Radiation Damage in the Human Body Acute Radiation Syndrome and Multiple Organ Failure

A radiation accident is an unintentional exposure to ionizing radiation or radioactive contamination, resulting in possible deleterious effects on the exposed individuals [1,2]. Since the discovery of X-rays in 1895 and radioactivity in 1896, there have been accidents caused by radiation exposure, although radiological accidents requiring medical care rarely occurred [3]. As early as 1897, Becquerel observed an erythema on his abdomen, ascribing it to radioactive materials [2]. Today, on the other hand, devices or locations from which an individual could be exposed to radioactive materials are not rare [4]. These potential sources of exposure accidents include industrial radiography causes, therapeutic devices, sterilizers, transportation accidents, and nuclear power plants; devices used for industrial radiography and accelerators are frequent sources of accidents for external exposure, since radiation such as Xor -rays and neutrons is characteristically able to penetrate human bodies or other materials. Among them, Ir, Co, and Cs sources which emit -rays are frequently employed for non-destructive testing or sterilizers and there are many reports of ARS caused by these sources. Accidents of external exposure are different from those of contamination with radionuclides; exposed patients do not carry radioactive materials after these radionuclides have been removed [5]. However, the radiation in criticality accidents is a complex combination of neutrons and -rays of different energies, and neutrons are known to induce radionuclides in human body or other materials. Thus, exposure to neurons may not only cause acute radiation syndrome (ARS) but also be the subject of a great deal of work and discussion for dose assessment. In 1999, a criticality accident occurred at Tokai-mura, Japan, and two victims with ARS died of multiple organ failure (MOF) [6,7]. This review outlines Whole-body exposure to high-dose radiation causes injury involving multiple organs that depends on their sensitivity to radiation. This acute radiation syndrome (ARS) is caused by a brief exposure of a major part of the body to radiation at a relatively high dose rate. ARS is characterized by an initial prodromal stage, a latent symptom-free period, a critical or manifestation phase that usually takes one of four forms (three forms): hematologic, gastrointestinal, or cardiovascular and neurological (neurovascular), depending upon the exposure dose, and a recovery phase or death. One of the most important factors in treating victims exposed to radiation is the estimation of the exposure dose. When high-dose exposure is considered, initial dose estimation must be performed in order to make strategy decisions for treatment as soon as possible. Dose estimation can be based on onset and severity of prodromal symptoms, decline in absolute lymphocyte count post exposure, and chromosomal analysis of peripheral blood lymphocytes. Moreover, dose assessment on the basis of calculation from reconstruction of the radiation event may be required. Experience of a criticality accident occurring in 1999 at Tokai-mura, Japan, showed that ARS led to multiple organ failure (MOF). This article will review ARS and discuss the possible mechanisms of MOF developing from ARS.