The ionizing radiation are electromagnetic waves of extremely high frequency (X and gamma rays), which contain sufficient photon energy to produce ionization (conversion of atoms or parts of molecules into ions electrically charged positively or negatively) by breaking the atomic bonds that hold together the molecules in the cell. 
The non-ionizing radiation are generally part of the electromagnetic spectrum whose photon energy is too weak to break atomic bonds. These include ultraviolet radiation, visible light, infrared radiation, RF fields and microwaves, extremely low frequency fields and static electric and magnetic fields. One way of transmitting energy is what is done through the radiation of electromagnetic waves, characterized by the existence of electric and magnetic fields perpendicular to each other and perpendicular to the direction of wave propagation. Electromagnetic waves differ from each other by the amount of energy that are capable of transmitting, and depends on its frequency. The set of all is the electromagnetic spectrum. Sorted from lowest to highest energy can summarize the different types of electromagnetic waves as follows:
* static electric and magnetic fields (magnets, DC electrical conductors, etc.).
* Electromagnetic waves of extremely low frequency. The frequency range reaches up to 3 KHz. (AC power lines)
* Electromagnetic waves of very low frequency. The frequency range is from 3 to 30 KHz. (Some induction welding machines)
* Electromagnetic Waves of Radio Frequency (RF). The frequency range is 30 KHz to 1,000 million Hz (= GHz). (Radio and television waves, welding of plastics, etc.).
* Microwave (MO). Electromagnetic waves between 1 and 300 GHz (microwave ovens, mobile phones, etc ...)
* Infrared (IR). Electromagnetic waves between 300 GHz and 385 THz (1 THz = 1,000 GHz). (Infrared lamps, hot material, etc.).
* visible light. Electromagnetic waves between 385 THz and 750 THz. (Lights)
* Ultraviolet (UV) non-ionizing. Electromagnetic waves between 750 THz and 3000 THz. (Solar lamps, lamps for detecting defects lamps, industrial insulation, etc.).
ORIGIN OF NON-IONIZING RADIATION
Electromagnetic fields are natural phenomena, the galaxies, the sun, stars emit radiation low density, and atmosphere are electric charges that generate magnetic fields which we are subjected constantly, and become much more intense, such as during thunderstorms.
But these natural electric and magnetic fields have joined in the last century a large number of fields manmade industrial machinery, power lines, household appliances. every day we are exposed to additional radiation. Although, with some exceptions, this whole artificial radiation is much weaker than the natural electromagnetic fields, in many professions in the electronics sector, railways, telecommunications and medical exposure is continued.
BIOLOGICAL EFFECTS
The non-ionizing radiation, even when of high intensity can not cause ionization in a biological system. However, it has been shown to produce other biological effects, such as heating, altering chemical reactions or inducing electrical currents in tissues and cells.
electromagnetic waves can cause biological effects that sometimes are harmful to health. It is important to understand the difference between the two: A biological effect occurs when exposure to electromagnetic waves causes a noticeable or detectable physiological change in a biological system, as an adverse health effect occurs when the biological effect exceeds the normal capacity of the body and causes compensation and pathological process.
Some biological effects may be innocuous, eg organic reaction increase cutaneous blood flow in response to a slight warming from the sun. Some effects may be helpful, eg the warmth of sunlight on a cold day, or even beneficial to health, such as function solar in the production of vitamin D by the body. However, other biological effects, such as sunburn or skin cancer , are harmful to health.
regard to their effects on the body are of different nature depending on the frequency band in which we move. High frequency radiation and microwave cause molecular vibrations , producing heat-hence domestic and industrial use, "and therefore can cause burns from a given amount of radiation absorbed. Thus, while ultraviolet radiation can cause disease in the skin (erythema) and conjunctivitis by exposure of the skin and eyes, respectively, the infrared radiation can damage the retina or cause clouding of the eye and skin damage by heat transfer.
Microwaves are particularly dangerous for the health effects arising from the large heat capacity they have, the enhanced impact of their action when water molecules are part of the tissues.
Less easily achieve the effect of tissue heating electromagnetic waves for the Radio Frequency and Very Low Frequency. It is known that RF fields induce currents produce heat and electricity. Also, other biological effects have been reported less tested.
respect to the static electric and magnetic fields and electromagnetic waves of extremely low frequency, are known to have adverse effects on the cardiovascular and nervous system. It is currently discussing the reliability of certain studies that provide the ability to produce certain types of cancer at extremely low frequency radiation, but the restrictions that currently apply to this type of radiation do not take into account those effects now.
Although undoubtedly exert biological effects, the role of non-ionizing radiation to cause cancer is controversial. It is thought that in any case, act as tumor promoters , with little or no initial power to convert normal genes into oncogenes . In many studies have identified an increased relative risk of leukemia, brain tumors and other cancers in subjects living near high voltage lines and between different populations at risk professionally. Suspected stronger partnership has been established with childhood leukemia.
