Research

Project Title:
Study to evaluate the effects of mobile telephone usage on labyrinthine function

Start Date:
November 2002

Expected Date of Completion:
September 2004

Cost:
£180,000

Principal Investigator:
Professor Linda Luxon

Contact Details:
Department of Neuro-otology
National Hospital for Neurology and Neurosurgery
Queen Square
London
WC1N 3BG

Project Team:
Dr Borka Ceranic, University College London
Dr Robin Cox
Dr Philip Chadwick, MCL

Expertise:

Professor Linda Luxon – particular interest in hearing and balance disorders, with research experience in subclinical detection of hearing and balance pathology.
Dr Borka Ceranic – research experience in otoacoustic emissions and subclinical auditory changes.
Dr Robin Cox – particular interest in radiofrequency emissions in the clinical field.
Dr Phillip Chadwick – particular expertise in electromagnetic fields and radiofrequency dosimetry.

Approach:

Low level, radio-frequency signals applied to one side of the head may produce vague symptoms of disorientation, headache and nausea as a result of stimulation of the balance receptors in the internal ear.

This double blind study will test at least 20 subjects, who complain of specific symptoms, defined by a questionnaire, after prolonged mobile telephone use (more than 15 minutes) and 20 people, who have no such complaint. Each person will undergo a series of trials, in which a specially designed device is held, in a standard position, to each ear for 30 minutes in one of three different test modes. The device can be programmed to emit a pulsed or continuous radio-frequency emission or no emission and, in the active pulsed and continuous modes, will deliver the same mean power, on the same GSM900 operating frequency, and will mimic the output of a typical handset. Before and after each trial, sensitive tests of the hearing and balance receptors will be conducted to determine whether radio-frequency signals cause stimulation of the internal ear.

The ear and mode of operation of the device will be randomly selected for each trial by a computer programme, such that neither the experimenter, nor the subject is aware of the test mode for any particular trial. After each trial, the subject will be asked if the device was emitting signals to confirm whether or not he/she was blind to any test radio-frequency stimulation. At the end of the protocol, each subject will have undergone trials of all three test modes in each ear. The results of the hearing and balance tests will be compared between trials with and without pulsed emissions and with and without continuous emissions, between the ears of those subjects with only one symptomatic ear, for both pulsed and continuous stimulation, and between subjects complaining of symptoms and those with no complaint.

Potential Difficulties:

Subjects are not truly “blinded” and can judge which trials involve radio-frequency stimulation.
Changes in the hearing and balance receptors are very transient such that they cannot be detected by the tests employed.
Symptoms are induced by thermal rather than radio-frequency stimulation and, thus, will not be detected by this work. (This aspect will be addressed in a second stage of study)
The standard positioning of the test device is sufficiently different from the usual position of the mobile phone, used by the individual subject, that the radio-frequency stimulation differs to such an extent that symptoms do not occur.

Importance:

Recent scientific and public interest concerning the effects of electromagnetic fields on biological systems has focussed on radio-frequency exposure of mobile telephones. Theoretical and experimental radio-frequency measurements have suggested that about 40-60% of transceiver output is absorbed in the head. This raises the probability of an interaction between the electromagnetic exposure and the brain tissue, or, because of local energy absorption, the internal ear. A multiplicity of symptoms, which may be generated by changes in hearing and balance function, have been attributed to mobile telephone usage, but most alarmingly there is a public perception that such symptoms may herald the development of brain tumours.

The current human volunteer research will determine whether or not mobile phones have any effect on normal internal ear function and whether some individuals may be susceptible to suffering hearing and balance symptoms, as a result of using cellular phones. Such a conclusion will provide unequivocal data on which Government advisers can base a definitive health assessment in respect of the transient symptoms of which some mobile telephone users currently complain. In addition, an understanding of the mechanism of generation of certain symptoms, associated with mobile telephone usage, may allay the perception that such symptoms may be precursors of brain tumours and help to clarify the suggested relationship between such symptoms and the development of tumours or other long-term effect. Thus, this work may contribute to a better understanding of reported adverse effects of cellular phones, which are at present highly publicised and controversial.