Some Effects of Weak Magnetic Fields on Biological Systems

IEEE Power Electronics Magazine

March 2016 2329-9207

Some Effects of Weak Magnetic Fields on Biological Systems

RF fields can change radical concentrations and cancer cell growth rates

by Frank Barnes and Ben Greenebaum

Concerns have been raised

about the possible


biological effects of nonionizing radiation since at least the late 1950s

with  respect to radar, other radio, and microwave sources.More recent

concerns  have arisen about the potential effects of low-intensity fields,

including  low frequency fields from the electric power generating,

transmission, and distribution system and the devices it

energizes, as well as intermediate, radio-frequency (RF),

and higher-frequency radiation from devices such as cell

phones, broadcast antennas, Wi-Fi, security monitors,

and so forth. These are concerns about the direct effects

of radiation on humans or other organisms. They are distinct

from the electromagnetic compatibility issues that

concern interference by the fields from one device with

the function of another, though human health can be

indirectly affected by electromagnetic interference with

the function of medical devices, including hospital

equipment or pacemakers.

Because of the difficulties in establishing the direct biological

effects of long-term low-level exposures, the lack of

an understood mechanism, and difficulties in obtaining reproducible

results, the guidelines for exposure limits have

been set based on relatively short term

exposures (minutes) that show

clear-cut damage with the addition of

a substantial safety factor. The current

guidelines from the U.S. Federal

Communications Commission (FCC)

for limiting exposures in free space

to the general public for the frequency

range 100 kHz–100 GHz are given in

Table 1. These guidelines are based

on American National Standards Institute

(ANSI) and IEEE recommendations.

For cell phones, the specific

absorption rate (SAR) is limited to

1.6 W/kg averaged over 1 g of tissue.











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