- Patrizia Frei, postdoctoral research fellow1,
- Aslak H Poulsen, doctoral student1,
- Christoffer Johansen, professor1,
- Jørgen H Olsen, director1,
- Marianne Steding-Jessen, statistician1,
- Joachim Schüz, head of section2
- 1Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, 2100 Copenhagen, Denmark
- 2International Agency for Research on Cancer (IARC), Section of Environment and Radiation, 150 Cours Albert Thomas, 69372 Lyon CEDEX 08, France
- Correspondence to: P Frei, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, PO Box, 4002 Basel, Switzerland
- Accepted 12 September 2011
Objective To investigate the risk of tumours in the central nervous system among Danish mobile phone subscribers.
Design Nationwide cohort study.
Participants All Danes aged ≥30 and born in Denmark after 1925, subdivided into subscribers and non-subscribers of mobile phones before 1995.
Main outcome measures Risk of tumours of the central nervous system, identified from the complete Danish Cancer Register. Sex specific incidence rate ratios estimated with log linear Poisson regression models adjusted for age, calendar period, education, and disposable income.
Results 358 403 subscription holders accrued 3.8 million person years. In the follow-up period 1990-2007, there were 10 729 cases of tumours of the central nervous system. The risk of such tumours was close to unity for both men and women. When restricted to individuals with the longest mobile phone use—that is, ≥13 years of subscription—the incidence rate ratio was 1.03 (95% confidence interval 0.83 to 1.27) in men and 0.91 (0.41 to 2.04) in women. Among those with subscriptions of ≥10 years, ratios were 1.04 (0.85 to 1.26) in men and 1.04 (0.56 to 1.95) in women for glioma and 0.90 (0.57 to 1.42) in men and 0.93 (0.46 to 1.87) in women for meningioma. There was no indication of dose-response relation either by years since first subscription for a mobile phone or by anatomical location of the tumour—that is, in regions of the brain closest to where the handset is usually held to the head.
Conclusions In this update of a large nationwide cohort study of mobile phone use, there were no increased risks of tumours of the central nervous system, providing little evidence for a causal association.
We thank the steering committee of the Danish cohort study on social inequality and cancer (cancer og social ulighed-CANULI) for providing the cohort data. We thank Lene Mellemkjær and Søren Friis for support with topography and morphology codes, Susanne Oksbjerg Dalton and Kathrine Grell for feedback on the manuscript draft, and Luise Cederkvist Kristiansen for support with drafting figure 2.
Contributors: JHO and CJ established the nationwide cohort of mobile subscription holders. JS had the idea for this study. PF was responsible for data management and statistical analyses and drafted the article. AHP did data management and statistical analyses. MS-J supported statistical analyses related to the CANULI cohort. All authors commented on and approved the final draft. PF is guarantor.
Funding: This study was funded by the Danish Strategic Research Council (grant No 09-059984, 09-059045) to cover costs for data linkage. PF received a fellowship for prospective researchers by the Swiss National Science Foundation for this project. AHP was supported by a stipend for PhD students from the Danish Graduate School in Public Health Science. All other authors contributed to this work based on their respective core budget positions.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: The study was approved by the Danish ethical committee system (KF 01-075/96), the Danish Data Protection Board (1996-1200-121), and the Danish Ministry of Justice (Jnr. 1996-760-0219).
Data sharing: No additional data available.
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