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.
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.
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
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".
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
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.
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.
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.
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.
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".
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.
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
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."
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
For more on this subject see "Research
- Laboratory Experiments - Cancer", and "Research
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
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
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".
on this subject, see "Research-Clinical-Other".
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.
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
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.
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
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
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
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".
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:
and most of the previous theoretical studies indicate that there is
no systematic difference in the RF energy absorption between child and
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
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.
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
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.
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
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.