What is the reason for the negative effects of radiation on living beings?
The image of a black fan on a poisonous yellow background is an international sign of radiation hazard. This sign indicates objects and devices that carry the threat of radiation exposure: nuclear power plants, physical laboratories, radiation waste disposal sites, specialized medical equipment, etc.
Its authors were American nuclear physicists who worked on the creation of the atomic and hydrogen bombs. Why did its creators choose such an image? The most acceptable version - inverted trefoil - a symbol of the death of nature. We humans are a part of this nature, what is the effect of radioactive radiation on living organisms?
Ways of radiation penetration into the human body
When exposed to radiation on a person, he receives radiation. What are the ways of radiation penetration into the human body? There are two channels of radiation penetration into body tissues.
- External radiation emanating from cosmic rays, atoms of natural radioactive elements and their fission products. This danger occurs when testing nuclear weapons and emergency situations at nuclear power plants and other facilities. In this case, the radiation dose is formed from x-rays and gamma rays, as well as high-energy beta particles.
- Internal radiation caused by radioactive substances that penetrate into the body with food and water, through cuts and other skin damage, as well as with inhaled air.
What kind of radioactive radiation is most dangerous for humans? It is internal exposure that represents the greatest danger and more severe consequences for the human body.
This can be explained as follows: a radioactive atom that has entered the body is in contact with the tissue being irradiated and the duration of action is limited only by the period of its stay in the human body. In addition, the local effect of radiation is enhanced, since radioactive substances are concentrated in organs selectively.
Unfortunately, decontamination methods used for external exposure are powerless here.
External and internal exposure
What type of radioactive radiation is most dangerous with external human exposure? External exposure affects a person only while he is in a radioactive zone. Danger exacerbates the presence of external neutron radiation in the spectrum. These tiny particles that do not have an electric charge, easily penetrate into the nuclei of atoms. As a result, atoms of new radioactive elements are formed. Thus, a source of secondary, already internal, radiation appears.
How does radiation affect the human body? Let us consider in more detail the processes occurring during external irradiation.
Some radioactive substances that enter the body through the skin enter the circulatory system and, together with the blood flow, are transferred to individual organs, creating high local sources of radiation.
The result of the penetration of radioactive substances with respiration depends on the size of the particles. Most of them are eventually removed along with exhaled air. The only exceptions are atoms that enter into chemical bonds with bone tissue (uranium, zirconium, etc.).
As a result of radiation exposure, the following diseases most often occur:
- external irradiation causes burns of the skin and mucous membranes of varying severity;
- Irradiation of internal organs causes leukemia and tumor processes.
What is the cause of the negative effects of radiation
The negative effect of radiation on living beings is explained by the following reason - as a result of the strong ionizing effect of radioactive radiation, very active molecules, called free radicals, are formed in living cells. They are the real aggressors for all body systems, damaging and killing living cells.
How do free radicals act on the human body?
- Their first "victims" are quickly dividing cells of the gastrointestinal tract, blood-forming organs, and also germ cells. Therefore, penetrating radiation can cause people to have fever, nausea, vomiting, decreased blood cells and loose stools.
- Organs and systems with a lower intensity of cell division undergo mainly dystrophic (qualitative) changes under irradiation.
- For the delicate tissues of our visual organs, exposure is extremely dangerous - it can cause radiation cataracts.
- Another serious consequence of irradiation is reduced immunity, vascular sclerosis, and genetic changes.
Genetic effects of radiation
What are the genetic effects of radiation? The mechanism of transmission of hereditary traits is a very thin and sensitive structure. Errors and failures in this system can be caused by a number of reasons, including radioactive radiation.
Transformations in genes (carriers of hereditary information) that occur during irradiation of germ cells, can cause changes (mutations) in the cells of the new organism. This negative effect can spread to subsequent generations. The descendants can form physical and mental disorders. But these deviations can exist only under the condition that the defective gene binds to another gene that has the same damage. The smaller the number of people exposed to radiation, the less the likelihood of such birth defects in the offspring.
What are the consequences of exposure
The effect of radiation on living organisms depends on several factors:
- type of radiation;
- its intensity;
- from individual susceptibility.
The human body is capable of regenerating damaged cells until their number exceeds a certain critical level. If this limit is exceeded, irreversible processes are triggered, leading to serious consequences or even death.
The effects of radiation may not appear immediately, but after many years. Moreover, short-term, but intensive exposure is more dangerous than its multiple, small doses.
There are several parameters for assessing the radiation state. The magnitude of the absorbed dose characterizes the ability of radiation to damage tissue cells. This parameter determines the degree of radiation exposure. It is measured in Sievert (Sv).
Natural background radiation is always present in nature. The level of external exposure, not exceeding 0.2 µZ / h (micro-sievert per hour), is considered the norm of radiation for humans. This is the situation when they say "radiation background is normal." Although there is a “non-threshold concept”, according to which there is no safe dose of radiation. The upper level of radiation up to 0.5 mkZ / h is considered safe for the body, called the permissible dose of radiation for humans. This value is equivalent to 50 microroentgen per hour.
It is believed that by reducing the time spent in the danger zone, the human body transfers radiation with a capacity of 10 µZ / h without harm to health. This refers to fluorography, x-rays. The X-ray of a sick tooth adds another 0.2 mSv to this insidious "piggy bank". These figures reflect only potential danger. In fact, no type of medical examination can cause radiation sickness.
The total absorbed dose should not exceed the threshold of 100–700 mSv. A single dose of 6–7 Sv is considered absolutely fatal.
Do not tempt fate - the natural instinct of self-preservation should work immediately when a radiation danger sign appears in your field of vision. The most reasonable thing is to leave this zone immediately. Remember, radioactivity has the ability to accumulate, and the dose of radiation to add up.