Biological and Chemical Weapons

Browse this alphabetical list of the most commonly known biological and chemical agents. Click on each one to get more information. And see category definitions below.

Category Definitions

Biological Diseases/Agents

The CDC divides biological diseases and agents into categories according to their threat to national security. The top two categories are:

Category A agents

• Easily disseminated or transmitted from person to person
• Result in high mortality rates and have the potential for major public health impact
• Might cause public panic and social disruption
• Require special action for public health preparedness

Category B agents

• Moderately easy to disseminate or transmit from person to person
• Result in moderate public health impact and low death rates
• Require enhancements of CDC's diagnostic and disease surveillance abilities

Chemical Agents

Most chemical warfare agents are liquids that evaporate into vapors at varying rates. As effective weapons, they would need to be widely spread by a spray or explosion indoors. Outdoors, even small breezes disperse dangerous vapors.

Blister agents (vesicants)

• Inhaled or absorbed via contact with skin
• Affect eyes, airways, skin, gastrointestinal tract
• Cause large, often life-threatening blisters that resemble burns

Blood agents

• Generally inhaled, distributed through blood
• Inhibit the body's ability to use oxygen effectively
• Cause body to "suffocate" from lack of oxygen

Nerve agents

• Block a key enzyme, which allows a chemical buildup at key places in the nervous system, causing hyperactivity of muscles and organs
• Absorbed through skin or lungs by liquid or vapor exposure
• Affect eyes, nose, airways, gastrointestinal tract, muscles, central nervous system (brain and spinal cord)

Choking (pulmonary) agents

• Inhaled and absorbed through lungs
• Irritate nose, throat, and lungs
• Cause fluid to build in lungs, effectively "drowning" victim