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Safety and Electromagnetic Field Guidelines
the protection of workers engaged in activities related to MRI to avoid sensory efects which may be
annoying and impair working ability. Te guideline was set to prevent magnetophosphene, peripheral
nerve stimulation, and vertigo as a consequence of movement in strong static magnetic felds. Te basic
restrictions have been defned for “the change in the external magnetic fux density (DB)” and for the
induced internal electric feld. In addition, reference levels expressed as the peak (amplitude) dB/dt have
been derived. A distinction is made between controlled and uncontrolled exposures. Basic restrictions
for controlled exposure are intended to be used in work environments where access is restricted to work
ers who have been trained to understand the biological efects that may result from exposure, and where
the workers are able to control their movements to prevent annoying and disturbing sensory efects.
7.7 Guidelines for Low-Frequency Electromagnetic Fields
For the low frequency, ICNIRP and IEEE/ICES produce guidelines/standard in 2010 and 2019 (ICNIRP,
2010; IEEE, 2019). Te low frequency covers the region from 1 Hz to 100 kHz. Te most interesting fre
quency is 50/60 Hz because this frequency is used as the frequency of electric power supply.
7.7.1 ICNIRP Guidelines
As the scientifc base to develop the rationale for the guidelines, review, documents published by IARC
(IARC, 2002), ICNIRP (ICNIRP, 2003), and the WHO (WHO, 2007) on the biological efects of expo
sure to low-frequency electromagnetic felds are referred. In the guidelines, the basic restrictions are
set based on the identifed risks related to transient nervous system responses to peripheral and central
nerve stimulation, the induction of retinal phosphenes, and possible efects on some aspects of brain
function (ICNIRP, 2010).
Te ICNIRP guidelines for low-frequency electric and magnetic felds were originally established in
1998 and revised in 2010 (ICNIRP, 2010). Te basic restrictions expressed as internal electric felds for
frequencies from 1 Hz to 10 MHz are tabulated in Table 7.2. Separate limits are given for “CNS (central
nervous system) tissues of the head” and “all tissues of head and body.” It is noted that in the frequency
range above 100 kHz, RF-specifc basic restrictions need to be considered additionally.
TABLE 7.2 Basic Restrictions in ICNIRP Guidelines for Low Frequencies
Exposure Characteristics
Frequency Range
Internal Electric Field (V/m)
Occupational exposure
CNS tissue of the head
1–10 Hz
0.5/f
10–25 Hz
0.05
25–400 Hz
2 × 10–3 f
400 Hz to 3 kHz
0.8
3 kHz to 10 MHz
2.7 × 104 f
All tissues of head and body
1 Hz to 3 kHz
0.8
3 kHz to 10 MHz
2.7 × 10−4 f
General public exposure
CNS tissue of the head
1–10 Hz
0.1/f
10–25 Hz
0.01
25–1,000 Hz
0.4 × 10–3 f
1,000 Hz to 3 kHz
0.4
3 kHz to 10 MHz
1.35 × 10–4 f
All tissues of head and body
1 Hz to 3 kHz
0.4
3 kHz to 10 MHz
1.35 × 10–4 f
Source: Reproduced from ICNIRP, Health Physics 99: 818–836, 2010.
Notes:
1. f is the frequency in Hz.
2. All values are rms.
3. In the frequency range above 100 kHz, RF-specifc basic restrictions need to be considered additionally.