Chemical Weapons (CWs) constitute a major but often under appreciated ethical and political challenge for science and technology. The following entry examines this challenge by describing the character of CWs, the history of their use, and efforts of ethical and political control.

Chemical Weapons: What Are They?

Definitions of chemical warfare and chemical weapon have changed over time. History is replete with examples of chemicals being employed either to kill individuals, for example, murder or assassination, or larger numbers during warfare, such as the use of Greek Fire (a mixture of petroleum, pitch, sulfur, and resins) during at least two sieges of Constantinople (673 and 718 C.E.) However the twenty-first-century understanding of CWs is based on a better scientific appreciation of the underlying chemical and biological processes involved, which began to take shape during the nineteenth century.

Knowledge of how the toxic properties of chemicals could be...