is known as the G series of nerve agents. Other G series members are sarin and soman. Sarin is particularly lethal; a small amount absorbed through the skin can kill someone within two minutes. When inhaled, death occurs within 15 minutes. Sarin is infamous as the gas released into the Tokyo subway system by the fringe group Aum Shinrikyo in 1995.

Another series of nerve agents are called the V series. Members of this series—which are commonly abbreviated according to their chemical composition—are more potent than the agents of the G series. As well, they persist longer in the environment. They can, for example, be applied to surfaces like roads as a slime.

Examples of V series agents include VX, VE, VG, and VM. VX is extremely potent; a drop of the liquid absorbed through the skin is lethal within a few hours if treatment is not provided.

Herbicides are chemicals that kill vegetation. Such chemicals are often used in everyday life to keep lawns free of weeds (although more environmentally-friendly alternatives are becoming popular). When used in war, herbicides are weapons of mass destruction to foliage. Destruction of plants and the resulting loss of leaf cover remove much of the concealment for an enemy in a forested area. These philosophies lead to the massive use of Agent Orange by the United States in the Vietnam War in the 1970s. Since that war, the damaging effects of herbicides like Agent Orange and paraquat on the human nervous and immune systems have become evident.

Incendiaries are chemicals that cause fires. In warfare, they are also used to remove vegetation. An infamous incendiary is napalm. Napalm is a mixture of naphthenic acid, coconut fatty acids, and palm oil. In addition to its highly flammable property, napalm absorbs into exposed skin, where it can cause severe burns if ignited.