CHEMICAL WARFARE AGENTS: TOXICITY AT LOW LEVELS

Abstract

We previously published a book on chemical warfare agents (Academic Press) in 1992. Since then, we have acquired considerable additional knowledge in this area. It is time to update our previous work, with particular emphasis on the low-level toxicology of chemical warfare (CW) agents. Chemical warfare agents are chemicals that have immediate, direct toxic effects on humans, animals, and plants and possible long-term, adverse effects on human health. Chlorine, phosgene, and mustard were CW agents used in World War I and in lesser conflicts thereafter. There was putative extensive use of CW agents in the Sino-Japanese War. Although CW agents were not used during World War II, much research was done in the development of toxicologic information and protective materials. However, mustard gas, defoliant, and nerve gases were used in localized wars in the 1960s, 1970s, and 1980s. Chemical warfare agents are primarily categorized as lethal and incapacitating agents. These agents also possess the attractive quality of being easy and inexpensive to synthesize on a large scale. A reasonable chemical-industrial set-up can be diverted to produce CW agents. Chemical warfare agents are particularly horrifying because their toxic effects are indiscriminate and thus affect not only military personnel but also the civilian population as a whole. Chemical warfare agents are becoming a major force in some of the militant developing countries. This is due to the fact that these agents can provide a substantial psychological edge to the military establishments of otherwise weak nations. Although acute toxicity and high-level dose toxicity were discussed in our previous volume, various review committees have suggested that there were data gaps in our information about the low-level toxicity of CW agents. The Gulf War of 1991 has raised our awareness of these gaps. Epidemiologic studies have indicated that more than 120,000 Gulf War veterans are suffering from many unexplained illnesses and are seeking medical care. Among the putative explanations for these illnesses include exposure to nerve agents or pretreatment drugs. Many United States and British troops were given pyridostigmine bromide as a pretreatment drug during 2 weeks of air and ground war to protect against the possible exposure to nerve gas. One of the notable nerve gases suspected to be present during the Gulf War was sarin. During war-time conditions, military personnel were under physical stress; some have argued for evidence of exposure to a low level of sarin. The toxicity of CW agents at low levels is a very special feature of this book. Certain factors such as stress, surroundings, and other chemical agents can interact with the toxicity of CW agents, and some of these interactions are described in this book.