Radio frequency (RF) radiation starts at a frequency of about 30 thousand cycles per second (30 kHz) in the radio wave region and reaches up to the microwave region, ending at about 300 GHz. Radio frequency radiation is given off purposely by transmitters, but also inadvertently by electronic equipment and electrical wiring (including harmonics). The various frequency bands can be divided into two sections: radio waves (longwave radio, AM radio, shortwave radio, FM radio, and TV stations) as well as microwaves (radar, cellular phone communication and microwave ovens). The unit of electromagnetic waves is either given as field strength or power density.
Biological effects of radio frequency radiation fall into two categories: thermal effects caused by heating and non-thermal effects mediated by the modulation type.
Thermal Effects of Radio Frequency
Biological effects of radio-frequency radiation based on thermal principles have been researched extensively and are well documented. In the past operators of radar equipment suffered from severe burning, even death. Unfortunately, official radiation protection agencies base their exposure limits exclusively on thermal findings, that is, effects caused by an immediate and measurable temperature increase in tissues.
How deeply a given RF radiation will actually penetrate into a biological tissue depends on its frequency. Across the cellular phone frequencies, penetration depth into the human body ranges from 1 to 10 cm (1/2 to 4”). In the case of frequencies above 10 GHz such as in radar equipment, the microwaves often reach only a few millimeters. Electric potentials across cell membranes are studied extensively. External electromagnetic fields can become superimposed over them, triggering resonance effects.
At present the scientific establishment acknowledges mainly biological effects of RF radiation, which can be explained through power density levels absorbed by the human body. A worldwide recognized, basic unit for the description of thermal effects is referred to as the specific absorption rate (SAR), which is given in watt per kilogram (W/kg). The SAR, however, only quantifies the portion of the RF energy that was absorbed as thermal energy.
Scientists from all over the world keep observing non-thermal effects, which are quite alarming. Electromagnetic waves exert forces on charged particles of matter, electric charges are changed in their sphere of influence; molecules and ions follow the orientation of the constantly alternating field. Microwave radiation, for example, is capable of exciting rotation or vibration in heavily polarized water molecules, converting radiation into heat along the way. It also seems to be more than likely that sensitive hydrogen bonds in cells and membranes are affected. These are some of the pathways through which radio frequency radiation can be taken in or absorbed by the body.
Biological effects are not only determined by the power density and specific frequency of radio frequency radiation, but also by its modulation. An electromagnetic wave consists of a carrier wave, which you can think of as an envelope, and a modulation, which is the “letter” conveying the actual information. These Information Carrying Radio Waves (ICRW) can be pictured as clothes on a clothesline, where the clothesline is the modulated signal and the information packets (communication data) are the clothes. The clothesline is operating at a fairly high frequency; say 700-900 MHz for cell phones, while the clothes themselves are superimposed upon the high-frequency carrier wave but run at an extremely low frequency (ELF).
Biologically speaking the modulation of the base frequency (clothesline) is relatively harmless while the ELF pulses (clothes) are the most critical of all modulation types. What this means, of course, is that the biological effect of a weak, but pulsed RF radiation would be more pronounced compared to a stronger, but frequency-modulated RF radiation. A low-level signal from a cellular phone base station, therefore, seems to have a bigger impact than a strong signal from an FM radio tower. Most scientists who research non-thermal biological effects see the problem of RF radiation in the associated ELF signals that modulate the carrier wave. In an everyday setting the field intensity and the carrier wave frequency on their own – without modulation – would probably have less of an impact.
According to George Carlo, 1 one of the observed biological effects from this “pulsed” signal is that the vibratory protein receptors within the cell wall that control the exchange of nutrients and toxins into and out of the cell will be negatively impacted. They will actually interpret this foreign vibration as an intruder and shut down the cell wall 0 thus starving the cell while trapping toxins internally. Ionic intercellular communication is also impacted – causing confusion within the cells as to how and when to divide.
According to Dr. Carlo, there is no safe level for this radiation 0 no acceptable threshold. We are all being affected not only by personal cell phone usage, but also as by-standers subject to radiation from nearby cell phone users and cell phone antennas. In large metropolitan areas there is no break from this assault. The effect will be devastating as reflected in the ever-increasing level of electromagnetic allergies.
James Oschman, PhD, describes the process as the cell communication responding as semi-conductors, more specifically, piezoelectric devices, that reach resonance with the external vibration. 2
In summary, radio frequency radiation as encountered in everyday life is less critical because of its level of power density than because of its ELF modulation. Excluded are those situations, of course, in which the power density is sufficiently high to cause heating of local body tissues, as can be the case while holding a cellular phone close to the body.
The above is extracted with permission from the International Institute for Bau-Biologie * Ecology (IBE) course material.
1 Carlo, George, Safe Wireless Initiative (www.safewireless.org) [not online as of July 2009]
2 Oschman, James. Energy Medicine. London: Churchill Livingstone, 2000.