4.2 Classification of Chemical Warfare Agents

Chemical warfare agents can be classified as lethal or disabling. Lethal agents are intended to kill or injure the enemy so severely as to necessitate evacuation. Disabling chemicals, on the other hand, incapacitate and disable the enemy, and those affected can often recover without any medical aid.

In addition to the known chemical warfare agents, beneficial industrial chemicals accidentally released in large doses, can cause great harm.  One example is the disasterous incident leading to release of tonnes of methyl isocyanate from a pesticide plant in Bhopal, India in 1984. This caused thousands of deaths and an even greater number of individuals with long term health problems. Therefore, when we think of chemicals as lethal agents, it is important to consider not just standard chemical warfare agents, but other lethal substances produced as intermediates or final products on large industrial scales.


Lethal chemicals
Lethal chemicals that have been developed into warfare agents may be divided into two further categories: tissue irritants and systemic poisons. Tissue irritants will damage skin and surfaces in the respiratory tract. Systemic poisons are substances which interfere with vital functions in the body. The tissue irritants include choking gases such as chlorine and phosgene, and blister gases such as mustard gas. Systemic poisons include chemicals such as hydrogen cyanide and nerve gases.

Chlorine, which is an asphyxiant, was the first lethal chemical used in World War One. In April 1915, large surprise attacks were launched by the German army, causing thousands of casualties among Franco-Algerian troops who had no protection against air-borne chemicals. Evidence suggests that the British and Canadian high commands were able to respond more rapidly to the initial attacks. Respirators used to protect the troops were crude at first but became increasingly more sophisticated. At the same time there was a hunt to find agents more aggressive than chlorine, leading to a wide spread in the use of phosgene, another lung irritant.

The most significant development during the First World War was the use of what are known as vesicant agents.  These cause blisters on skin and they will severely damage any tissue with which they are in contact. Mustard gas is in this category, and it will poison both through inhalation and skin penetration.
Chemical Warfare Agents , page 2 of 7