Radiation sickness

Overview  

Radiation sickness, also known as acute radiation syndrome (ARS) or radiation poisoning, is a life–threatening condition that occurs when the entire body or a large portion of it is exposed to significant levels of ionizing radiation. This exposure can result in death within hours or several months later. It’s important to note that radiation sickness is not caused by common imaging tests that utilize low–dose radiation, such as X–rays or computed tomography (CT) scans.   

The severity of radiation sickness depends on the dose of radiation and the length of time over which a person is exposed. When a high, single dose of radiation is received over a short period, typically minutes to hours, the damage to the body is more severe than when smaller doses are given over a longer period, such as weeks or months, targeting a specific area for cancer therapy. 

The objectives of treating radiation sickness involve preventing additional radioactive exposure, addressing life–threatening injuries resulting from burns or trauma, alleviating symptoms, and effectively managing pain. 

Symptoms  

The severity of signs and symptoms of radiation sickness is determined by the amount of radiation absorbed, which in turn depends on the strength of the radiated energy, duration of exposure, and distance from the radiation source. The type of exposure, whether it affects the entire body or only specific areas, also influences the symptoms experienced. Additionally, the sensitivity of the affected tissue plays a role in determining the severity of radiation sickness. Symptoms can manifest immediately after exposure or gradually emerge over a period of days, weeks, or months. 

Following acute exposure to a high dose of radiation, several distinct syndromes can manifest, including the following: 

• Cerebrovascular syndrome: This syndrome impacts the circulation of blood to the brain, leading to potential neurological complications. 
• Gastrointestinal (GI) syndrome: This syndrome affects the functionality of the digestive system, specifically hindering the passage of food and waste materials. 
• Hematopoietic syndrome: This syndrome disrupts the process of generating all types of blood cells, which can have profound effects on the body’s ability to maintain a healthy blood supply. 

Each of these syndromes consists of three distinct phases: 

• Prodromal phase: This phase occurs within minutes to two days after exposure. During this phase, individuals may experience symptoms such as drowsiness, weakness, and gastrointestinal issues like nausea, vomiting, or diarrhea. 
• Latent asymptomatic phase: This phase occurs within hours to 21 days after exposure. It is characterized by the absence of any noticeable symptoms. 
• Overt systemic illness phase: This phase occurs within hours to less than 60 days after exposure. The specific symptoms experienced during this phase depend on which main organ system is affected by the respective syndromes.

Symptoms of cerebrovascular syndrome 

Cerebrovascular syndrome is a condition that is typically caused by extremely high levels of radiation exposure, specifically more than 30 Gy. It is considered to be fatal. The initial phase of symptoms occurs within minutes to an hour after exposure, followed by a brief or non–existent latent phase. During the final phase, people experience symptoms such as tremors, seizures, ataxia (loss of coordination), and cerebral edema (fluid buildup around the brain leading to increased pressure). Sadly, death usually occurs within a span of a few hours to one or two days. 

Symptoms of gastrointestinal (GI) syndrome 

Gastrointestinal (GI) syndrome occurs when a person is exposed to high doses of whole–body radiation, typically between 6 to 30 Gy. The symptoms of GI syndrome can be divided into three phases. In the prodromal phase, which starts within an hour of exposure and lasts for about two days, you may experience initial symptoms such as severe nausea, vomiting, and diarrhea, which eventually go away. The latent phase follows, lasting around four to five days. The final phase is the overt systemic illness phase, where symptoms become more severe and include intense nausea, vomiting, and diarrhea, leading to dehydration and electrolyte imbalances. This phase can also result in a lack of plasma in the blood, which is mostly water, as well as cardiovascular collapse, intestine damage leading to sepsis, and ultimately, death. Survivors of GI syndrome also commonly experience the hematopoietic syndrome, which affects the production of blood cells in the body. 

Symptoms of hematopoietic syndrome 

Hematopoietic syndrome occurs when the entire body is exposed to radiation doses between 1 and 6 Gy, leading to a condition where all three essential components of blood (red cells, white cells, and platelets) are deficient. The syndrome follows a three–phase pattern. The initial phase, known as the prodromal phase, is mild and typically begins within one to six hours after exposure, lasting for 24 to 48 hours. This is followed by a latent asymptomatic phase that spans approximately four weeks. The overt phase, characterized by noticeable symptoms, includes a heightened risk of various infections due to low levels of white blood cells and decreased antibody production. Additionally, individuals may experience small red spots on the skin (petechiae) and bleeding from mucous membranes, which can persist for months. Anemia, a condition where the body lacks a sufficient number of red blood cells, develops slowly over time. It’s important to note that survivors of hematopoietic syndrome face an increased likelihood of developing radiation–induced cancers, such as leukemia and thyroid cancer. 

Causes  

Radiation is the energy released by atoms in the form of waves or tiny particles. Radiation sickness can occur when a person is exposed to a significant amount of radiation, such as in the event of an industrial accident. Various sources can lead to high–dose radiation, including accidents or attacks on nuclear industrial facilities, the detonation of radioactive or dirty bombs, or the use of standard nuclear weapons. When high–energy radiation interacts with the body, it can damage or destroy specific cells, particularly those in the lining of the intestinal tract (including the stomach) and the bone marrow cells responsible for producing blood cells.