what is health risk of living near to a tvs transmission towers?

Current Issues Brief 26 1996-97

Rod Panter
Science, Engineering science, Environment and Resources Group

Contents

Introduction

The Electromagnetic Spectrum - Radiofrequency Range

Thermal Effects of Radiofrequency EMR - Relation to Standards

Energy of RF Radiation from TV and Mobile Phone Towers

Non-Thermal Effects of RF Radiations

Government Responses

References

Introduction

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 shut 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. Information technology is the newness and the close proximity of these towers that has made them more than controversial than the established radio and TV towers. However, all transmit electromagnetic radiation (often referred to by officials as 'electromagnetic energy' in order to avert 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 belfry placement; some residents detect them very ugly and likely to depress business firm values for that reason alone. Simply a Four Corners program in July 1995 alerted many Australians for the first fourth dimension to the possible health effects not merely of high-power transmitters but of mobile phone use. Anecdotal but still compelling accounts of cancer clan with exposure to transmitters and mobile phone use featured in the program. A CSIRO report of the previous year(i) had urged that more inquiry on health effects be carried out. Also in 1995, a preliminary study of cancer incidence in Sydney appeared to show an increase of babyhood leukaemia in homes relatively shut to TV transmitters(ii). Meanwhile, there has been a controversial move to have the existing Australian radiations standard loosened by a factor of five in gild 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 ground for such standards in terms of what laboratory or other results have been relied on for setting standards. The relative energy of radiations 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 about the standard or less; are they meaningful? The paper concludes with a suggested arroyo to experimental work which may help usa to determine whether Australian and world standards are soundly based or non.

The Electromagnetic Spectrum - Radiofrequency Range

For an agreement of the issues involved, it is necessary to have some knowledge of the range and nature of the electromagnetic radiations (EMR) spectrum. Electromagnetic radiation may exist thought of in terms of waves in air which transmit energy merely can also be modulated (controlled) through amplitude, pulsing, etc. to transmit speech, TV images and and so on. These waves have a range or spectrum of frequency expressed in hertz, i.e. cycles per 2d. At the higher frequencies we accept kilohertz, megahertz and gigahertz. The greater the frequency, the shorter the wavelength and the greater the free energy transmitted.

A significant division within the EMR spectrum is the frequency at about ten one thousand thousand 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, 10-rays and gamma radiations 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 textile (DNA). Too much sunlight, as well many 10-rays or besides much exposure to the gamma-radiating isotope cobalt-threescore can cause cancer.

That role of the EMR spectrum of concern in this paper is non-ionising and is known equally 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 free energy, waves from AM radio, FM radio, TV (very loftier and ultra high frequency), mobile phones, law radar, microwave ovens and satellite stations.

All electromagnetic radiation involves an oscillating electrical field and a magnetic field. Whereas at the extremely low frequency end of the spectrum (e.m. AC electric current at 50 or 60 hertz) the 2 fields can be measured and considered separately, in the radiofrequency spectrum they are measured together. The intensity ('power density') of the combined fields tin can be readily expressed in terms of a power unit relative to expanse (due east.g. watts per square centimetre) which denotes the electric and magnetic fields as a multiple. Assimilation of electromagnetic radiation energy by living organisms tin 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 almost the source of radiation (the principle of the microwave oven) every bit wave energy is converted to heat energy on contact with the cells. This is known as a thermal event. Nonetheless, considering 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 fugitive thermal effects (come across below).

Thermal Effects of Radiofrequency EMR - Relation to Standards

The thermal or heating effects of radiofrequency radiations (including microwaves) on living organisms are well known, they are dose-related and they are mostly reproducible. These crucial characteristics take been regarded by many scientists as justifying the choice of thermal furnishings as a powerful and single ground for determining health standards. The post-obit 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 aquiver very rapidly (moving ridge frequency), the water molecules are rapidly swinging i way so some other in sympathy, thus generating heat. Some biological molecules are also influenced by applied electric fields.

Exposure of people to a dose of radiofrequency radiations of less than almost four watts per kilogram body weight is idea to give rise to an increase in torso temperature of less than 1o Centrigrade and can be reasonably well tolerated for curt periods. College induced temperatures are not tolerated, nonetheless, and have several well-known deleterious effects, depending on the precise location of radiation assimilation. An issue observed at RF intensities sufficient to raise the rectal temperature of an experimental creature by 1o C or more is classified as thermal in nature. Such furnishings could be induced by any method designed to raise body temperature.

• Firstly, the skin can detect RF radiation only the awareness is much less than that from infrared radiation and is extremely dependent on frequency which determines penetration. In the range 0.5-100 gigahertz, pare detection is not regarded every bit a reliable warning mechanism.
• Heat effects on encephalon tissue are thought to exist the reason why people can actually hear pulsed radiofrequencies between 200 megahertz and half-dozen.5 gigahertz. The sound is described as 'buzzing, clicking, hissing or popping'.
• Thirdly, the eyes are felt to be particularly sensitive to RF radiation. Lens tissue has no blood supply to act as coolant, there is footling self-repair at that site and thus damage and impairment products tend to accumulate. At a threshold of almost 41o C, exposed laboratory rabbits show cataract germination. Further work needs to be washed 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 partitioning pattern of germ cells.
• Fifthly, the thermal disruption of behaviour by RF radiation, e.k. task learning and short term retention, has been demonstrated in the rat. Effects were observed at doses between 0.half dozen and 8 watts per kilogram.
• Sixthly, the circulatory and immune organisation in rodents shows some alterations in response to RF radiation. For example, claret 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 eleven watts per kilogram of RF radiation caused abnormalities and death of embryos. So long as there is a temperature increment of at least 2.5o C, birth defects can be expected to occur.

Information technology has already been observed that RF standards are based on the prevention of thermal effects since these are well accepted in the scientific customs and are by and large reproducible. Two standards will be mentioned hither, namely, the American National Standards Institute/American Institute of Electric and Electronic Engineers (ANSI/IEEE) Standard C95.ane-1991 and the Australian Standard 2772.1-1990 (Standards Commonwealth of australia). Both are designed for the RF/microwave spectrum (100 kilohertz to 300 gigahertz).

ANSI ability density limits for members of the public vary within the RF range from a low of 0.2 milliwatts per foursquare centimetre (mW/square cm) at 100 megahertz to a high of 10 mW/square cm from virtually x gigahertz. The ANSI standard at the frequency used for Australian mobile phones (800-m megahertz) is slightly less than ane mW/square cm.

Australian Standard 2772.one-1990 lists a constant limit of 0.two mW/foursquare cm (equal to 200 microwatts/square cm for members of the public at frequencies between 30 megahertz and 300 gigahertz. Thus, at Australian mobile phone frequencies our national standard is about five times stricter than the ANSI standard.

Equally is the case for many other US standards, the ANSI determination is influential here and in that location is a stiff motility for the Australian standard to be loosened past a factor of five in order to represent to ANSI'southward limit. It is therefore important to exist able to assess the ground of ANSI reckoning on RF safety.

According to the CSIRO, the US arroyo to its standard has been to consider thermal effects of RF radiation but, and to regard behavioural changes in experimental animals as the most sensitive of those effects. In contrast to ionising radiations, where adverse effects on people are well documented, RF furnishings on humans are inadequately described, which explains the need for animate being results. Of course this raises the immediate question: tin can experimental animals, specially small animals, provide an adequate model?

Since it is ever necessary to dose not-man primates with more than than 4 watts per kilogram body weight for behavioural effects to announced, this has been taken past ANSI as the official threshold for humans. Equally mentioned earlier, 4 watts per kilogram is also the approximate threshold for human tolerance of the heat generated. A tenfold and a fifty-fold safety factor has been practical to the threshold for occupational and non-occupational exposure limits and the respective ability density figure worked out. Thus, the five-fold stricter Australian (non-occupational) standard is 250 times (i.e. 50x5) below the experimental creature threshold for thermally induced behavioural changes.

Energy of RF Radiation from Tv set and Mobile Phone Towers

In this paper it has been necessary to describe RF standards and their basis in some detail in order to appraise emissions of radiation from TV and mobile phone towers. Notation that both telecommunications carriers and broadcasting stations are required to adhere to Australian Standard 2772.1-1990.

Television towers have a much higher power rating-and thus give out more than intense radiations- than mobile phone towers. For instance, the Tv set transmitter on height of Blackness Mountain, Canberra, is rated at 300 kilowatts. A typical mobile telephone tower is emitting only about twenty watts, i.e. 15 000 times weaker. Maybe fortunately, nigh large TV towers are situated on hilltops which are relatively far from housing. Information technology is the occasional exception, for example, on Sydney'southward North Shore, that deserves special attention.

Since radiations from both TV and mobile phone towers is not directed vertically downwards, there is not a simple relationship between the tower-observer distance and the strength of electrical and magnetic fields combined as EMR. Take firstly the example of mobile phone towers. Between 0 and 10 metres from a digital mobile phone tower, levels of exposure are approximately the same. The level of radiation peaks at between 100 and 150 metres, intensity values ranging from 0.i up to ane.0 microwatt/foursquare cm, depending on how many telephones are in utilize at the time (notation that one microwatt equals one-thousandth of a milliwatt). Further away than 10 metres, radiation intensity falls off apace, approximating the 'changed square' law. Radiation from analogue mobile phone towers is slightly more than intense, peaking at iv-vi microwatts. These figures have been supplied by the Australian Radiation Laboratory.

In comparison with the Australian Standard(3) (200 microwatts/square cm), a power density level of 6 microwatt/foursquare cm from a mobile phone tower (said to be a maximum value) represents only 3% of the value of the maximum allowable power density. A more typical effigy of 0.ane microwatt/foursquare cm is but 0.05% of the standard.

Turning to larger TV circulate towers, a person standing one kilometre away would expect to exist exposed to a power density of five-10 microwatts/foursquare cm of radiations. At ii kilometres this reduces greatly to about 0.five microwatt/square cm. These figures are withal far less than the prescribed limit of 200 microwatts/square cm.

Dr Bruce Hocking, a former Telstra medical director, has presented findings in a recent consequence of The Medical Periodical of Australia(4) linking leukaemia incidence with proximity to TV towers . Radiations levels of 8 microwatts/square cm were cited near the towers, decreasing to 0.two microwatts/foursquare cm at a radius of 4 kilometres and 0.02 microwatts/square cm at a radius of 12 kilometres.

In summary, children under 15 years of age living in three Sydney suburbs within four kilometres of Television set towers (N Sydney, Willoughby and Lane Cove) appear more likely to suffer from leukaemia than similarly aged children from Ryde, Kuringai and Wahroonga, localities more distant from TV towers. The information was retrieved from the NSW Cancer Registry(five) between 1972 and 1990. A similar type of study found increased levels of cancer in Honolulu, Hawaii, among people living near TV towers(6).

Dr Hocking stresses that his results are preliminary only they show that further research is warranted. The association between TV towers and cancer is certainly not proven but tin be regarded as 'hypothesis-generating'. Dr Hocking also regards the results as unexpected considering the measured radiation levels (up to 8 microwatts/square cm) are and then far below the Australian Standard of 200 microwatts/square cm.

Opposition to mobile phone towers placed near houses can only increase in response to this preliminary finding of a cancer link in respect of TV transmitters. People tend to feel that sites near to schools are particularly undesirable because children are exposed throughout the day, yet have no selection in the thing and derive no do good. This is in spite of the fact that mobile phone towers are of very low power. Mobile phone users take a much greater exposure to radiation but at least they get the benefit of the calls too as being able to control their exposure past shortening conversations.

What is the RF exposure from personal mobile phone use as compared with exposure to a mobile telephone belfry? As described above, such towers radiate very small power densities of not more than about six microwatts but more typically 0.1 microwatt/square cm at close range. Past contrast, an analogue phone is said to generate a power density of 0.27 milliwatts/square cm at a altitude of five centimetres. This can be calculated as betwixt 45 and 2700 times greater than radiation intensity from a mobile phone tower. Much discussion has centred on the actual dose to the head resulting from normal apply of an counterpart or digital phone. In terms of power density, however, the radiations generated is clearly of the same society of magnitude as ready out in the Australian Standard for members of the public. This suggests that there may be some pressure level from manufacturers of mobile phones to accept the Australian Standard relaxed somewhat.

Non-Thermal Effects of RF Radiation

There are three levels of ability densities (watts/square centimetre readings) in relation to heating effects on tissue. They are:

• High ability densities, more often than not greater than 10 milliwatts/square cm, at which distinct thermal effects predominate (equally listed before in this paper).
• Medium ability densities, between 1 and 10 milliwatts/foursquare cm, where weak merely noticeable thermal effects exist, and
• Low ability densities, below one milliwatt/foursquare cm (the Australian upper limit for occupational exposure) where thermal effects do not appear to exist just other furnishings have been reported.

This department of the newspaper deals with the claimed not-thermal effects which accept been reported at low and medium power densities, and discusses the reasons why these furnishings have been discounted, rightly or wrongly, as a ground for Australian and overseas standards.

Possible behavioural changes or indirect promotion of cancer is a master focus of low-power radiofrequency (microwave) studies. As stated earlier, the RF spectrum is non energetic enough to cause mutation damage to cell genetic material (Dna) and thus directly initiate cancer. However, among the hundreds of reports of RF effects there are some which tin be interpreted as possibly assisting the spread of cancer.

Firstly, some experiments (e.g. Ref. vii) accept indicated radiations-caused changes in the so-called claret-brain bulwark. The healthy brain is an exclusive organ which does non admit entry of many types of chemic and biochemical substances. The enquiry has measured abnormal passage across the blood-brain bulwark of protein-spring dyes, radioactively labelled sugars or peroxidase enzyme in irradiated rats and hamsters.

Secondly, there are examples of disturbances to foetal development (teratogenic effects) in mice, chicks and rats at depression RF power. Retarded development (low birth weight), eye malformations, reduction in organ weight and embryonic decease have been observed.

Experiments with RF radiation and cultured cells are idea by some scientists to demonstrate low power (non-thermal) effects on the prison cell membrane. The best-known work, that of Professor Ross Adey, has shown a consequent increase of calcium loss from encephalon tissue. This indicates that the membrane permeability has been changed. Calcium is known to be a highly significant biochemical regulator, eastward.1000. it controls the sectionalization of certain cells. The RF waves may be creating free radicals or irresolute the concrete characteristics of fats in the jail cell membrane.

Non-thermal treatment which increases the rate of division of prison cell lines or increases cancers in whole animals is of particular interest. Lymphocytes, a line of white claret cells, accept been reported to proliferate more quickly under what are claimed to be non-thermal conditions of irradiation. Spontaneous mammary cancers and artificially induced lung and skin cancers in mice take been said to increase nether low ability RF radiation practical over varying periods up to x months. Some other written report has establish that the number of spontaneous cancers in irradiated rats increases significantly.

The above examples, plus many others in the scientific literature, are sufficient to agitate concern over possible health consequences of not-thermal RF irradiation in the same range of intensity or less than Australian and overseas standards. Why and so are non-thermal effects disregarded in the current standards?

The truth is that there is no scientific consensus on non-thermal furnishings, and the literature overall reveals a highly unsatisfactory land of affairs. The effects listed above represent the most positive results; nonetheless, lack of confirmation is a chronic trouble. Many laboratories simply cannot replicate the results of others, and negative results are difficult to have published. One of the difficulties with this blazon of enquiry is that the experimental variables, e.g. radiations frequency, orientation, method of modulation, etc. are numerous and very few scientists seem to try difficult plenty to standardise others' experimental conditions. Also, experiments which are claimed to be not-thermal can exist judged to involve local temperature changes or irrelevant stress conditions. Non-thermal effects are oftentimes not dose-dependent and therefore lack scientific credibility. Lastly, in that location is notwithstanding no universally accepted physical or chemic mechanism to explain how RF radiation can interfere with animal metabolism apart from heating effects. For example, the function of the magnetic component as distinct from the electrical field component, if any, tin can but be guessed at.

Government Responses

At the Federal level there is a committee and a plan dealing with radiofrequency radiations and health.

The Commission on Electromagnetic Energy Public Health Problems is located in the Department of Communications and the Arts. It is fabricated up of representatives from that Section, the Department of Health and Family Services, The Australian Radiations Laboratory, the Spectrum Management Agency, the Therapeutic Appurtenances Administration, AUSTEL and the CSIRO. The Commission'southward function is to coordinate the $4.v one thousand thousand Radiofrequency Electromagnetic Energy Plan announced by the Government on 15 October 1996. The Program has three parts, namely:

• public education on radiofrequency health issues
• Australian participation in a Earth Wellness Plan
• the setting upward of a research program in Australia.

With regard to the research program, the Committee is preparing a priorities newspaper which is intended to be released for public discussion. When the priorities are finalised, it will exist the responsibility of the National Wellness and Medical Research Council (NH&MRC) to manage the enquiry, in the offset case past calling for specific proposals.

Under the circumstances, the all-time arroyo for the NH&MRC would be to encourage good quality research at low power (non-thermal) radiation levels. Much more than scientific effort has to exist invested in making the RF field respectable. While there is no convincing evidence as yet that low ability RF sources such equally mobile phone towers can increase the incidence of cancer, some caution is warranted given that existing health standards are based on rather narrow criteria, and that cancers often have a long lead fourth dimension (as for instance, with asbestos and mesothelioma). Since the sum of less than $4.5 million for inquiry volition not make it, a small levy on every mobile telephone sold would help to speed upward our understanding in this area.

References

1. Barnett, Due south. B. CSIRO Study on the Condition of Enquiry on the Biological Effects and Safe of Electromagnetic Radiation: Telecommunications Frequencies. CSIRO Division of Radiophysics, June 1994.

2. Hocking, B., Gordon, I. R., Grain, H. L. and Hatfield, G. E. Cancer incidence and mortality and proximity to TV towers. Med. J. Aust. December 1996, p. 601.

3. Australian Standard AS 2772.1 Radiofrequency Radiation Part 1: Maximum Exposure Levels-100kHz to 300 GHz. Sydney: Standards Australia, 1990.

four. Hocking et al., loc. cit.

5. HealthWiz. National health database. Republic Department of Homo Services and Wellness. 1991-1996. Canberra: Prometheus Pty Ltd, 1996.

6. Maskarinec, G., Cooper, J. and Swygert, L. Investigation of increased incidence in childhood leukaemia near radio towers in Hawaii: preliminary observations. J. Environ. Pathol. Toxicol. Oncol. 1994: 13:33.

7. Salford, L.G., Brun, A., Eberhardt, J. L., Malmgren, L. and Persson, R.R. in: Interaction Mechanism of Depression-Level Electromagnetic Fields in Living Systems. C. Ramel and B. Norden, eds. Oxford University Press, 1992.

Back to top

---

gregoryunrarken.blogspot.com

Source: https://www.aph.gov.au/sitecore/content/Home/About_Parliament/Parliamentary_Departments/Parliamentary_Library/Publications_Archive/CIB/CIB9697/97cib26