Bacteria - microscopic organisms that exist in almost every environment known to man. The diseases they cause can usually be treated with antibiotics. An example would be Anthrax.

Viruses - microscopic organisms that produce a wide variety of diseases, which are usually only treated by antiviral medications or prevented by previous vaccination. Antibiotics have no effect on viruses and, therefore, do not cure viral diseases. An example would be the pox virus.

Toxins - chemicals produced from living plants, animals, or microorganisms which can cause various symptoms sometimes leading to death. Toxins may be cleared from the body by medical treatment. An example would be ricin.

Blister agents (vesicants) - produce blisters all over the body.

Blood agents - prevent tissue cells from using oxygen so that vital organs quickly shut down.

Choking agents - attack the respiratory system.

Incapacitating agents - cause physical or mental incapacitation, such as dizziness, confusion, stupor or coma.

Nerve agents - disrupt proper nerve function. Nerve agents, a type of poison gas, are the most lethal form of chemical warfare. Exposure to these odorless, colorless substances can occur through inhalation, skin contact or ingestion. They cause paralysis or uncontrollable muscle movement, seizures and death by suffocation (asphyxiation). Although many nerve agents are called gases, they are actually liquids that can be released as an aerosol or mixed with other liquids.