- G James Rubin, research fellow ()1,
- Gareth Hahn, senior research nurse1,
- Brian S Everitt, professor emeritus of biostatistics2,
- Anthony J Cleare, senior lecturer1,
- Simon Wessely, professor of epidemiological and liaison psychiatry1
- 1 King's College London, Institute of Psychiatry, Department of Psychological Medicine, Section of General Hospital Psychiatry, Weston Education Centre (PO62), London SE5 9RJ
- 2 King's College London, Institute of Psychiatry, Department of Biostatistics and Computing, London SE5 8AF
- Correspondence to: G J Rubin
- Accepted 9 February 2006
Objective To test whether people who report being sensitive to mobile phone signals have more symptoms when exposed to a pulsing mobile signal than when exposed to a sham signal or a non-pulsing signal.
Design Double blind, randomised, within participants provocation study.
Setting Dedicated suite of offices at King's College London, between September 2003 and June 2005.
Participants 60 “sensitive” people who reported often getting headache-like symptoms within 20 minutes of using a global system for mobile communication (GSM) mobile phone and 60 “control” participants who did not report any such symptoms.
Intervention Participants were exposed to three conditions: a 900 MHz GSM mobile phone signal, a non-pulsing carrier wave signal, and a sham condition with no signal present. Each exposure lasted for 50 minutes.
Main outcome measures The principal outcome measure was headache severity assessed with a 0-100 visual analogue scale. Other outcomes included six other subjective symptoms and participants' ability to judge whether a signal was present.
Results Headache severity increased during exposure and decreased immediately afterwards. However, no strong evidence was found of any difference between the conditions in terms of symptom severity. Nor did evidence of any differential effect of condition between the two groups exist. The proportion of sensitive participants who believed a signal was present during GSM exposure (60%) was similar to the proportion who believed one was present during sham exposure (63%).
Conclusions No evidence was found to indicate that people with self reported sensitivity to mobile phone signals are able to detect such signals or that they react to them with increased symptom severity. As sham exposure was sufficient to trigger severe symptoms in some participants, psychological factors may have an important role in causing this condition.
Contributors GJR had the original idea for the study and developed the study design with AJC, GH, and SW. GH and GJR did the testing. BSE analysed the symptom severity data; GJR did all other analyses. GJR wrote the first draft of the paper, and all authors contributed to further drafts. SW is the guarantor.
Funding This study was funded by the Programme Management Committee (PMC) of the Mobile Telecommunications and Health Research (MTHR) programme (www.mthr.org.uk), an independent body set up to provide funding for research into the possible health effects of mobile telecommunications. The MTHR is itself jointly funded by the UK Department of Health and the mobile telecommunications industry. The PMC contributed to the study design by proposing a reduction in overlap with other ongoing studies by focusing on symptom reporting, an increase in sample size, and an alteration in inclusion criteria to allow more highly sensitive people to participate. It had no role in the collection, analysis, or interpretation of the data, writing of the report, or decision to submit the paper for publication. The views expressed in this paper are those of the authors and not necessarily those of the funders.
Competing interests None declared.
Ethical approval The South London and Maudsley NHS Trust Research Ethics Committee granted approval for the study.