Acute Radiation Syndrome - Cause

Cause

Radiation sickness is caused by exposure to a large dose of ionizing radiation (>~0.1 Gy) over a short period of time. (>~0.1 Gy/h) This might be the result of a nuclear explosion, a criticality accident, a radiotherapy accident as in Therac-25, a solar flare during interplanetary travel, escape of radioactive waste as in the 1987 Goiânia accident, human error in a nuclear reactor, or other possibilities. Acute radiation sickness due to ingestion of radioactive material is possible, but rare; examples include the 1987 contamination of Leide das Neves Ferreira and the 2006 poisoning of Alexander Litvinenko.

Alpha and beta radiation have low penetrating power and are unlikely to affect vital internal organs from outside the body. Any type of ionizing radiation can cause burns, but alpha and beta radiation can only do so if radioactive contamination or nuclear fallout is deposited on the individual's skin or clothing. Gamma and neutron radiation can travel much further distances and penetrate the body easily, so whole-body irradiation generally causes ARS before skin effects are evident. Local gamma irradiation can cause skin effects without any sickness. In the early twentieth century, radiographers would commonly calibrate their machines by irradiating their own hand and measuring the time to onset of erythema.