KNOW ABOUT ELECTROMAGNETIC RAYS FROM THE PHONES AND TVs

The acceptance of mobile phones in Australia has been phenomenal, a total of about four and a half million being presently in use. However, not so welcome for many people has been the sprouting of mobile telephone towers in unexpected places close to homes and schools. There are now about 2000 of them. It is reported that expanding phone companies in the US are hiding the antennae in church steeples, arena lighting, artificial trees and flagpoles. It is the newness and the close proximity of these towers that has made them more controversial than the established radio and TV towers. However, all transmit electromagnetic radiation (often referred to by officials as 'electromagnetic energy' in order to avoid the term 'radiation') which some scientists have implicated in increased incidence of cancer.
Undoubtedly there has been an aesthetic angle to the debate on mobile phone tower placement; some residents find them very ugly and likely to depress house values for that reason alone. But a Four Corners program in July 1995 alerted many Australians for the first time to the possible health effects not only of high-power transmitters but of mobile phone use. Anecdotal but still compelling accounts of cancer association with exposure to transmitters and mobile phone use featured in the program. A CSIRO report of the previous year(1) had urged that more research on health effects be carried out. Also in 1995, a preliminary study of cancer incidence in Sydney appeared to show an increase of childhood leukaemia in homes relatively close to TV transmitters(2). Meanwhile, there has been a controversial move to have the existing Australian radiation standard loosened by a factor of five in order to bring it into line with overseas standards.
This paper is intended to provide background on the two-year Australian debate on the possible hazards of electromagnetic radiation from transmitter towers. Of immediate importance is the prospect of looser national electromagnetic radiation standards, which raises questions as to the validity of the basis for such standards in terms of what laboratory or other results have been relied on for setting standards. The relative energy of radiation received from transmitter towers compared with hand-held mobile phones is relevant and is discussed. So also is the range of reported laboratory effects on test animals and cells observed at very low levels of radiation near the standard or less; are they meaningful? The paper concludes with a suggested approach to experimental work which may help us to determine whether Australian and world standards are soundly based or not.
The Electromagnetic Spectrum - Radiofrequency Range
For an understanding of the issues involved, it is necessary to have some knowledge of the range and nature of the electromagnetic radiation (EMR) spectrum . Electromagnetic radiation may be thought of in terms of waves in air which transmit energy but can also be modulated (controlled) through amplitude, pulsing, etc. to transmit speech, TV images and so on. These waves have a range or spectrum of frequency expressed in hertz, i.e. cycles per second. At the higher frequencies we have kilohertz, megahertz and gigahertz. The greater the frequency, the shorter the wavelength and the greater the energy transmitted.
A significant division within the EMR spectrum is the frequency at about 10 million gigahertz above which waves become ionising in nature, i.e. they are capable of knocking electrons out of atoms to form ions. Thus ultraviolet rays, X-rays and gamma radiation are ionising because they are of greater frequency than 10 million gigahertz. When directed at the body, such radiation is known to be capable of initiating cancer through damage to genetic material (DNA). Too much sunlight, too many X-rays or too much exposure to the gamma-radiating isotope cobalt-60 can cause cancer.
That part of the EMR spectrum of concern in this paper is non-ionising and is known as radiofrequency/microwave radiation (RF radiation for short). This is defined in the Australian Standard (AS 2772.-1990) as waves having frequencies from 100 kilohertz up to 300 gigahertz . The radiofrequency spectrum includes, in increasing order of energy, waves from AM radio, FM radio, TV (very high and ultra high frequency), mobile phones, police radar, microwave ovens and satellite stations.
All electromagnetic radiation involves an oscillating electric field and a magnetic field. Whereas at the extremely low frequency end of the spectrum (e.g. AC current at 50 or 60 hertz) the two fields can be measured and considered separately, in the radiofrequency spectrum they are measured together. The intensity (' power density ') of the combined fields can be readily expressed in terms of a power unit relative to area (e.g. watts per square centimetre) which denotes the electric and magnetic fields as a multiple. Absorption of electromagnetic radiation energy by living organisms can be expressed in terms of watts per kilogram. This represents the dose, or more correctly, the specific absorption rate (SAR). The value for SAR is not always easy to calculate, especially in respect of individual organs or cell types.
Intense waves in the radiofrequency spectrum are readily able to raise the temperature of, say, a culture of cells brought near the source of radiation (the principle of the microwave oven) as wave energy is converted to heat energy on contact with the cells. This is known as a thermal effect . However, because the radiation is non-ionising there is no electron stripping of cellular DNA and therefore no direct initiation of cancer. Radiofrequency standards to protect health are totally based on avoiding thermal effects (see below).
Thermal Effects of Radiofrequency EMR - Relation to Standards
The thermal or heating effects of radiofrequency radiation (including microwaves) on living organisms are well known, they are dose-related and they are mostly reproducible. These crucial characteristics have been regarded by many scientists as justifying the selection of thermal effects as a powerful and single basis for determining health standards. The following information has been adapted from information contained in the previously mentioned CSIRO review report.
Heating caused by RF radiation is caused mainly by water molecules lining up with the electric field imposed by the radiation. Since the field is oscillating very rapidly (wave frequency), the water molecules are rapidly swinging one way then another in sympathy, thus generating heat. Some biological molecules are also influenced by applied electric fields.
Exposure of people to a dose of radiofrequency radiation of less than about 4 watts per kilogram body weight is thought to give rise to an increase in body temperature of less than 1o Centrigrade and can be reasonably well tolerated for short periods. Higher induced temperatures are not tolerated, however, and have several well-known deleterious effects, depending on the precise location of radiation absorption. An effect observed at RF intensities sufficient to raise the rectal temperature of an experimental animal by 1o C or more is classified as thermal in nature. Such effects could be induced by any method designed to raise body temperature.
Firstly, the skin can detect RF radiation but the sensation is much less than that from infrared radiation and is extremely dependent on frequency which determines penetration. In the range 0.5-100 gigahertz, skin detection is not regarded as a reliable warning mechanism.
Heat effects on brain tissue are thought to be the reason why people can actually hear pulsed radiofrequencies between 200 megahertz and 6.5 gigahertz. The sound is described as 'buzzing, clicking, hissing or popping'.
Thirdly, the eyes are felt to be peculiarly sensitive to RF radiation. Lens tissue has no blood supply to act as coolant, there is little self-repair at that site and thus damage and damage products tend to accumulate. At a threshold of about 41o C, exposed laboratory rabbits show cataract formation. Further work needs to be done on the susceptibility of primate eyes, which seem to be less sensitive.
Fourthly, rat testes exposed to RF radiation leading to temperature increases of 1.5-3.5o C are damaged to the extent that there is temporary infertility and an altered division pattern of germ cells.
Fifthly, the thermal disruption of
behaviour by RF radiation, e.g. task learning and short term memory, has been demonstrated in the rat. Effects were observed at doses between 0.6 and 8 watts per kilogram.
Sixthly, the circulatory and immune system in rodents shows some alterations in response to RF radiation. For example, blood cell counts decline in some experiments while the immune system appears to be stimulated. Once again, these effects appear to be thermally induced.
One laboratory has reported symptoms similar to heat stroke leading to death in rats following exposure at three microwave frequencies.
Lastly, a body temperature of 43o C in pregnant rats brought about by a dose of 11 watts per kilogram of RF radiation caused abnormalities and death of embryos. So long as there is a temperature increase of at least 2.5o C, birth defects can be expected to occur.