Part Three: Biologic Effects of Radiation, Acute Radiation Sickness
As discussed in part one and part two, the biological effects of radiation are dependent upon the type of exposure a person actually has. Simply stated, the duration of the exposure as well as the intensity of the material play a role. We also have to include the role of personal protection such as Time, Distance, Shielding and its effectiveness.
In part three of our series, we'll discuss the details of Acute Radiation Sickness (ARS). Acute Radiation Sickness (sometimes called Acute Radiation Syndrome) or ARS, occurs when an individual is exposed to a large amount of radiation in a short period time… and acute exposure, or a total doses greater than 100 REM (100 RAD for gamma radiation). Acute radiation sickness has a variety of clinical manifestations which can be obvious with some symptoms yet, less than obvious with others. Generally speaking, the clinical manifestations of acute radiation sickness include the following:
- changes in blood cell count, specifically lymphocytes decrease
- vascular permeability changes
- gastrointestinal irritation; nausea, vomiting, and diarrhea
- hair loss, in uneven patterns
- skin rash, skin burns, in general skin irritation
- vague symptoms such as flu-like symptoms
Acute radiation sickness has four phases and may manifest with four separate syndromes.
The four syndromes of acute radiation sickness are:
- Hematopoietic Syndrome
- gastrointestinal syndrome
- cardiovascular syndrome
- and central nervous system syndrome
- prodromal phase
- latent phase
- manifest phase (sometimes called the period of illness)
- and recovery or death
Gastrointestinal syndrome is a condition in which the epithelial lining of the G.I. system is gradually destroyed. Epithelial cells decline in results in nausea, vomiting, diarrhea, and sepsis. Sepsis is a result of the loss of protective barrier that separates normal bacteria from the bloodstream. Gastrointestinal syndrome may impact the lower G.I. or upper G.I. tract, or both. In the lower G.I. system bloody diarrhea (frank in nature) is most common.
Large doses of whole body radiation can cause Central Nervous System and Cardiovascular syndrome. Both are caused by a destruction of blood vessels and an increase in capillary permeability. Symptoms usually appear fairly rapidly and take the form of cerebral edema, pulmonary edema, cardiogenic shock, and death. Victims exposed to large amounts of whole body radiation may often die within 72 to 80 hours, often before the symptoms of G.I. syndrome or hematopoietic develop.
Acute radiation sickness may present within four distinct stages. As mentioned earlier, prodromal, latent, manifest, recovery/death. In the prodromal phase (approximately 48 hours after exposure) victims may present with:
- nausea and vomiting, diarrhea
- fatigue and headache
- fluid shifts due to increased permeability and electrolyte losses
In part four of our series we will discuss contamination and exposure issues as well as decontamination and monitoring. Will also review the severity levels and associated symptoms/indicators for each level. Later, in our final installment (part five), will discuss issues of planning and preparedness for radiologic emergencies.
Links and References
You'll also find these links and references useful. I've used them, in part and along with references, to put this series together. Again, the complete bibliography will be posted along with the final installment of the series.
Radiation Injury Treatment Network
Radiation Emergency Medical Treatment (from the U.S. Department of Health and Human Services)
Get the Mobile REMM app, FREE and worth the time!