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Electromagnetic fields from Power lines, Wiring & Appliances

2. What is known about exposure to Extremely Low Frequency (ELF) fields?


Electric and magnetic fields can be measured in practically every environment or estimated from other parameters. Environmental levels of ELF fields are very low, typically 5-50 V/m for electric fields and 0.01-0.2 µT for magnetic fields. Much higher exposures can take place in some workplaces and possibly outside the workplace for many of us for shorter durations.

There are very precise instruments to measure electric and magnetic fields, but there is a lack of consensus on what exposure characteristics should be measured to determine health effects.

Calculation methods are available to evaluate human exposure, but there are uncertainties in the results. More...


ELF electric fields are greatly attenuated (weakened) inside the body.

A well-established interaction mechanism is that external ELF electric and magnetic fields induce electric fields and currents in biological tissues. This is a basic physical mechanism for interaction of ELF fields with living organisms. The electric field induced within the body increases with the frequency of the external field and the size of the exposed body. Above a certain threshold level, these induced electric fields and currents provoke a reaction from some specific cells. This threshold is well above typical human exposure levels.

Typical exposure at home results in very small induced electric fields, while some exposure at work and exposure directly under very high-voltage power lines may be greater resulting in electric fields of about 1 mV/m in some tissues.

Beyond this well-established interaction mechanism, a number of hypothetical explanations have been proposed and may even be more relevant at typical exposure levels: radical pair mechanisms, ion charge-to-mass resonance mechanisms, stochastic resonance, action on biogenic magnetite, etc. The relevance of these hypothetical mechanisms is being researched. More...

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