1. ^aInstitute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
2. ^bDepartment of Public Health Sciences, Division of Occupational Medicine, Karolinska Institutet, Stockholm, Sweden
3. ^cStockholm Centre for Public Health, Stockholm County Council, Stockholm, Sweden
4. ^dDepartment of Epidemiology and Public Health, Faculty of Medicine, Imperial College London, UK

Correspondence: Dr. Lena Hillert, Department of Public Health Sciences, Division of Occupational Medicine, Norrbacka, 3rd floor, SE-171 76 Stockholm, Sweden. Tel.: +46-8-7373655; Fax: +46-8-7373770; E-mail: lena.hillert@ki.se

Received 28 September 2005; Accepted 5 March 2006; Published online 3 May 2006.

Abstract

Mobile phone use is increasing but there is also concern for adverse health effects. Well-designed prospective studies to assess several health outcomes are required. In designing a study of mobile phone use, it is important to assess which factors need to be considered in classifying the exposure to radiofrequency fields (RF). A pilot study was performed in Sweden and in the UK 2002 to 2003 to test the feasibility of recruiting a cohort of mobile phone users from a random population sample and from mobile phone subscription lists for a prospective study. As one part of this pilot study, different factors were evaluated regarding possible influence on the output power of the phones. By local switch logging, information on calls made from predefined subscriptions or dedicated handsets were obtained and the output power of phones during calls made indoors and outdoors, in moving and stationary mode, and in rural as well in urban areas were compared. In this experiment, calls were either 1, 1.5 or 5 min long. The results showed that high mobile phone output power is more frequent in rural areas whereas the other factors (length of call, moving/stationary, indoor/outdoor) were of less importance. Urban and rural area should be considered in an exposure index for classification of the exposure to RF from mobile phones and may be assessed by first base station during mobile phone calls or, if this information is not available, possibly by using home address as a proxy.