Impact of EMF Exposure Limits and MRI

Impact of EMF Exposure Limits and MRI

Articles, by Professor J.C. Lin of the University of Illinois in Chicago, highlighting ICNIRP’s role in establishing limits for EMF exposure during MRI procedures were published in IEEE periodicals Microwave Magazine, vol. 12, no. 4, pp. 46-56, June 2011, and in Antennas and Propagation Magazine, vol. 53, no. 1, pp. 169-174, Feb.2011.  The articles provide useful information but do not tell the whole story regarding low frequency exposure limits, specifically recognition of the work of the IEEE International Committee on Electromagnetic Safety (ICES – Standards Coordinating Committee 39).

In 2004, in an attempt to protect workers in the EU, draft Directive 2004/40/EC [1] required that workplace exposures meet the 1998 ICNIRP exposure values (reference levels).  It was then discovered that compliance with the ICNIRP reference levels would preclude certain interventional MRI procedures (where the operator may be exposed to the same field intensities as is the patient), which created a need to examine the scientific basis and rationale for the ICNIRP values at low frequencies.  In 2005, a member of ICES analyzed the large differences in the low frequency electric and magnetic field exposure values between ICES and ICNIRP and provided explanations of how the ICES limits were derived [2].  At that time, for example, the 1998 ICNIRP reference level for occupational magnetic field exposure at 1 kHz was 24.4 A/m [3] while the ICES limit was 1640 A/m [4].  The ICNIRP value was relaxed in 2010 and is now 240 A/m at 1 kHz [5].  The Lin article is significantly incomplete in that there is no mention of the work of IEEE ICES, especially the significant work accomplished in the publication of the IEEE C95 series of standards (C95.1 was first published in 1966) addressing human exposure to electric, magnetic and electromagnetic fields from 0 Hz to 300 GHz.

ICES is an international committee with membership representing academia, federal public health and other government agencies, the military and other users of electromagnetic energy and the product manufacturer communities. Currently the membership of the ICES committee and subcommittees that develop the exposure standards stands at 180 with members from 29 countries.  Since the work of IEEE ICES is based on scientific review of the many sources of relevant data and an open consensus process, and operates under the strict rules and oversight of IEEE Standards Association, it seems incomplete to avoid mention of the IEEE ICES and its accomplishments.  The IEEE ICES website is at; a descriptive brochure can be found at;.  IEEE C95 standards arenow publicly available through the “IEEE Get Program” (   


[1] Directive  2004/40/EC of the European Parliament and of the Council of 29 April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (18th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC)

[2] Reilly J. P. “An Analysis of Differences in the Low Frequency Electric and Magnetic Field Exposure Standards of ICES and ICNIRP”, Health Phys, Vol. 89, Pg. 71 – 80, 2005.

[3] ICNIRP (International Commission on Non-Ionizing Radiation Protection), “Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 GHz),” Health Physics, vol. 74, no. 4, pp. 494 – 522, 1998

[4] IEEE Std C95.6-2002 (R2007), IEEE Standard for Safety Levels with respect to Human Exposure to Electromagnetic Fields, 0 – 3 kHz

[5] ICNIRP (ICNIRP (International Commission on Non-Ionizing Radiation Protection), “Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz),” Health Physics, vol.99, no. 6, pp. 818 – 836, 2010

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