Introduction
This topic covers weapons of mass destruction (WMD), the four main classes of agents and devices able to cause mass casualties: nuclear, radiological, chemical and biological. It explains how each type acts, how it presents clinically, and what medical and organisational actions are needed when such an event occurs. Specific blistering and riot control agents, and decontamination procedures, are covered in topics 42, 43 and 46.
Definition and general principles
A weapon of mass destruction is a device or agent that can cause death or serious harm to large numbers of people, often with lasting damage to the environment and infrastructure. In medical terms, the defining feature is that the number of casualties overwhelms the usual capacity of health services, so the response must shift from individual care to mass casualty management. Most WMD events are not recognised for hours, so early recognition and alerting are as important as treatment.
Nuclear and radiological weapons
- Primary injuries: blast injuries (lung barotrauma, eardrum rupture, crush and penetrating trauma), flash burns and ionising radiation exposure.
- Acute radiation syndrome (ARS) appears after a significant whole-body dose, roughly from 0.7 to 1 Gy upwards. Main forms are haematopoietic (bone marrow), gastrointestinal, and at very high doses cerebrovascular/neurological.
- Phases of ARS: prodromal (nausea, vomiting, which appear early at high dose), latent period, manifest illness, then recovery or death. An early fall in lymphocyte count is a useful indicator of dose.
- Fallout and contamination: radioactive particles cause external contamination and internal contamination by inhalation or ingestion. Radioactive iodine is concentrated by the thyroid.
- Radiological dispersal: the main harm is conventional blast injury, contamination and psychological distress, not usually acute radiation illness.