Under the influence of ionizing radiation, atoms and molecules of living cells get ionized, which results in complicated physical and chemical processes that affect the nature of human’s further vital activity.
There exists an opinion that ionization of atoms and molecules under the influence of radiation emission leads to breaking bonds in protein molecules, which results in cell death and irradiation of the whole body. However, there is a different opinion that radiolysis products of water, which is known to make up 70% of human body mass, take part in the formation of the biological consequences of ionizing emission. When water is ionized, free radicals H+ and OH- are formed, and, if oxygen is present, peroxide compounds, which are powerful oxidants, are formed as well. The latter enter into a chemical reaction with molecules of protein and enzyme, ruining them, and, as a result, compounds not native to living organisms are formed. This leads to violation of metabolism, oppression of enzyme and certain functioning systems, which means the violation of vital activity of the whole human body.
The peculiarity of ionizing radiation activity is that the intensity of chemical reactions caused by free radicals is growing, and hundreds and thousands of molecules which are not irradiated are involved.
It is also necessary to point out that some peculiarities of ionizing radiation effect on the human body:
– sense organs do not respond to radiation;
– small radiation doses can sum up and accumulate in the body (cumulative effect);
– radiation affects not only the specific living organism, but also its prospective inheritance (genetic effect);
- – different organisms have different sensitivity to radiation.
The strongest effect is experienced by the cells of the red bone marrow, thyroid, lungs, and internal organs’ that is the organs with the cells that have a high level of division. The same radiation dose affects more cells in children’s organisms than in the adult ones as all the cells of children’s bodies are in the state of division. The level of danger of different radioactive elements for a person is defined by the ability of the body to absorb and accumulate them.
Radioactive isotopes get inside the human body with dust, air, food or water, and can behave in many ways, e.g.:
– be distributed evenly in the human body (tritium, carbon, iron, polonium)
– be accumulated in bones (radium, phosphorus, strontium)
– remain in muscles (potassium, rubidium, cesium)
– accumulated in thyroid (iodine), liver, kidneys, spleen (ruthenium, polonium, niobium), etc.
The effects of ionizing radiation are classified according to kinds of damages and time of manifestation.
According to kinds of damages they are classified into three groups:
– somatic-stochastic (casual, probable)
According to manifestation time, they are classified into two groups:
– early (or acute)
Early radiation damage can only be somatic. It results in death or radiation sickness. The suppliers of such particles are mainly isotopes with a short lifetime. Acute form is a result of irradiation in large doses within the short period of time. Chronic form develops as a result of long irradiation. Beam cataracts, malignant tumours and other diseases might be the further consequences of radiation injury.