Abstracts

No evidence of link between cell phone use and nervous system tumours

Patrizia Frei and colleagues assessed the risk of tumours in the central nervous system among Danish mobile phone subscribers using a nationwide cohort study in Denmark.

The participants were all Danes aged ≥30 and born in Denmark after 1925, subdivided into subscribers and non-subscribers of mobile phones before 1995.

The main outcome measures were risk of tumours of the central nervous system, identified from the complete Danish Cancer Register. Sex-specific incidence rate ratios were estimated with log linear Poisson regression models adjusted for age, calendar period, education and disposable income.

The investigators found that 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 - 1.27) in men and 0.91 (0.41 - 2.04) in women. Among those with subscriptions of ≥10 years, ratios were 1.04 (0.85 - 1.26) in men and 1.04 (0.56 - 1.95) in women for glioma and 0.90 (0.57 - 1.42) in men and 0.93 (0.46 - 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.

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.

Frei P et al. BMJ 2011;343:bmj.d6387

Bridget Farham