A study of the effects of cellular telephone microwave radiation on the auditory system in healthy men

Ear, Nose & Throat Journal, March, 2006 by Renzo Mora, Barbara Crippa, Francesco Mora, Massimo Dellepiane

Abstract

We conducted a study of the effects of mobile cellular telephone microwave radiation on the auditory system in 20 healthy men. After the subjects underwent baseline measurements of transient evoked otoacoustic emission (TEOAE) and auditory brainstem response (ABR), they participated in three sessions of exposure to an electromagnetic field of 900 to 1,800 MHz produced by a cellular phone. Sessions ranged from 15 to 30 minutes in length. TEOAE and ABR were again measured after or during each exposure. Throughout the study, no significant changes in either measurement were noted. We conclude that the use of cellular phones does not alter the auditory system in the short term.

Introduction

The relationship between exposure to electromagnetic fields and human health has been put into sharper focus because of the rapidly expanding use of electromagnetic fields in modem society. Exposure to electromagnetic fields has been linked to different forms of cancer (e.g., brain tumors and leukemia), to neurologic diseases (e.g., Alzheimer's disease), to asthma and allergy, and to two phenomena called electrosupersensitivity and screen dermatitis. (1-5) In this article, we describe our study of the possible short-term effects of cellular-phone-generated electromagnetic waves on the auditory system.

Patients and methods

Our study population was made up of 20 healthy men, aged 20 to 40 years, who were of normal height and weight. These subjects were chosen at random from among the staff at San Martino Hospital in Genoa, Italy. All had normal hearing.

Prior to the start of the study, baseline measurements of transient evoked otoacoustic emission (TEOAE) and auditory brainstem response (ABR) were obtained in all subjects. The study was then conducted in three phases:

Phase 1. Subjects were first exposed to an electromagnetic field of 900 to 1,800 MHz that was produced by a global system for mobile communication (GSM) cellular telephone (Motorola V3690). The phone was placed in the normal position for conversation, with the receiver pressed against each subject's left ear; the phone was supported by a metal stand. The aerial was extended away from the head. Each subject maintained physical contact between the ear and the receiver for 30 minutes continuously. No conversation occurred; subjects were quiet as they were exposed to the silent energy. At the end of this initial exposure period, TEOAE and ABR were again measured.

Phase 2. One hour later, the same ear was then intermittently exposed to the same electromagnetic field for another 30-minute period. During this second phase, subjects carried on 12 telephone conversations of 2 minutes and 30 seconds each. Afterward, TEOAE and ABR were again recorded.

Phase 3. In the third phase 1 hour later, subjects were continuously exposed to the same electromagnetic field for 15 minutes. During this phase, the receiver was held in contact with the left retroauricular mastoid area rather than the ear. TEOAE was recorded during the exposure at 0, 10, and 15 minutes.

Results

All baseline TEOAE and ABR measurements were normal. Following exposure during phase 1, no significant changes were observed in TEOAE or ABR. Likewise, no significant changes were observed after phase 2 and during phase 3.

After each phase, all subjects reported a warm sensation in the area of contact with the receiver and in the area of the antenna.

Discussion

The degree of adverse biologic effects of cellular phone microwave radiation (e.g., radiofrequency sickness, electroencephalographic and blood pressure changes, and cancer risks) depends on many factors, including the duration of exposure to the radiation and the individual characteristics of a given patient's central nervous system and immune status . (2,4,6,7) Cellular phone microwave radiation can induce reversible, nonspecific adaptive responses when the duration of exposure is short and the affected organism is very radiosensitive. The results of some studies of the biologic effects of low-intensity modulated microwave radiation, including that generated by cellular phones, have led investigators to conclude that such radiation does not exert any lasting pathologic effects on the body. (6,7)

Other studies have shown that ultrahigh-frequency radiation induces significant changes in local temperature and in the physiologic parameters of the central nervous and cardiovascular systems. (8-12) Among these changes are an increase in blood pressure values, locoregional vasodilation, and transient inflammation brought about by an increase in the permeability of the erythrocyte membrane. The mechanism of the increase in the permeability of the erythrocyte membrane is not well understood. It might be the result of a hemolytic effect linked to the destabilization of divalent calcium-protein bridges. Such effects occur only after tissue has been exposed to microwave fields for at least 30 consecutive minutes. (8,13)

The heat sensation reported by our subjects was caused by the activation of inflammatory mechanisms. The release of inflammatory substances (e.g., histamine) from macrophages in the skin results in a local erythema, edema, and sensations of itching and pain, and the release of somatostatin from the dendritic ceils may give rise to subjective sensations of ongoing inflammation. (14,15)