Radioactivity is called spontaneous transformation of unstable varieties of a chemical element in an unstable kind of another element, which is accompanied by the emission of elementary particles or nuclear (ionizing radiation). Such transformations are called nuclei of radioactive transformations, and themselves nuclei, atoms and elements - radioactive.
Types of radiation
Radioactive elements can produce three types of radiation: alpha, beta and gamma radiation, which can lead to serious diseases, genetic disorders and loss of life. Ionizing radiation occurs and with it the excitation of atoms and molecules are the trigger processes leading to the process of radiation damage to biological structures - cells, tissues, organs, systems and whole organism
How will the radiation on the human body depends on the type, dose, timing and frequency of exposure.
Thus, severe exposure to lead to death, can occur both in a single bulk irradiation, and in constant contact with a weakly radioactive objects at home (e.g., treated with radiation jewels).
The sources of radiation are the various nuclear-technical installations (such as nuclear reactors, X-ray equipment) and radioactive substances. Their effect on the human body for a long time can not be shown.
The absorbed dose of radiation is determined by the impact of different kinds of radiation on a living organism, it is measured in rads. In order to compare the possible effects of radiation on different body, introduced the concept of an equivalent dose of radiation, which is a unit of one rem, which is the roentgen equivalent (X-rays - is a measure of radiation).
Under natural conditions, the human body is exposed to constant influence of cosmic rays and radiation of natural radioactive elements present in water, soil and tissues of the body. The levels of natural radiation corresponds to 100 mrem per year, but in some areas reach up to 1,000 millirem per year. We also introduce the concept of the maximum permissible dose (PDD) of radiation to the whole body - it is equal to 5 beram year.
Most household dosimeters measure the ionization over time, in mikrorentgenah per hour. According to the results of these measurements, we can judge the absorbed energy in biological tissue in normal room rate should not exceed 20 micro-roentgen per hour.
Biological effects of ionizing radiation
Under the influence of ionizing radiation in a human body are formed with a material of high chemical activity - free atoms or radicals, which destroy the cells of the organism. Ionizing radiation can also have a direct impact on biological molecules.
Damage to cells is largely dependent on how rapidly they pass metabolism: the higher the level of metabolic processes, and the higher susceptibility of radioactive radiation. Most Affected cells are cells of the blood, intestinal epithelium (there are a lot of immune cells), germ cells, the epithelium of the skin, bags, lens, connective tissue, cartilage, bone, muscle, nerve tissue. Defeat some kinds of proteins of cells may cause cancer and genetic mutations transmitted through several generations.
With a total dose of external irradiation of man 150 - 400 rad radiation sickness develops mild to moderate severity, at a dose of 400 - 600 rad - severe radiation sickness, radiation more than 600 rad is lethal.
Exposure can cause a variety of diseases: infection (decreased immunity), metabolic disorders
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, Cancer, infertility, cataracts
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and much more. Particularly acute radiation affects the growing organism, so it is very dangerous for children and adolescents. Exposure to small doses of radiation very difficult to detect, because their effect is manifested through the decades. Even small doses of radiation can cause permanent genetic changes that will be inherited, resulting in the birth of children with various genetic diseases (eg, Down syndrome), epilepsy
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, Violation of intellectual and physical development.
Radiation sickness develops when exposed to radiation in excess of the permissible dose. Depending on the nature of the impact (single massive or long-term repeated low doses) are acute and chronic radiation syndrome.
Acute radiation sickness begins with a period of overall response (about two days) - nausea, vomiting, headache, fever, weakness, lethargy, drowsiness. Gradually, over several weeks picking up changes in some of the most affected body irradiation (latent period) for some calming common manifestations. After that comes the period of marked clinical manifestations (last two - three weeks) with deep lesions of the blood, intestinal tissue and immunosuppression
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. If the dose was significant, that without medical help patients die. Then gradually begin the recovery period, which can last from one to three years.
Chronic radiation sickness - a disease with multiple clinical manifestations, it develops with prolonged exposure to ionizing radiation in a relatively small, but doses exceeding the SDA. Specific manifestations of this disease are lesions of different organs, duration and undulating course.
Radiation has a long (sometimes for life) the impact on the human body.