Introduction

In recent years, mobile telecommunication systems have grown significantly, to the point where more
than a sixth of the world’s population use mobile phones. By the end of 2004, more than a billion
subscribers across more than 200 countries were estimated to be using mobile phones (1, 2).
The development of mobile communications has moved rapidly. In the 1980s, first generation mobile
phones, using analogue technology, allowed the transmission of sound only. Digital transmission, and
the global system for mobile communication, started in 1991 and includes such new developments as
data and image transmission. Third generation mobile phones currently in the market offer additional
services to the users (such as fax, e-mail and Internet access). For both analogue and digital mobile
phones, the signals transmitted and received are in the form of waves in the radio frequency (RF)
(analogue) and microwave parts of the electromagnetic spectrum. RFs are non-ionizing radiation with,
wavelengths that range from 3 kHz to 300 MHz, and microwaves range from 300 MHz to 300 GHz1.
The frequencies that mobile phones and telecommunication networks use range from 900 MHz to
1.8 GHz and up to 2.1 GHz, although it should be noted that the wavelength of the different types of
mobile phones varies. This applies to both mobile phones and their base stations, which send and
receive calls.
People have welcomed the technology, as indicated by the widespread use of mobile phones, which
suggests that they do not perceive it as a potential health hazard. However, concerns about the possible
adverse effects on health, as a result of the exposure to RF and microwave electromagnetic fields, have
been expressed since the introduction of mobile phones.
Since the year 2000, several reports have reviewed relevant studies and summarized current
knowledge about mobile phones and health, particularly that related to the commonly accepted
carcinogenic effects of RF and microwave energy. The aim of this synthesis is to combine the
available epidemiological evidence, to learn whether exposure to RF and microwave radiation from
mobile phones and their base stations might affect health. This synthesis does not aim to analyse the
effect of other man-made sources of electromagnetic fields, nor does it aim to develop safety
standards. The WHO International EMF Project is currently producing this information.

Sources for this review

This synthesis assesses the clinical effects of day-to-day exposure to mobile phones in general
populations, such as communities – specifically, the impact on developing head and brain tumours
(benign and malignant). It also addresses other morbidity related outcomes and summarizes the
biological effects of RF and microwave radiation.
Two main sources of information were considered and reviewed. A search of scientific and biomedical
databases was performed until March 2006. Observational studies that assessed the effects of mobile
phones on general populations were included in the synthesis. Experimental studies that assessed
clinical effects were excluded, as were those of occupational settings. The quality of the studies was
assessed by using the grading system developed by the Scottish Intercollegiate Guidelines Network. Also, a review of documents and web sites of governments, health councils, radiological
protection boards, advisory and expert groups, and the like, was undertaken. Annex 1 gives details
about the literature search strategy.