Electric and Magnetic Fields
Regulations concerning electric and magnetic fields
No exposure limits have ever been established in response to the apprehended risk of cancer. Current recommendations focus on preventing short-term exposure at very high levels.
In Canada and Québec, there are no regulations setting safety standards for exposure to EMFs. Electric and magnetic field exposure limits are therefore based on the recommendations of professional associations:
The ICNIRP and IEEE have set EMF exposure limits for workers with occupational exposure to EMFs as well as for the public, without specifying any maximum duration. The ACGIH has established exposure limits only for workers which are valid for a maximum exposure of eight hours a day.
Electric and magnetic fields induce very weak currents in the human body. The purpose of the maximum exposure levels recommended by the ICNIRP, IEEE and ACGIH is to limit these induced currents to levels presenting no health risks.
At this time, 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 estimated that an induced electric field of over 120 mV/m can produce a reversible stimulation of the nervous system (magnetic phosphenes). For its part, the IEEE concluded that the same effect can be observed starting at an induced voltage of 159 mV/m. To apply these threshold values to human beings safely, the ICNIRP and IEEE came up with 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. Finally, the ACGIH established a basic restriction for workers of 10 mA/m2. Note that in the human body, a current density of 10 mA/m2 generates a voltage of approximately 50 mV/m at 60 Hz.
To make it easier to adhere to the basic restrictions, the ICNIRP, IEEE and ACGIH have calculated EMF exposure levels corresponding to their basic restrictions. If these exposure levels or limits are respected, the basic restrictions are always respected too. However, the three agencies authorize exceeding these values provided that it can be shown that the basic restrictions are normally adhered to.
The 60-Hz EMF exposure limits recommended by the ICNIRP, IEEE and ACGIH are set out in Tables 1 and 2. The reason why the exposure limits determined by the three agencies differ from one another, despite the fact that their basic restrictions are equivalent, is because they used different models of the human body to calculate their limits.
1Maximum permitted: 10 kV/m under high-voltage lines.
ICNIRP. Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz). [PDF] International Commission on Non-Ionizing Radiation Protection. 2010.
IEEE. C95.6-2002 IEEE Standard for Safety Levels with Respect to Human Exposure to Electromagnetic Fields 0 to 3 kHz. New York, IEEE, 2002.
ACGIH. TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents. Biological Exposure Indices. Cincinnati, American Conference of Governmental Industrial Hygienists. 2003.
In the case of workers wearing a pacemaker or other electronic medical device, the ACGIH recommends limiting exposure to 1 kV/m for electric fields and 100 µT for magnetic fields. The guidelines set by the ICNIRP and IEEE do not specifically address the issue of medical devices.
There are no health regulations or guidelines 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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