# 5914
Yesterday, the British Medical Journal published the results of a follow up to large Danish cohort study that found no link between cell phone usage and an increase in brain tumors.
Although evidence for it has been scant, for a number of years some scientists have expressed concerns that prolonged exposure to cell phone RF (radio frequency) electromagnetic fields might cause certain types of head and neck cancers.
In 2010, the International Agency for Research on Cancer (IARC) released their long-delayed INTERPHONE report, which was unable to establish a link between cell phone use and brain tumors (see The IARC Cell Phone Report).
Despite that initial finding, a year later (May 2011) the IARC released a statement (IARC Press Release N° 208) that listed mobile phone use in same `possibly’ carcinogenic hazard category as exposure to gasoline, engine exhaust and lead.
For details on this statement, you may wish to revisit IARC: Cell Phones `Possibly Carcinogenic’.
A couple of months later we saw a study that appeared in the Journal of the National Cancer Institute (see Reassuring Study On Cell Phones & Brain Cancer Risks) that found no link between cell phone use and brain tumors in children and adolescents.
While it is unlikely to be the final word on the subject, the study published yesterday in the BMJ follows up on the largest cohort study on mobile phone users to date.
And once again, the news is reassuring; long-term subscribers to cellular phone services showed no increase in brain or central nervous system tumors over non-subscribers.
Use of mobile phones and risk of brain tumours: update of Danish cohort study
OPEN ACCESS
BMJ 2011; 343:d6387
Patrizia Frei, Aslak H Poulsen, Christoffer Johansen, Jørgen H Olsen, Marianne Steding-Jessen, Joachim Schüz
ABSTRACT
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.
While this study was subject (as are all studies) to some limitations, In an accompanying BMJ editorial (Mobile telephones and brain tumours) professors Anders Ahlbom and Maria Feychting called the evidence in this report `reassuring’.
They cautioned, however, that `continued monitoring of health registers and prospective cohorts is still warranted.’
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