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electromagnetic field


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(EMF)

The zone around an electrical power source in which instruments can detect electromagnetic radiation. This has two components: electric power measured by voltage and magnetic radiation produced by the current. Electromagnetic fields that may harm health possibly include those generated by mobile or cellular telephones. Electric field strength (volts/meter) depends on the voltage independent of current size. Magnetic field strength (amps/meter) reflects the amount of current passing through a conductor, independent of voltage, and is produced by moving electric charges. A 50 to 60 Hz electrical and magnetic field moves along a live domestic electric power cable, but the strength diminishes with distance from the source. Common building materials shield against electric, but not against magnetic, fields. Both components have biological effects at extremely high levels not experienced by the general population. Power frequency magnetic fields from high-voltage electric power lines, transformers, etc., have been found in epidemiological studies to be associated with an increased risk of cancer, especially leukemia and possibly brain cancer in occupationally exposed adults and residentially exposed children. The mechanism is unknown. See also extremely low frequency (ELF) electromagnetic radiation.

Subjects: Public Health and Epidemiology.


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