The book contains the contributions at the NATO Advanced Study Institute on Chemicals as Intentional and Accidental Global Environmental Threats, which took place in Borovetz, Bulgaria, November 16-27, 2005. A diverse group of scientists, representing the fields of ecology, chemistry, medicine, epidemiology, public health, toxicology, risk assessment, environmental protection and management, modelling, environmental remediation technologies came together to discuss the chemicals threats for the global environment. The intentional or accidental release of chemicals into environment poses a global threat to public health and security. There is a forecast that terrorists could begin to use more advanced technologies including chemicals to threaten or attack civil and political institutions. Terrorism is expected to increase the threat of chemicals in environment through direct release of chemical agents or sabotage of existing chemical facilities. The intentional release of chemicals into environment can cause widespread panic, injury and mortality due to the potentials of exposure of large population. In addition, the management of accidental chemical releases and historical chemical contamination represents a significant economic burden to society.