» Electromagnetic Fields
Electromagnetic Fields 2009 Update
Context - Safety limits have been set by the European Union for the protection of workers and
the general public against the effects of mobile phones and other electromagnetic
fields. Are these safety limits adequate in the light of recent scientific evidence?
The Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) of the European Commission has updated its 2007 opinion on "Possible effects of Electromagnetic Fields (EMF) on Human Health", with respect to whether or not exposure to electromagnetic fields (EMF) is a cause of disease or other health effects.
The answers to these questions are a faithful summary of the scientific opinion produced in 2009 by the Scientific Committee on Emerging and Newly Identified
Health Risks (SCENIHR): "Health Effects of exposure to Electromagnetic Fields (EMF)" Learn more...
GreenFacts was contracted to prepare this summary by the DG Health and Consumers of the European Commission, which authorised its publication. See this publication on europa.eu
.Text copyright© DG Health and Consumers
of the European Commission.
- Source document:SCENIHR (2009)
- Summary & Details: GreenFacts
1. Introduction to electromagnetic fields
Electromagnetic fields are a
combination of invisible electric and
magnetic fields of force. They are
generated by natural phenomena, but also by human activities, mainly
through the use of electricity.
electromagnetic fields reverse
their direction with time at a specific frequency, ranging from high
radio frequencies (RF) – such as used by mobile phones – through
intermediate frequencies (IF) – such as generated by computer screens –
to extremely low frequencies (ELF) – such as generated by power
The term static refers to fields that do not vary with time. Static
magnetic fields are used in medical
imaging and generated by appliances using
The present SCENIHR opinion uses the most recent scientific findings
to assess whether exposure to
electromagnetic fields may increase
the risk of some
adverse health effects. It considers
both potential effects on groups of people who have been exposed to
electromagnetic fields in their daily lives
(epidemiological evidence) and
potential effects observed in laboratory experiments carried out on
human volunteers, animals, and
cell cultures (experimental
2. What are the sources of exposure to radio frequency fields?
Local wireless computer networks generate radio fields
Credit: Ramzi Mashisho
Radio frequency (RF) fields have many applications in modern
communications. Familiar sources include mobile phones, cordless phones,
local wireless networks and radio transmission towers. Medical scanners,
radar systems and microwave ovens also use RF fields. Radio frequencies
range from 100 kHz to 300 GHz.
When exposed to RF fields, the body absorbs energy from them.
Evaluating how much RF energy an individual absorbs every day is not
obvious as the level of exposure depends on many factors, especially
distance from the various sources and duration of exposure. Field
strength or the amount of energy the field transmits, falls rapidly with
distance, meaning a person may absorb more energy from a device used at
close quarters – a handheld mobile phone, for example – than from a more
powerful source, like a radio transmission tower, that is farther away.
The European Union has set safety limits on exposure to RF fields. For
handheld mobile phones, these limits are given in terms of the energy
absorbed by the head, the part of the body most exposed during use.
Other wireless devices used in close quarters, like cordless phones and
wireless computer networks, also generate radio waves but exposure from
these sources is generally lower than from mobile phones.
Mobile phone base stations and radio transmission towers
are structures designed to support antennas that transmit radio signals.
Because the field strength decreases rapidly with distance, most people
are exposed to only a fraction of the maximum recommended limit. People
who live or work near transmission towers are most exposed because that
is where the fields are strongest.
In medicine, strong RF fields are used to heat body
tissue, which can ease pain or kill cancer
cells. Such fields are also used to
produce images of the brain and other body parts by
magnetic resonance imaging
(MRI). Exposure of patients or
medical staff could exceed the usual safety limits for the general
3. Can mobile phones cause cancer?
More than 2 billion people use mobile phones worldwide
Credit: Juha Blomberg
In recent years many studies have investigated whether mobile phones
and radio frequency (RF) fields in general could cause
Epidemiological studies on mobile
phone users have focused on cancers
originating in the head, especially brain
tumours. Overall, research indicates
that mobile phone use does not increase the risk of cancer, especially
when used for less than ten years. Findings from published studies in
the ongoing Interphone project, which pools data from 13 countries,
supports that finding. More research is needed to establish whether or
not there is a risk associated with long term mobile phone usage well
beyond ten years.
Animal studies that investigated if RF fields could induce
cancer, enhance the effects of
cancer-causing substances, or accelerate the development of
tumours found no or no consistent
effects when the study was repeated. Recent studies have used higher
field strengths than previous ones, without any further effect.
Overall, research on how RF energy affects
cells grown in the laboratory shows
little evidence of health-relevant effects when exposure is below the
one that causes a warming effect. Some studies suggest effects on
DNA at exposure levels close to
guideline limits, but there is little agreement between studies, and the
significance of the effects observed remains unclear.
Few users have had mobile phones for more than ten years, which makes
it difficult to investigate the
cancer risk of longer term use.
Different biological effects have been investigated in
cell cultures, but so far no
mechanism that might lead to cancer
could be found for radio frequency fields below the recommended safety
limit for exposure from mobile phones.
4. Can mobile phones or base stations trigger headaches or other health effects?
Mobile phone base station
Some people attribute headaches, fatigue and dizziness to radio
frequency (RF) fields. Such complaints have raised concern that certain
individuals may be more sensitive than others to
Present knowledge suggests that these symptoms are not linked to
exposure to radio frequency fields, but to a “nocebo” effect, an effect
caused by the expectation or belief that something is harmful.
Because mobile phones are used near the head, there have been concerns
they could affect the brain.
There is some evidence that radio frequency exposure might influence
brain activity or sleep. However, the health relevance of these results
is uncertain and how this may occur is not yet explained. Further
investigation of these effects is needed.
Many studies on development and reproduction in animals have shown
that radio frequency fields can cause birth defects at levels well above
safety limits, when the exposure is high enough to warm up the
tissue significantly, but not at
lower exposure levels. Recent studies have looked into potential effects
on the development of animals before birth and on the fertility of men
who work near strong radio field sources. However, it is not possible to
draw conclusions from these studies because of methodological
Few studies have addressed the possible effects of mobile phones on
children, despite concern that children could be more
vulnerable than adults because
their nervous systems are still
developing, their brain tissue is
more conductive, and their heads might absorb more energy from mobile
phones. Also, children who start using mobile phones will have a greater
lifetime exposure than people who were adults when they began using
5. Conclusions on mobile phones and radio frequency fields
Few studies have looked at effects on children
Extensive research has been conducted in recent years on how radio
frequency fields, including those generated by mobile phones, might
affect health. A variety of possible effects has been studied, both
inside the laboratory and among human populations.
Research indicates that a person who has used a mobile phone for up to
10 years does not have a higher risk of brain
tumours or other
cancers in the head. This also
appears to be the case for someone who has used a mobile phone for more
than 10 years, but few persons have used mobile phones for longer than
Research has found no evidence that exposure to radio frequency fields
at levels below existing safety guidelines could cause symptoms like
headaches and dizziness. New data suggests the existence of a “nocebo”
effect, an effect caused by the expectation or belief that something is
harmful. Few studies have looked at possible health effects in children,
despite the growing popularity of mobile phones among the young and
concern that children might be more
vulnerable because of their still
developing nervous system.
6. Intermediate frequency fields like those from computer screens and anti-theft devices
Cathode ray tube screens generate intermediate frequency fields
Credit: Anissa Thompson
In this assessment, “intermediate” refers to frequencies ranging
from 300 Hz to 100 kHz. These are
lower than radio frequencies and higher than extremely low frequencies.
Technologies generating intermediate frequency fields have increased
in recent years and include some anti-theft devices, induction
hotplates, cathode ray tube screens and radio transmitters. Intermediate
fields are also used by medical devices, and are generated by industrial
processes such as welding.
Well-known biological effects in the intermediate frequency range are
nerve stimulation at the lower end of the range and heating at the upper
end of the range. Few data are available on the exposure of individuals
to intermediate frequency fields and on possible health effects. Since a
growing number of workers are exposed to intermediate frequency fields,
it is important that research on possible health effects is given
7. Extremely low frequency fields like those from power lines and household appliances
Power lines generate ELF fields Credit: Miguel Saavedra
Extremely low frequencies (ELF) are those
below 300 Hz. Such fields are for
instance generated by the
alternating current (AC) used in
most power lines, wiring and appliances. Other important sources of ELF
fields are the generators used in power plants, welding machines,
induction heaters as well as trains, trams and subway systems.
ELF fields have electric and magnetic components. ELF
electric fields are particularly
strong close to high voltage power lines, and ELF
magnetic fields are particularly
strong near induction furnaces and welding machines.
In the areas that are accessible to the public, exposure to extremely
low frequency fields is below the set limits. When people pass directly
below a high voltage power line, their level of exposure to such fields
is relatively high, though still within safety limits. Low voltage power
lines cause much lower exposure, and buried cables virtually none. At
home, fields are strongest very near electric appliances such as vacuum
cleaners, when in use.
Workers in the electric power industry and welders can be exposed to
high levels of
electromagnetic fields, and
adequate safety measures are needed. Some medical applications also make
use of extremely low frequency fields, for instance to stimulate bone
growth, to treat pain, or to detect
There is some evidence that ELF
magnetic fields can cause
cancer in humans but it is far from
conclusive. This was concluded based on studies indicating that children
exposed to relatively strong ELF magnetic fields from power lines
(although still well below safety limits) were more likely to develop
leukaemia than those exposed to
weaker fields. These results have not been confirmed or explained by
experiments on animals and
No relation has been demonstrated between extremely low frequency
fields and self-reported symptoms such as fatigue, headache, and
concentration difficulties. For other suspected effects, there is a need
for targeted laboratory studies on
cell cultures to examine if and how
extremely low frequency fields act on cellular components.
For some other diseases such as cardiovascular diseases, recent
research indicates that a link to extremely low frequency fields is
unlikely, but further study is needed on how they may affect the brain
and spinal cord.
8. Static magnetic fields like those used in medical imaging
MRI scanners use static magnetic fields
Static magnetic fields such as
those generated by a permanent magnet do not vary over time, and as such
do not have a frequency
Man-made static magnetic fields
are generated wherever electricity is used in the form of
direct current (DC), for instance
in some rail and subway systems, in aluminium production and in welding.
In medicine, MRI
(Magnetic Resonance Imaging)
scanners use static magnetic fields to provide three-dimensional images
of the brain and other body parts. In this application the exposure can
exceed the usual recommended limit, both for the MRI operator and the
Evidence is insufficient for drawing conclusions about potential
health effects. Static
magnetic fields can have an effect
on biological molecules and
cellular components with magnetic properties such as
haemoglobin, and on those with
electric properties like brain
Data for risk assessment of
static magnetic fields are still
inadequate, and the effects of mixed fields, where static fields
interact with other
electromagnetic fields, are still
largely unknown. A number of new technologies, such as
MRI equipment, are using
combinations of different fields, which makes this a priority for
9. What is known about environmental effects of electromagnetic fields?
Migratory birds rely on magnetic fields for orientation
Credit: Michael Hatherly
Field studies on individual animal and plant species living in close
proximity to sources of
electromagnetic fields provide
information on possible effects on ecosystems.
Past field studies have mainly focused on wild birds and on potential
effects on reproduction and orientation. Though some new study results
have recently been published, overall, the current database is
inadequate for the purposes of the assessment of possible risks due to
environmental exposure to Radio, Intermediate and Extremely-low
Several studies indicate that exposure of wild birds to radio
frequency fields can, under certain circumstances, lead to changes, for
instance in behaviour, reproductive success, or growth and development.
However, the changes observed are not consistent. A possible explanation
of observed effects is that radio frequency fields discourage some bird
species and encourage others or affect the insects they feed on. Other
factors such as pollution might play a role.
The possible effects of extremely low frequency fields on reproduction
have been studied in birds of prey living around overhead power lines,
but findings vary widely, and no clear overall conclusion can be drawn.
Afield study observed a reduction of the biological activity in the soil
surrounding a buried electricity transmission cable, but the
environmental significance of this finding is unclear.
Studies on plants have shown that ELF
magnetic fields can promote the
growth of certain plant species.
10. Conclusions on electromagnetic fields
There is no evidence that exposure to radio frequency fields through
the use of mobile phones increases the risk of
cancer when used for a period of up
to 10 years, and data are still too limited to conclude on the use of
mobile phones over longer periods. Self-reported symptoms like
headaches, fatigue, or concentration difficulties have not been linked
to exposure to radio frequency fields, but may be due to the
individuals’ expectation that such exposure is harmful. Information on
potential effects of radio-frequency fields on children is still
Because data for the intermediate frequency fields are sparse, the
assessment of health risks of short-term exposure to high levels of
intermediate frequency fields is currently based on known biological
effects at lower and higher frequencies. Proper assessment of possible
health effects from long-term exposure is important because exposure to
such fields is increasing, especially at certain workplaces, due to the
use of new technologies.
The past conclusion that extremely low frequency
magnetic fields are possibly
carcinogenic is still valid. This
was concluded based on studies indicating that children exposed to
relatively strong magnetic fields from power lines were more likely to
develop leukaemia. New studies on
human populations indicate a possible increase in Alzheimer's disease
arising from exposure to extremely low frequency fields. The results
related to leukaemia and Alzheimer’s have not been confirmed or
explained by experiments on animals and
cell cultures. Further research on
cells is needed to examine effects
on specific diseases.
No consistent relationship between self-reported symptoms and
extremely low frequency fields has been demonstrated.
New applications of strong static
magnetic fields, used alone or in
association with other fields, will require risk assessments for people
who use these new technologies at work, as for instance operators of
The data on how
electromagnetic fields may affect
animals and plants are insufficient to assess possible risks due to
environmental exposure to radio frequency, intermediate frequency and
extremely low frequency fields.
To fill the important gaps in knowledge, research efforts are
recommended, notably on long- term exposure and effects on children and
personnel dealing with equipment generating strong fields.