1. How is radiation protection in the vicinity of mobile base stations guaranteed?

2. How are limit values determined?

3. What limits apply for mobile phones?

4. How can mobile phone users reduce their personal radiation exposure?

5. What is the SAR value?

6. Are there any problems when using a mobile phone in a car?

7. Is it permitted to use mobile phones in hospitals?

8. Should people with pacemakers use mobile phones?

9. Is it true that the use of mobile phones can cause cancer?

10. Are there any reasons for concern in connection with cordless phones?

1. How is radiation protection in the vicinity of mobile base stations guaranteed?

In order to protect the public from adverse effects, the exposure of the human body to high frequency electromagnetic fields used for mobile telecommunication is restricted by law.

The operators of mobile phone base stations are responsible for compliance with the legal limit values. Compliance with relevant limit values is necessary for mobile phone base stations to be approved. If an installation exceeds the maximum transmitter power of 10 Watts EIRP (EIRP is an operand used to describe the antenna’s irradiation properties), the operator has to apply to the German Federal Network Agency (Bundesnetzagentur) for a site authorisation. Such a site authorisation includes the determination of a distance to the antenna that needs to be kept for compliance with the limit values.

According to the current state of knowledge, if legal regulations are adhered to, no adverse health effects from high frequency electromagnetic fields are expected, even in case of a permanent daily exposure. This statement also applies to possibly sensitive persons such as pregnant women, children and sick people. The distances from mobile phone base station antennas needed for compliance with the limits are usually between 1 and 10 meters (in the main radiation direction of the antenna). You will find further information (in German only) on the approval procedure for mobile phone base stations here.

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2. How are limit values determined?

According to the current scientific knowledge, which is regularly reviewed by national (e.g. the German Commission on Radiological Protection, SSK) and international (e.g. the International Commission on Non-Ionizing Radiation Protection, ICNIRP) expert groups, scientifically established adverse health effects are due to a temperature increase in tissue. In consideration of sensitive persons such as pregnant women, children, the elderly and the sick and of scientific uncertainties as well, the threshold value of the specific absorption rate above which health effects are proven, current SAR limit values have been reduced by factor 50 and therefore for whole body exposure a basic limit of 0.08 Watt/kg was recommended. Absorption of high frequency energy in the body may be very inhomogeneous. Thus, in special situations very high SAR values in certain organs can result even if the basic limit for whole body exposure is nor exceeded. To prevent excessive local absorption, SAR limits for partial body exposure have been established (2 W/kg for head and torso, 4 W/kg for limbs).

SAR values can only be determined using elaborate procedures, therefore, in many cases derived, easily measurable physical quantities, the electric and magnetic field intensities for compliance testing with regard to the whole body SAR are used instead. Limit values for electric and magnetic field intensities are defined in the 26. Ordinance on the Implementation of the Federal Pollution Control Act (26. BImSchV). No SAR limits are defined in this Ordinance.

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3. What limit values apply to mobile phones?

The mobile phones’ antennas emit high-frequency energy – usually in the immediate vicinity of the head.

The maximum energy absorption in the head must be limited in order to avoid adverse health effects. It must not exceed the partial body limit of the “specific absorption rate” (SAR) of 2 Watts per kilogram (2 W/kg, averaged over 10 grams of tissue) – as recommended by the German Commission on Radiological Protection. All mobile phones sold in Germany must comply with this limit value. Usually the manufacturers provide the SAR value of each phone in the instruction manual and on their website. You will find a list of SAR values for the available mobile phones on the BfS’ websites. The BfS recommends using mobile phones whose SAR value is as low as possible. In order to receive the environmental label “Blue Angel”, established in June 2002, which is awarded to mobile phones with particularly low radiation, a mobile phone must not exceed a SAR value of 0.6 W/kg and must comply with a series of other criteria (see also "Precaution regarding electromagnetic fields“).  

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4. How can mobile phone users reduce their personal radiation exposure?

The high-frequency electromagnetic fields which are produced when using mobile phones are often much stronger than the fields people are exposed to from mobile phone base stations in their vicinity. Therefore, BfS considers it especially important to minimise as far as possible the intensity of the fields mobile phone users are exposed to. The following recommendations may be helpful:
Use a fixed network telephone if you have the choice.
Use mobile phone headsets. The field intensity decreases strongly with the distance to the antenna. A headset serves to increase the distance between the head and the antenna of the mobile phone so that the user's head is exposed to lower fields during phone calls.
Preferably do not make phone calls if the reception is poor. The mobile phone's transmitting power depends on the quality of the connection to the next base station. The car body, for example, can affect the connection so that the mobile phone's transmitting power is increased.
Only make short calls with your mobile phone.
Send text messages. The mobile phone is in greater distance from the head and the fields the head is exposed to are lower.
Wait until the connection has been established. The GSM mobile phone uses maximum transmitting power while connecting. Do not hold the mobile phone to your ear while you are waiting for the connection to be established. This is not valid if mobile phones are using the UMTS network. In that case they start with minimum transmitting power and increase it if necessary.
Use a mobile phone with a low SAR value which exposes the user's head to lower fields. The smaller the field intensity, the less energy is deposited in the human tissues. Information is available from the manufacturers or at the webpages of BfS.

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5. What is the SAR value?

The specific absorption rate (SAR) is a measure for the energy absorbed by the body. The SAR value specifies the power (energy per time unit) which is absorbed per kilogram of tissue and is expressed in Watt per kilogram (W/kg). To determine the whole body SAR value, exposure is averaged over the whole body and the partial body SAR value (which plays a role, e.g., when using a mobile phone) is averaged over ten grams of tissue. In both cases the SAR is averaged over a time interval of 6 minutes.

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6. Are there any problems when using a mobile phone in a car?

For reasons of road safety, using a mobile phone while driving is only permitted when using a hands-free set.  However, even when using a hands-free set, you are recommended to make no or only short phone calls while driving hence contributing towards increased road safety.

When using a mobile phone in a car without an external antenna the field distribution in the vicinity of the phone can be extremely inhomogeneous. The intensity of the electromagnetic field inside the car depends, among others, on the construction of the phone, the characteristic of the mobile network, the form of the car body as well as the materials inside the car. As a result of frequent handovers between mobile phone base stations while the car is moving as well as the partially shielding from the metallic car body, mobile phones frequently must use increased or maximum transmitting power in order to maintain the necessary connection with mobile phone base stations. In addition reflections of the electromagnetic waves within the car may lead to a localised intensification of the electromagnetic field. The field intensities produced by a mobile phone can therefore be higher inside a car than outdoor. However, there are no indications that limit values are exceeded in such situations.

When using an external antenna the passengers in the car are only exposed to very low field intensities. Therefore, whenever possible, mobile phones with an external antenna should be used in a car, to reduce personal radiation exposure. By the way, mobile phones where the external antenna can be connected directly to the phone via a plug-in connection are particularly recommended. This means that the transmitting antenna inside the phone is nearly completely switched off.

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7. Is it permitted to use mobile phones in hospitals?

The use of mobile phones in hospitals can result in a possible interference of high frequency electromagnetic fields with different electronic devices. Malfunctions of sensitive medical equipment at a distance of 1 or 2 meters have been observed.

It is often difficult to control the behaviour of the large number of visitors to hospitals. It is therefore left to the discretion of the hospital management to take measures aimed at preventing malfunctions of sensitive medical equipment and thus at preventing potential consequences for the patients’ health. This is frequently done by completely prohibiting the use of mobile phones. Since the interference of mobile phones with medical equipment cannot be excluded, corresponding instructions in hospitals have to be obeyed strictly.

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8. Can people with pacemakers use mobile phones safely?

It cannot be excluded that mobile phones interfere with the functioning of pacemakers. The user should therefore maintain a distance of at least 20 cm between the mobile phone and the pacemaker. Pacemaker patients can safely use mobile phones, although they should not have their phone ready for use in the breast pocket directly above the pacemaker.

Adverse health effects are not expected from the use of cordless phones (DECT phones) even at distances of less than 20 cm between the phone and the pacemaker as the cordless phone’s transmitting power is much lower than that of a mobile phone.

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9. Is it true that the use of mobile phones can cause cancer?

The prevailing topics of current research programmes include projects which seek to clarify whether a connection exists between cancer incidence and high frequency electromagnetic fields. Since exposure of the head is highest when using a mobile phone,  the question of an increased brain tumour risk as a result of mobile phone use plays a special role.

During recent years a large epidemiologic study with international participation, the so-called INTERPHONE study, was carried out on this subject. The German subproject was funded within the scope of the German Mobile Telecommunication Research Programme (DMF). For a time period of usage of less than 10 years no increased risk for brain tumours, acoustic neuroma (benign tumour of the acoustic nerve) or ocular tumours was observed. Due to the long latency period of cancer and the comparably short-term use of mobile communication technology by the general public reliable conclusions on long-term health effects over a period of more than 10 years cannot be drawn yet. Therefore this question is further examined.

The Federal Office for Radiation Protection calls for further research in this field in order to clarify existing scientific uncertainties. In particular with regard to long-term effects of intensive mobile phone usage where no sound information is available, people should keep the exposure to electromagnetic fields as low as possible.  As the exposure to the head is higher when using a mobile phone compared to the exposure to mobile phone base stations recommendations of BfS relate especially to the reduction of personal radiation exposure when using a mobile phone (see "Recommendations of the Federal Office for Radiation Protection on mobile phone use" (in German only).

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10. Are there any reasons for conern with regard to the use of cordless phones?

Cordless phones used in home and garden (with a range of up to 300 m) transmit the voice from the fixed line network via a radio link to the handset. The frequency band used is 1800 to 1900 Megahertz (MHz). The devices in use today apply the so called DECT Standard (Digital Enhanced Cordless Telephone). The maximum transmitter power of 250 mW for DECT systems (base station and handset) is rather low compared to mobile phones (maximum transmitter power 1000 mW), which operate on a similar frequency (around 1800 MHz). Due to the technique used, i.e. the time division multiple access system, the average power radiated by a DECT device amounts to a maximum of 10 mW. This leads to a maximum specific absorption rate (SAR) of less than 0.1 W/kg, which is far below the maximum value for energy absorption in the head recommended by the German Commission on Radiological Protection (partial body SAR limit of 2 W/kg, averaged over 10 grams of tissue). In contrast to mobile phones there is no power control for DECT systems, i.e. the base station and handset of many such devices always use the same transmitter power, regardless of whether the user is 1 m or 250 m away from the base station. Moreover the base station of many cordless phones permanently sends control signals to the handset/s even in stand-by-mode. Handsets, however, only send during phone calls. There are no scientifically proven health risks when using these devices even for possibly sensitive persons.

Irrespective of the fact that according to the current state of knowledge the DECT technology does not lead to negative health effects, it is always advisable to minimise the personal radiation exposure. This can for example be achieved by avoiding permanent exposure in the immediate vicinity of DECT base stations. Base stations should not, e.g., be operated in children’s rooms, bedrooms or right on the desk. If you wish to reduce exposure of your head to electromagnetic fields, try making only short phone calls with the handset or use a fixed telephone.

In the meantime ‘conditionally low-radiation’ DECT phones have become available where the control signal from the base station to the handset is shut off or its transmitter power is severely reduced in stand-by mode. For some devices this is only valid as long as only one handset is registered and remains in the base station. Some devices also reduce the transmitter power of the handset when the distance between base station and handset is small. In addition, for some devices the base station’s transmitter power can be regulated manually. (see "Cordless phones with low EMF radiation levels"  (in German)).

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