Radiation may affect living things by damaging the cells that make up the living organism. Radiation effects on a cell are random. That is, the same type and amount of radiation could strike the same cell many times and have a different effect, including no effect, each time. However, in general, the more radiation that strikes a cell, the greater the chances of causing an effect. If a significant number of cells are affected, the organism may be damaged or even die. All living things are constantly exposed to background radiation. Most cells have the ability to repair some damage done by this level of radiation. As a result, the effects of doses similar to background levels are impossible to measure. Effects of such low levels of radiation are often estimated for very large groups of people rather than for individuals.
Effects of Radiation – Understanding Radiation Risks:
- Radiation can damage living tissue by damaging DNA and changing cell structure. The damage amount depends on its energy, the total amount of radiation absorbed and the type of radiation. Some cells are more sensitive to radiation. The effect from small or even moderate exposure may not be noticeable because damage is at the cellular level . But most of these cellular damages can be repaired. Some cells, however, may not recover and could become cancerous. Cells can also get killed because of radiation.
- The major risk from exposure to radiation is cancer. At the end of World War II, Hiroshima and Nagasaki, Japan were attacked with atomic bombs and more than 1,00,000 survived during that attack and they are the real examples of the consequence of atomic bomb. Other studies of radiation industry workers and studies of people receiving large doses of medical radiation also have been an important source of knowledge. Scientists learned many things from these studies.
The most important are:
- The higher the radiation dose, the greater the chance of developing cancer.
- The chance of developing cancer, not the seriousness of cancer, increases as
the radiation dose increases.
- Cancers caused by radiation do not appear until years after the radiation exposure.
- Some people are more likely to develop cancer from radiation exposure than others.
Health Effects of Radiation:
These are divided into two categories: threshold effects and non-threshold effects. Threshold effects appear after a certain level of radiation exposure is reached and enough cells have been damaged to make the effect apparent. Non-threshold effects can occur at lower levels of radiation exposure.
Threshold Effects of Radiation:
It occurs when levels of radiation exposure are tens, hundreds, or thousands of times higher than the background, and usually when the exposure is over a very short time, such as a few minutes. They do not occur when doses of radiation are smaller than the threshold value.
Non-threshold Effects of Radiation:
It can occur at any level of radiation exposure. However, the risk of harmful health effects generally increases the amount of radiation absorbed. The most studied non-threshold effect is cancer. Studies are somewhat complicated by the facts that most cancers are not caused by radiation, exposure to a particular dose may cause cancer in one person but not in another, and cancer often doesn’t appear until many years after the exposure
Effects of Radiation – How it affects the Body:
- The way radiation causes damage to any material is by ionizing the atoms in that material changing the atomic structure of the material. When atoms are ionized, the chemical properties of those atoms are altered. This is how radiation can damage a cell; it ionizes the atoms and changes the resulting chemical behavior of the atoms and/or molecules in the cell. If a person receives a sufficiently high dose of radiation and many cells are damaged, there may be noticeable observable health effects.
- The amount of the body exposed to radiation is a factor in determining the biological effect. While many cancer patients receive large doses of radiation to destroy tumors, this radiation is concentrated on a specific portion of the body. Exposing the whole body poses more risk because the radiation-induced damage affects a larger area.
- Some parts of the body are more sensitive to radiation-induced damage than others. Radiation damage to the cells of the body depends on how sensitive the cells are to ionizing radiation. Generally speaking, the most sensitive cells are those that divide rapidly or those that are in the process of dividing. These cells are most vulnerable because it is difficult or impossible for them to repair any damage that may occur during cell division.
Examples of rapidly dividing cells include:
- Blood-forming cells
- Lining of cells in the intestinal tract
- Cells in an embryo or fetus
Cells are not easily damaged by ionizing radiations if they divide more slowly and if they are more specialized. Examples include:
- Nerve cells
- Brain cells
- Muscle cells
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