Cellular Communication may damage your health !!!
Introduction
Could it really be? Are all those upwardly mobile people who walk around with mobile phones stuck to their ears destined for an early grave due to cancer or brain damage? There have been many papers and journals written on this very topic, studying the biological effects of electromagnetic radiation, which is emitted by cellular hand-held transceivers. Specifically, these papers have investigated the effect of electromagnetic radiation on the areas of the human body which are exposed to the cellular phone when it is being used ie: the head, ear, eye and hand.
This article will describe the biological effects that Electromagnetic (EM) radiation (Electromagnetic spectrum shown below) may have. Ways of measuring radiation emission levels to the head will also be described including a way of modeling the human head for this purpose. This information can then be used to assess the real danger posed by the future usage of cellular communication for digital data and voice transmission.
The Electromagnetic Spectrum
The electric fields that are induced, may cause changes in psychological responses such as changes in complex reasoning and arousal of the human being. These effects may occur at levels of EM radiation present in the proximity of overhead power lines which are a very common site all over the UK. It has been shown experimentally that other physiological, psychological and behavioural effects do occur at certain conditions ie: certain magnitudes of electric and magnetic fields. These include the following:
Another majorly publicised affect is that of the inducement of cancers. As explained above, depression of melatonin production has been related to causing cancer, but only at excessive levels of EM fields. There have been no conclusive results to prove any relationship between exposure to EM fields and cancer.
There are problems with this model. The skin surrounding the skull, the facial muscles, eye chamber and the ears are not easily represented by the phantom model. In order to simulate this, extra simulated brain and muscle tissue needs to be used with the fibreglass model. Fatty tissue is approximated by using the same liquid as for brain tissue. This results in a higher measured value of radiation absorbed by the brain than the actual value. This is acceptable in these situations where safety levels of radiation emission are calculated and so the worst case level will be measured. The measurements are shown for a single unit cellular phone as an example. The measurements are given in Specific Absorption Rate explained below.
SAR values in the proximity of the head.
Using the example of two types of cellular transcievers, a one unit phone and a flip phone, the diagrams below show the SAR distribution across the simulated tissue of a phantom model, when the phone is being used. This shows that the exposure of the face is well spread across the area of the phone and peaks of SAR occur at few points. This is advantageous as it implies that there are no major concentrations of field intensity on the head. As it has been explained above, intense concentration of EM fields may have dangerous implications.
SAR Distributions for two types of Cellular Transceivers.
The experiments have shown that the area of the head which is exposed to the largest SAR value of fields is the area shaded in the diagram below. This area contains the phone display and touch tone pad on the phone unit. The National Council for Radiation Protection and Measurements (NCRP) use SAR values to specify the maximum safe limits of radiation allowed to be emitted from cellular transceivers.
Area of highest EM exposure on a human head.
Further research is always being carried out, with phone companies eager to invest in research so as to ease their consumer's fears. Many companies are taking advantage of the public's fear by selling products such as shielding cases which enclose the cellular tranceiver and shield the user from the majority of EM radiation emitted by the phone. These tend to decrease the reception capability of the phone units.
This article will describe the biological effects that Electromagnetic (EM) radiation (Electromagnetic spectrum shown below) may have. Ways of measuring radiation emission levels to the head will also be described including a way of modeling the human head for this purpose. This information can then be used to assess the real danger posed by the future usage of cellular communication for digital data and voice transmission.
The Electromagnetic Spectrum
General Biological Effects of Radiation
When ionizing radiation interacts with cells in the human body, the following events may occur:- Cells may repair themselves with no abnormal side effects.
- Cells may die and be replaced by new cells created through the body's normal regenerative processes or
- Cells may change in terms of their reproductive structure causing deformities in future cell reproduction.
Biological effects of Electromagnetic Radiation
Exposure to electromagnetic fields results in the induction of electrical fields in biological tissues of the body. One of the most commonly visible effects of electric fields is the movement of body hair when a charged object is passed across it. A simple example being a charged comb which is passed over body hair.The electric fields that are induced, may cause changes in psychological responses such as changes in complex reasoning and arousal of the human being. These effects may occur at levels of EM radiation present in the proximity of overhead power lines which are a very common site all over the UK. It has been shown experimentally that other physiological, psychological and behavioural effects do occur at certain conditions ie: certain magnitudes of electric and magnetic fields. These include the following:
- Resting heart rate has been shown to be reduced by a few beats per minute, as well as changes in the pattern of electrical impulses produced by the brain (Electroencephalogram or EEG). All of these changes are not regarded as dangerous because they all occur within the ranges of normal fluctuations of these values.
An EEG Trace - The biological rhythm of the human body (metabolic rate for example) may be influenced by very weak electric fields. This result has only been shown in humans exposed to an electric field while they were living in an underground apartment without access to natural light and dark intervals. Experiments have shown that, in animals, extreme exposure to electric fields does affect various aspects of the animals biological rhythm including the process by which the melatonin hormone is produced. This is hormone affects pigmentation of skin.Changes in this hormone level have been associated with causing cancer and so this is a very significant result. It isnt really clear if this gives conclusive evidence as to the danger of EM radiation when applied to cellular transceivers because usage of cellular transceivers would not give such a chronic level of exposure to a human being. Also very recent studies have not always observed these effects hence doubting the conclusion first made.
- In some cases of acute field exposure to humans, headaches were observed as well as alterations in the visually evoked responses. This is very significant as these type of symptoms would not necessarily be associated to the cellular transceiver but more due to other factors ie: stress or overexposure to the sun etc.
Another majorly publicised affect is that of the inducement of cancers. As explained above, depression of melatonin production has been related to causing cancer, but only at excessive levels of EM fields. There have been no conclusive results to prove any relationship between exposure to EM fields and cancer.
Measurement of Electromagnetic Radiation effects
If the future of data communications becomes more and more mobile orientated hence using cellular technology to a far greater extent than currently, then users of the system will not only utilise the data communciation facilities but also the voice communication facilities that are so common nowadays. This implies that exposure to EM radiation will be more intense in the vicinity of the head. So it is very useful to try to model the human head and measure the amount of radiation that would be absorbed by the head when a cellular transceiver is being used for voice communication (ie: as a mobile phone).Modelling the human head
The human head can be modelled using the "phantom" model. This is a fibreglass shell filled with a liquid having the same dielectric as human brain tissue. The magnitude of EM fields can then be measured at specific points and depths in the modelled human skull when a cellular transceiever is placed in a close proximity ie: In these experiments a cellular phone was used in a regular position, by the ear.There are problems with this model. The skin surrounding the skull, the facial muscles, eye chamber and the ears are not easily represented by the phantom model. In order to simulate this, extra simulated brain and muscle tissue needs to be used with the fibreglass model. Fatty tissue is approximated by using the same liquid as for brain tissue. This results in a higher measured value of radiation absorbed by the brain than the actual value. This is acceptable in these situations where safety levels of radiation emission are calculated and so the worst case level will be measured. The measurements are shown for a single unit cellular phone as an example. The measurements are given in Specific Absorption Rate explained below.
SAR values in the proximity of the head.
Quantification of Radiation absorption.
A widely adopted measurement of radiation absorption is the Specific Absorption Rate (SAR). This is defined as the derivative of energy divided by mass ie: dW/dm. It is measured in Watts per kilogram (W/kg).Using the example of two types of cellular transcievers, a one unit phone and a flip phone, the diagrams below show the SAR distribution across the simulated tissue of a phantom model, when the phone is being used. This shows that the exposure of the face is well spread across the area of the phone and peaks of SAR occur at few points. This is advantageous as it implies that there are no major concentrations of field intensity on the head. As it has been explained above, intense concentration of EM fields may have dangerous implications.
SAR Distributions for two types of Cellular Transceivers.
Area of highest EM exposure on a human head.
Summary
There have been many studies of the the biological effects of EM radiation, many of these have been inconclusive. Using the research available, the following observations can be made:- Electrical fields of intensity similar to that found in the proximity of overhead power lines, may cause psychological responses such as changes in complex reasoning and arousal of humans.
- In very special conditions as explained earlier, in the presence of weak radiation, the human body's biological rhythm may be altered, and in animals it has been shown the intense exposure to radiation can slow down the production of the hormone Melatonin. Changes in the level of this hormone have been linked to causing cancer.
- Acute radiation exposure in human subjects has been shown to cause headaches and alterations in visual responses evoked by the radiation.
- In the presence of intense radiation, human reproduction may experience behavioural deficiencies as well as retardation in development.
Further research is always being carried out, with phone companies eager to invest in research so as to ease their consumer's fears. Many companies are taking advantage of the public's fear by selling products such as shielding cases which enclose the cellular tranceiver and shield the user from the majority of EM radiation emitted by the phone. These tend to decrease the reception capability of the phone units.
References
- "Current and SAR induced in a human head model by the electromagnetic fields irradiated from a cellular phone." Journal Paper. Hsing-Yi Chen; Hou-Hwa Wang. IEEE Transactions on Microwave theory and Techniques Dec 1994. Vol: 42 Iss: 12 pt.1 pp2249-54.
- "Modeling of hand-held recieving antennas in the presence of a human head" Conference Paper. Thiry X; Mittra R. IEEE Antennas and Propagation Society International Symposium 1995. pp 1116-1119, vol 2.
- "Health Effects of exposure to electromagnetic fields" Conference paper. Stuchly, M.A. 1995 IEEE Aerospace Applications Conference. pp 351-68, vol 1.
- "Modeling biological effects from magnetic fields". Journal paper. Blanchard J.P. IEEE Aerospace and Electronics Systems Magazine Feb 1996. Vol:11 Iss: 2 p 6-10.
- "Magnetic Fields and cancer". Journal Paper. Carstensen E.L. IEEE Engineering in Medicine and Biology magazine July-Aug 1995. Vol: 14 Iss: 4 p 362-9.
- "Three dimensional modelling of EM fields in the human head". Conference paper. Huang Y; Dilworth I.J. 9th IEE Internatinal Conference on Antennas and Propagation 1995. p 223-6 vol 1.
- "Electromagnetic Energy exposure of Simulated Users of Portable Cellular Telephones". Journal Paper. Balzano Q; Garay O; Manning T,J. IEEE Transactions on Vehicular Technology Aug 1995. Vol: 44 Iss:3 p 390-403.
- Interview with Mr.George Stavrides, 2nd Year Biology Student, Imperial College 30.05.1996.
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