This is a question which WHO takes very seriously. Given the immense number of people who use mobile phones, even a small increase in the incidence of adverse effects on health could have major public health implications. Because exposure to the radiofrequency (RF) fields emitted by mobile phones is generally more than a 1000 times higher than from base stations, and the greater likelihood of any adverse effect being due to handsets, research has almost exclusively been conducted on possible effects of mobile phone exposure. Research has concentrated on the following areas: cancertraffic accidents electromagnetic interference other health effects.Cancer: Current scientific evidence indicates that exposure to RF fields, such as those emitted by mobile phones and their base stations, is unlikely to induce or promote cancers. Several studies are under way to determine whether the results of some studies on animals have any relevance to cancer in human beings. Recent epidemiological studies have found no convincing evidence of an increased cancer risk or any other disease with mobile phone use. Traffic accidents: Research has clearly shown an increased risk of traffic accidents, some 3-4 times greater chance of an accident, when mobile phones (either handheld or with a "hands-free" kit) are used while driving. Electromagnetic interference: When mobile phones are used close to some medical devices (including pacemakers, implantable defibrillators, and certain hearing aids) there is the possibility of causing interference with their operation. There is also the potential of interference between mobile phones signals and aircraft electronics. Other health effects: Scientists have reported other health effects of using mobile phones including changes in brain activity, reaction times, and sleep patterns. These effects are minor and have no apparent health significance. More studies are underway to try to confirm these findings. Conclusions: No recent national or international reviews have concluded that exposure to the RF fields from mobile phones or their base stations causes any adverse health consequence. However, areas have been identified by the WHO's EMF Project for further research to better assess health risks and have led to over US$ 250 million in research worldwide to study RF effects on health. It will take about 2-3 years for the required RF research to be completed, evaluated and to publish an updated WHO health risk assessment.