1.  What is electromagnetic energy?

Electromagnetic energy consists of waves of electric and magnetic energy radiating through space, and travelling at the speed of light. The area where these waves are found is called an electromagnetic field. The main source of electromagnetic energy is the sun, but man-made sources account for large amounts of the electromagnetic radiation in our day-to-day environment. Items such as hairdryers, electrical ovens, fluorescent lights, microwave ovens, stereos, wireless phones and computers produce electromagnetic fields of varying intensities.

2.  How is electromagnetic energy measured?

Electromagnetic energy is measured in units of wavelength and frequency. The wavelength is the distance that a wave travels in one cycle and is measured in metres. The frequency is measured by the number of cycles per second and the unit of measurement is the Hertz (Hz). One cycle per second equals one Hertz. One kilohertz (kHz) is 1,000 Hz; one megahertz (MHz) is one million Hz; one gigahertz is one billion Hz. The frequency of a wave is inversely related to its length - at 50 Hz the wavelengths are 6,000 Km, and at 100 MHz they are 3 metres. Electromagnetic fields are arranged according to their frequencies in an orderly fashion in what is known as the electromagnetic spectrum.

3.  What is radiofrequency radiation?

Radiofrequency (RF) fields are part of the electromagnetic (EM) spectrum. The EM spectrum is divided into ionizing and non-ionizing bands based on how the wave interacts with biological tissue.

The non-ionizing portion, usually in the frequency range up to 300 GHz, doesn't affect biological tissue and includes the extremely low frequency (ELF) band, radio waves and microwaves in the radiofrequency communication band, and infrared and visible light. The RF part of the spectrum is usually defined as being between 30 kHz and 300 GHz. RF radiation is mainly used in telecommunications. Mobile phones employ frequencies in the range of 800 MHz to 2GHz. Other uses of RF energy include microwave ovens and medical treatments.

The ionizing portion of the EM spectrum (made up of ultraviolet light, gamma rays and X-rays that have very short wavelengths, very high frequencies, and very high intensities) does affect biological tissue. Mobile phones do not operate in this spectrum. For more on this, see "Primer".

4.  Do electric power lines produce radiofrequency radiation?

Extremely low frequencies (ELF) are from 0 to 300Hz, and include those arising from power lines, which are at 50/60 Hz. They also originate from electrical wiring in buildings and from electrical appliances. Radiofrequencies (RF) are in the range 30 kHz to 300 GHz. Mobile phones operate in the approximate range of 800 MHz to 2GHz. These differences in frequencies result in very different interactions with tissues. Strong ELF fields can cause nerve and muscle cell stimulation. Strong RF fields can heat tissues.

The WHO states that "the only way ELF fields interact with living tissues is by inducing electric fields and currents in them. However, the magnitude of these induced currents from exposure to ELF fields at levels normally found in our environment is less than the currents occurring naturally in the body" (WHO Fact Sheet 205).

Some epidemiological studies have suggested an association between the occurrence of leukaemia in children and living near power lines or being exposed to magnetic fields in the home, but the findings are inconclusive.

5.  Are x-rays the same as radiofrequency radiation?

X-rays have enough energy to cause ionization, that is, break the bonds that hold molecules, thus creating positive and negative electrically charged atoms. Therefore x-rays have the potential to disrupt DNA, the building blocks of cells of the body. As a result, excessive doses of x-rays can cause adverse effects, including cancer. Radiofrequency radiation is different, in that it does not cause ionization.

6,  How is radiofrequency radiation measured?
The measurements used depend on whether the source of energy is remote from or near to the person exposed to the radiation. In situations where the person is more than several wavelengths from a RF source, power density is used. This is defined as the rate of energy flow through a given surface area, and it is measured in watts per square metre. When the person is close to the RF source, as when using a wireless phone held to the head, the Specific Absorption Rate is used.

7.  What is Specific Absorption Rate?

Energy absorption from radiofrequency fields in the frequencies used by mobile phones is measured by the specific absorption rate (SAR) within the tissue. It is defined as the rate of energy absorption per unit mass, and is measured in watts per kilogram.

Governments or governmental agencies in individual countries have established the maximum permissible SAR values for wireless phones. For more on this, see the section on "Specific Absorption Rate". There you will find a link to the web site of the Mobile Manufacturers' Forum. On this site there is a health issues section that includes SAR information on many cell phone models.

8.  What are the safe limits for radiofrequency radiation in humans?

Health Canada issued Safety Code 6 in 1991, which specified the limits of exposure to radiofrequency fields at frequencies 10 kHz - 300 GHz. The limit for the general population for whole-body average SAR is 0.08 W/kg. Safety standards in several other countries such as the USA, United Kingdom, other European Community countries, Australia and Japan recommend very similar limits to those outlined in Safety Code 6. For more, see "Phones - Exposure Limits".

9.  Does radiofrequency radiation have biological effects?
Radiofrequency radiation (RFR) is non-ionizing. This means it cannot break molecules and directly disrupt DNA, the building block molecule of genetic material in the body. However, RFR at sufficiently high power can cause the conversion of energy into heat, a concept that is used in microwave ovens. While non-ionizing radiation may be too weak to cause direct damage to biological material, it may cause biological effects through the creation of thermal (the heating of tissues) mechanisms. These thermal mechanisms are well established, and are used to set guidelines restricting occupational and general exposure to radiofrequency fields. Effects that can occur in humans when the body, or part of it, is sufficiently heated by RFR include a decreased mental ability, opacity of the eye, and various physiological responses to heat.

10.  Is radiofrequency radiation harmful?

The World Health Organization (WHO) has stated that "although hazards from exposure to high level (thermal) radiofrequency fields were established, no known health hazards were associated with exposure to radiofrequency sources emitting fields too low to cause a significant temperature rise in tissue." Biological effects from low-level radiofrequency exposures were identified as needing further study.

An Expert Panel of the Royal Society of Canada said "To date, human health studies have examined the relationship between exposure to radiofrequency fields and different types of cancer, reproductive problems, congenital anomalies, epilepsy, headache and suicide. Overall, these studies do not provide conclusive evidence of adverse health effects from radiofrequency exposure. However, given the limitations of the currently published studies in this area, particularly the difficulty in determining the precise nature of the exposure to radiofrequency fields that people have actually received, more research is required on radiofrequency field exposure and human health."

The Independent Expert Group on Mobile phones in the UK (May, 2000, page 3) stated that "the balance of evidence to date suggests that exposure to RF radiation below NRPB and ICNIRP guidelines do not cause adverse health effects to the general population."

11.  Does radiofrequency radiation cause cancer?

Several expert groups have made statements on this subject. In 1996, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reviewed health issues related to mobile phone use and base transmitters. The ICNIRP report stated that the results of epidemiological and laboratory studies relevant to cancer do not form an adequate basis for limiting human exposure to wireless phones. At an international seminar in Munich in 1996 sponsored by WHO, ICNIRP and others, expert working groups concluded that, "from the current scientific literature, there is no convincing evidence that exposure to RF shortens the life span of humans, induces or promotes cancer."

In addition, an Expert Panel of the Royal Society of Canada stated "The level of evidence, and the limitations of the studies to date, do not support a conclusion that exposure to RF fields of the type and intensity produced by wireless telecommunication devices contributes to the development of tumours."

For more on this subject see "Research - Laboratory Experiments - Cancer", and "Research - Epidemiology".

12.  Does radiofrequency radiation cause genetic damage?

An Expert Panel of the Royal Society of Canada stated "although some investigations have suggested that RF fields may damage DNA, most studies conducted to date in this area have been negative."

The Independent Expert Group on Mobile Phones in the UK said: "Several different assays of genotoxicity have failed to produce clear evidence that RF radiation is genotoxic at non-thermal levels".

For more on this, see "Research - Laboratory Experiments -cancer -genotoxicity"



13. Are some individuals hypersensitive to electromagnetic fields?

Some individuals report health symptoms that they relate to exposure to EMF. These effects have been termed electromagnetic hypersensitivity (EHS). On occasion these effects can have profound effects on the individuals' way of life. They complain of a variety of non-specific symptoms, which vary from person to person, and include general complaints like tiredness and dizziness, as well as skin, digestive, and other symptoms. There are more reports of EHS in Scandinavian countries than elsewhere. Provocation studies almost all have shown that individuals with EHS cannot detect EMF exposure any more accurately than non-EHS individuals. A WHO workshop on EHS in Prague in 1994 concluded that: "The symptoms are certainly real and can vary widely in their severity. Whatever its cause, EHS can be a disabling problem for the affected individual. EHS has no clear diagnostic criteria and there is no scientific basis to link EHS symptoms to EMF exposure".

For more information on the subject, see WHO's web site at www.who.int/peh-emf/en/ and search for "Electrical hypersensitivity".

The web site of the Committee on Man and Radiation of the Institute of Electric and Electronic Engineers also has a useful report on electromagnetic hypersensitivity. This can be accessed at http://ewh.ieee.org/soc/embs/comar/ or through "Links".

For more on this subject, see "Research-Clinical-Other".

14.  What is a wireless phone?

A wireless phone is a two-way radio. It has both a receiver and a transmitter. When a user makes a call, the voice sound is converted to radiofrequency energy and is transmitted to the nearest base station. Hence, a wireless phone exposes the user to small amounts of radiofrequency energy because of the short distance between the phone and the head. Wireless phones are also called mobile phones because they are hand-held and do not use wires and cables like conventional phones. (However, they are different from "cordless" phones that have a base unit connected to the telephone wiring system. These operate at very low power levels). Wireless phones are also called cellular or cell phones, for reasons that are explained in FAQ #21.

15.  How much power does a wireless phone produce?

Older systems used an analogue means of transferring information. These have gradually been replaced by systems in which the information is transferred digitally. This method is used in GSM phones (Global System for Mobile Communications). This standard is now used in many parts of the world. For instance it is also used in the PCS (Personal Communications Services) mobile phones. The maximum power that GSM phones are permitted to transmit by the present standards are 2W (900 MHz) and 1W (1800 MHz). However, the average powers transmitted by a phone are never more than one-eighth of these maximum values (0.25 W and 0.125 W respectively). (Independent Expert Group on Mobile Phones, page 31 - www.iegmp.org.uk ).

Cordless phones operate for short distances between a phone socket outlet and the cordless phone handset. The average power emitted is about 0.01 W.

16.  Do wireless phones have any harmful effects in humans?

Most reviews have concluded that there is no evidence that wireless phones have any adverse effects. However, they also conclude that RF radiation in the wireless phone range may produce biological effects, and that more research is needed. It is important to note the difference between biological effects and adverse effects due to exposure to electromagnetic fields. Biological effects are detectable changes that occur in an organism, tissue or cell. They may or may not be harmful to the organism. They may even be advantageous, as in the case of sunlight acting on skin cells to produce vitamin D. Adverse effects are harmful or detrimental to an organism and occur when the organism is unable to compensate for biological effects.


17.  Do wireless phones cause brain cancer in humans?

This is examined under Reseach - Epidemiology - Cell Phone Studies. All of the studies except that of Hardell and colleagues showed no association between wireless phones and brain cancer. Hardell's 2000 study showed a slightly increased risk of tumours on the same side as the phone was used, but this was based on small numbers and was not supported in the studies by Inskip and Muscat. His 2002 study, which led to 2 papers in 2002 and 2 more in 2003, showed similar findings. There was no risk for malignant tumours, but an increased risk for benign tumours. This latter finding was due to the increased risk for acoustic neuroma.


Acoustic neuroma is a tumour of the auditory nerve, and is also known as acoustic neurilemoma or vestibular schwannoma. It is a benign tumour and has slow growth. Its incidence is in the range of 1 - 20 per million population per year (Christensen 2004). It manifests itself by hearing loss, dizziness, and tinnitus (a ringing in the ears). There have been a number of studies that have examined the association between this tumour and cell phone use, and these are summarised below. Most have very few cases that have used cell phones for 10 years or more. Hardell's study is unusual in that an increased risk was reported in those with > 5 years use. Studies of acoustic neuroma are summarized under Reseach - Epidemiology - Cell Phone Studies


18.  Do wireless phones affect brain function?

Some research suggests that RF radiation in the cell phone range may have subtle effects on brain wave patterns as seen on electroencephalograms (EEGs), on sleep, and cognitive function. The results, however, have not been consistent. There is no evidence that RF radiation in the cell phone range causes adverse effects on brain function in humans. As a result, the effects of cell phones on brain function continue to be an area that requires further research. For more information, see "Research - Clinical".


19.  Do wireless phones cause headaches or other general health effects?

The list of alleged health outcomes associated with the use of wireless phones includes headaches, memory loss, fatigue, and other subjective symptoms. None of these has been proven to be due to the electromagnetic field (EMF) generated by the phone. Controlled experiments have not been able to show an increased incidence of these symptoms in those exposed to the EMF from a phone, compared to those sham-exposed. This result was even seen in one study that used subjects who felt that they were hypersensitive to EMFs. For more, see "Research - Clinical - Other".

The web site of the Committee on Man and Radiation of the Institute of Electric and Electronic Engineers has a useful report on electromagnetic hypersensitivity. This can be accessed at www.seas.upenn.edu/~kfoster/comar.htm or through "Links".

20.  Should children use wireless phones?

There is no evidence from research studies that children are at particular risk of harmful effects as a result of use of a wireless phone. There are different views on whether or not children absorb more radiation than adults do when using a wireless phone. Some of these studies have been discussed in the "What's New" section of our web site, in September '03, March '04, and April and July '05. Another report, by Keshvari and Lang, compared radio frequency energy absorption in the ear and eye region of children and adults at different frequencies. These authors state:

"Our study and most of the previous theoretical studies indicate that there is no systematic difference in the RF energy absorption between child and adult heads".

The Independent Expert Group in the UK, however, recommended in 2000 that the widespread use of mobile phones by children for non-essential calls should be discouraged. This was a precautionary recommendation only and the Group acknowledged that it was not based on scientific evidence of increased risk. On the other hand the Health Council of the Netherlands in its 2002 report stated "there is no reason to recommend that mobile telephone use by children should be limited as far as possible".

A Workshop, sponsored by WHO and other agencies, was held in June 2004, on "Sensitivity of Children to EMF Exposure". It was concluded that there is no direct evidence that children are more vulnerable to EMF, but more research needs to be done.

This topic is also reviewed in the following paper: Lin JC. Mental process of children and mobile-phone electromagnetic fields. Radio Science Bulletin #316 (March ’06). This can be found at www.ursi.org


21.  What is a wireless phone base station?

A wireless phone base station receives and transmits radio signals in its area. This area is called a cell - this is why wireless phones are sometimes called cell or cellular phones. As the phone user moves around, the radio signal can be switched from one cell to another, maintaining a good connection. The call is connected with the local phone network and delivered by phone lines, using a ground based antenna, or when the call is going to another wireless phone, by radio signals. Base stations need to be high up, so they are often located on towers or rooftops. The antenna may be like a pole or like a rectangle.

22.  How much radiation does a base station produce?
The power output is measured in watts, and is about 1,000 times less than is produced by a television transmitter. Maximum powers radiated from the antenna at the top of the mast are in the region of 60 watts. The power density (strength) decreases rapidly with distance. Base stations have limited beams of radiation that intersect with the ground a considerable distance away from the antenna tower - usually between 50 and 200 metres from the foot of the mast. Outside this small beam there is no radiation at all.

The total power output of a typical base station depends on the type of antenna, the number of channels that operate at a given time and at their maximum strength, and the antenna gain which gives the signals direction and strength. The power output is less when the base station is close to the phone user. Hence, base stations are being placed closer together, to make it simpler for a phone and a base station to communicate reliably.


23.  Is a base station dangerous to people living nearby?
Independent expert groups around the world have stated that there is no risk to the general public from base stations. The World Health Organization, for example, stated: "None of the recent reviews have concluded that exposure to the radiofrequency fields from mobile phones or their base stations causes any adverse health consequence".

An Expert Panel of the Royal Society of Canada said "it appears that exposure of the public to radiofrequency fields emitted from wireless telecommunication base station transmitters is of sufficiently low intensity that biological or adverse health effects are not anticipated".

The Independent Expert Group on Mobile Phones in the UK said "there is no general risk to the health of people living near to base stations where the exposures are only small fractions of guidelines".

In Canada a survey of five Vancouver schools, conducted in response to parental concerns about safety, showed levels of radiofrequency radiation many times below established safety limits. In the UK, the NRPB took measurements at 118 locations of public access near base stations and found that the maximum exposure was 0.023% of their guidelines. In 2001 the Radiocommunications Agency, a government agency in the UK, undertook an audit of mobile phone base stations with a focus on those sited on schools. The audit surveyed 101 sites and recorded emissions "typically many thousands of times below" the guidelines of the International Commission on Non-Ionizing Radiation Protection.

24.  Who regulates the level of radiation from base stations?
Each country has its own regulatory system. In Canada, Industry Canada requires that all operators of radiofrequency transmitters ensure that electromagnetic fields produced by installations do not exceed maximum levels contained in Canada's Safety Code 6. In the USA the Federal Communications Commission (FCC) performs this function, and in the UK it is the National Radiological Protection Board (NRPB).For further regulations in your country, see the web site of the World Health Organization International EMF Project. This is found at www.who.int/peh-emf . Follow the links to the EMF Worldwide Standards database.

 

 



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