BMJ  2006;332:864-865 (15 April), doi:10.1136/bmj.332.7546.864

Editorial

Brains and mobile phones

The biggest risk to health from mobile phones is using them while driving

There are more than 50 million mobile phones in the United Kingdom, and more than 1 billion worldwide. Mobile phones allow people to communicate with flexibility and ease. In addition, having a personal and mobile means of communication has helped to save lives through quicker notification of accidents, trauma, and other dangers.¹ But concerns about the safety of mobile phones have been raised.

In 2000 the UK Independent Expert Group on Mobile Phones (IEGMP) published the Stewart report.² The report recommended a programme of research and a precautionary approach to the use of mobile phones, especially use by children. As a result of the recommendations a research programme was launched in 2001 with a budget of £7.36m (10.5m; $13m), jointly funded by government and industry. Two papers in this week's BMJ come out of this initiative.^{3 4}

Hepworth and colleagues (p 883) conducted a population based case-control study of 966 patients with gliomas and found that use of mobile phones, in the short and medium term, is not associated with increased risk of developing a glioma.³ The response rate of only 51% in this study, predominantly from patients with low grade tumours, may contribute to missing a real but small effect. The study illustrates the difficulty of estimating use of mobile phones over many years and with different technology (analogue and digital), and thus the uncertainty in estimating exposure to radiofrequency radiation.

As there is no obvious biological mechanism for cancer to be caused by radiofrequency radiation, there is probably no relation between mobile phone use and development of gliomas. But the latency period for formation of gliomas could be longer than the period studied by Hepworth and colleagues, and longer surveillance will be necessary to reach more reliable conclusions. Greenfield's neuropathology textbook states: "Such an association [between radiofrequency radiation from mobile phones and malignant gliomas] would be surprising given the short time since the introduction of the widespread use of mobile phones: in adult humans, all known environmental carcinogens, including radiation, require a latency period of usually more than 20 and often more than 30 years."⁵ In Hepworth and colleagues' study only a small number of participants with glioma reported exposure of more than 10 years.

Some evidence indicates, however, that acoustic neuromas and salivary tumours may be related to use of mobile phones. Hepworth and colleagues' paper derives from an international collaborative study on use of mobile phones and risks of intracranial tumours, and perhaps these associations will also be studied.

Also in this week's BMJ (p 886) Rubin and colleagues examine the phenomenon of "electromagnetic hypersensitivity."⁴ This is a collection of symptoms such as headache, nausea, fatigue, dizziness, and loss of memory or concentration apparently precipitated by exposure to electromagnetic radiation. In Sweden it is accepted as a physical impairment, and a national scheme exists to improve home and work conditions for sufferers.

Rubin and colleagues conducted a double blind randomised within participants provocation study in a group of people who reported sensitivity to electromagnetic fields. The study failed to show that symptoms were associated with exposure to mobile phone radiation. People in the sensitive group had more severe symptoms (compared to controls), but their symptoms of electromagnetic hypersensitivity occurred with the same frequency when the mobile phone was switched on and during sham exposure. The authors describe this as a nocebo phenomenon, and suggest the role of psychological factors.

The IEGMP accepted that mobile phone radiation may produce biological effects, but it did not think that such radiation caused adverse health effects. In 2005 the National Radiological Protection Board updated the Stewart report and proposed that this conclusion still holds true.⁶ Hepworth's paper gives some further reassurance but, as the Global System for Mobile Communications (GSM) is now barely 10 years old, the question remains whether this technology has been in use for a sufficient period to allow recognition of an effect of exposure on the development of brain pathology. Rubin's study shows that some people develop symptoms to expected exposures even in the absence of such exposure. This finding does not necessarily preclude a real effect.

The evidence to date suggests that any risk to the individual mobile phone user of developing brain pathology is fleetingly small. The Health Council of the Netherlands even states that there is no reason to recommend that mobile phone use by children should be limited, and no need to apply the precautionary principle.⁷

The most important established risk of mobile phones to people is their use while driving. This is true for hand held phones as well as for hands free ones. Since 2003 it has been illegal in the United Kingdom to drive a car while using a hand held phone, but still legal to use a hands free one. It is time to correct this discrepancy.

Division of Neuroscience and Mental Health, Charing Cross Campus, Imperial College, London W6 8RP
(michael.maier{at}imperial.ac.uk)

---

Competing interests: None declared.

Research pp 883, 886

References

1. Chapman S, Schofield WN. Emergency use of cellular (mobile) telephones. Lancet 1998;351: 650.[ISI][Medline]
2. Independent Expert Group on Mobile Phones. Report of the Group (The Stewart Report). 2000. www.iegmp.org.uk/report/index.htm (accessed 1 Apr 2006).
3. Hepworth SJ, Schoemaker MJ, Muir KR, Swerdlow AJ, van Tongeren MJA, McKinney PA. Mobile phone use and risk of glioma in adults: case-control study. BMJ 2006:332: 883-6.[Abstract/Free Full Text]
4. Rubin GJ, Hahn G, Everitt BS, Cleare AJ, Wessely S. Are some people sensitive to mobile phone signals? Within participants double blind randomised provocation study. BMJ 2006:332: 886-9.[Abstract/Free Full Text]
5. Graham DI, Lantos PL. Greenfield's neuropathology. 7th ed. London: Arnold, 2002.
6. National Radiological Protection Board. Mobile Phones and Health 2004: Report by the NRPB. Didcot: NRPB, 2005. www.hpa.org.uk/radiation/publications/documents_of_nrpb/pdfs/doc_15_5.pdf (accessed 31 Mar 2006).
7. Health Council of the Netherlands. Mobile telephones: an evaluation of health effects. 2002. www.gr.nl/pdf.php?ID=377&p=1 (accessed 31 Mar 2006).

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