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Source document:
SCENIHR (2007)

Summary & Details:
GreenFacts (2008)

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Electromagnetic Fields


 
Glossary Terms

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 EC Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) has updated the previous opinion on “Possible effects of Electromagnetic Fields (EMF), Radio Frequency Fields (RF) and Microwave Radiation on human health” by the Scientific Committee on Toxicity, Ecotoxicity and the Environment (CSTEE) from 2001, 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 2007 by EC Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR):
"Possible effects of Electromagnetic Fields (EMF) on Human HealthLearn more...

 

1. Introduction to electromagnetic fields

1.1 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.

Most man-made 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 lines.

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 direct current. More...

1.2 Exposure to electromagnetic fields triggers immediate biological effects if they are strong enough. Effects range from stimulation of nerves and muscles to heating of the body tissues, depending on the frequency. Exposure guidelines have been established to protect against these effects. More...

 

2. What are the sources of exposure to radio frequency (RF) fields?

Local wireless computer networks generate radio 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 radio frequency fields. Radio frequencies range from 100 kHz to 300 GHz.

When exposed to radio frequency fields, the body absorbs energy over time. How much radio frequency energy an individual absorbs every day is not obvious as the exposure depends on many factors, especially distance from the various sources. Field strength 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. More...

2.1 Europe has set safety limits on exposure to radio frequency 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. More...

2.2 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. People who live or work near transmission towers are most exposed because that is where the fields are strongest. More...

2.3 In medicine, strong radio frequency 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. More...

 

3. Can mobile phones cause cancer?

More than 2 billion people use mobile phones worldwide
More than 2 billion people use mobile phones worldwide
Credit: Juha Blomberg

3.1 In recent years many studies have investigated whether mobile phones and radio frequency (RF) fields in general could cause cancer. 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 less than 10 years. More research is needed before a risk can be ruled out for use beyond 10 years.

Some studies have raised concern of a link between mobile phone use and benign tumours of the auditory nerve, which is responsible for balance and hearing. People who have been using mobile phones for less than 10 years do not appear to have a higher risk of this benign tumour (acoustic neuroma). But there is some evidence of a risk beyond 10 years, and more study is needed. More...

3.2 Animal studies have provided no consistent evidence on whether radio frequency fields could induce cancer, enhance the effects of cancer-causing substances, or accelerate the development of tumours. But most of these studies involved relatively low exposure, calling for more research. More...

3.3 In recent years, research on how radio-frequency energy affects cells has expanded to include more kinds of cell cultures. Overall such studies show little evidence of health-relevant effects when exposure is below existing safety guidelines. But some studies suggest effects on DNA at exposure levels close to guidelines. More...

 

4. Can mobile phones or base stations trigger headaches or other health effects?

Mobile phone base station
Mobile phone base station
Credit: Pyb

4.1 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 electromagnetic energy.

Present knowledge suggests that these symptoms are not linked to exposure to radio frequency fields, but few studies have addressed this issue directly. More...

4.2 Because mobile phones are used near the head, there have been concerns they could affect the brain.

Minor changes in the brain functions of people exposed to radio frequency fields have been observed in some studies but not in others. Suspicions that radio frequency fields could affect memory and learning have not been confirmed.

Conflicting results were reported on whether low levels of radio frequency fields increase the permeability of the barrier that keeps harmful substances from reaching the brain (blood-brain barrier). More...

4.3 Research on female health workers exposed while on the job revealed no harmful effect on pregnancies. More...

4.4 Few studies have addressed the possible effects of mobile phones on children, despite concern that children could be more vulnerable than adults and will get more exposure over their lifetimes. One area for investigation would be whether radio frequency fields can cause childhood brain tumours. More...

 

5. Conclusions on mobile phones and radio frequency fields

Few studies have looked at effects on children
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.

No health effect has been consistently demonstrated at exposure levels below existing guidelines for the general public. Some studies suggest an increased number of cases of benign tumours of the auditory nerve (acoustic neuroma) could be linked to long-term mobile phone use, but overall results are not conclusive at the present time.

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 skull. This also appears to be the case for someone who has used a mobile phone for more than 10 years, but more study is needed.

Research has found no evidence that exposure to radio frequency fields at levels below existing safety guidelines could cause symptoms like headaches and dizziness.

Few studies have looked at possible health effects on 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. More...

 

6. Intermediate frequency fields like those from computer screens and anti theft devices

Cathode ray tube screens generate intermediate frequency
							fields
Cathode ray tube screens generate intermediate frequency fields
Credit: Anissa Thompson

6.1 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. More...

6.2 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. The few studies conducted have focused on potential effects on the eyes, the cardiovascular system, cancer, and reproduction. More...

6.3 Long-term studies on human populations are needed to evaluate the risks to human health and to confirm that the current recommended limits on exposure are adequate. More...

 

7. Extremely low frequency fields like those from power lines and household appliances

Power lines generate ELF fields
Power lines generate ELF fields
Credit: Miguel Saavedra

7.1 Extremely low frequencies (ELF) are those below 300 Hz. Such fields are for instance generated by alternating current (AC), the type of electricity used in most power lines, wiring and appliances. Other important sources of extremely low frequency fields are power plants, welding machines, induction heaters as well as trains, trams and subway systems.

Extremely low frequency 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. More...

7.2 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 below 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.

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 cancer. More...

7.3 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 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 cell cultures. More...

7.4 No relation has been demonstrated between extremely low frequency fields and self-reported symptoms such as fatigue, headache, and concentration difficulties. More...

7.5 For some other diseases, notably breast cancer and 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. More...

 

8. Static magnetic fields like those used in medical imaging

MRI scanners use static magnetic fields
MRI scanners use static magnetic fields
Credit: Kasuga Huang

8.1 Static magnetic fields such as those generated by a permanent magnet do not vary over time, and as such do not have a frequency (0 Hz).

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 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 patient. More...

8.2 Evidence is insufficient for drawing conclusions about potential health effects. Static magnetic fields can exert small forces that result in changes in the orientation or position of biological molecules and cellular components with magnetic properties. They can also exert forces on, and affect the functioning of, implanted devices like pacemakers. More...

8.3 Adequate data for risk assessment of static magnetic fields are almost totally lacking. The advent of new technology, and in particular MRI equipment, makes this a priority for research. More...

 

9. What is known about environmental effects of electromagnetic fields?

Migratory birds rely on magnetic fields for orientation
Migratory birds rely on magnetic fields for orientation
Credit: Michael Hatherly

A few studies looked at effects of electromagnetic fields on certain plants and animals, either in the laboratory or near overhead power cables. More...

9.1 Some animal species might be particularly sensitive to electromagnetic fields generated by manmade equipment. Migratory birds, for instance, rely on magnetic fields for orientation and sharks possess electric sense organs. More...

9.2 The few studies on how electromagnetic fields may affect the environment focused on extremely low frequency fields like those generated by overhead power cables. They mostly considered plants – not species that might be particularly sensitive to electromagnetic fields. More...

9.3 There are insufficient data to determine whether a single exposure standard is sufficient to protect all environmental species from electromagnetic fields or to judge whether standards for animals and plants should differ from those for humans. Good quality data are needed on species that are expected to be among the most sensitive to electromagnetic fields. Long-term monitoring of relevant species and ecosystems may be valuable to assess the potential of electromagnetic fields to influence human health. More...

 

10. What comments were expressed on the findings of this assessment?

The public was invited to comment on this assessment by the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR).

While interesting, many of the comments addressed aspects that were beyond the task of this assessment.

Certain comments showed that some sentences or paragraphs could be misinterpreted and that the wording did not accurately reflect the viewpoint of the working group or the SCENIHR. In those instances the text was revised accordingly.

Other than that, none of the comments received during the public consultation process led to changes in the overall conclusions or in the opinion. More...

 
 

11. Conclusions on electromagnetic fields

For many of the possible health effects the data available are still very limited, especially for long-term low-level exposure. More...

11.1 New scientific evidence does not call for a revision of the exposure limits to radio frequency fields. There is some indication of a link between long-term mobile phone use and a benign tumour of the auditory nerve (acoustic neuroma), but more study is needed. Self-reported symptoms like headaches, fatigue, or concentration difficulties have not been linked to exposure to radio frequency fields. To date no epidemiologic studies on children are available, even though they may be more sensitive than adults to radio frequency fields from mobile phones. More...

11.2 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 due to new technologies. More...

11.3 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 . These results have not been confirmed or explained by experiments on animals and cell cultures. In European countries, the proportion of children exposed to such levels is less than 1%. Whether recommended exposure limits ought to be changed is a risk management decision.

No consistent relationship between self-reported symptoms and extremely low frequency fields has been demonstrated. More...

11.4 New applications of strong static magnetic fields will require risk assessments for people who use the new technology at work, as for instance operators of MRI scanners. More...

11.5 The data on how electromagnetic fields may affect animals and plants are insufficient to determine whether a single exposure standard is appropriate for all plants/animals and whether the standards for animals and plants should differ from those for humans. More...

11.6 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. More...


The Three-Level Structure used to communicate this SCENIHR Opinion is copyrighted by GreenFacts asbl/vzw.