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 RADIATION AND BIOLOGICAL EFFECTS
It is called a radiation to all energy that propagates in the shape of wave across the space. In the concept radiation is included, then, from the visible light to the waves of radio and television (radiations not ionizantes), and from the ultraviolet light to the x-rays or the energy fotónica (radiations ionizantes).
Two types of radiations exist ionizantes:
- electromagnetic, constituted for beams ultraviolet gamma, x-rays and beams;
- the constituted one by subatomic particles (electrons, neutrons, protons).
Every atomic element is characterized by his number of protons, which is constant; but it can present different number of neutrons, and the number of these is what it defines to the different isotopes of every chemical element. Many isotopes are unstable, and they can change his number másico (sum of neutrons and protons) into particles emission. Depending on what type of particles are they expressed, we speak about radiation alpha, beta or gamma, with different interaction on the matter.
The radiation alpha remains braked in the exterior layers of the skin, and it is not dangerous, unless it interferes straight across wounds, food, etc. The radiation beta is more penetrating, interfering one or two centimeters in the living textiles. The radiation gamma, or electromagnetic radiation of high energy, is capable of penetrating deeply in the textiles; nevertheless, it liberates less energy in the textile that the alpha or beta. These intergesticulate with the atoms and molecules that are to his step, what is much more harmful.
The radioactivity of an isotope can measure itself, as well as the absorbed radiation dose ionizante in a certain textile.
ORIGIN OF THE RADIATIONS IONIZANTES
- Natural radioactivity. It results from the intrinsic instability of a series of present atoms in the Nature (uranium, thorium, etc), as well as the proceeding one from cosmic beams - the latter exhibition is bigger in the assiduous ones than the plane-.
- Radioactivity incorporated in food, drinks, etc. The crustaceans and marine mollusks (mussels, mussels, clams) concentrate it especially.
- Medical procedures (you X-ray, etc). There are the principal source of artificial radiation in the general population.
- "Nuclear garbage". The radioactive materials of waste of the nuclear industry, the hospitals and the research centers.
- Radon. Gas proceeding from the uranium, which is of natural form in the ground. It comes from building materials, fertilizers fosfatados, components of radioemisores, detectors of smokes, natural gas in the hearths, etc. The exhibition grade to the radon increases significantly in closed places and domiciles with good thermal isolation.
- Professional exhibition. In Spain approximately 60.000 persons are included in this category. 95 % receives dose ten times below the authorized limit.
- Nuclear explosions. Accidental, warlike or experimental.
RADIATIONS IONIZANTES AND CANCER
The radiations ionizantes behave like a demonstrated carcinogen, dose - clerk and without a threshold for that kidlings carcinogénesis; that is to say, doses, even daily, can unleash a cancer on having accumulated.
When it is a question of exhibition to big doses, the temporary profile of the risk differs according to the type of cancer: for the leukemia the risk increases quickly in the first years, declining later; in the solid tumors the risk increases slowly in the course of time.
On the general, and excluded population the radiation proceeding from radiographies and medical explorations, the biggest expositional risk comes from the disintegration of the uranium in radon. Although it is not possible to avoid completely the home exhibition to radon, yes that can be diminished; the simple ventilation of the houses diminishes drastically the radon levels in his interior.
RADIATIONS ULTRAVIOLET AND CANCER
The ultraviolet radiation is part of the called electromagnetic bogey, with scarce power ionizante, due to his fall energy. In the classification of the radiations, they are placed on horseback with the not ionizantes.
In his bogey three areas differ in reason of his energy:
- GRAPE (or of long wave): 320 to 400 nm. Those of minor frequency and energy.
- UVB (or of average wave): 320 to 290 nm.
- UVC (or of short wave): 290 to 200 nm. For his biggest energy, they are the most dangerous for the health.
The ultraviolet radiation sources are natural (the sun) and artificial (hospitals, industries, cosmetics, etc). The radiation UVC does not reach the terrestrial surface, since she remains retained by the ozone layer in the stratosphere. The natural radiation that comes to us is therefore GRAPE and UVB.
The carcinogenic effect of the beams UV is tied to the wavelength. Two principal risk factors for the leather cancer are the exhibition to the radiation UV, and the type of skin, with more risk in persons with type of clear skin and less in more pigmentadas. The beams UV have effect direct, opening carcinogen and promoter on the skin, influencing the development of so much of epiteliomas as of melanomas. In the first ones there seems more important the radiation of fund, accumulative - occupational, for example-. In the melanomas the intermittent exhibition would have major effect, recreacional.
The bogey UVB of the solar radiation possesses the biggest potency of induction of leather cancer, since it induces structural damage in the cellular ADN, at the same time that it stimulates the proliferation of the epidermis. Recent estimations have calculated that for every reduction of a 1 % in the ozone layer, the radiation UVB/UVC will increase in 2 % and the leather cancer in 2 6 %.
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RADIATION 
