The modern person daily is affected by both artificial, and natural sources of radiation which results from radioactive decay of radionuclides.
Definition
Radionuclides are a set of the atoms which are characterized by a certain mass number, a power condition of kernels, atomic number which kernels are unstable and experience radioactive decay.
The quantity of the known radioactive nuclides exceeds 1800. As disintegration allocate: a-radionuclides, b-radionuclides. Kernels of some radionuclides are subject to spontaneous division, and others break up as electronic capture at which the kernel, taking atom from one of covers, allocates a neutrino.
The most part of radionuclides are sources of radioactive radiation since emission of a- and b-particles and electronic capture usually are followed by formation of g-radiation, as leads to formation of electromagnetic radiation.
Sources
Natural sources create a natural radiation background which represents the space radiation and radionuclides of terrestrial origin which are contained in the soil, water, rocks. These radionuclides are an external source of radiation. For example, radionuclides of uranium and thorium, coming to an organism with food, air, are in an organism in equilibrium concentration and are sources of internal radiation. Besides natural sources of radiation, radionuclides can be received also in the artificial (technogenic) way. They are formed on nuclear reactors, in connection with nuclear weapons test, are also used in medicine, agriculture, science and other industries, having internal and external impact on a human body.
Influence on a human body
Getting to a living organism, radioactive elements cause emergence of the particles making destructive impact on living cells. High doses damage and kill a cage, stop its division and cause serious damage to fabrics. Small doses of radiation can cause genetic changes that can be shown at future descendants undergone radiation. Most quicker radioactive materials are removed from soft fabrics and internals (caesium, molybdenum, ruthenium, iodine), and concentrated in bones (strontium, plutonium, barium, yttrium, zirconium) – slowly. The considerable amount of radionuclides comes to a human body with food. The leading supplier are bread; further on decrease: milk, vegetables, fruit, meat, fish. And in sea fish of radionuclides contains less, than in freshwater that is connected with a high mineralization of sea water. For removal from an organism of radioactive materials it is recommended to use 2-6 g in day of an egg shell in view of the calcium which is contained in it.