What's the Hype About EMF?
Advisory Report - September 2000
What's the Hype About EMF?
Over the past 20 years, much attention has been given to the possibility of adverse effects resulting from exposure to electromagnetic fields (EMF) arising from electric distribution lines and electronic devices. In particular, homeowners and home buyers have raised concern with the extremely low frequency (ELF) electromagnetic fields arising from power lines.
Since 1979, several studies have been performed, pursuing the possible association between ELF electromagnetic fields and forms of cancer. To date, no conclusive evidence supports an association between ELF and cancer.
EMF
As the name implies, electromagnetic fields consist of electric and magnetic fields traveling together, characterized by frequency and wavelength. Based on the frequency and wavelength, the following chart illustrates the electromagnetic spectrum. Note as the frequency increases the wavelength decreases or becomes more concentrated. Thus, the higher the frequency, the more dramatic the characteristic effect on biological material.
The characteristic effects of the various types of electromagnetic energy are identified at the bottom of the illustration. However, the extremely low frequency energies (50-60 Hz) associated with electrical devices and power lines do not have a determined biological effect other than inducing a low current in biological material.
ELF electric and magnetic fields are present in any home that uses electricity. Electric fields arise from the presence of electric charges and thus arise whenever electricity is present. Magnetic fields arise with the motion of electricity (current) and are thus present whenever electricity is used. For an example, an electric field is present when an appliance is plugged into an outlet. A magnetic field is present when the appliance is turned on and the current is moving through the appliance.
Findings
After multiple studies, employing different criteria and methodology, the prevailing opinion in the scientific community is that ELF electromagnetic fields in the range (50-60 Hz) that are associated with powerlines have not been shown to cause cancer. Although several studies have indicated an association, no quantitative dose relation has been established nor have the studies indicating an association been duplicated successfully.
The U.S. National Research Council (NRC) expresses the broad consensus in the scientific community when it states:
Based on a comprehensive evaluation of published studies relating to the effects of power frequency electric and magnetic fields on cells, tissues, and organisms (including humans), the conclusion of the committee is that the current body of evidence does not show that exposure to these fields presents a human-health hazard. Specifically, no conclusive and consistent evidence shows that exposures to residential electric and magnetic fields produce cancer, adverse neurobehavioral effects, or reproductive and developmental effects.
Finally, although the consensus is that there is no causal association, it does not, nor cannot prove ELF to be safe. This position is represented by the National Institutes of Health 1998 press release statement regarding power-frequency fields as a "possible," but not "probable" human carcinogen. Meaning, it can not be excluded as a cause, but has not been shown to be a cancer-causing agent.
For more information, visit the following Web sites: