Biological Effects of Radiation Exposure

Sunlight, natural minerals and natural gases all emit low doses of radiation every day. The human body is designed to be a self-repairing system that can stand up against these natural elements. When radiation amounts exceed a certain limit, the body can begin to break down if it's unable to properly repair damaged tissues.

Types of Radiation

• Radiation waves come in two categories: ionized, and non-ionized. Non-ionized waves are the types found in natural sources of radiation. The atoms contained inside these waves are relatively stable and cause little to no damage to living tissue. Ionized radiation waves are made up of unstable atoms, meaning their atomic structures have been altered. Unstable atoms have missing (or extra) electrons, protons or neutrons. When these atoms come into contact with living cells, they try to replace missing particles or get rid of extra particles. When this happens, they disrupt the atomic structures contained inside these living cells.

Cell Structures

• Healthy cell structures follow certain biochemical processes that work to maintain the life and health of the cell. When these structures are altered by radiation waves, this can cause a breakdown in cell function. The most damaging effects can occur when a cell's DNA molecules are altered or made unstable. The DNA molecule is responsible for repairing damaged cell structures and for cell division reproduction. If these molecules undergo permanent damage, any attempts to repair or reproduce the cell can weaken, mutate or kill it.

Acute Doses

• Acute radiation doses are known to cause cancerous cell mutations. Nuclear reactor accidents like the one that occurred in the Ukraine in 1986 (Chernobyl) caused cancerous formations to appear in those who were exposed. The symptoms that result from acute exposures can lead to what is called acute radiation syndrome. The amount of damage that results depends on whether a person's entire body has undergone exposure or just a portion of the body. When the entire body is exposed, there is a 50 percent probability that the person will die shortly after exposure. The amount of exposure and the health of the individual will determine how severe a person's symptoms will be when only a portion of the body is exposed.

Chronic Doses

• People undergo low-dose exposures from natural sources of radiation every day, but these are not considered powerful enough to cause cell mutations. Natural sources include sunlight, radon gas and uranium. These sources emit radiation in chronic doses, meaning they take place over prolonged periods of time. No apparent damage is caused because the doses are low enough to allow the body to repair itself and function normally. And while chronic doses are considered low-risk exposures, it's not known for sure whether any delayed, long-term effects are possible.

Symptoms

• The symptoms of radiation exposure vary according to the dose amount. Doses of 100 rad or more affect the organs that contribute to blood production in the body---bone marrow, the spleen and lymphatic tissue, among them. Fatigue, infection, internal bleeding and reduced white blood cell counts are symptoms of such exposure. Doses of 1,000 rads or more also affect organs in the gastrointestinal system, such as the stomach and intestines. Dehydration, bleeding ulcers, nausea, vomiting and a dramatic reduction in white blood cell count are symptoms of this higher-dose exposure. The more severe (and lethal) radiation exposures result in damage to the central nervous system. When nerve cell damage is present, multiple body processes can potentially break down at once.