Non-ionizing radiation
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Image:Radio waves hazard symbol.svg Non-ionizing radiation (or, esp. in British English, non-ionising radiation) refers to any type of electromagnetic radiation that does not carry enough energy to ionize atoms or molecules - that is, to completely remove an electron from an atom or molecule.
The composition of this radiation can vary depending on what may be ionized. Visible light, near ultraviolet, infrared, microwave and radio waves are all examples of non-ionizing radiation, though visible and near ultraviolet can also ionize some molecules. The light from the Sun that reaches the earth is largely composed of non-ionizing radiation, with the notable exception of some ultraviolet rays. However, most ionizing radiation is filtered out by the atmosphere.
Because it is lower energy radiation, the use of this type of radiation in medical fields and everyday life poses fewer health risks than ionizing radiation in forms such as X-rays.
"IARC [International Agency for Research on Cancer] has now concluded [2001] that ELF magnetic fields are possibly carcinogenic to humans, based on consistent statistical associations of high level residential magnetic fields with a doubling of risk of childhood leukaemia. Children who are exposed to residential ELF magnetic fields less than 0.4 microTesla have no increased risk for leukaemia. Because of insufficient data, static magnetic fields and static and extremely low frequency electric fields could not be classified as to carcinogenic risk to humans.
"However pooled analyses of data from a number of well-conducted studies show a fairly consistent statistical association between a doubling of risk of childhood leukaemia and power-frequency (50 or 60 Hz) residential ELF magnetic field strengths above 0.4 microTesla. In contrast, no consistent evidence was found that childhood exposures to ELF electric or magnetic fields are associated with brain tumours or any other kinds of solid tumours. No consistent evidence was found that residential or occupational exposures of adults to ELF magnetic fields increase risk for any kind of cancer". From http://www.iarc.fr/ENG/Press_Releases/archives/pr136a.html Overall evaluation of IARC (VOL.: 80 (2002))
- Extremely low-frequency magnetic fields are possibly carcinogenic to humans (Group 2B).
- Static electric and magnetic fields and extremely low-frequency electric fields are not classifiable as to their carcinogenicity to humans (Group 3).
[edit] See also
pt:Radiação não ionizante ru:Радиобиология неионизирующих излучений
