Newswise — With the rapid spread of mobile phones throughout all segments of society there remains a deep concern about associated radiation-related hazards on the user's health and welfare. In addition to anxiety generated by concern over electromagnetic "pollution," there is apprehension related to two basic assumptions (1) Conceivable thermal radiation/tissue-interactions, a "microwave effect" suspected to cause damage by heating exposed areas of the body, creating a thermal effect; and (2) Electromagnetic (EM) radiation may interfere with metabolic and functional activities of cells and tissues, or the sole-called non-thermal effects. Supporters and opponents of mobile phone technology have proved no clear verdict about these concerns.
Besides the eye, the ear is often regarded as endangered not the least because of its proximity to the radiation emitting mobile phone. On the other hand, the vestibular part of the inner ear is a perfect sensor by which the theory of thermal effects can easily be proven. If local warming by EM radiation should exceed 0.1°C at the level of the horizontal semicircular canal, nystagmus, or involuntary oscillation of the eyeballs, should occur together with some kind of dizziness.
A team of German researchers have set out to attempt to detect nystagmus during exposure to EM fields from a standardized radiation source similar to a mobile phone. Additionally, they sought to assess the dimension of thermal effects on the outer surface of the mobile phone and on tissues exposed to its EM radiation. In this regard, temperatures were measured by means of infrared (IR)- thermography
The authors of "Can Electromagnetic Fields Emitted by Mobile Phones Stimulate the Vestibular Organ?" are Hans Wilhelm Pau MD, and Uwe Sievert PhD, both from the ENT department, Medical School, University of Rostock; Siegfried Eggert PhD, at the Federal Institute for Occupational Safety and Health, Research Group 2.7 Vibration, Electromagnetic Fields, Berlin; and Walter Wild PhD, Professor at the Institute for Measurement and Control Techniques, University of Rostock, all in Germany. Their findings will be presented at the American Academy of Otolaryngology-Head and Neck Surgery Foundation http://www.entnet.org Annual Meeting and OTO EXPO, being held September 21-24, 2003, at the Orange County Convention Center, Orlando, FL.
Methodology: The standardized radiation was provided by a special set up using two mobile phones S 10 D (SIEMENS) converted to external power supply. For simulating the pulsed GSM-Signal, the signal generator was preset to the following parameters: Assigned frequency f = 889.6 MHz; Modulation: puls; period: 4.61 ms; width: 576 s; pulse delay: 1s; Level: 100 mV. Power applied to the connection sockets of the phones could be controlled and balanced by a power meter (M 8055.12) with measuring head M 8858.21 and upstream 30 dB- attenuator.For measurements the following power parameters were adjusted at the point of delivery of the mobile phones:Continuous field: 2.2 mW (corresponding to 2.2 W at the point of delivery of the mobile phone, when using the 30dB attenuator at the measuring head).
The test series was performed in 13 healthy volunteers with no evidence of vestibular disorders, (five males, eight females, age 29-58 years, mean 47.5 years). For detecting potential signs of nystagmus, a video-computer-nystagmographic device (HORTMANN) was used. Tests were carried out each ear at a time with/without continuous/pulsed EM fields, meaning four measurements for each inner ear (eight tests for each individual).
According the arrangement for caloric vestibular stimulation, for measurements the test person was in a lying position, the upper part of the body being raised to 30°. If there should be any thermal effects, this position is generally accepted to give the utmost stimulation to the vestibular receptor.
During measurements the laboratory was darkened, the glasses for video-nystagmography were covered - thus avoiding any visual suppression of potential EM-induced nystagmus.
Results: Key findings of the experiment included:"¢ It thus can be stated, that there were no evidences for vestibular stimulation caused by thermal effects of EM radiation from the mobile phone.
"¢ Identifying temperature distribution in the human skull with regard to the vestibular organ led the researchers to cut a fresh human temporal bone (body donator) parallel to its squama in a plane crossing the pneumatized middle ear in the level of the horizontal semicircular canal. This section of bone and soft tissues (about 18 mm thick ) was exposed to EM fields like described above. Neither with pulsed nor with continuous fields any temperature change could be observed.
In summary, the researchers determined a significant temperature rise at the mobile phone (mostly the antenna) itself. In a test of very thin layers of tissue (absorption foil, slice of sausage , they found increasing temperature as well - but only with the continuous field, which is much more powerful than the pulsed. Thicker tissue layers (like the temporal bone), showed no changes in temperature at all. Temporal bones, particularly the area of the vestibular organ, were chosen as a model for the conditions in living individuals.
Conclusions: The research results do not support the initial hypothesis of EM field-induced thermal interaction with the inner ear. There are some adverse effects accused for being caused by thermal effects of EM radiation on the head such as headaches. warmth or burning feelings in the area of the ear, within the ear or face, and alterations of the blood/brain barrier. Other findings, rather related to non-thermal effects are possibly alterations of the EEG, sleep disorders or at least changes in sleep patterns, increase of blood pressure, and deviations in cognitive functions.
This study we examined the vestibular part of the inner ear. The vestibular part of the inner ear is not only a sense organ that can be altered, but also a very sensitive measuring system for local temperature differences. Essentially, the complete vestibular system is very complex, sensitively balanced between the vestibular organs of both ears. If one side is altered anyhow, the imbalance will be indicated by nystagmus.
The measurements recorded could not indicate any mobile phone-related nystagmus. The researchers interpret this as absence of significant (bigger than 0.1°C) thermal effects or any other damaging events towards the unilateral vestibular system. Associated thermographic experiments demonstrate that there is heat development in tissues next to the mobile phone antenna. Most easily these can be seen during application of "high power fields" (2 Watts / continuous mode). Thus warm or burning sensations at back of the head or face in sensitive patients can be explained. These effects, however, are too small for influencing structures deep in the skull like the vestibular part of the inner ear.
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