Mobile phones and health 

The radio signals will cause a certain increase of temperature in liquids, which is what our body largely consists of. The rate of this increase will depend on the intensity and frequency of the radio signals. Radio signals from a cellular phone have a favourable frequency and the intensity is very low. Even at maximum effect, the radio signals from the mobile phone will never raise the temperature by more than 0.1 degrees, an increase that cannot be registered by human beings. Batteries, however, and in particular the amplifying chip in the mobile phone, will heat up during long periods of use. The phone is constructed in such a way as to lead heat away from this chip and distribute it evenly all over the handset. If you hold any warm object to your ear, you will feel a warm sensation. The pressure against your ear ensures that the bloodstream around the ear is altered (your skin turns red when something is pressed against it). Since your blood temperature is higher than that of the skin surface, this will feel like a slight increase in the temperature in your ear. This heat is not created by radio signals.

Occasionally, people report various health problems such as headaches, aching muscles or skin irritations, which they ascribe to exposure to electromagnetic fields such as radio signals. Various kinds of equipment are identified as possible sources of such afflictions, including power lines, antennas, PCs or TV screens, electric cookers and/or mobile phones. This type of sensitivity to electromagnetic fields is described as a form of allergy, and is often referred to as electromagnetic hypersensitivity. However, research and blind tests have failed to establish any connection between the reported afflictions and exposure to electromagnetic fields. The WHO has prepared a fact sheet about electromagnetic hypersensitivity. For more information, please refer to the WHO website.

Research does not indicate that children’s use of mobile phones involves any added health risk. It is, however, not possible to provide irrefutable evidence that mobile phone use is 100 per cent risk-free. Although the research in this field is at an advanced stage, extensive new research is being carried out in certain areas of focus. Meanwhile, both national and international health institutions have adopted a precautionary approach to children’s use of mobile phones. The is because children’s brains are in a development phase, and previous research from other areas has shown that children are more influenced by the environment. To rule out any possible negative effects, although no such effects have ever been documented, certain precautionary measures could be introduced for children, such as:

• Using an earplug and a cable (hands-free equipment)

• Avoiding long calls

• Sending messages rather than calling

If you do not own such hands-free equipment, it is recommended that the mobile phone is used outdoors in densely populated areas where there is good mobile coverage. The mobile handset will then emit much weaker signals.

The WHO has introduced a means of measuring and a unit of measurement for radio signal from mobile phones. This standard is called SAR (Specific Absorption Rate). In practice, the exposure from mobile phones is measured by placing finely tuned sensors inside an artificial head, made to resemble a human head. The mobile phone is at the same time attached to the head’s artificial “ear” while it emits signals at full strength.

In this way, it is possible to measure the SAR, which is the total radio signal exposure that can be measured during a mobile phone call. The SAR is measured in Watts/kilogram. The WHO has introduced a limit of 2 Watts per kilo of human tissue. All mobile phones currently available at sales outlets must be SAR tested, and the test results shall be printed on the product packaging or in the user manual. Today’s mobile phones normally have a SAR of between 0.5 – 1.2 W/kg. Most major phone manufacturers (e.g. Apple and Samsung) publish their phones’ SAR values.

The limit values for radio signal exposure are issued with a wide safety margin with respect to health hazards and have a safety factor of 50. This means that the human body will endure a strain that is 50 times higher than the limit value.

The quality of the mobile coverage is the deciding factor when it comes to how strong a signal your mobile phone emits. The more “bars” you see on the phone, the better the mobile coverage is and the less power the mobile phone will need to use to stay connected. The SAR limit described in the above question (2 Watt/kg) is applicable where the mobile coverage is weak, and the mobile signals are transmitted at maximum strength to reach the closest mobile antenna. In most situations, the mobile phone will reduce its transmitting power significantly, as the nearest mobile antenna is likely to be fairly close. If the coverage is excellent, the mobile phone may reduce its output power level by as much as 99.9 per cent.

In principle, no. The mobile phone ensures that the signals sent are not stronger than required to reach the nearest antenna. If you want to keep the signal strength at a minimum, you will benefit from calling from an area that has good mobile coverage. You should be aware that metal handset cases, un-original antenna capsules, etc. might block the radio signals from the mobile phone’s antenna. If this happens, the mobile phone will increase its transmitting power to compensate for the loss of signal due to metal blocking radio signals.

No. Even though 4G and 5G will transmit larger quantities of digital information, such as live images, the signals from these handsets will be less than with the 2G system. This is because the 3G, 4G and 5G phones’ transmitting power is weaker than from 2G phones. Users will also more often hold a 4G or 5G smartphone in front of them rather than directly against their ears. Available phones today have a maximum transmitting power of 0.25 Watts. The phone will check whether it is possible to reduce this transmitting power 1500 times per second. As a result, the phone will always choose the weakest signal required for maintaining contact with the mobile network.

For a given monthly data volume, 4G and (even more so) 5G phones will have lower radio signal strength than older phones. The higher data speeds in newer generations will reduce the time it takes to send a given data volume. Hence, exposure time goes down relative to older phones. When a smartphone is used for uploading of data it will operate at full strength (0.25 Watts) but only during the short periods when the actual data transfer happens and only to ensure the swiftest possible transfer. When the phone is used to send data it will rarely be placed next to the ear, and the exposure will be less than during a regular phone call.

Users should be aware that inside every new handset there is also a 2G phone that is used as backup for the 3G, 4G or 5G signals in areas that have no 3G, 4G or 5G coverage. When the phone is used in areas without such coverage, it will send the same signals as a regular 2G phone.

All new mobile phones comply with the WHO’s requirements for maximum exposure when placed directly against users’ ears. The intensity of the radio signals is greatly reduced with distance. The margins up to the recommended limit value (see the above question “How do you measure the signal strength from mobile phones?”) will therefore be even higher when the distance between the mobile phone and the body increases. Radio signal exposure will be reduced to approximately 1/100 (i.e. a 99 per cent reduction) of its original amount if the mobile phone is held at a distance of 50 cm from the body. For daily use, the earplug and cable will represent the best solution if you want minimum radio signal exposure.

All mobile phones that are “on” will send short messages to the mobile network at intervals (approximately once every hour when the mobile handset is stationary, more often when the handset is moving fast, e.g. when in a car). The reason for this is that the mobile network must receive information of where your mobile phone is at all times. These messages typically last for three seconds or less. This procedure is called signalling. The transmitting power of such signalling will correspond to the mobile coverage that exists in the area. Modern smartphones are likely to have programs (apps) installed that send and receive signals from the internet at intervals, typically of a duration of 1-5 seconds. The more apps, the more such update messages are sent. In many cases, users can regulate the frequency of such traffic. When the mobile phone is set in flight mode, no radio signals will be transmitted.

Bluetooth is the common name for a technology for wireless transmission of signals over short distances (up to ten metres). Since the Bluetooth earplug is designed to transmit signals to mobile phones that are maximum ten metres away, the transmitting power will be very low. As long as you keep the mobile phone at least 20 centimetres away from your body, you will achieve a substantial reduction in the radio signal exposure. Bluetooth hands-free equipment is therefore a good solution for people who want the greatest possible safety margin, and who dislike having a cable running between the mobile phone and the earplug.

Continuous research is done to work out any possible health effects of mobile phone use. The situation is made complex by the fact that contradictory reports are produced at regular intervals. Some research reports claim that mobile phone use involves increased health hazards, whereas others conclude that it is impossible to prove that there is any link between radio signals from mobile telecommunication and health. Quite frequently, new research results are mixed with old reports that are brought to light again. More than 150 independent authorities and expert panels in Norway have all arrived at similar conclusions: Based on today’s extensive knowledge, it is impossible to provide evidence that mobile phones affect people’s health, but it cannot be effectively ruled out.

The International Agency for Research on Cancer (IARC) has classified mobile phone use as possibly carcinogenic (group 2B). The IARC concluded that although there is no solid evidence as of today, it cannot be 100 per cent ruled out that there is a risk that has not yet been identified, which means that additional research is needed. The WHO is to conduct more thorough studies on possible causal relations, but it is important to underline that no causal relation between electromagnetic radiation and cancer has been verified today. The new classification does not imply changes in limit values or usage advice, but simply states the need for more research over time.

According to the Norwegian Radiation Protection Authority, any harm suffered from the use of mobile phones will be microscopic. The Authority still recommends a “strategy of caution until conclusive research can be produced.” Norwegian authorities have not found reason to issue any warnings against mobile phone use as long as the phones comply with the established SAR limit value.

All electric devices emit a certain level of radio signals (electromagnetic fields). The signals from mobile phones and other devices are not always comparable, since the emitted radio frequencies and power can be very different. Our bodies have different limits of tolerance to the various frequencies, and the limit values take this into account. The strongest signals emit from devices that contain radio transmitters or high-voltage circuits, such as wireless telephones, microwave ovens and old TV/PC tube screens. Lamps and fluorescent tubes also emit stronger electromagnetic fields than what is commonly assumed.

The WHO limit values apply for all such equipment, not only for mobile phone systems. There is also a clear tendency that current flatscreen televisions, flat PC screens and microwave ovens have weaker electromagnetic fields than their older counterparts.

Radio signals from mobile phones are of the same kind (i.e. they use approximately the same frequency) as microwave ovens and wireless phones. The signals from a mobile phone in use will be just as modest as the signals from these devices.

There are many reliable sources of information on the internet regarding radio signals and health. Here is a selection:

• WHO: 5G mobile networks and health

• WHO overview of research on radio waves and health

• ICNIRP: Mobile phones, base stations (masts) and 5G specific update from 2020

• The Norwegian Radiation Protection Authority (in Norwegian)

• GSMA: Overview of more than 150 independent publications on radiofrequency safety    

• US Committee on Man and Radiation (COMAR) of the Institute of Electrical and Electronics Engineers, IEEE 

• US National Cancer Institute