Electric and Magnetic Fields and Health
In Canada and Québec, there are no regulations setting safety standards for exposure to electric and magnetic fields (EMFs). Exposure limits are therefore based on the recommendations of two international organizations:
The ICNIRP and IEEE have set EMF exposure limits for workers with occupational exposure to EMFs as well as for the general public, without specifying any maximum duration.
EMFs induce very weak currents in the human body. The purpose of the maximum exposure levels recommended by the ICNIRP and IEEE is to limit these induced currents to levels presenting no health risks.
Current technology does not allow us to measure currents induced inside the body directly. However, their intensity can be estimated using models of the human body of varying complexity. Another possibility is to calculate induced voltage instead of induced current, as the IEEE has done.
For 60-Hz fields, the ICNIRP determined that an induced electric field of over 120 mV/m can produce a reversible stimulation of the nervous system, which in turn induces "magnetic phosphenes". The IEEE concluded that the same effect can be observed starting at an induced voltage of 159 mV/m. To safely adapt these threshold values to humans, the ICNIRP and IEEE determined some "basic restrictions" based on a number of safety factors.
The ICNIRP established a basic restriction of 120 mV/m for workers with occupational exposure to EMFs, and 24 mV/m for the general public. The IEEE established basic restrictions of 50 mV/m and 17 mV/m, respectively.
To facilitate compliance with the basic restrictions, and using prudent assumptions, the ICNIRP and IEEE have calculated EMF exposure levels corresponding to their basic restrictions. If these exposure levels or limits are respected, the basic restrictions are automatically respected as well. However, both agencies authorize exceeding these values provided it can be shown that the basic restrictions are followed in every situation.
The 60-Hz EMF exposure limits recommended by the ICNIRP and IEEE are set out in Tables 1 and 2. The exposure limits determined by the two agencies differ, despite the fact that their basic restrictions are equivalent, because they used different models of the human body to calculate the limits.
1Maximum permitted: 10 kV/m under high-voltage lines.
International standards allow for the conclusion that cardiac implants operating under normal conditions are not affected by an electric field of at least 5 kV/m and a magnetic field of 100 µT. However, the guidelines set by the ICNIRP and IEEE do not take into account the specific situation of workers wearing medical devices.
Hydro-Québec has a well-established procedure for assessing the safe return-to-work of employees wearing a pacemaker or an implantable automatic defibrillator.
There are no health regulations or recommendations that specifically address the exposure of pregnant women to EMFs. Exposure limits for pregnant women are therefore the same as for the rest of the population.
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