Recommendations from the BfS for making telephone calls on mobile phones

Mobile communications use high-frequency electromagnetic fields to transmit information. Mobile phones generate these fields directly by the head when making telephone calls without using hands-free equipment. According to current knowledge, the internationally recommended limit values are sufficient to protect the user from proven health risks.

There are uncertainties in the risk assessment that the German mobile communications research programme has not been able to remove completely. These include in particular:

• possible health risks of the long-term exposure of adults to high frequency electromagnetic fields when making mobile telephone calls (intensive mobile use over more than 10 years)
• the question of whether the use of mobile phones by children could have an effect on health.

Due to these scientific uncertainties, the BfS recommends to reduce individual exposure to electromagnetic fields for precautionary reasons.

Tips when using a mobile phone

The electromagnetic fields that occur close to the body when using a mobile phone are generally a great deal stronger than the fields encountered for example around mobile communications base stations. The recommendations of the BfS therefore relate to the use of mobile phones. They aim to reduce the strength (intensity) of the high frequency fields and to shorten the duration of exposure:

• Use a landline if you have a choice between landline and mobile telephone.
• Keep mobile telephone calls as short as possible.
• If possible, do not make calls when you have poor reception, for example in a car without an external aerial. The poorer the connection to the nearest base station, the greater the signal that the mobile phone must emit – and therefore the strength (intensity) of the high frequency field. The car chassis for example worsens the connection and the mobile phone therefore transmits with a higher output.
• Use mobile phones that subject your head to the lowest intensity fields. The lower the SAR value (specific absorption rate) of your mobile phone, the lower the field intensity. The SAR value of available mobile phone models can be found in the SAR list. Mobile phone manufacturers usually indicate the SAR value under prescribed conditions in the instruction manual. Corresponding information can often be found on the websites of mobile phone manufacturers.
• Use headsets. The intensity of the fields drops rapidly with increasing distance from the antenna. Using a headset greatly increases the distance between head and antenna. The head is therefore subject to lesser fields during telephone calls.
• Make use of text messages, as then the mobile telephone is not held to the head.

These recommendations simply and efficiently minimise personal radiation exposure without forgoing the advantages of mobile phones. Of particular importance is the minimisation of children’s radiation exposure as they are still developing and could therefore react more sensitively in terms of health. The BfS therefore recommends restricting children's use of mobile phones as far as possible.

Electronic implants

Electronic devices can react more sensitively than the human body to high frequency radiation. An example is an implanted pacemaker, which under adverse conditions can be interrupted in its function. Interference effects from mobile phones have been observed on individual pacemakers at a distance of maximum 20 cm between the devices. Those fitted with cardiac pacemakers should guard against this and not keep their mobile phones directly by the upper body, i.e. for example not carry it in standby mode in their jacket pocket. At the usual distance of more than 20 cm between mobile phone antenna and pacemakers, normal telephone use has no effect on the cardiac pacemaker.

Hearing aids

Noise interference can occur when hearing aids are used close to mobile communications devices. The recommendation here is to keep your distance or switch off the hearing aid when making a call yourself!

In hospital

Problems can also occur through mobile phone use in hospitals; occasionally, sensitive medical equipment can suffer interference even at a distance of 1 to 2 metres. Take care to ensure sufficient distance from sensitive medical electronic equipment - in particular in intensive care wards and operating theatres. Mobile communications bans in hospitals are therefore to be strictly adhered to.

In aircraft

To avoid interference to onboard electronics, the use of mobile phones during flights must be restricted (Article 27, Para. 3 of the Air Traffic Act). In Germany it is usual to prohibit their use during take off and landing. During the flight however, the airline can enable the use of mobile phones.

In the car

The prohibition of the use of mobile phones without hands-free equipment when driving is justified by the associated distraction of the driver. As a distraction occurs even when hands-free equipment is used, making calls while driving should be avoided as far as possible.