Aims: To investigate the association between the use of cellular or cordless telephones and the risk for brain tumours in different geographical areas, urban and rural.
Methods: Patients aged 20-80 years, living in the middle part of Sweden, and diagnosed between 1 January 1997 and 30 June 2000 were included. One control matched for sex and age in five year age groups was selected for each case. Use of different phone types was assessed by a questionnaire.
Results: The number of participating cases was 1429; there were 1470 controls. An effect of rural living was most pronounced for digital cellular telephones. Living in rural areas yielded an odds ratio (OR) of 1.4 (95% CI 0.98 to 2.0), increasing to 3.2 (95% CI 1.2 to 8.4) with >5 year latency time for digital phones. The corresponding ORs for living in urban areas were 0.9 (95% CI 0.8 to 1.2) and 0.9 (95% CI 0.6 to 1.4), respectively. This effect was most obvious for malignant brain tumours.
Conclusion: In future studies, place of residence should be considered in assessment of exposure to microwaves from cellular telephones, although the results in this study must be interpreted with caution due to low numbers in some of the calculations.