Microwave exposure from the use of cellular telephones has been discussed in recent years as a potential risk factor for brain tumours. We included in a case–control study 1617 patients aged 20–80 years of both sexes with brain tumour diagnosed between 1 January 1997 and 30 June 2000. They were alive at the study time and had histopathologically verified brain tumour. One matched control to each case was selected from the Swedish Population Register. The study area was the Uppsala-Örebro, Stockholm, Linköping and Göteborg medical regions of Sweden. Exposure was assessed by a questionnaire that was answered by 1429 (88%) cases and 1470 (91%) controls. In total, use of analogue cellular telephones gave an increased risk with an odds ratio (OR) of 1.3 (95% confidence interval (CI) 1.02–1.6). With a tumour induction period of >10 years the risk increased further: OR 1.8 (95% CI 1.1–2.9). No clear association was found for digital or cordless telephones. With regard to the anatomical area of the tumour and exposure to microwaves, the risk was increased for tumours located in the temporal area on the same side of the brain that was used during phone calls; for analogue cellular telephones the OR was 2.5 (95% CI 1.3–4.9). Use of a telephone on the opposite side of the brain was not associated with an increased risk for brain tumours. With regard to different tumour types, the highest risk was for acoustic neurinoma (OR 3.5, 95% CI 1.8–6.8) among analogue cellular telephone users.
1Department of Oncology, University Hospital, S-701 85 Örebro and Department of Natural Sciences, Örebro University, S-701 82 Örebro, Sweden
2Department of Oncology/Pathology, Karolinska Institute, Radiumhemmet, S-171 76 Stockholm, Sweden
3National Institute for Working Life, S-907 13 Umeå and Department of Natural Sciences, Örebro University, S-701 82 Örebro, Sweden
4Department of Neurology, University Hospital, S-701 85 Örebro, Sweden
5Department of Neuroradiology, Karolinska Institute, S-112 35 Stockholm, Sweden
Correspondence to: L Hardell. Fax: (+46) 19 10 17 68. E-mail: firstname.lastname@example.org
Received 29 January 2002 accepted 10 March 2002