ARPANSA - Australian Radiation Protection and Nuclear Safety Agency

Introduction

There are mobile phone base station antennas on towers and buildings throughout Australia’s metropolitan areas. These antennas are part of the mobile (or cellular) telephone network and they emit radiofrequency (RF) radiation. This fact sheet provides information about the possibility of adverse health effects arising from exposure to this radiation.

Current research indicates that no adverse health effects should be expected from exposure to the RF radiation from mobile phone base station antennas. Read on for more detail.

Antenna Description and Operation

When a call is made from a mobile telephone, RF signals are transmitted between its antenna and the antenna at a nearby base station. The telephone call is then routed through telephone network (cable or radio) to the destination telephone.

Mobile telephones emit signals at the frequency of around 800 MHz for the CDMA (Code Division Multiple Access) network, 900 & 1800 MHz for the GSM (Global System for Mobile Communication) network and 2100 MHz for the 3G network. These signals are picked up by antennas which are on the towers. The signals may also be transmitted between base stations and are in a higher frequency range, 15 to 23 gigahertz, and radiated as a very narrow beam by dish shaped antennas, also mounted near the top of the tower.

Radio Frequency Radiation

RF radiation, as well as ultraviolet radiation, visible light, infrared radiation and power frequency fields, are types of non-ionising radiation. These radiations, together with ionising electromagnetic radiation (X radiation and gamma radiation) make up the electromagnetic spectrum (Download a chart (PDF 384kb) of the electromagnetic spectrum).

When ionising radiations collide with biological material, they create positively and negatively charged particles, which may have adverse effects. Non-ionising radiations cannot create such particles. As far as is currently known, RF radiation, for example, can only cause the molecules in biological material to vibrate and thereby generate heat.

Exposure Levels and Recommended Limits

The exposure levels of RF radiation are measured in microwatts per square centimeter (abbreviated as μW/cm²). One μW is a millionth of a watt. The maximum exposure levels measured adjacent to the base station towers are less than 2 μW/cm². The exposure level decreases with increasing distance from the base of the tower.

These levels can be compared with 450 μW/cm², which is the exposure limit at 900MHz for members of the public (that is, unlimited exposure duration) recommended by the ARPANSA Radiation Protection Standard - "Maximum exposure levels to radiofrequency fields - 3kHz to 300GHz"

Health Effects

Current research indicates that, at the exposure levels indicated above, RF radiation is not known to have any adverse health effects.

It is considered that rises in tissue or body temperature of about 1.0 ^oC or more are required before any adverse effects will occur. In cases of pregnancy, rises in the temperature of the foetus of 2.5 to 5 ^oC are necessary before defects are seen in the newborn. These temperature rises will not occur unless the exposure level is greatly in excess of the Australian Standard mentioned above. Exposure to the low level of RF radiation emitted from base station antennas will not, in fact, cause any noticeable temperature rise.

There are many reports in the literature of research on non-thermal effects, usually of a subjective nature. Studies that have investigated if RF radiation affects biological cells, other than by heating them, are inconclusive. In addition, the exposure levels used in these studies are higher than those mentioned above.

The present concern that people have about RF exposure is whether these non-thermal effects also include cancer. While human studies to assess the possibility that RF exposure increases the risk of cancer are few in number, laboratory studies do not provide evidence to support the notion that RF fields cause cancer. Review groups evaluating the state of knowledge about possible links between RF exposure and excess risk of cancer have concluded that there is no clear evidence for any links. The Australian Radiation Protection and Nuclear Safety Agency continues to closely monitor the research being conducted in this field.

Conclusion

No adverse health effects are expected from continuous exposure to the RF radiation emitted by the antennas on mobile telephone base station towers.

 

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