A blister agent, also known as a vesicant, is a type of chemical weapon or warfare agent that causes severe irritation and blisters on exposed skin and other tissues. Blister agents are classified as chemical weapons due to their potential to cause significant harm and long-lasting effects on humans and the environment. These agents typically consist of sulfur mustard, such as the well-known chemical compound called "mustard gas," or certain organic compounds, such as nitrogen mustards and lewisite.
Blister agents are often delivered as aerosols, liquids, or solid particles, allowing them to be dispersed over a wide area or delivered through explosive devices. Upon exposure, blister agents penetrate the skin, eyes, and respiratory system, causing severe damage and irritation. These agents react with proteins in tissues, leading to the formation of painful blisters, skin necrosis, and damage to the respiratory and digestive systems.
The effects of blister agents can vary depending on the concentration, duration of exposure, and individual susceptibility. Symptoms typically manifest within hours or days and may include skin redness, itching, and swelling, followed by the appearance of large fluid-filled blisters. Severe exposure can result in respiratory distress, eye injuries, secondary infections, and even death.
Due to their devastating consequences and indiscriminate nature, blister agents are prohibited by international treaties, such as the Chemical Weapons Convention signed by numerous countries worldwide. The manufacture, stockpiling, and use of blister agents are strictly controlled and considered illegal under international law.
